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Android example source code file (ViewGroup.java)

This example Android source code file (ViewGroup.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" TM.

Java - Android tags/keywords

android, draw_animation, drawing, flag_animation_cache, flag_children_drawn_with_cache, flag_invalidate_required, focus_after_descendants, focus_block_descendants, focused, graphics, has_bounds, layoutparams, override, paint, rect, ui, util, view, visibility_mask, visible

The ViewGroup.java Android example source code

/*
 * Copyright (C) 2006 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.view;

import com.android.internal.R;

import android.content.Context;
import android.content.res.Configuration;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.RectF;
import android.graphics.Region;
import android.os.Parcelable;
import android.os.SystemClock;
import android.util.AttributeSet;
import android.util.Config;
import android.util.EventLog;
import android.util.Log;
import android.util.SparseArray;
import android.view.accessibility.AccessibilityEvent;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.view.animation.LayoutAnimationController;
import android.view.animation.Transformation;

import java.util.ArrayList;

/**
 * <p>
 * A <code>ViewGroup is a special view that can contain other views
 * (called children.) The view group is the base class for layouts and views
 * containers. This class also defines the
 * {@link android.view.ViewGroup.LayoutParams} class which serves as the base
 * class for layouts parameters.
 * </p>
 *
 * <p>
 * Also see {@link LayoutParams} for layout attributes.
 * </p>
 *
 * @attr ref android.R.styleable#ViewGroup_clipChildren
 * @attr ref android.R.styleable#ViewGroup_clipToPadding
 * @attr ref android.R.styleable#ViewGroup_layoutAnimation
 * @attr ref android.R.styleable#ViewGroup_animationCache
 * @attr ref android.R.styleable#ViewGroup_persistentDrawingCache
 * @attr ref android.R.styleable#ViewGroup_alwaysDrawnWithCache
 * @attr ref android.R.styleable#ViewGroup_addStatesFromChildren
 * @attr ref android.R.styleable#ViewGroup_descendantFocusability
 */
public abstract class ViewGroup extends View implements ViewParent, ViewManager {
    private static final boolean DBG = false;

    /**
     * Views which have been hidden or removed which need to be animated on
     * their way out.
     * This field should be made private, so it is hidden from the SDK.
     * {@hide}
     */
    protected ArrayList<View> mDisappearingChildren;

    /**
     * Listener used to propagate events indicating when children are added
     * and/or removed from a view group.
     * This field should be made private, so it is hidden from the SDK.
     * {@hide}
     */
    protected OnHierarchyChangeListener mOnHierarchyChangeListener;

    // The view contained within this ViewGroup that has or contains focus.
    private View mFocused;

    // The current transformation to apply on the child being drawn
    private Transformation mChildTransformation;
    private RectF mInvalidateRegion;

    // Target of Motion events
    private View mMotionTarget;
    private final Rect mTempRect = new Rect();

    // Layout animation
    private LayoutAnimationController mLayoutAnimationController;
    private Animation.AnimationListener mAnimationListener;

    /**
     * Internal flags.
     *
     * This field should be made private, so it is hidden from the SDK.
     * {@hide}
     */
    protected int mGroupFlags;

    // When set, ViewGroup invalidates only the child's rectangle
    // Set by default
    private static final int FLAG_CLIP_CHILDREN = 0x1;

    // When set, ViewGroup excludes the padding area from the invalidate rectangle
    // Set by default
    private static final int FLAG_CLIP_TO_PADDING = 0x2;

    // When set, dispatchDraw() will invoke invalidate(); this is set by drawChild() when
    // a child needs to be invalidated and FLAG_OPTIMIZE_INVALIDATE is set
    private static final int FLAG_INVALIDATE_REQUIRED  = 0x4;

    // When set, dispatchDraw() will run the layout animation and unset the flag
    private static final int FLAG_RUN_ANIMATION = 0x8;

    // When set, there is either no layout animation on the ViewGroup or the layout
    // animation is over
    // Set by default
    private static final int FLAG_ANIMATION_DONE = 0x10;

    // If set, this ViewGroup has padding; if unset there is no padding and we don't need
    // to clip it, even if FLAG_CLIP_TO_PADDING is set
    private static final int FLAG_PADDING_NOT_NULL = 0x20;

    // When set, this ViewGroup caches its children in a Bitmap before starting a layout animation
    // Set by default
    private static final int FLAG_ANIMATION_CACHE = 0x40;

    // When set, this ViewGroup converts calls to invalidate(Rect) to invalidate() during a
    // layout animation; this avoid clobbering the hierarchy
    // Automatically set when the layout animation starts, depending on the animation's
    // characteristics
    private static final int FLAG_OPTIMIZE_INVALIDATE = 0x80;

    // When set, the next call to drawChild() will clear mChildTransformation's matrix
    private static final int FLAG_CLEAR_TRANSFORMATION = 0x100;

    // When set, this ViewGroup invokes mAnimationListener.onAnimationEnd() and removes
    // the children's Bitmap caches if necessary
    // This flag is set when the layout animation is over (after FLAG_ANIMATION_DONE is set)
    private static final int FLAG_NOTIFY_ANIMATION_LISTENER = 0x200;

    /**
     * When set, the drawing method will call {@link #getChildDrawingOrder(int, int)}
     * to get the index of the child to draw for that iteration.
     * 
     * @hide
     */
    protected static final int FLAG_USE_CHILD_DRAWING_ORDER = 0x400;

    /**
     * When set, this ViewGroup supports static transformations on children; this causes
     * {@link #getChildStaticTransformation(View, android.view.animation.Transformation)} to be
     * invoked when a child is drawn.
     *
     * Any subclass overriding
     * {@link #getChildStaticTransformation(View, android.view.animation.Transformation)} should
     * set this flags in {@link #mGroupFlags}.
     *
     * {@hide}
     */
    protected static final int FLAG_SUPPORT_STATIC_TRANSFORMATIONS = 0x800;

    // When the previous drawChild() invocation used an alpha value that was lower than
    // 1.0 and set it in mCachePaint
    private static final int FLAG_ALPHA_LOWER_THAN_ONE = 0x1000;

    /**
     * When set, this ViewGroup's drawable states also include those
     * of its children.
     */
    private static final int FLAG_ADD_STATES_FROM_CHILDREN = 0x2000;

    /**
     * When set, this ViewGroup tries to always draw its children using their drawing cache.
     */
    private static final int FLAG_ALWAYS_DRAWN_WITH_CACHE = 0x4000;

    /**
     * When set, and if FLAG_ALWAYS_DRAWN_WITH_CACHE is not set, this ViewGroup will try to
     * draw its children with their drawing cache.
     */
    private static final int FLAG_CHILDREN_DRAWN_WITH_CACHE = 0x8000;

    /**
     * When set, this group will go through its list of children to notify them of
     * any drawable state change.
     */
    private static final int FLAG_NOTIFY_CHILDREN_ON_DRAWABLE_STATE_CHANGE = 0x10000;

    private static final int FLAG_MASK_FOCUSABILITY = 0x60000;

    /**
     * This view will get focus before any of its descendants.
     */
    public static final int FOCUS_BEFORE_DESCENDANTS = 0x20000;

    /**
     * This view will get focus only if none of its descendants want it.
     */
    public static final int FOCUS_AFTER_DESCENDANTS = 0x40000;

    /**
     * This view will block any of its descendants from getting focus, even
     * if they are focusable.
     */
    public static final int FOCUS_BLOCK_DESCENDANTS = 0x60000;

    /**
     * Used to map between enum in attrubutes and flag values.
     */
    private static final int[] DESCENDANT_FOCUSABILITY_FLAGS =
            {FOCUS_BEFORE_DESCENDANTS, FOCUS_AFTER_DESCENDANTS,
                    FOCUS_BLOCK_DESCENDANTS};

    /**
     * When set, this ViewGroup should not intercept touch events.
     */
    private static final int FLAG_DISALLOW_INTERCEPT = 0x80000;

    /**
     * Indicates which types of drawing caches are to be kept in memory.
     * This field should be made private, so it is hidden from the SDK.
     * {@hide}
     */
    protected int mPersistentDrawingCache;

    /**
     * Used to indicate that no drawing cache should be kept in memory.
     */
    public static final int PERSISTENT_NO_CACHE = 0x0;

    /**
     * Used to indicate that the animation drawing cache should be kept in memory.
     */
    public static final int PERSISTENT_ANIMATION_CACHE = 0x1;

    /**
     * Used to indicate that the scrolling drawing cache should be kept in memory.
     */
    public static final int PERSISTENT_SCROLLING_CACHE = 0x2;

    /**
     * Used to indicate that all drawing caches should be kept in memory.
     */
    public static final int PERSISTENT_ALL_CACHES = 0x3;

    /**
     * We clip to padding when FLAG_CLIP_TO_PADDING and FLAG_PADDING_NOT_NULL
     * are set at the same time.
     */
    protected static final int CLIP_TO_PADDING_MASK = FLAG_CLIP_TO_PADDING | FLAG_PADDING_NOT_NULL;

    // Index of the child's left position in the mLocation array
    private static final int CHILD_LEFT_INDEX = 0;
    // Index of the child's top position in the mLocation array
    private static final int CHILD_TOP_INDEX = 1;

    // Child views of this ViewGroup
    private View[] mChildren;
    // Number of valid children in the mChildren array, the rest should be null or not
    // considered as children
    private int mChildrenCount;

    private static final int ARRAY_INITIAL_CAPACITY = 12;
    private static final int ARRAY_CAPACITY_INCREMENT = 12;

    // Used to draw cached views
    private final Paint mCachePaint = new Paint();

    public ViewGroup(Context context) {
        super(context);
        initViewGroup();
    }

    public ViewGroup(Context context, AttributeSet attrs) {
        super(context, attrs);
        initViewGroup();
        initFromAttributes(context, attrs);
    }

    public ViewGroup(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        initViewGroup();
        initFromAttributes(context, attrs);
    }

    private void initViewGroup() {
        // ViewGroup doesn't draw by default
        setFlags(WILL_NOT_DRAW, DRAW_MASK);
        mGroupFlags |= FLAG_CLIP_CHILDREN;
        mGroupFlags |= FLAG_CLIP_TO_PADDING;
        mGroupFlags |= FLAG_ANIMATION_DONE;
        mGroupFlags |= FLAG_ANIMATION_CACHE;
        mGroupFlags |= FLAG_ALWAYS_DRAWN_WITH_CACHE;

        setDescendantFocusability(FOCUS_BEFORE_DESCENDANTS);

        mChildren = new View[ARRAY_INITIAL_CAPACITY];
        mChildrenCount = 0;

        mCachePaint.setDither(false);

        mPersistentDrawingCache = PERSISTENT_SCROLLING_CACHE;
    }

    private void initFromAttributes(Context context, AttributeSet attrs) {
        TypedArray a = context.obtainStyledAttributes(attrs,
                R.styleable.ViewGroup);

        final int N = a.getIndexCount();
        for (int i = 0; i < N; i++) {
            int attr = a.getIndex(i);
            switch (attr) {
                case R.styleable.ViewGroup_clipChildren:
                    setClipChildren(a.getBoolean(attr, true));
                    break;
                case R.styleable.ViewGroup_clipToPadding:
                    setClipToPadding(a.getBoolean(attr, true));
                    break;
                case R.styleable.ViewGroup_animationCache:
                    setAnimationCacheEnabled(a.getBoolean(attr, true));
                    break;
                case R.styleable.ViewGroup_persistentDrawingCache:
                    setPersistentDrawingCache(a.getInt(attr, PERSISTENT_SCROLLING_CACHE));
                    break;
                case R.styleable.ViewGroup_addStatesFromChildren:
                    setAddStatesFromChildren(a.getBoolean(attr, false));
                    break;
                case R.styleable.ViewGroup_alwaysDrawnWithCache:
                    setAlwaysDrawnWithCacheEnabled(a.getBoolean(attr, true));
                    break;
                case R.styleable.ViewGroup_layoutAnimation:
                    int id = a.getResourceId(attr, -1);
                    if (id > 0) {
                        setLayoutAnimation(AnimationUtils.loadLayoutAnimation(mContext, id));
                    }
                    break;
                case R.styleable.ViewGroup_descendantFocusability:
                    setDescendantFocusability(DESCENDANT_FOCUSABILITY_FLAGS[a.getInt(attr, 0)]);
                    break;
            }
        }

        a.recycle();
    }

    /**
     * Gets the descendant focusability of this view group.  The descendant
     * focusability defines the relationship between this view group and its
     * descendants when looking for a view to take focus in
     * {@link #requestFocus(int, android.graphics.Rect)}.
     *
     * @return one of {@link #FOCUS_BEFORE_DESCENDANTS}, {@link #FOCUS_AFTER_DESCENDANTS},
     *   {@link #FOCUS_BLOCK_DESCENDANTS}.
     */
    @ViewDebug.ExportedProperty(mapping = {
        @ViewDebug.IntToString(from = FOCUS_BEFORE_DESCENDANTS, to = "FOCUS_BEFORE_DESCENDANTS"),
        @ViewDebug.IntToString(from = FOCUS_AFTER_DESCENDANTS, to = "FOCUS_AFTER_DESCENDANTS"),
        @ViewDebug.IntToString(from = FOCUS_BLOCK_DESCENDANTS, to = "FOCUS_BLOCK_DESCENDANTS")
    })
    public int getDescendantFocusability() {
        return mGroupFlags & FLAG_MASK_FOCUSABILITY;
    }

    /**
     * Set the descendant focusability of this view group. This defines the relationship
     * between this view group and its descendants when looking for a view to
     * take focus in {@link #requestFocus(int, android.graphics.Rect)}.
     *
     * @param focusability one of {@link #FOCUS_BEFORE_DESCENDANTS}, {@link #FOCUS_AFTER_DESCENDANTS},
     *   {@link #FOCUS_BLOCK_DESCENDANTS}.
     */
    public void setDescendantFocusability(int focusability) {
        switch (focusability) {
            case FOCUS_BEFORE_DESCENDANTS:
            case FOCUS_AFTER_DESCENDANTS:
            case FOCUS_BLOCK_DESCENDANTS:
                break;
            default:
                throw new IllegalArgumentException("must be one of FOCUS_BEFORE_DESCENDANTS, "
                        + "FOCUS_AFTER_DESCENDANTS, FOCUS_BLOCK_DESCENDANTS");
        }
        mGroupFlags &= ~FLAG_MASK_FOCUSABILITY;
        mGroupFlags |= (focusability & FLAG_MASK_FOCUSABILITY);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    void handleFocusGainInternal(int direction, Rect previouslyFocusedRect) {
        if (mFocused != null) {
            mFocused.unFocus();
            mFocused = null;
        }
        super.handleFocusGainInternal(direction, previouslyFocusedRect);
    }

    /**
     * {@inheritDoc}
     */
    public void requestChildFocus(View child, View focused) {
        if (DBG) {
            System.out.println(this + " requestChildFocus()");
        }
        if (getDescendantFocusability() == FOCUS_BLOCK_DESCENDANTS) {
            return;
        }

        // Unfocus us, if necessary
        super.unFocus();

        // We had a previous notion of who had focus. Clear it.
        if (mFocused != child) {
            if (mFocused != null) {
                mFocused.unFocus();
            }

            mFocused = child;
        }
        if (mParent != null) {
            mParent.requestChildFocus(this, focused);
        }
    }

    /**
     * {@inheritDoc}
     */
    public void focusableViewAvailable(View v) {
        if (mParent != null
                // shortcut: don't report a new focusable view if we block our descendants from
                // getting focus
                && (getDescendantFocusability() != FOCUS_BLOCK_DESCENDANTS)
                // shortcut: don't report a new focusable view if we already are focused
                // (and we don't prefer our descendants)
                //
                // note: knowing that mFocused is non-null is not a good enough reason
                // to break the traversal since in that case we'd actually have to find
                // the focused view and make sure it wasn't FOCUS_AFTER_DESCENDANTS and
                // an ancestor of v; this will get checked for at ViewRoot
                && !(isFocused() && getDescendantFocusability() != FOCUS_AFTER_DESCENDANTS)) {
            mParent.focusableViewAvailable(v);
        }
    }

    /**
     * {@inheritDoc}
     */
    public boolean showContextMenuForChild(View originalView) {
        return mParent != null && mParent.showContextMenuForChild(originalView);
    }

    /**
     * Find the nearest view in the specified direction that wants to take
     * focus.
     *
     * @param focused The view that currently has focus
     * @param direction One of FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, and
     *        FOCUS_RIGHT, or 0 for not applicable.
     */
    public View focusSearch(View focused, int direction) {
        if (isRootNamespace()) {
            // root namespace means we should consider ourselves the top of the
            // tree for focus searching; otherwise we could be focus searching
            // into other tabs.  see LocalActivityManager and TabHost for more info
            return FocusFinder.getInstance().findNextFocus(this, focused, direction);
        } else if (mParent != null) {
            return mParent.focusSearch(focused, direction);
        }
        return null;
    }

    /**
     * {@inheritDoc}
     */
    public boolean requestChildRectangleOnScreen(View child, Rect rectangle, boolean immediate) {
        return false;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean dispatchUnhandledMove(View focused, int direction) {
        return mFocused != null &&
                mFocused.dispatchUnhandledMove(focused, direction);
    }

    /**
     * {@inheritDoc}
     */
    public void clearChildFocus(View child) {
        if (DBG) {
            System.out.println(this + " clearChildFocus()");
        }

        mFocused = null;
        if (mParent != null) {
            mParent.clearChildFocus(this);
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void clearFocus() {
        super.clearFocus();

        // clear any child focus if it exists
        if (mFocused != null) {
            mFocused.clearFocus();
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    void unFocus() {
        if (DBG) {
            System.out.println(this + " unFocus()");
        }

        super.unFocus();
        if (mFocused != null) {
            mFocused.unFocus();
        }
        mFocused = null;
    }

    /**
     * Returns the focused child of this view, if any. The child may have focus
     * or contain focus.
     *
     * @return the focused child or null.
     */
    public View getFocusedChild() {
        return mFocused;
    }

    /**
     * Returns true if this view has or contains focus
     *
     * @return true if this view has or contains focus
     */
    @Override
    public boolean hasFocus() {
        return (mPrivateFlags & FOCUSED) != 0 || mFocused != null;
    }

    /*
     * (non-Javadoc)
     *
     * @see android.view.View#findFocus()
     */
    @Override
    public View findFocus() {
        if (DBG) {
            System.out.println("Find focus in " + this + ": flags="
                    + isFocused() + ", child=" + mFocused);
        }

        if (isFocused()) {
            return this;
        }

        if (mFocused != null) {
            return mFocused.findFocus();
        }
        return null;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean hasFocusable() {
        if ((mViewFlags & VISIBILITY_MASK) != VISIBLE) {
            return false;
        }

        if (isFocusable()) {
            return true;
        }

        final int descendantFocusability = getDescendantFocusability();
        if (descendantFocusability != FOCUS_BLOCK_DESCENDANTS) {
            final int count = mChildrenCount;
            final View[] children = mChildren;

            for (int i = 0; i < count; i++) {
                final View child = children[i];
                if (child.hasFocusable()) {
                    return true;
                }
            }
        }

        return false;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void addFocusables(ArrayList<View> views, int direction) {
        addFocusables(views, direction, FOCUSABLES_TOUCH_MODE);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void addFocusables(ArrayList<View> views, int direction, int focusableMode) {
        final int focusableCount = views.size();

        final int descendantFocusability = getDescendantFocusability();

        if (descendantFocusability != FOCUS_BLOCK_DESCENDANTS) {
            final int count = mChildrenCount;
            final View[] children = mChildren;

            for (int i = 0; i < count; i++) {
                final View child = children[i];
                if ((child.mViewFlags & VISIBILITY_MASK) == VISIBLE) {
                    child.addFocusables(views, direction, focusableMode);
                }
            }
        }

        // we add ourselves (if focusable) in all cases except for when we are
        // FOCUS_AFTER_DESCENDANTS and there are some descendants focusable.  this is
        // to avoid the focus search finding layouts when a more precise search
        // among the focusable children would be more interesting.
        if (
            descendantFocusability != FOCUS_AFTER_DESCENDANTS ||
                // No focusable descendants
                (focusableCount == views.size())) {
            super.addFocusables(views, direction, focusableMode);
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void dispatchWindowFocusChanged(boolean hasFocus) {
        super.dispatchWindowFocusChanged(hasFocus);
        final int count = mChildrenCount;
        final View[] children = mChildren;
        for (int i = 0; i < count; i++) {
            children[i].dispatchWindowFocusChanged(hasFocus);
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void addTouchables(ArrayList<View> views) {
        super.addTouchables(views);

        final int count = mChildrenCount;
        final View[] children = mChildren;

        for (int i = 0; i < count; i++) {
            final View child = children[i];
            if ((child.mViewFlags & VISIBILITY_MASK) == VISIBLE) {
                child.addTouchables(views);
            }
        }
    }
    
    /**
     * {@inheritDoc}
     */
    @Override
    public void dispatchDisplayHint(int hint) {
        super.dispatchDisplayHint(hint);
        final int count = mChildrenCount;
        final View[] children = mChildren;
        for (int i = 0; i < count; i++) {
            children[i].dispatchDisplayHint(hint);
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected void dispatchVisibilityChanged(View changedView, int visibility) {
        super.dispatchVisibilityChanged(changedView, visibility);
        final int count = mChildrenCount;
        final View[] children = mChildren;
        for (int i = 0; i < count; i++) {
            children[i].dispatchVisibilityChanged(changedView, visibility);
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void dispatchWindowVisibilityChanged(int visibility) {
        super.dispatchWindowVisibilityChanged(visibility);
        final int count = mChildrenCount;
        final View[] children = mChildren;
        for (int i = 0; i < count; i++) {
            children[i].dispatchWindowVisibilityChanged(visibility);
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void dispatchConfigurationChanged(Configuration newConfig) {
        super.dispatchConfigurationChanged(newConfig);
        final int count = mChildrenCount;
        final View[] children = mChildren;
        for (int i = 0; i < count; i++) {
            children[i].dispatchConfigurationChanged(newConfig);
        }
    }
    
    /**
     * {@inheritDoc}
     */
    public void recomputeViewAttributes(View child) {
        ViewParent parent = mParent;
        if (parent != null) parent.recomputeViewAttributes(this);
    }

    @Override
    void dispatchCollectViewAttributes(int visibility) {
        visibility |= mViewFlags&VISIBILITY_MASK;
        super.dispatchCollectViewAttributes(visibility);
        final int count = mChildrenCount;
        final View[] children = mChildren;
        for (int i = 0; i < count; i++) {
            children[i].dispatchCollectViewAttributes(visibility);
        }
    }

    /**
     * {@inheritDoc}
     */
    public void bringChildToFront(View child) {
        int index = indexOfChild(child);
        if (index >= 0) {
            removeFromArray(index);
            addInArray(child, mChildrenCount);
            child.mParent = this;
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean dispatchKeyEventPreIme(KeyEvent event) {
        if ((mPrivateFlags & (FOCUSED | HAS_BOUNDS)) == (FOCUSED | HAS_BOUNDS)) {
            return super.dispatchKeyEventPreIme(event);
        } else if (mFocused != null && (mFocused.mPrivateFlags & HAS_BOUNDS) == HAS_BOUNDS) {
            return mFocused.dispatchKeyEventPreIme(event);
        }
        return false;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean dispatchKeyEvent(KeyEvent event) {
        if ((mPrivateFlags & (FOCUSED | HAS_BOUNDS)) == (FOCUSED | HAS_BOUNDS)) {
            return super.dispatchKeyEvent(event);
        } else if (mFocused != null && (mFocused.mPrivateFlags & HAS_BOUNDS) == HAS_BOUNDS) {
            return mFocused.dispatchKeyEvent(event);
        }
        return false;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean dispatchKeyShortcutEvent(KeyEvent event) {
        if ((mPrivateFlags & (FOCUSED | HAS_BOUNDS)) == (FOCUSED | HAS_BOUNDS)) {
            return super.dispatchKeyShortcutEvent(event);
        } else if (mFocused != null && (mFocused.mPrivateFlags & HAS_BOUNDS) == HAS_BOUNDS) {
            return mFocused.dispatchKeyShortcutEvent(event);
        }
        return false;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean dispatchTrackballEvent(MotionEvent event) {
        if ((mPrivateFlags & (FOCUSED | HAS_BOUNDS)) == (FOCUSED | HAS_BOUNDS)) {
            return super.dispatchTrackballEvent(event);
        } else if (mFocused != null && (mFocused.mPrivateFlags & HAS_BOUNDS) == HAS_BOUNDS) {
            return mFocused.dispatchTrackballEvent(event);
        }
        return false;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {
        final int action = ev.getAction();
        final float xf = ev.getX();
        final float yf = ev.getY();
        final float scrolledXFloat = xf + mScrollX;
        final float scrolledYFloat = yf + mScrollY;
        final Rect frame = mTempRect;

        boolean disallowIntercept = (mGroupFlags & FLAG_DISALLOW_INTERCEPT) != 0;

        if (action == MotionEvent.ACTION_DOWN) {
            if (mMotionTarget != null) {
                // this is weird, we got a pen down, but we thought it was
                // already down!
                // XXX: We should probably send an ACTION_UP to the current
                // target.
                mMotionTarget = null;
            }
            // If we're disallowing intercept or if we're allowing and we didn't
            // intercept
            if (disallowIntercept || !onInterceptTouchEvent(ev)) {
                // reset this event's action (just to protect ourselves)
                ev.setAction(MotionEvent.ACTION_DOWN);
                // We know we want to dispatch the event down, find a child
                // who can handle it, start with the front-most child.
                final int scrolledXInt = (int) scrolledXFloat;
                final int scrolledYInt = (int) scrolledYFloat;
                final View[] children = mChildren;
                final int count = mChildrenCount;
                for (int i = count - 1; i >= 0; i--) {
                    final View child = children[i];
                    if ((child.mViewFlags & VISIBILITY_MASK) == VISIBLE
                            || child.getAnimation() != null) {
                        child.getHitRect(frame);
                        if (frame.contains(scrolledXInt, scrolledYInt)) {
                            // offset the event to the view's coordinate system
                            final float xc = scrolledXFloat - child.mLeft;
                            final float yc = scrolledYFloat - child.mTop;
                            ev.setLocation(xc, yc);
                            child.mPrivateFlags &= ~CANCEL_NEXT_UP_EVENT;
                            if (child.dispatchTouchEvent(ev))  {
                                // Event handled, we have a target now.
                                mMotionTarget = child;
                                return true;
                            }
                            // The event didn't get handled, try the next view.
                            // Don't reset the event's location, it's not
                            // necessary here.
                        }
                    }
                }
            }
        }

        boolean isUpOrCancel = (action == MotionEvent.ACTION_UP) ||
                (action == MotionEvent.ACTION_CANCEL);

        if (isUpOrCancel) {
            // Note, we've already copied the previous state to our local
            // variable, so this takes effect on the next event
            mGroupFlags &= ~FLAG_DISALLOW_INTERCEPT;
        }

        // The event wasn't an ACTION_DOWN, dispatch it to our target if
        // we have one.
        final View target = mMotionTarget;
        if (target == null) {
            // We don't have a target, this means we're handling the
            // event as a regular view.
            ev.setLocation(xf, yf);
            if ((mPrivateFlags & CANCEL_NEXT_UP_EVENT) != 0) {
                ev.setAction(MotionEvent.ACTION_CANCEL);
                mPrivateFlags &= ~CANCEL_NEXT_UP_EVENT;
            }
            return super.dispatchTouchEvent(ev);
        }

        // if have a target, see if we're allowed to and want to intercept its
        // events
        if (!disallowIntercept && onInterceptTouchEvent(ev)) {
            final float xc = scrolledXFloat - (float) target.mLeft;
            final float yc = scrolledYFloat - (float) target.mTop;
            mPrivateFlags &= ~CANCEL_NEXT_UP_EVENT;
            ev.setAction(MotionEvent.ACTION_CANCEL);
            ev.setLocation(xc, yc);
            if (!target.dispatchTouchEvent(ev)) {
                // target didn't handle ACTION_CANCEL. not much we can do
                // but they should have.
            }
            // clear the target
            mMotionTarget = null;
            // Don't dispatch this event to our own view, because we already
            // saw it when intercepting; we just want to give the following
            // event to the normal onTouchEvent().
            return true;
        }

        if (isUpOrCancel) {
            mMotionTarget = null;
        }

        // finally offset the event to the target's coordinate system and
        // dispatch the event.
        final float xc = scrolledXFloat - (float) target.mLeft;
        final float yc = scrolledYFloat - (float) target.mTop;
        ev.setLocation(xc, yc);

        if ((target.mPrivateFlags & CANCEL_NEXT_UP_EVENT) != 0) {
            ev.setAction(MotionEvent.ACTION_CANCEL);
            target.mPrivateFlags &= ~CANCEL_NEXT_UP_EVENT;
            mMotionTarget = null;
        }

        return target.dispatchTouchEvent(ev);
    }

    /**
     * {@inheritDoc}
     */
    public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) {

        if (disallowIntercept == ((mGroupFlags & FLAG_DISALLOW_INTERCEPT) != 0)) {
            // We're already in this state, assume our ancestors are too
            return;
        }

        if (disallowIntercept) {
            mGroupFlags |= FLAG_DISALLOW_INTERCEPT;
        } else {
            mGroupFlags &= ~FLAG_DISALLOW_INTERCEPT;
        }

        // Pass it up to our parent
        if (mParent != null) {
            mParent.requestDisallowInterceptTouchEvent(disallowIntercept);
        }
    }

    /**
     * Implement this method to intercept all touch screen motion events.  This
     * allows you to watch events as they are dispatched to your children, and
     * take ownership of the current gesture at any point.
     *
     * <p>Using this function takes some care, as it has a fairly complicated
     * interaction with {@link View#onTouchEvent(MotionEvent)
     * View.onTouchEvent(MotionEvent)}, and using it requires implementing
     * that method as well as this one in the correct way.  Events will be
     * received in the following order:
     *
     * <ol>
     * <li> You will receive the down event here.
     * <li> The down event will be handled either by a child of this view
     * group, or given to your own onTouchEvent() method to handle; this means
     * you should implement onTouchEvent() to return true, so you will
     * continue to see the rest of the gesture (instead of looking for
     * a parent view to handle it).  Also, by returning true from
     * onTouchEvent(), you will not receive any following
     * events in onInterceptTouchEvent() and all touch processing must
     * happen in onTouchEvent() like normal.
     * <li> For as long as you return false from this function, each following
     * event (up to and including the final up) will be delivered first here
     * and then to the target's onTouchEvent().
     * <li> If you return true from here, you will not receive any
     * following events: the target view will receive the same event but
     * with the action {@link MotionEvent#ACTION_CANCEL}, and all further
     * events will be delivered to your onTouchEvent() method and no longer
     * appear here.
     * </ol>
     *
     * @param ev The motion event being dispatched down the hierarchy.
     * @return Return true to steal motion events from the children and have
     * them dispatched to this ViewGroup through onTouchEvent().
     * The current target will receive an ACTION_CANCEL event, and no further
     * messages will be delivered here.
     */
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        return false;
    }

    /**
     * {@inheritDoc}
     *
     * Looks for a view to give focus to respecting the setting specified by
     * {@link #getDescendantFocusability()}.
     *
     * Uses {@link #onRequestFocusInDescendants(int, android.graphics.Rect)} to
     * find focus within the children of this group when appropriate.
     *
     * @see #FOCUS_BEFORE_DESCENDANTS
     * @see #FOCUS_AFTER_DESCENDANTS
     * @see #FOCUS_BLOCK_DESCENDANTS
     * @see #onRequestFocusInDescendants
     */
    @Override
    public boolean requestFocus(int direction, Rect previouslyFocusedRect) {
        if (DBG) {
            System.out.println(this + " ViewGroup.requestFocus direction="
                    + direction);
        }
        int descendantFocusability = getDescendantFocusability();

        switch (descendantFocusability) {
            case FOCUS_BLOCK_DESCENDANTS:
                return super.requestFocus(direction, previouslyFocusedRect);
            case FOCUS_BEFORE_DESCENDANTS: {
                final boolean took = super.requestFocus(direction, previouslyFocusedRect);
                return took ? took : onRequestFocusInDescendants(direction, previouslyFocusedRect);
            }
            case FOCUS_AFTER_DESCENDANTS: {
                final boolean took = onRequestFocusInDescendants(direction, previouslyFocusedRect);
                return took ? took : super.requestFocus(direction, previouslyFocusedRect);
            }
            default:
                throw new IllegalStateException("descendant focusability must be "
                        + "one of FOCUS_BEFORE_DESCENDANTS, FOCUS_AFTER_DESCENDANTS, FOCUS_BLOCK_DESCENDANTS "
                        + "but is " + descendantFocusability);
        }
    }

    /**
     * Look for a descendant to call {@link View#requestFocus} on.
     * Called by {@link ViewGroup#requestFocus(int, android.graphics.Rect)}
     * when it wants to request focus within its children.  Override this to
     * customize how your {@link ViewGroup} requests focus within its children.
     * @param direction One of FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, and FOCUS_RIGHT
     * @param previouslyFocusedRect The rectangle (in this View's coordinate system)
     *        to give a finer grained hint about where focus is coming from.  May be null
     *        if there is no hint.
     * @return Whether focus was taken.
     */
    @SuppressWarnings({"ConstantConditions"})
    protected boolean onRequestFocusInDescendants(int direction,
            Rect previouslyFocusedRect) {
        int index;
        int increment;
        int end;
        int count = mChildrenCount;
        if ((direction & FOCUS_FORWARD) != 0) {
            index = 0;
            increment = 1;
            end = count;
        } else {
            index = count - 1;
            increment = -1;
            end = -1;
        }
        final View[] children = mChildren;
        for (int i = index; i != end; i += increment) {
            View child = children[i];
            if ((child.mViewFlags & VISIBILITY_MASK) == VISIBLE) {
                if (child.requestFocus(direction, previouslyFocusedRect)) {
                    return true;
                }
            }
        }
        return false;
    }
    
    /**
     * {@inheritDoc}
     * 
     * @hide
     */
    @Override
    public void dispatchStartTemporaryDetach() {
        super.dispatchStartTemporaryDetach();
        final int count = mChildrenCount;
        final View[] children = mChildren;
        for (int i = 0; i < count; i++) {
            children[i].dispatchStartTemporaryDetach();
        }
    }
    
    /**
     * {@inheritDoc}
     * 
     * @hide
     */
    @Override
    public void dispatchFinishTemporaryDetach() {
        super.dispatchFinishTemporaryDetach();
        final int count = mChildrenCount;
        final View[] children = mChildren;
        for (int i = 0; i < count; i++) {
            children[i].dispatchFinishTemporaryDetach();
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    void dispatchAttachedToWindow(AttachInfo info, int visibility) {
        super.dispatchAttachedToWindow(info, visibility);
        visibility |= mViewFlags & VISIBILITY_MASK;
        final int count = mChildrenCount;
        final View[] children = mChildren;
        for (int i = 0; i < count; i++) {
            children[i].dispatchAttachedToWindow(info, visibility);
        }
    }

    @Override
    public boolean dispatchPopulateAccessibilityEvent(AccessibilityEvent event) {
        boolean populated = false;
        for (int i = 0, count = getChildCount(); i < count; i++) {
            populated |= getChildAt(i).dispatchPopulateAccessibilityEvent(event);
        }
        return populated;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    void dispatchDetachedFromWindow() {
        // If we still have a motion target, we are still in the process of
        // dispatching motion events to a child; we need to get rid of that
        // child to avoid dispatching events to it after the window is torn
        // down. To make sure we keep the child in a consistent state, we
        // first send it an ACTION_CANCEL motion event.
        if (mMotionTarget != null) {
            final long now = SystemClock.uptimeMillis();
            final MotionEvent event = MotionEvent.obtain(now, now,
                    MotionEvent.ACTION_CANCEL, 0.0f, 0.0f, 0);
            mMotionTarget.dispatchTouchEvent(event);
            event.recycle();
            mMotionTarget = null;
        }

        final int count = mChildrenCount;
        final View[] children = mChildren;
        for (int i = 0; i < count; i++) {
            children[i].dispatchDetachedFromWindow();
        }
        super.dispatchDetachedFromWindow();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void setPadding(int left, int top, int right, int bottom) {
        super.setPadding(left, top, right, bottom);

        if ((mPaddingLeft | mPaddingTop | mPaddingRight | mPaddingRight) != 0) {
            mGroupFlags |= FLAG_PADDING_NOT_NULL;
        } else {
            mGroupFlags &= ~FLAG_PADDING_NOT_NULL;
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected void dispatchSaveInstanceState(SparseArray<Parcelable> container) {
        super.dispatchSaveInstanceState(container);
        final int count = mChildrenCount;
        final View[] children = mChildren;
        for (int i = 0; i < count; i++) {
            children[i].dispatchSaveInstanceState(container);
        }
    }

    /**
     * Perform dispatching of a {@link #saveHierarchyState freeze()} to only this view,
     * not to its children.  For use when overriding
     * {@link #dispatchSaveInstanceState dispatchFreeze()} to allow subclasses to freeze
     * their own state but not the state of their children.
     *
     * @param container the container
     */
    protected void dispatchFreezeSelfOnly(SparseArray<Parcelable> container) {
        super.dispatchSaveInstanceState(container);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected void dispatchRestoreInstanceState(SparseArray<Parcelable> container) {
        super.dispatchRestoreInstanceState(container);
        final int count = mChildrenCount;
        final View[] children = mChildren;
        for (int i = 0; i < count; i++) {
            children[i].dispatchRestoreInstanceState(container);
        }
    }

    /**
     * Perform dispatching of a {@link #restoreHierarchyState thaw()} to only this view,
     * not to its children.  For use when overriding
     * {@link #dispatchRestoreInstanceState dispatchThaw()} to allow subclasses to thaw
     * their own state but not the state of their children.
     *
     * @param container the container
     */
    protected void dispatchThawSelfOnly(SparseArray<Parcelable> container) {
        super.dispatchRestoreInstanceState(container);
    }

    /**
     * Enables or disables the drawing cache for each child of this view group.
     *
     * @param enabled true to enable the cache, false to dispose of it
     */
    protected void setChildrenDrawingCacheEnabled(boolean enabled) {
        if (enabled || (mPersistentDrawingCache & PERSISTENT_ALL_CACHES) != PERSISTENT_ALL_CACHES) {
            final View[] children = mChildren;
            final int count = mChildrenCount;
            for (int i = 0; i < count; i++) {
                children[i].setDrawingCacheEnabled(enabled);
            }
        }
    }

    @Override
    protected void onAnimationStart() {
        super.onAnimationStart();

        // When this ViewGroup's animation starts, build the cache for the children
        if ((mGroupFlags & FLAG_ANIMATION_CACHE) == FLAG_ANIMATION_CACHE) {
            final int count = mChildrenCount;
            final View[] children = mChildren;

            for (int i = 0; i < count; i++) {
                final View child = children[i];
                if ((child.mViewFlags & VISIBILITY_MASK) == VISIBLE) {
                    child.setDrawingCacheEnabled(true);
                    child.buildDrawingCache(true);
                }
            }

            mGroupFlags |= FLAG_CHILDREN_DRAWN_WITH_CACHE;
        }
    }

    @Override
    protected void onAnimationEnd() {
        super.onAnimationEnd();

        // When this ViewGroup's animation ends, destroy the cache of the children
        if ((mGroupFlags & FLAG_ANIMATION_CACHE) == FLAG_ANIMATION_CACHE) {
            mGroupFlags &= ~FLAG_CHILDREN_DRAWN_WITH_CACHE;

            if ((mPersistentDrawingCache & PERSISTENT_ANIMATION_CACHE) == 0) {
                setChildrenDrawingCacheEnabled(false);
            }
        }
    }

    @Override
    Bitmap createSnapshot(Bitmap.Config quality, int backgroundColor, boolean skipChildren) {
        int count = mChildrenCount;
        int[] visibilities = null;

        if (skipChildren) {
            visibilities = new int[count];
            for (int i = 0; i < count; i++) {
                View child = getChildAt(i);
                visibilities[i] = child.getVisibility();
                if (visibilities[i] == View.VISIBLE) {
                    child.setVisibility(INVISIBLE);
                }
            }
        }

        Bitmap b = super.createSnapshot(quality, backgroundColor, skipChildren);

        if (skipChildren) {
            for (int i = 0; i < count; i++) {
                getChildAt(i).setVisibility(visibilities[i]);
            }        
        }

        return b;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected void dispatchDraw(Canvas canvas) {
        final int count = mChildrenCount;
        final View[] children = mChildren;
        int flags = mGroupFlags;

        if ((flags & FLAG_RUN_ANIMATION) != 0 && canAnimate()) {
            final boolean cache = (mGroupFlags & FLAG_ANIMATION_CACHE) == FLAG_ANIMATION_CACHE;

            for (int i = 0; i < count; i++) {
                final View child = children[i];
                if ((child.mViewFlags & VISIBILITY_MASK) == VISIBLE) {
                    final LayoutParams params = child.getLayoutParams();
                    attachLayoutAnimationParameters(child, params, i, count);
                    bindLayoutAnimation(child);
                    if (cache) {
                        child.setDrawingCacheEnabled(true);
                        child.buildDrawingCache(true);
                    }
                }
            }

            final LayoutAnimationController controller = mLayoutAnimationController;
            if (controller.willOverlap()) {
                mGroupFlags |= FLAG_OPTIMIZE_INVALIDATE;
            }

            controller.start();

            mGroupFlags &= ~FLAG_RUN_ANIMATION;
            mGroupFlags &= ~FLAG_ANIMATION_DONE;

            if (cache) {
                mGroupFlags |= FLAG_CHILDREN_DRAWN_WITH_CACHE;
            }

            if (mAnimationListener != null) {
                mAnimationListener.onAnimationStart(controller.getAnimation());
            }
        }

        int saveCount = 0;
        final boolean clipToPadding = (flags & CLIP_TO_PADDING_MASK) == CLIP_TO_PADDING_MASK;
        if (clipToPadding) {
            saveCount = canvas.save();
            canvas.clipRect(mScrollX + mPaddingLeft, mScrollY + mPaddingTop,
                    mScrollX + mRight - mLeft - mPaddingRight,
                    mScrollY + mBottom - mTop - mPaddingBottom);

        }

        // We will draw our child's animation, let's reset the flag
        mPrivateFlags &= ~DRAW_ANIMATION;
        mGroupFlags &= ~FLAG_INVALIDATE_REQUIRED;

        boolean more = false;
        final long drawingTime = getDrawingTime();

        if ((flags & FLAG_USE_CHILD_DRAWING_ORDER) == 0) {
            for (int i = 0; i < count; i++) {
                final View child = children[i];
                if ((child.mViewFlags & VISIBILITY_MASK) == VISIBLE || child.getAnimation() != null) {
                    more |= drawChild(canvas, child, drawingTime);
                }
            }
        } else {
            for (int i = 0; i < count; i++) {
                final View child = children[getChildDrawingOrder(count, i)];
                if ((child.mViewFlags & VISIBILITY_MASK) == VISIBLE || child.getAnimation() != null) {
                    more |= drawChild(canvas, child, drawingTime);
                }
            }
        }

        // Draw any disappearing views that have animations
        if (mDisappearingChildren != null) {
            final ArrayList<View> disappearingChildren = mDisappearingChildren;
            final int disappearingCount = disappearingChildren.size() - 1;
            // Go backwards -- we may delete as animations finish
            for (int i = disappearingCount; i >= 0; i--) {
                final View child = disappearingChildren.get(i);
                more |= drawChild(canvas, child, drawingTime);
            }
        }

        if (clipToPadding) {
            canvas.restoreToCount(saveCount);
        }

        // mGroupFlags might have been updated by drawChild()
        flags = mGroupFlags;

        if ((flags & FLAG_INVALIDATE_REQUIRED) == FLAG_INVALIDATE_REQUIRED) {
            invalidate();
        }

        if ((flags & FLAG_ANIMATION_DONE) == 0 && (flags & FLAG_NOTIFY_ANIMATION_LISTENER) == 0 &&
                mLayoutAnimationController.isDone() && !more) {
            // We want to erase the drawing cache and notify the listener after the
            // next frame is drawn because one extra invalidate() is caused by
            // drawChild() after the animation is over
            mGroupFlags |= FLAG_NOTIFY_ANIMATION_LISTENER;
            final Runnable end = new Runnable() {
               public void run() {
                   notifyAnimationListener();
               }
            };
            post(end);
        }
    }

    /**
     * Returns the index of the child to draw for this iteration. Override this
     * if you want to change the drawing order of children. By default, it
     * returns i.
     * <p>
     * NOTE: In order for this method to be called, you must enable child ordering
     * first by calling {@link #setChildrenDrawingOrderEnabled(boolean)}.
     *
     * @param i The current iteration.
     * @return The index of the child to draw this iteration.
     * 
     * @see #setChildrenDrawingOrderEnabled(boolean)
     * @see #isChildrenDrawingOrderEnabled()
     */
    protected int getChildDrawingOrder(int childCount, int i) {
        return i;
    }

    private void notifyAnimationListener() {
        mGroupFlags &= ~FLAG_NOTIFY_ANIMATION_LISTENER;
        mGroupFlags |= FLAG_ANIMATION_DONE;

        if (mAnimationListener != null) {
           final Runnable end = new Runnable() {
               public void run() {
                   mAnimationListener.onAnimationEnd(mLayoutAnimationController.getAnimation());
               }
           };
           post(end);
        }

        if ((mGroupFlags & FLAG_ANIMATION_CACHE) == FLAG_ANIMATION_CACHE) {
            mGroupFlags &= ~FLAG_CHILDREN_DRAWN_WITH_CACHE;
            if ((mPersistentDrawingCache & PERSISTENT_ANIMATION_CACHE) == 0) {
                setChildrenDrawingCacheEnabled(false);
            }
        }

        invalidate();
    }

    /**
     * Draw one child of this View Group. This method is responsible for getting
     * the canvas in the right state. This includes clipping, translating so
     * that the child's scrolled origin is at 0, 0, and applying any animation
     * transformations.
     *
     * @param canvas The canvas on which to draw the child
     * @param child Who to draw
     * @param drawingTime The time at which draw is occuring
     * @return True if an invalidate() was issued
     */
    protected boolean drawChild(Canvas canvas, View child, long drawingTime) {
        boolean more = false;

        final int cl = child.mLeft;
        final int ct = child.mTop;
        final int cr = child.mRight;
        final int cb = child.mBottom;

        final int flags = mGroupFlags;

        if ((flags & FLAG_CLEAR_TRANSFORMATION) == FLAG_CLEAR_TRANSFORMATION) {
            if (mChildTransformation != null) {
                mChildTransformation.clear();
            }
            mGroupFlags &= ~FLAG_CLEAR_TRANSFORMATION;
        }

        Transformation transformToApply = null;
        final Animation a = child.getAnimation();
        boolean concatMatrix = false;

        if (a != null) {
            if (mInvalidateRegion == null) {
                mInvalidateRegion = new RectF();
            }
            final RectF region = mInvalidateRegion;

            final boolean initialized = a.isInitialized();
            if (!initialized) {
                a.initialize(cr - cl, cb - ct, getWidth(), getHeight());
                a.initializeInvalidateRegion(0, 0, cr - cl, cb - ct);
                child.onAnimationStart();
            }

            if (mChildTransformation == null) {
                mChildTransformation = new Transformation();
            }
            more = a.getTransformation(drawingTime, mChildTransformation);
            transformToApply = mChildTransformation;

            concatMatrix = a.willChangeTransformationMatrix();

            if (more) {
                if (!a.willChangeBounds()) {
                    if ((flags & (FLAG_OPTIMIZE_INVALIDATE | FLAG_ANIMATION_DONE)) ==
                            FLAG_OPTIMIZE_INVALIDATE) {
                        mGroupFlags |= FLAG_INVALIDATE_REQUIRED;
                    } else if ((flags & FLAG_INVALIDATE_REQUIRED) == 0) {
                        // The child need to draw an animation, potentially offscreen, so
                        // make sure we do not cancel invalidate requests
                        mPrivateFlags |= DRAW_ANIMATION;
                        invalidate(cl, ct, cr, cb);
                    }
                } else {
                    a.getInvalidateRegion(0, 0, cr - cl, cb - ct, region, transformToApply);

                    // The child need to draw an animation, potentially offscreen, so
                    // make sure we do not cancel invalidate requests
                    mPrivateFlags |= DRAW_ANIMATION;

                    final int left = cl + (int) region.left;
                    final int top = ct + (int) region.top;
                    invalidate(left, top, left + (int) region.width(), top + (int) region.height());
                }
            }
        } else if ((flags & FLAG_SUPPORT_STATIC_TRANSFORMATIONS) ==
                FLAG_SUPPORT_STATIC_TRANSFORMATIONS) {
            if (mChildTransformation == null) {
                mChildTransformation = new Transformation();
            }
            final boolean hasTransform = getChildStaticTransformation(child, mChildTransformation);
            if (hasTransform) {
                final int transformType = mChildTransformation.getTransformationType();
                transformToApply = transformType != Transformation.TYPE_IDENTITY ?
                        mChildTransformation : null;
                concatMatrix = (transformType & Transformation.TYPE_MATRIX) != 0;
            }
        }

        // Sets the flag as early as possible to allow draw() implementations
        // to call invalidate() successfully when doing animations
        child.mPrivateFlags |= DRAWN;

        if (!concatMatrix && canvas.quickReject(cl, ct, cr, cb, Canvas.EdgeType.BW) &&
                (child.mPrivateFlags & DRAW_ANIMATION) == 0) {
            return more;
        }

        child.computeScroll();

        final int sx = child.mScrollX;
        final int sy = child.mScrollY;

        boolean scalingRequired = false;
        Bitmap cache = null;
        if ((flags & FLAG_CHILDREN_DRAWN_WITH_CACHE) == FLAG_CHILDREN_DRAWN_WITH_CACHE ||
                (flags & FLAG_ALWAYS_DRAWN_WITH_CACHE) == FLAG_ALWAYS_DRAWN_WITH_CACHE) {
            cache = child.getDrawingCache(true);
            if (mAttachInfo != null) scalingRequired = mAttachInfo.mScalingRequired;
        }

        final boolean hasNoCache = cache == null;

        final int restoreTo = canvas.save();
        if (hasNoCache) {
            canvas.translate(cl - sx, ct - sy);
        } else {
            canvas.translate(cl, ct);
            if (scalingRequired) {
                // mAttachInfo cannot be null, otherwise scalingRequired == false
                final float scale = 1.0f / mAttachInfo.mApplicationScale;
                canvas.scale(scale, scale);
            }
        }

        float alpha = 1.0f;

        if (transformToApply != null) {
            if (concatMatrix) {
                int transX = 0;
                int transY = 0;
                if (hasNoCache) {
                    transX = -sx;
                    transY = -sy;
                }
                // Undo the scroll translation, apply the transformation matrix,
                // then redo the scroll translate to get the correct result.
                canvas.translate(-transX, -transY);
                canvas.concat(transformToApply.getMatrix());
                canvas.translate(transX, transY);
                mGroupFlags |= FLAG_CLEAR_TRANSFORMATION;
            }

            alpha = transformToApply.getAlpha();
            if (alpha < 1.0f) {
                mGroupFlags |= FLAG_CLEAR_TRANSFORMATION;
            }

            if (alpha < 1.0f && hasNoCache) {
                final int multipliedAlpha = (int) (255 * alpha);
                if (!child.onSetAlpha(multipliedAlpha)) {
                    canvas.saveLayerAlpha(sx, sy, sx + cr - cl, sy + cb - ct, multipliedAlpha,
                            Canvas.HAS_ALPHA_LAYER_SAVE_FLAG | Canvas.CLIP_TO_LAYER_SAVE_FLAG);
                } else {
                    child.mPrivateFlags |= ALPHA_SET;
                }
            }
        } else if ((child.mPrivateFlags & ALPHA_SET) == ALPHA_SET) {
            child.onSetAlpha(255);
        }

        if ((flags & FLAG_CLIP_CHILDREN) == FLAG_CLIP_CHILDREN) {
            if (hasNoCache) {
                canvas.clipRect(sx, sy, sx + (cr - cl), sy + (cb - ct));
            } else {
                if (!scalingRequired) {
                    canvas.clipRect(0, 0, cr - cl, cb - ct);
                } else {
                    canvas.clipRect(0, 0, cache.getWidth(), cache.getHeight());
                }
            }
        }

        if (hasNoCache) {
            // Fast path for layouts with no backgrounds
            if ((child.mPrivateFlags & SKIP_DRAW) == SKIP_DRAW) {
                if (ViewDebug.TRACE_HIERARCHY) {
                    ViewDebug.trace(this, ViewDebug.HierarchyTraceType.DRAW);
                }
                child.mPrivateFlags &= ~DIRTY_MASK;
                child.dispatchDraw(canvas);
            } else {
                child.draw(canvas);
            }
        } else {
            final Paint cachePaint = mCachePaint;
            if (alpha < 1.0f) {
                cachePaint.setAlpha((int) (alpha * 255));
                mGroupFlags |= FLAG_ALPHA_LOWER_THAN_ONE;
            } else if  ((flags & FLAG_ALPHA_LOWER_THAN_ONE) == FLAG_ALPHA_LOWER_THAN_ONE) {
                cachePaint.setAlpha(255);
                mGroupFlags &= ~FLAG_ALPHA_LOWER_THAN_ONE;
            }
            if (Config.DEBUG && ViewDebug.profileDrawing) {
                EventLog.writeEvent(60003, hashCode());
            }
            canvas.drawBitmap(cache, 0.0f, 0.0f, cachePaint);
        }

        canvas.restoreToCount(restoreTo);

        if (a != null && !more) {
            child.onSetAlpha(255);
            finishAnimatingView(child, a);
        }

        return more;
    }

    /**
     * By default, children are clipped to their bounds before drawing. This
     * allows view groups to override this behavior for animations, etc.
     *
     * @param clipChildren true to clip children to their bounds,
     *        false otherwise
     * @attr ref android.R.styleable#ViewGroup_clipChildren
     */
    public void setClipChildren(boolean clipChildren) {
        setBooleanFlag(FLAG_CLIP_CHILDREN, clipChildren);
    }

    /**
     * By default, children are clipped to the padding of the ViewGroup. This
     * allows view groups to override this behavior
     *
     * @param clipToPadding true to clip children to the padding of the
     *        group, false otherwise
     * @attr ref android.R.styleable#ViewGroup_clipToPadding
     */
    public void setClipToPadding(boolean clipToPadding) {
        setBooleanFlag(FLAG_CLIP_TO_PADDING, clipToPadding);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void dispatchSetSelected(boolean selected) {
        final View[] children = mChildren;
        final int count = mChildrenCount;
        for (int i = 0; i < count; i++) {
            children[i].setSelected(selected);
        }
    }

    @Override
    protected void dispatchSetPressed(boolean pressed) {
        final View[] children = mChildren;
        final int count = mChildrenCount;
        for (int i = 0; i < count; i++) {
            children[i].setPressed(pressed);
        }
    }

    /**
     * When this property is set to true, this ViewGroup supports static transformations on
     * children; this causes
     * {@link #getChildStaticTransformation(View, android.view.animation.Transformation)} to be
     * invoked when a child is drawn.
     *
     * Any subclass overriding
     * {@link #getChildStaticTransformation(View, android.view.animation.Transformation)} should
     * set this property to true.
     *
     * @param enabled True to enable static transformations on children, false otherwise.
     *
     * @see #FLAG_SUPPORT_STATIC_TRANSFORMATIONS
     */
    protected void setStaticTransformationsEnabled(boolean enabled) {
        setBooleanFlag(FLAG_SUPPORT_STATIC_TRANSFORMATIONS, enabled);
    }

    /**
     * {@inheritDoc}
     *
     * @see #setStaticTransformationsEnabled(boolean)
     */
    protected boolean getChildStaticTransformation(View child, Transformation t) {
        return false;
    }

    /**
     * {@hide}
     */
    @Override
    protected View findViewTraversal(int id) {
        if (id == mID) {
            return this;
        }

        final View[] where = mChildren;
        final int len = mChildrenCount;

        for (int i = 0; i < len; i++) {
            View v = where[i];

            if ((v.mPrivateFlags & IS_ROOT_NAMESPACE) == 0) {
                v = v.findViewById(id);

                if (v != null) {
                    return v;
                }
            }
        }

        return null;
    }

    /**
     * {@hide}
     */
    @Override
    protected View findViewWithTagTraversal(Object tag) {
        if (tag != null && tag.equals(mTag)) {
            return this;
        }

        final View[] where = mChildren;
        final int len = mChildrenCount;

        for (int i = 0; i < len; i++) {
            View v = where[i];

            if ((v.mPrivateFlags & IS_ROOT_NAMESPACE) == 0) {
                v = v.findViewWithTag(tag);

                if (v != null) {
                    return v;
                }
            }
        }

        return null;
    }

    /**
     * Adds a child view. If no layout parameters are already set on the child, the
     * default parameters for this ViewGroup are set on the child.
     *
     * @param child the child view to add
     *
     * @see #generateDefaultLayoutParams()
     */
    public void addView(View child) {
        addView(child, -1);
    }

    /**
     * Adds a child view. If no layout parameters are already set on the child, the
     * default parameters for this ViewGroup are set on the child.
     *
     * @param child the child view to add
     * @param index the position at which to add the child
     *
     * @see #generateDefaultLayoutParams()
     */
    public void addView(View child, int index) {
        LayoutParams params = child.getLayoutParams();
        if (params == null) {
            params = generateDefaultLayoutParams();
            if (params == null) {
                throw new IllegalArgumentException("generateDefaultLayoutParams() cannot return null");
            }
        }
        addView(child, index, params);
    }

    /**
     * Adds a child view with this ViewGroup's default layout parameters and the
     * specified width and height.
     *
     * @param child the child view to add
     */
    public void addView(View child, int width, int height) {
        final LayoutParams params = generateDefaultLayoutParams();
        params.width = width;
        params.height = height;
        addView(child, -1, params);
    }

    /**
     * Adds a child view with the specified layout parameters.
     *
     * @param child the child view to add
     * @param params the layout parameters to set on the child
     */
    public void addView(View child, LayoutParams params) {
        addView(child, -1, params);
    }

    /**
     * Adds a child view with the specified layout parameters.
     *
     * @param child the child view to add
     * @param index the position at which to add the child
     * @param params the layout parameters to set on the child
     */
    public void addView(View child, int index, LayoutParams params) {
        if (DBG) {
            System.out.println(this + " addView");
        }

        // addViewInner() will call child.requestLayout() when setting the new LayoutParams
        // therefore, we call requestLayout() on ourselves before, so that the child's request
        // will be blocked at our level
        requestLayout();
        invalidate();
        addViewInner(child, index, params, false);
    }

    /**
     * {@inheritDoc}
     */
    public void updateViewLayout(View view, ViewGroup.LayoutParams params) {
        if (!checkLayoutParams(params)) {
            throw new IllegalArgumentException("Invalid LayoutParams supplied to " + this);
        }
        if (view.mParent != this) {
            throw new IllegalArgumentException("Given view not a child of " + this);
        }
        view.setLayoutParams(params);
    }

    /**
     * {@inheritDoc}
     */
    protected boolean checkLayoutParams(ViewGroup.LayoutParams p) {
        return  p != null;
    }

    /**
     * Interface definition for a callback to be invoked when the hierarchy
     * within this view changed. The hierarchy changes whenever a child is added
     * to or removed from this view.
     */
    public interface OnHierarchyChangeListener {
        /**
         * Called when a new child is added to a parent view.
         *
         * @param parent the view in which a child was added
         * @param child the new child view added in the hierarchy
         */
        void onChildViewAdded(View parent, View child);

        /**
         * Called when a child is removed from a parent view.
         *
         * @param parent the view from which the child was removed
         * @param child the child removed from the hierarchy
         */
        void onChildViewRemoved(View parent, View child);
    }

    /**
     * Register a callback to be invoked when a child is added to or removed
     * from this view.
     *
     * @param listener the callback to invoke on hierarchy change
     */
    public void setOnHierarchyChangeListener(OnHierarchyChangeListener listener) {
        mOnHierarchyChangeListener = listener;
    }

    /**
     * Adds a view during layout. This is useful if in your onLayout() method,
     * you need to add more views (as does the list view for example).
     *
     * If index is negative, it means put it at the end of the list.
     *
     * @param child the view to add to the group
     * @param index the index at which the child must be added
     * @param params the layout parameters to associate with the child
     * @return true if the child was added, false otherwise
     */
    protected boolean addViewInLayout(View child, int index, LayoutParams params) {
        return addViewInLayout(child, index, params, false);
    }

    /**
     * Adds a view during layout. This is useful if in your onLayout() method,
     * you need to add more views (as does the list view for example).
     *
     * If index is negative, it means put it at the end of the list.
     *
     * @param child the view to add to the group
     * @param index the index at which the child must be added
     * @param params the layout parameters to associate with the child
     * @param preventRequestLayout if true, calling this method will not trigger a
     *        layout request on child
     * @return true if the child was added, false otherwise
     */
    protected boolean addViewInLayout(View child, int index, LayoutParams params,
            boolean preventRequestLayout) {
        child.mParent = null;
        addViewInner(child, index, params, preventRequestLayout);
        child.mPrivateFlags = (child.mPrivateFlags & ~DIRTY_MASK) | DRAWN;
        return true;
    }

    /**
     * Prevents the specified child to be laid out during the next layout pass.
     *
     * @param child the child on which to perform the cleanup
     */
    protected void cleanupLayoutState(View child) {
        child.mPrivateFlags &= ~View.FORCE_LAYOUT;
    }

    private void addViewInner(View child, int index, LayoutParams params,
            boolean preventRequestLayout) {

        if (child.getParent() != null) {
            throw new IllegalStateException("The specified child already has a parent. " +
                    "You must call removeView() on the child's parent first.");
        }

        if (!checkLayoutParams(params)) {
            params = generateLayoutParams(params);
        }

        if (preventRequestLayout) {
            child.mLayoutParams = params;
        } else {
            child.setLayoutParams(params);
        }

        if (index < 0) {
            index = mChildrenCount;
        }

        addInArray(child, index);

        // tell our children
        if (preventRequestLayout) {
            child.assignParent(this);
        } else {
            child.mParent = this;
        }

        if (child.hasFocus()) {
            requestChildFocus(child, child.findFocus());
        }

        AttachInfo ai = mAttachInfo;
        if (ai != null) {
            boolean lastKeepOn = ai.mKeepScreenOn;
            ai.mKeepScreenOn = false;
            child.dispatchAttachedToWindow(mAttachInfo, (mViewFlags&VISIBILITY_MASK));
            if (ai.mKeepScreenOn) {
                needGlobalAttributesUpdate(true);
            }
            ai.mKeepScreenOn = lastKeepOn;
        }

        if (mOnHierarchyChangeListener != null) {
            mOnHierarchyChangeListener.onChildViewAdded(this, child);
        }

        if ((child.mViewFlags & DUPLICATE_PARENT_STATE) == DUPLICATE_PARENT_STATE) {
            mGroupFlags |= FLAG_NOTIFY_CHILDREN_ON_DRAWABLE_STATE_CHANGE;
        }
    }

    private void addInArray(View child, int index) {
        View[] children = mChildren;
        final int count = mChildrenCount;
        final int size = children.length;
        if (index == count) {
            if (size == count) {
                mChildren = new View[size + ARRAY_CAPACITY_INCREMENT];
                System.arraycopy(children, 0, mChildren, 0, size);
                children = mChildren;
            }
            children[mChildrenCount++] = child;
        } else if (index < count) {
            if (size == count) {
                mChildren = new View[size + ARRAY_CAPACITY_INCREMENT];
                System.arraycopy(children, 0, mChildren, 0, index);
                System.arraycopy(children, index, mChildren, index + 1, count - index);
                children = mChildren;
            } else {
                System.arraycopy(children, index, children, index + 1, count - index);
            }
            children[index] = child;
            mChildrenCount++;
        } else {
            throw new IndexOutOfBoundsException("index=" + index + " count=" + count);
        }
    }

    // This method also sets the child's mParent to null
    private void removeFromArray(int index) {
        final View[] children = mChildren;
        children[index].mParent = null;
        final int count = mChildrenCount;
        if (index == count - 1) {
            children[--mChildrenCount] = null;
        } else if (index >= 0 && index < count) {
            System.arraycopy(children, index + 1, children, index, count - index - 1);
            children[--mChildrenCount] = null;
        } else {
            throw new IndexOutOfBoundsException();
        }
    }

    // This method also sets the children's mParent to null
    private void removeFromArray(int start, int count) {
        final View[] children = mChildren;
        final int childrenCount = mChildrenCount;

        start = Math.max(0, start);
        final int end = Math.min(childrenCount, start + count);

        if (start == end) {
            return;
        }

        if (end == childrenCount) {
            for (int i = start; i < end; i++) {
                children[i].mParent = null;
                children[i] = null;
            }
        } else {
            for (int i = start; i < end; i++) {
                children[i].mParent = null;
            }

            // Since we're looping above, we might as well do the copy, but is arraycopy()
            // faster than the extra 2 bounds checks we would do in the loop?
            System.arraycopy(children, end, children, start, childrenCount - end);

            for (int i = childrenCount - (end - start); i < childrenCount; i++) {
                children[i] = null;
            }
        }

        mChildrenCount -= (end - start);
    }

    private void bindLayoutAnimation(View child) {
        Animation a = mLayoutAnimationController.getAnimationForView(child);
        child.setAnimation(a);
    }

    /**
     * Subclasses should override this method to set layout animation
     * parameters on the supplied child.
     *
     * @param child the child to associate with animation parameters
     * @param params the child's layout parameters which hold the animation
     *        parameters
     * @param index the index of the child in the view group
     * @param count the number of children in the view group
     */
    protected void attachLayoutAnimationParameters(View child,
            LayoutParams params, int index, int count) {
        LayoutAnimationController.AnimationParameters animationParams =
                    params.layoutAnimationParameters;
        if (animationParams == null) {
            animationParams = new LayoutAnimationController.AnimationParameters();
            params.layoutAnimationParameters = animationParams;
        }

        animationParams.count = count;
        animationParams.index = index;
    }

    /**
     * {@inheritDoc}
     */
    public void removeView(View view) {
        removeViewInternal(view);
        requestLayout();
        invalidate();
    }

    /**
     * Removes a view during layout. This is useful if in your onLayout() method,
     * you need to remove more views.
     *
     * @param view the view to remove from the group
     */
    public void removeViewInLayout(View view) {
        removeViewInternal(view);
    }

    /**
     * Removes a range of views during layout. This is useful if in your onLayout() method,
     * you need to remove more views.
     *
     * @param start the index of the first view to remove from the group
     * @param count the number of views to remove from the group
     */
    public void removeViewsInLayout(int start, int count) {
        removeViewsInternal(start, count);
    }

    /**
     * Removes the view at the specified position in the group.
     *
     * @param index the position in the group of the view to remove
     */
    public void removeViewAt(int index) {
        removeViewInternal(index, getChildAt(index));
        requestLayout();
        invalidate();
    }

    /**
     * Removes the specified range of views from the group.
     *
     * @param start the first position in the group of the range of views to remove
     * @param count the number of views to remove
     */
    public void removeViews(int start, int count) {
        removeViewsInternal(start, count);
        requestLayout();
        invalidate();
    }

    private void removeViewInternal(View view) {
        final int index = indexOfChild(view);
        if (index >= 0) {
            removeViewInternal(index, view);
        }
    }

    private void removeViewInternal(int index, View view) {
        boolean clearChildFocus = false;
        if (view == mFocused) {
            view.clearFocusForRemoval();
            clearChildFocus = true;
        }

        if (view.getAnimation() != null) {
            addDisappearingView(view);
        } else if (view.mAttachInfo != null) {
           view.dispatchDetachedFromWindow();
        }

        if (mOnHierarchyChangeListener != null) {
            mOnHierarchyChangeListener.onChildViewRemoved(this, view);
        }

        needGlobalAttributesUpdate(false);

        removeFromArray(index);

        if (clearChildFocus) {
            clearChildFocus(view);
        }
    }

    private void removeViewsInternal(int start, int count) {
        final OnHierarchyChangeListener onHierarchyChangeListener = mOnHierarchyChangeListener;
        final boolean notifyListener = onHierarchyChangeListener != null;
        final View focused = mFocused;
        final boolean detach = mAttachInfo != null;
        View clearChildFocus = null;

        final View[] children = mChildren;
        final int end = start + count;

        for (int i = start; i < end; i++) {
            final View view = children[i];

            if (view == focused) {
                view.clearFocusForRemoval();
                clearChildFocus = view;
            }

            if (view.getAnimation() != null) {
                addDisappearingView(view);
            } else if (detach) {
               view.dispatchDetachedFromWindow();
            }

            needGlobalAttributesUpdate(false);

            if (notifyListener) {
                onHierarchyChangeListener.onChildViewRemoved(this, view);
            }
        }

        removeFromArray(start, count);

        if (clearChildFocus != null) {
            clearChildFocus(clearChildFocus);
        }
    }

    /**
     * Call this method to remove all child views from the
     * ViewGroup.
     */
    public void removeAllViews() {
        removeAllViewsInLayout();
        requestLayout();
        invalidate();
    }

    /**
     * Called by a ViewGroup subclass to remove child views from itself,
     * when it must first know its size on screen before it can calculate how many
     * child views it will render. An example is a Gallery or a ListView, which
     * may "have" 50 children, but actually only render the number of children
     * that can currently fit inside the object on screen. Do not call
     * this method unless you are extending ViewGroup and understand the
     * view measuring and layout pipeline.
     */
    public void removeAllViewsInLayout() {
        final int count = mChildrenCount;
        if (count <= 0) {
            return;
        }

        final View[] children = mChildren;
        mChildrenCount = 0;

        final OnHierarchyChangeListener listener = mOnHierarchyChangeListener;
        final boolean notify = listener != null;
        final View focused = mFocused;
        final boolean detach = mAttachInfo != null;
        View clearChildFocus = null;

        needGlobalAttributesUpdate(false);

        for (int i = count - 1; i >= 0; i--) {
            final View view = children[i];

            if (view == focused) {
                view.clearFocusForRemoval();
                clearChildFocus = view;
            }

            if (view.getAnimation() != null) {
                addDisappearingView(view);
            } else if (detach) {
               view.dispatchDetachedFromWindow();
            }

            if (notify) {
                listener.onChildViewRemoved(this, view);
            }

            view.mParent = null;
            children[i] = null;
        }

        if (clearChildFocus != null) {
            clearChildFocus(clearChildFocus);
        }
    }

    /**
     * Finishes the removal of a detached view. This method will dispatch the detached from
     * window event and notify the hierarchy change listener.
     *
     * @param child the child to be definitely removed from the view hierarchy
     * @param animate if true and the view has an animation, the view is placed in the
     *                disappearing views list, otherwise, it is detached from the window
     *
     * @see #attachViewToParent(View, int, android.view.ViewGroup.LayoutParams)
     * @see #detachAllViewsFromParent()
     * @see #detachViewFromParent(View)
     * @see #detachViewFromParent(int)
     */
    protected void removeDetachedView(View child, boolean animate) {
        if (child == mFocused) {
            child.clearFocus();
        }

        if (animate && child.getAnimation() != null) {
            addDisappearingView(child);
        } else if (child.mAttachInfo != null) {
            child.dispatchDetachedFromWindow();
        }

        if (mOnHierarchyChangeListener != null) {
            mOnHierarchyChangeListener.onChildViewRemoved(this, child);
        }
    }

    /**
     * Attaches a view to this view group. Attaching a view assigns this group as the parent,
     * sets the layout parameters and puts the view in the list of children so it can be retrieved
     * by calling {@link #getChildAt(int)}.
     *
     * This method should be called only for view which were detached from their parent.
     *
     * @param child the child to attach
     * @param index the index at which the child should be attached
     * @param params the layout parameters of the child
     *
     * @see #removeDetachedView(View, boolean)
     * @see #detachAllViewsFromParent()
     * @see #detachViewFromParent(View)
     * @see #detachViewFromParent(int)
     */
    protected void attachViewToParent(View child, int index, LayoutParams params) {
        child.mLayoutParams = params;

        if (index < 0) {
            index = mChildrenCount;
        }

        addInArray(child, index);

        child.mParent = this;
        child.mPrivateFlags = (child.mPrivateFlags & ~DIRTY_MASK & ~DRAWING_CACHE_VALID) | DRAWN;

        if (child.hasFocus()) {
            requestChildFocus(child, child.findFocus());
        }
    }

    /**
     * Detaches a view from its parent. Detaching a view should be temporary and followed
     * either by a call to {@link #attachViewToParent(View, int, android.view.ViewGroup.LayoutParams)}
     * or a call to {@link #removeDetachedView(View, boolean)}. When a view is detached,
     * its parent is null and cannot be retrieved by a call to {@link #getChildAt(int)}.
     *
     * @param child the child to detach
     *
     * @see #detachViewFromParent(int)
     * @see #detachViewsFromParent(int, int)
     * @see #detachAllViewsFromParent()
     * @see #attachViewToParent(View, int, android.view.ViewGroup.LayoutParams)
     * @see #removeDetachedView(View, boolean)
     */
    protected void detachViewFromParent(View child) {
        removeFromArray(indexOfChild(child));
    }

    /**
     * Detaches a view from its parent. Detaching a view should be temporary and followed
     * either by a call to {@link #attachViewToParent(View, int, android.view.ViewGroup.LayoutParams)}
     * or a call to {@link #removeDetachedView(View, boolean)}. When a view is detached,
     * its parent is null and cannot be retrieved by a call to {@link #getChildAt(int)}.
     *
     * @param index the index of the child to detach
     *
     * @see #detachViewFromParent(View)
     * @see #detachAllViewsFromParent()
     * @see #detachViewsFromParent(int, int)
     * @see #attachViewToParent(View, int, android.view.ViewGroup.LayoutParams)
     * @see #removeDetachedView(View, boolean)
     */
    protected void detachViewFromParent(int index) {
        removeFromArray(index);
    }

    /**
     * Detaches a range of view from their parent. Detaching a view should be temporary and followed
     * either by a call to {@link #attachViewToParent(View, int, android.view.ViewGroup.LayoutParams)}
     * or a call to {@link #removeDetachedView(View, boolean)}. When a view is detached, its
     * parent is null and cannot be retrieved by a call to {@link #getChildAt(int)}.
     *
     * @param start the first index of the childrend range to detach
     * @param count the number of children to detach
     *
     * @see #detachViewFromParent(View)
     * @see #detachViewFromParent(int)
     * @see #detachAllViewsFromParent()
     * @see #attachViewToParent(View, int, android.view.ViewGroup.LayoutParams)
     * @see #removeDetachedView(View, boolean)
     */
    protected void detachViewsFromParent(int start, int count) {
        removeFromArray(start, count);
    }

    /**
     * Detaches all views from the parent. Detaching a view should be temporary and followed
     * either by a call to {@link #attachViewToParent(View, int, android.view.ViewGroup.LayoutParams)}
     * or a call to {@link #removeDetachedView(View, boolean)}. When a view is detached,
     * its parent is null and cannot be retrieved by a call to {@link #getChildAt(int)}.
     *
     * @see #detachViewFromParent(View)
     * @see #detachViewFromParent(int)
     * @see #detachViewsFromParent(int, int)
     * @see #attachViewToParent(View, int, android.view.ViewGroup.LayoutParams)
     * @see #removeDetachedView(View, boolean)
     */
    protected void detachAllViewsFromParent() {
        final int count = mChildrenCount;
        if (count <= 0) {
            return;
        }

        final View[] children = mChildren;
        mChildrenCount = 0;

        for (int i = count - 1; i >= 0; i--) {
            children[i].mParent = null;
            children[i] = null;
        }
    }

    /**
     * Don't call or override this method. It is used for the implementation of
     * the view hierarchy.
     */
    public final void invalidateChild(View child, final Rect dirty) {
        if (ViewDebug.TRACE_HIERARCHY) {
            ViewDebug.trace(this, ViewDebug.HierarchyTraceType.INVALIDATE_CHILD);
        }

        ViewParent parent = this;

        final AttachInfo attachInfo = mAttachInfo;
        if (attachInfo != null) {
            final int[] location = attachInfo.mInvalidateChildLocation;
            location[CHILD_LEFT_INDEX] = child.mLeft;
            location[CHILD_TOP_INDEX] = child.mTop;

            // If the child is drawing an animation, we want to copy this flag onto
            // ourselves and the parent to make sure the invalidate request goes
            // through
            final boolean drawAnimation = (child.mPrivateFlags & DRAW_ANIMATION) == DRAW_ANIMATION;

            // Check whether the child that requests the invalidate is fully opaque
            final boolean isOpaque = child.isOpaque() && !drawAnimation &&
                    child.getAnimation() != null;
            // Mark the child as dirty, using the appropriate flag
            // Make sure we do not set both flags at the same time
            final int opaqueFlag = isOpaque ? DIRTY_OPAQUE : DIRTY;

            do {
                View view = null;
                if (parent instanceof View) {
                    view = (View) parent;
                }

                if (drawAnimation) {
                    if (view != null) {
                        view.mPrivateFlags |= DRAW_ANIMATION;
                    } else if (parent instanceof ViewRoot) {
                        ((ViewRoot) parent).mIsAnimating = true;
                    }
                }

                // If the parent is dirty opaque or not dirty, mark it dirty with the opaque
                // flag coming from the child that initiated the invalidate
                if (view != null && (view.mPrivateFlags & DIRTY_MASK) != DIRTY) {
                    view.mPrivateFlags = (view.mPrivateFlags & ~DIRTY_MASK) | opaqueFlag;
                }

                parent = parent.invalidateChildInParent(location, dirty);
            } while (parent != null);
        }
    }

    /**
     * Don't call or override this method. It is used for the implementation of
     * the view hierarchy.
     *
     * This implementation returns null if this ViewGroup does not have a parent,
     * if this ViewGroup is already fully invalidated or if the dirty rectangle
     * does not intersect with this ViewGroup's bounds.
     */
    public ViewParent invalidateChildInParent(final int[] location, final Rect dirty) {
        if (ViewDebug.TRACE_HIERARCHY) {
            ViewDebug.trace(this, ViewDebug.HierarchyTraceType.INVALIDATE_CHILD_IN_PARENT);
        }

        if ((mPrivateFlags & DRAWN) == DRAWN) {
            if ((mGroupFlags & (FLAG_OPTIMIZE_INVALIDATE | FLAG_ANIMATION_DONE)) !=
                        FLAG_OPTIMIZE_INVALIDATE) {
                dirty.offset(location[CHILD_LEFT_INDEX] - mScrollX,
                        location[CHILD_TOP_INDEX] - mScrollY);

                final int left = mLeft;
                final int top = mTop;

                if (dirty.intersect(0, 0, mRight - left, mBottom - top) ||
                        (mPrivateFlags & DRAW_ANIMATION) == DRAW_ANIMATION) {
                    mPrivateFlags &= ~DRAWING_CACHE_VALID;

                    location[CHILD_LEFT_INDEX] = left;
                    location[CHILD_TOP_INDEX] = top;

                    return mParent;
                }
            } else {
                mPrivateFlags &= ~DRAWN & ~DRAWING_CACHE_VALID;

                location[CHILD_LEFT_INDEX] = mLeft;
                location[CHILD_TOP_INDEX] = mTop;

                dirty.set(0, 0, mRight - location[CHILD_LEFT_INDEX],
                        mBottom - location[CHILD_TOP_INDEX]);

                return mParent;
            }
        }

        return null;
    }

    /**
     * Offset a rectangle that is in a descendant's coordinate
     * space into our coordinate space.
     * @param descendant A descendant of this view
     * @param rect A rectangle defined in descendant's coordinate space.
     */
    public final void offsetDescendantRectToMyCoords(View descendant, Rect rect) {
        offsetRectBetweenParentAndChild(descendant, rect, true, false);
    }

    /**
     * Offset a rectangle that is in our coordinate space into an ancestor's
     * coordinate space.
     * @param descendant A descendant of this view
     * @param rect A rectangle defined in descendant's coordinate space.
     */
    public final void offsetRectIntoDescendantCoords(View descendant, Rect rect) {
        offsetRectBetweenParentAndChild(descendant, rect, false, false);
    }

    /**
     * Helper method that offsets a rect either from parent to descendant or
     * descendant to parent.
     */
    void offsetRectBetweenParentAndChild(View descendant, Rect rect,
            boolean offsetFromChildToParent, boolean clipToBounds) {

        // already in the same coord system :)
        if (descendant == this) {
            return;
        }

        ViewParent theParent = descendant.mParent;

        // search and offset up to the parent
        while ((theParent != null)
                && (theParent instanceof View)
                && (theParent != this)) {

            if (offsetFromChildToParent) {
                rect.offset(descendant.mLeft - descendant.mScrollX,
                        descendant.mTop - descendant.mScrollY);
                if (clipToBounds) {
                    View p = (View) theParent;
                    rect.intersect(0, 0, p.mRight - p.mLeft, p.mBottom - p.mTop);
                }
            } else {
                if (clipToBounds) {
                    View p = (View) theParent;
                    rect.intersect(0, 0, p.mRight - p.mLeft, p.mBottom - p.mTop);
                }
                rect.offset(descendant.mScrollX - descendant.mLeft,
                        descendant.mScrollY - descendant.mTop);
            }

            descendant = (View) theParent;
            theParent = descendant.mParent;
        }

        // now that we are up to this view, need to offset one more time
        // to get into our coordinate space
        if (theParent == this) {
            if (offsetFromChildToParent) {
                rect.offset(descendant.mLeft - descendant.mScrollX,
                        descendant.mTop - descendant.mScrollY);
            } else {
                rect.offset(descendant.mScrollX - descendant.mLeft,
                        descendant.mScrollY - descendant.mTop);
            }
        } else {
            throw new IllegalArgumentException("parameter must be a descendant of this view");
        }
    }

    /**
     * Offset the vertical location of all children of this view by the specified number of pixels.
     *
     * @param offset the number of pixels to offset
     *
     * @hide
     */
    public void offsetChildrenTopAndBottom(int offset) {
        final int count = mChildrenCount;
        final View[] children = mChildren;

        for (int i = 0; i < count; i++) {
            final View v = children[i];
            v.mTop += offset;
            v.mBottom += offset;
        }
    }

    /**
     * {@inheritDoc}
     */
    public boolean getChildVisibleRect(View child, Rect r, android.graphics.Point offset) {
        int dx = child.mLeft - mScrollX;
        int dy = child.mTop - mScrollY;
        if (offset != null) {
            offset.x += dx;
            offset.y += dy;
        }
        r.offset(dx, dy);
        return r.intersect(0, 0, mRight - mLeft, mBottom - mTop) &&
               (mParent == null || mParent.getChildVisibleRect(this, r, offset));
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected abstract void onLayout(boolean changed,
            int l, int t, int r, int b);

    /**
     * Indicates whether the view group has the ability to animate its children
     * after the first layout.
     *
     * @return true if the children can be animated, false otherwise
     */
    protected boolean canAnimate() {
        return mLayoutAnimationController != null;
    }

    /**
     * Runs the layout animation. Calling this method triggers a relayout of
     * this view group.
     */
    public void startLayoutAnimation() {
        if (mLayoutAnimationController != null) {
            mGroupFlags |= FLAG_RUN_ANIMATION;
            requestLayout();
        }
    }

    /**
     * Schedules the layout animation to be played after the next layout pass
     * of this view group. This can be used to restart the layout animation
     * when the content of the view group changes or when the activity is
     * paused and resumed.
     */
    public void scheduleLayoutAnimation() {
        mGroupFlags |= FLAG_RUN_ANIMATION;
    }

    /**
     * Sets the layout animation controller used to animate the group's
     * children after the first layout.
     *
     * @param controller the animation controller
     */
    public void setLayoutAnimation(LayoutAnimationController controller) {
        mLayoutAnimationController = controller;
        if (mLayoutAnimationController != null) {
            mGroupFlags |= FLAG_RUN_ANIMATION;
        }
    }

    /**
     * Returns the layout animation controller used to animate the group's
     * children.
     *
     * @return the current animation controller
     */
    public LayoutAnimationController getLayoutAnimation() {
        return mLayoutAnimationController;
    }

    /**
     * Indicates whether the children's drawing cache is used during a layout
     * animation. By default, the drawing cache is enabled but this will prevent
     * nested layout animations from working. To nest animations, you must disable
     * the cache.
     *
     * @return true if the animation cache is enabled, false otherwise
     *
     * @see #setAnimationCacheEnabled(boolean)
     * @see View#setDrawingCacheEnabled(boolean)
     */
    @ViewDebug.ExportedProperty
    public boolean isAnimationCacheEnabled() {
        return (mGroupFlags & FLAG_ANIMATION_CACHE) == FLAG_ANIMATION_CACHE;
    }

    /**
     * Enables or disables the children's drawing cache during a layout animation.
     * By default, the drawing cache is enabled but this will prevent nested
     * layout animations from working. To nest animations, you must disable the
     * cache.
     *
     * @param enabled true to enable the animation cache, false otherwise
     *
     * @see #isAnimationCacheEnabled()
     * @see View#setDrawingCacheEnabled(boolean)
     */
    public void setAnimationCacheEnabled(boolean enabled) {
        setBooleanFlag(FLAG_ANIMATION_CACHE, enabled);
    }

    /**
     * Indicates whether this ViewGroup will always try to draw its children using their
     * drawing cache. By default this property is enabled.
     *
     * @return true if the animation cache is enabled, false otherwise
     *
     * @see #setAlwaysDrawnWithCacheEnabled(boolean)
     * @see #setChildrenDrawnWithCacheEnabled(boolean)
     * @see View#setDrawingCacheEnabled(boolean)
     */
    @ViewDebug.ExportedProperty
    public boolean isAlwaysDrawnWithCacheEnabled() {
        return (mGroupFlags & FLAG_ALWAYS_DRAWN_WITH_CACHE) == FLAG_ALWAYS_DRAWN_WITH_CACHE;
    }

    /**
     * Indicates whether this ViewGroup will always try to draw its children using their
     * drawing cache. This property can be set to true when the cache rendering is
     * slightly different from the children's normal rendering. Renderings can be different,
     * for instance, when the cache's quality is set to low.
     *
     * When this property is disabled, the ViewGroup will use the drawing cache of its
     * children only when asked to. It's usually the task of subclasses to tell ViewGroup
     * when to start using the drawing cache and when to stop using it.
     *
     * @param always true to always draw with the drawing cache, false otherwise
     *
     * @see #isAlwaysDrawnWithCacheEnabled()
     * @see #setChildrenDrawnWithCacheEnabled(boolean)
     * @see View#setDrawingCacheEnabled(boolean)
     * @see View#setDrawingCacheQuality(int)
     */
    public void setAlwaysDrawnWithCacheEnabled(boolean always) {
        setBooleanFlag(FLAG_ALWAYS_DRAWN_WITH_CACHE, always);
    }

    /**
     * Indicates whether the ViewGroup is currently drawing its children using
     * their drawing cache.
     *
     * @return true if children should be drawn with their cache, false otherwise
     *
     * @see #setAlwaysDrawnWithCacheEnabled(boolean)
     * @see #setChildrenDrawnWithCacheEnabled(boolean)
     */
    @ViewDebug.ExportedProperty
    protected boolean isChildrenDrawnWithCacheEnabled() {
        return (mGroupFlags & FLAG_CHILDREN_DRAWN_WITH_CACHE) == FLAG_CHILDREN_DRAWN_WITH_CACHE;
    }

    /**
     * Tells the ViewGroup to draw its children using their drawing cache. This property
     * is ignored when {@link #isAlwaysDrawnWithCacheEnabled()} is true. A child's drawing cache
     * will be used only if it has been enabled.
     *
     * Subclasses should call this method to start and stop using the drawing cache when
     * they perform performance sensitive operations, like scrolling or animating.
     *
     * @param enabled true if children should be drawn with their cache, false otherwise
     *
     * @see #setAlwaysDrawnWithCacheEnabled(boolean)
     * @see #isChildrenDrawnWithCacheEnabled()
     */
    protected void setChildrenDrawnWithCacheEnabled(boolean enabled) {
        setBooleanFlag(FLAG_CHILDREN_DRAWN_WITH_CACHE, enabled);
    }

    /**
     * Indicates whether the ViewGroup is drawing its children in the order defined by
     * {@link #getChildDrawingOrder(int, int)}.
     *
     * @return true if children drawing order is defined by {@link #getChildDrawingOrder(int, int)},
     *         false otherwise
     *
     * @see #setChildrenDrawingOrderEnabled(boolean)
     * @see #getChildDrawingOrder(int, int)
     */
    @ViewDebug.ExportedProperty
    protected boolean isChildrenDrawingOrderEnabled() {
        return (mGroupFlags & FLAG_USE_CHILD_DRAWING_ORDER) == FLAG_USE_CHILD_DRAWING_ORDER;
    }

    /**
     * Tells the ViewGroup whether to draw its children in the order defined by the method
     * {@link #getChildDrawingOrder(int, int)}.
     *
     * @param enabled true if the order of the children when drawing is determined by
     *        {@link #getChildDrawingOrder(int, int)}, false otherwise
     *
     * @see #isChildrenDrawingOrderEnabled()
     * @see #getChildDrawingOrder(int, int)
     */
    protected void setChildrenDrawingOrderEnabled(boolean enabled) {
        setBooleanFlag(FLAG_USE_CHILD_DRAWING_ORDER, enabled);
    }

    private void setBooleanFlag(int flag, boolean value) {
        if (value) {
            mGroupFlags |= flag;
        } else {
            mGroupFlags &= ~flag;
        }
    }

    /**
     * Returns an integer indicating what types of drawing caches are kept in memory.
     *
     * @see #setPersistentDrawingCache(int)
     * @see #setAnimationCacheEnabled(boolean)
     *
     * @return one or a combination of {@link #PERSISTENT_NO_CACHE},
     *         {@link #PERSISTENT_ANIMATION_CACHE}, {@link #PERSISTENT_SCROLLING_CACHE}
     *         and {@link #PERSISTENT_ALL_CACHES}
     */
    @ViewDebug.ExportedProperty(mapping = {
        @ViewDebug.IntToString(from = PERSISTENT_NO_CACHE,        to = "NONE"),
        @ViewDebug.IntToString(from = PERSISTENT_ALL_CACHES,      to = "ANIMATION"),
        @ViewDebug.IntToString(from = PERSISTENT_SCROLLING_CACHE, to = "SCROLLING"),
        @ViewDebug.IntToString(from = PERSISTENT_ALL_CACHES,      to = "ALL")
    })
    public int getPersistentDrawingCache() {
        return mPersistentDrawingCache;
    }

    /**
     * Indicates what types of drawing caches should be kept in memory after
     * they have been created.
     *
     * @see #getPersistentDrawingCache()
     * @see #setAnimationCacheEnabled(boolean)
     *
     * @param drawingCacheToKeep one or a combination of {@link #PERSISTENT_NO_CACHE},
     *        {@link #PERSISTENT_ANIMATION_CACHE}, {@link #PERSISTENT_SCROLLING_CACHE}
     *        and {@link #PERSISTENT_ALL_CACHES}
     */
    public void setPersistentDrawingCache(int drawingCacheToKeep) {
        mPersistentDrawingCache = drawingCacheToKeep & PERSISTENT_ALL_CACHES;
    }

    /**
     * Returns a new set of layout parameters based on the supplied attributes set.
     *
     * @param attrs the attributes to build the layout parameters from
     *
     * @return an instance of {@link android.view.ViewGroup.LayoutParams} or one
     *         of its descendants
     */
    public LayoutParams generateLayoutParams(AttributeSet attrs) {
        return new LayoutParams(getContext(), attrs);
    }

    /**
     * Returns a safe set of layout parameters based on the supplied layout params.
     * When a ViewGroup is passed a View whose layout params do not pass the test of
     * {@link #checkLayoutParams(android.view.ViewGroup.LayoutParams)}, this method
     * is invoked. This method should return a new set of layout params suitable for
     * this ViewGroup, possibly by copying the appropriate attributes from the
     * specified set of layout params.
     *
     * @param p The layout parameters to convert into a suitable set of layout parameters
     *          for this ViewGroup.
     *
     * @return an instance of {@link android.view.ViewGroup.LayoutParams} or one
     *         of its descendants
     */
    protected LayoutParams generateLayoutParams(ViewGroup.LayoutParams p) {
        return p;
    }

    /**
     * Returns a set of default layout parameters. These parameters are requested
     * when the View passed to {@link #addView(View)} has no layout parameters
     * already set. If null is returned, an exception is thrown from addView.
     *
     * @return a set of default layout parameters or null
     */
    protected LayoutParams generateDefaultLayoutParams() {
        return new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
    }

    /**
     * @hide
     */
    @Override
    protected boolean dispatchConsistencyCheck(int consistency) {
        boolean result = super.dispatchConsistencyCheck(consistency);

        final int count = mChildrenCount;
        final View[] children = mChildren;
        for (int i = 0; i < count; i++) {
            if (!children[i].dispatchConsistencyCheck(consistency)) result = false;
        }

        return result;
    }

    /**
     * @hide
     */
    @Override
    protected boolean onConsistencyCheck(int consistency) {
        boolean result = super.onConsistencyCheck(consistency);

        final boolean checkLayout = (consistency & ViewDebug.CONSISTENCY_LAYOUT) != 0;
        final boolean checkDrawing = (consistency & ViewDebug.CONSISTENCY_DRAWING) != 0;

        if (checkLayout) {
            final int count = mChildrenCount;
            final View[] children = mChildren;
            for (int i = 0; i < count; i++) {
                if (children[i].getParent() != this) {
                    result = false;
                    android.util.Log.d(ViewDebug.CONSISTENCY_LOG_TAG,
                            "View " + children[i] + " has no parent/a parent that is not " + this);
                }
            }
        }

        if (checkDrawing) {
            // If this group is dirty, check that the parent is dirty as well
            if ((mPrivateFlags & DIRTY_MASK) != 0) {
                final ViewParent parent = getParent();
                if (parent != null && !(parent instanceof ViewRoot)) {
                    if ((((View) parent).mPrivateFlags & DIRTY_MASK) == 0) {
                        result = false;
                        android.util.Log.d(ViewDebug.CONSISTENCY_LOG_TAG,
                                "ViewGroup " + this + " is dirty but its parent is not: " + this);
                    }
                }
            }
        }

        return result;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected void debug(int depth) {
        super.debug(depth);
        String output;

        if (mFocused != null) {
            output = debugIndent(depth);
            output += "mFocused";
            Log.d(VIEW_LOG_TAG, output);
        }
        if (mChildrenCount != 0) {
            output = debugIndent(depth);
            output += "{";
            Log.d(VIEW_LOG_TAG, output);
        }
        int count = mChildrenCount;
        for (int i = 0; i < count; i++) {
            View child = mChildren[i];
            child.debug(depth + 1);
        }

        if (mChildrenCount != 0) {
            output = debugIndent(depth);
            output += "}";
            Log.d(VIEW_LOG_TAG, output);
        }
    }

    /**
     * Returns the position in the group of the specified child view.
     *
     * @param child the view for which to get the position
     * @return a positive integer representing the position of the view in the
     *         group, or -1 if the view does not exist in the group
     */
    public int indexOfChild(View child) {
        final int count = mChildrenCount;
        final View[] children = mChildren;
        for (int i = 0; i < count; i++) {
            if (children[i] == child) {
                return i;
            }
        }
        return -1;
    }

    /**
     * Returns the number of children in the group.
     *
     * @return a positive integer representing the number of children in
     *         the group
     */
    public int getChildCount() {
        return mChildrenCount;
    }

    /**
     * Returns the view at the specified position in the group.
     *
     * @param index the position at which to get the view from
     * @return the view at the specified position or null if the position
     *         does not exist within the group
     */
    public View getChildAt(int index) {
        try {
            return mChildren[index];
        } catch (IndexOutOfBoundsException ex) {
            return null;
        }
    }

    /**
     * Ask all of the children of this view to measure themselves, taking into
     * account both the MeasureSpec requirements for this view and its padding.
     * We skip children that are in the GONE state The heavy lifting is done in
     * getChildMeasureSpec.
     *
     * @param widthMeasureSpec The width requirements for this view
     * @param heightMeasureSpec The height requirements for this view
     */
    protected void measureChildren(int widthMeasureSpec, int heightMeasureSpec) {
        final int size = mChildrenCount;
        final View[] children = mChildren;
        for (int i = 0; i < size; ++i) {
            final View child = children[i];
            if ((child.mViewFlags & VISIBILITY_MASK) != GONE) {
                measureChild(child, widthMeasureSpec, heightMeasureSpec);
            }
        }
    }

    /**
     * Ask one of the children of this view to measure itself, taking into
     * account both the MeasureSpec requirements for this view and its padding.
     * The heavy lifting is done in getChildMeasureSpec.
     *
     * @param child The child to measure
     * @param parentWidthMeasureSpec The width requirements for this view
     * @param parentHeightMeasureSpec The height requirements for this view
     */
    protected void measureChild(View child, int parentWidthMeasureSpec,
            int parentHeightMeasureSpec) {
        final LayoutParams lp = child.getLayoutParams();

        final int childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec,
                mPaddingLeft + mPaddingRight, lp.width);
        final int childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec,
                mPaddingTop + mPaddingBottom, lp.height);

        child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
    }

    /**
     * Ask one of the children of this view to measure itself, taking into
     * account both the MeasureSpec requirements for this view and its padding
     * and margins. The child must have MarginLayoutParams The heavy lifting is
     * done in getChildMeasureSpec.
     *
     * @param child The child to measure
     * @param parentWidthMeasureSpec The width requirements for this view
     * @param widthUsed Extra space that has been used up by the parent
     *        horizontally (possibly by other children of the parent)
     * @param parentHeightMeasureSpec The height requirements for this view
     * @param heightUsed Extra space that has been used up by the parent
     *        vertically (possibly by other children of the parent)
     */
    protected void measureChildWithMargins(View child,
            int parentWidthMeasureSpec, int widthUsed,
            int parentHeightMeasureSpec, int heightUsed) {
        final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();

        final int childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec,
                mPaddingLeft + mPaddingRight + lp.leftMargin + lp.rightMargin
                        + widthUsed, lp.width);
        final int childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec,
                mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin
                        + heightUsed, lp.height);

        child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
    }

    /**
     * Does the hard part of measureChildren: figuring out the MeasureSpec to
     * pass to a particular child. This method figures out the right MeasureSpec
     * for one dimension (height or width) of one child view.
     *
     * The goal is to combine information from our MeasureSpec with the
     * LayoutParams of the child to get the best possible results. For example,
     * if the this view knows its size (because its MeasureSpec has a mode of
     * EXACTLY), and the child has indicated in its LayoutParams that it wants
     * to be the same size as the parent, the parent should ask the child to
     * layout given an exact size.
     *
     * @param spec The requirements for this view
     * @param padding The padding of this view for the current dimension and
     *        margins, if applicable
     * @param childDimension How big the child wants to be in the current
     *        dimension
     * @return a MeasureSpec integer for the child
     */
    public static int getChildMeasureSpec(int spec, int padding, int childDimension) {
        int specMode = MeasureSpec.getMode(spec);
        int specSize = MeasureSpec.getSize(spec);

        int size = Math.max(0, specSize - padding);

        int resultSize = 0;
        int resultMode = 0;

        switch (specMode) {
        // Parent has imposed an exact size on us
        case MeasureSpec.EXACTLY:
            if (childDimension >= 0) {
                resultSize = childDimension;
                resultMode = MeasureSpec.EXACTLY;
            } else if (childDimension == LayoutParams.MATCH_PARENT) {
                // Child wants to be our size. So be it.
                resultSize = size;
                resultMode = MeasureSpec.EXACTLY;
            } else if (childDimension == LayoutParams.WRAP_CONTENT) {
                // Child wants to determine its own size. It can't be
                // bigger than us.
                resultSize = size;
                resultMode = MeasureSpec.AT_MOST;
            }
            break;

        // Parent has imposed a maximum size on us
        case MeasureSpec.AT_MOST:
            if (childDimension >= 0) {
                // Child wants a specific size... so be it
                resultSize = childDimension;
                resultMode = MeasureSpec.EXACTLY;
            } else if (childDimension == LayoutParams.MATCH_PARENT) {
                // Child wants to be our size, but our size is not fixed.
                // Constrain child to not be bigger than us.
                resultSize = size;
                resultMode = MeasureSpec.AT_MOST;
            } else if (childDimension == LayoutParams.WRAP_CONTENT) {
                // Child wants to determine its own size. It can't be
                // bigger than us.
                resultSize = size;
                resultMode = MeasureSpec.AT_MOST;
            }
            break;

        // Parent asked to see how big we want to be
        case MeasureSpec.UNSPECIFIED:
            if (childDimension >= 0) {
                // Child wants a specific size... let him have it
                resultSize = childDimension;
                resultMode = MeasureSpec.EXACTLY;
            } else if (childDimension == LayoutParams.MATCH_PARENT) {
                // Child wants to be our size... find out how big it should
                // be
                resultSize = 0;
                resultMode = MeasureSpec.UNSPECIFIED;
            } else if (childDimension == LayoutParams.WRAP_CONTENT) {
                // Child wants to determine its own size.... find out how
                // big it should be
                resultSize = 0;
                resultMode = MeasureSpec.UNSPECIFIED;
            }
            break;
        }
        return MeasureSpec.makeMeasureSpec(resultSize, resultMode);
    }


    /**
     * Removes any pending animations for views that have been removed. Call
     * this if you don't want animations for exiting views to stack up.
     */
    public void clearDisappearingChildren() {
        if (mDisappearingChildren != null) {
            mDisappearingChildren.clear();
        }
    }

    /**
     * Add a view which is removed from mChildren but still needs animation
     *
     * @param v View to add
     */
    private void addDisappearingView(View v) {
        ArrayList<View> disappearingChildren = mDisappearingChildren;

        if (disappearingChildren == null) {
            disappearingChildren = mDisappearingChildren = new ArrayList<View>();
        }

        disappearingChildren.add(v);
    }

    /**
     * Cleanup a view when its animation is done. This may mean removing it from
     * the list of disappearing views.
     *
     * @param view The view whose animation has finished
     * @param animation The animation, cannot be null
     */
    private void finishAnimatingView(final View view, Animation animation) {
        final ArrayList<View> disappearingChildren = mDisappearingChildren;
        if (disappearingChildren != null) {
            if (disappearingChildren.contains(view)) {
                disappearingChildren.remove(view);

                if (view.mAttachInfo != null) {
                    view.dispatchDetachedFromWindow();
                }

                view.clearAnimation();
                mGroupFlags |= FLAG_INVALIDATE_REQUIRED;
            }
        }

        if (animation != null && !animation.getFillAfter()) {
            view.clearAnimation();
        }

        if ((view.mPrivateFlags & ANIMATION_STARTED) == ANIMATION_STARTED) {
            view.onAnimationEnd();
            // Should be performed by onAnimationEnd() but this avoid an infinite loop,
            // so we'd rather be safe than sorry
            view.mPrivateFlags &= ~ANIMATION_STARTED;
            // Draw one more frame after the animation is done
            mGroupFlags |= FLAG_INVALIDATE_REQUIRED;
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean gatherTransparentRegion(Region region) {
        // If no transparent regions requested, we are always opaque.
        final boolean meOpaque = (mPrivateFlags & View.REQUEST_TRANSPARENT_REGIONS) == 0;
        if (meOpaque && region == null) {
            // The caller doesn't care about the region, so stop now.
            return true;
        }
        super.gatherTransparentRegion(region);
        final View[] children = mChildren;
        final int count = mChildrenCount;
        boolean noneOfTheChildrenAreTransparent = true;
        for (int i = 0; i < count; i++) {
            final View child = children[i];
            if ((child.mViewFlags & VISIBILITY_MASK) != GONE || child.getAnimation() != null) {
                if (!child.gatherTransparentRegion(region)) {
                    noneOfTheChildrenAreTransparent = false;
                }
            }
        }
        return meOpaque || noneOfTheChildrenAreTransparent;
    }

    /**
     * {@inheritDoc}
     */
    public void requestTransparentRegion(View child) {
        if (child != null) {
            child.mPrivateFlags |= View.REQUEST_TRANSPARENT_REGIONS;
            if (mParent != null) {
                mParent.requestTransparentRegion(this);
            }
        }
    }


    @Override
    protected boolean fitSystemWindows(Rect insets) {
        boolean done = super.fitSystemWindows(insets);
        if (!done) {
            final int count = mChildrenCount;
            final View[] children = mChildren;
            for (int i = 0; i < count; i++) {
                done = children[i].fitSystemWindows(insets);
                if (done) {
                    break;
                }
            }
        }
        return done;
    }

    /**
     * Returns the animation listener to which layout animation events are
     * sent.
     *
     * @return an {@link android.view.animation.Animation.AnimationListener}
     */
    public Animation.AnimationListener getLayoutAnimationListener() {
        return mAnimationListener;
    }

    @Override
    protected void drawableStateChanged() {
        super.drawableStateChanged();

        if ((mGroupFlags & FLAG_NOTIFY_CHILDREN_ON_DRAWABLE_STATE_CHANGE) != 0) {
            if ((mGroupFlags & FLAG_ADD_STATES_FROM_CHILDREN) != 0) {
                throw new IllegalStateException("addStateFromChildren cannot be enabled if a"
                        + " child has duplicateParentState set to true");
            }

            final View[] children = mChildren;
            final int count = mChildrenCount;

            for (int i = 0; i < count; i++) {
                final View child = children[i];
                if ((child.mViewFlags & DUPLICATE_PARENT_STATE) != 0) {
                    child.refreshDrawableState();
                }
            }
        }
    }

    @Override
    protected int[] onCreateDrawableState(int extraSpace) {
        if ((mGroupFlags & FLAG_ADD_STATES_FROM_CHILDREN) == 0) {
            return super.onCreateDrawableState(extraSpace);
        }

        int need = 0;
        int n = getChildCount();
        for (int i = 0; i < n; i++) {
            int[] childState = getChildAt(i).getDrawableState();

            if (childState != null) {
                need += childState.length;
            }
        }

        int[] state = super.onCreateDrawableState(extraSpace + need);

        for (int i = 0; i < n; i++) {
            int[] childState = getChildAt(i).getDrawableState();

            if (childState != null) {
                state = mergeDrawableStates(state, childState);
            }
        }

        return state;
    }

    /**
     * Sets whether this ViewGroup's drawable states also include
     * its children's drawable states.  This is used, for example, to
     * make a group appear to be focused when its child EditText or button
     * is focused.
     */
    public void setAddStatesFromChildren(boolean addsStates) {
        if (addsStates) {
            mGroupFlags |= FLAG_ADD_STATES_FROM_CHILDREN;
        } else {
            mGroupFlags &= ~FLAG_ADD_STATES_FROM_CHILDREN;
        }

        refreshDrawableState();
    }

    /**
     * Returns whether this ViewGroup's drawable states also include
     * its children's drawable states.  This is used, for example, to
     * make a group appear to be focused when its child EditText or button
     * is focused.
     */
    public boolean addStatesFromChildren() {
        return (mGroupFlags & FLAG_ADD_STATES_FROM_CHILDREN) != 0;
    }

    /**
     * If {link #addStatesFromChildren} is true, refreshes this group's
     * drawable state (to include the states from its children).
     */
    public void childDrawableStateChanged(View child) {
        if ((mGroupFlags & FLAG_ADD_STATES_FROM_CHILDREN) != 0) {
            refreshDrawableState();
        }
    }

    /**
     * Specifies the animation listener to which layout animation events must
     * be sent. Only
     * {@link android.view.animation.Animation.AnimationListener#onAnimationStart(Animation)}
     * and
     * {@link android.view.animation.Animation.AnimationListener#onAnimationEnd(Animation)}
     * are invoked.
     *
     * @param animationListener the layout animation listener
     */
    public void setLayoutAnimationListener(Animation.AnimationListener animationListener) {
        mAnimationListener = animationListener;
    }

    /**
     * LayoutParams are used by views to tell their parents how they want to be
     * laid out. See
     * {@link android.R.styleable#ViewGroup_Layout ViewGroup Layout Attributes}
     * for a list of all child view attributes that this class supports.
     *
     * <p>
     * The base LayoutParams class just describes how big the view wants to be
     * for both width and height. For each dimension, it can specify one of:
     * <ul>
     * <li>FILL_PARENT (renamed MATCH_PARENT in API Level 8 and higher), which
     * means that the view wants to be as big as its parent (minus padding)
     * <li> WRAP_CONTENT, which means that the view wants to be just big enough
     * to enclose its content (plus padding)
     * <li> an exact number
     * </ul>
     * There are subclasses of LayoutParams for different subclasses of
     * ViewGroup. For example, AbsoluteLayout has its own subclass of
     * LayoutParams which adds an X and Y value.
     *
     * @attr ref android.R.styleable#ViewGroup_Layout_layout_height
     * @attr ref android.R.styleable#ViewGroup_Layout_layout_width
     */
    public static class LayoutParams {
        /**
         * Special value for the height or width requested by a View.
         * FILL_PARENT means that the view wants to be as big as its parent,
         * minus the parent's padding, if any. This value is deprecated
         * starting in API Level 8 and replaced by {@link #MATCH_PARENT}.
         */
        @SuppressWarnings({"UnusedDeclaration"})
        @Deprecated
        public static final int FILL_PARENT = -1;

        /**
         * Special value for the height or width requested by a View.
         * MATCH_PARENT means that the view wants to be as big as its parent,
         * minus the parent's padding, if any. Introduced in API Level 8.
         */
        public static final int MATCH_PARENT = -1;

        /**
         * Special value for the height or width requested by a View.
         * WRAP_CONTENT means that the view wants to be just large enough to fit
         * its own internal content, taking its own padding into account.
         */
        public static final int WRAP_CONTENT = -2;

        /**
         * Information about how wide the view wants to be. Can be one of the
         * constants FILL_PARENT (replaced by MATCH_PARENT ,
         * in API Level 8) or WRAP_CONTENT. or an exact size.
         */
        @ViewDebug.ExportedProperty(mapping = {
            @ViewDebug.IntToString(from = MATCH_PARENT, to = "MATCH_PARENT"),
            @ViewDebug.IntToString(from = WRAP_CONTENT, to = "WRAP_CONTENT")
        })
        public int width;

        /**
         * Information about how tall the view wants to be. Can be one of the
         * constants FILL_PARENT (replaced by MATCH_PARENT ,
         * in API Level 8) or WRAP_CONTENT. or an exact size.
         */
        @ViewDebug.ExportedProperty(mapping = {
            @ViewDebug.IntToString(from = MATCH_PARENT, to = "MATCH_PARENT"),
            @ViewDebug.IntToString(from = WRAP_CONTENT, to = "WRAP_CONTENT")
        })
        public int height;

        /**
         * Used to animate layouts.
         */
        public LayoutAnimationController.AnimationParameters layoutAnimationParameters;

        /**
         * Creates a new set of layout parameters. The values are extracted from
         * the supplied attributes set and context. The XML attributes mapped
         * to this set of layout parameters are:
         *
         * <ul>
         *   <li>layout_width: the width, either an exact value,
         *   {@link #WRAP_CONTENT}, or {@link #FILL_PARENT} (replaced by
         *   {@link #MATCH_PARENT} in API Level 8)</li>
         *   <li>layout_height: the height, either an exact value,
         *   {@link #WRAP_CONTENT}, or {@link #FILL_PARENT} (replaced by
         *   {@link #MATCH_PARENT} in API Level 8)</li>
         * </ul>
         *
         * @param c the application environment
         * @param attrs the set of attributes from which to extract the layout
         *              parameters' values
         */
        public LayoutParams(Context c, AttributeSet attrs) {
            TypedArray a = c.obtainStyledAttributes(attrs, R.styleable.ViewGroup_Layout);
            setBaseAttributes(a,
                    R.styleable.ViewGroup_Layout_layout_width,
                    R.styleable.ViewGroup_Layout_layout_height);
            a.recycle();
        }

        /**
         * Creates a new set of layout parameters with the specified width
         * and height.
         *
         * @param width the width, either {@link #WRAP_CONTENT},
         *        {@link #FILL_PARENT} (replaced by {@link #MATCH_PARENT} in
         *        API Level 8), or a fixed size in pixels
         * @param height the height, either {@link #WRAP_CONTENT},
         *        {@link #FILL_PARENT} (replaced by {@link #MATCH_PARENT} in
         *        API Level 8), or a fixed size in pixels
         */
        public LayoutParams(int width, int height) {
            this.width = width;
            this.height = height;
        }

        /**
         * Copy constructor. Clones the width and height values of the source.
         *
         * @param source The layout params to copy from.
         */
        public LayoutParams(LayoutParams source) {
            this.width = source.width;
            this.height = source.height;
        }

        /**
         * Used internally by MarginLayoutParams.
         * @hide
         */
        LayoutParams() {
        }

        /**
         * Extracts the layout parameters from the supplied attributes.
         *
         * @param a the style attributes to extract the parameters from
         * @param widthAttr the identifier of the width attribute
         * @param heightAttr the identifier of the height attribute
         */
        protected void setBaseAttributes(TypedArray a, int widthAttr, int heightAttr) {
            width = a.getLayoutDimension(widthAttr, "layout_width");
            height = a.getLayoutDimension(heightAttr, "layout_height");
        }

        /**
         * Returns a String representation of this set of layout parameters.
         *
         * @param output the String to prepend to the internal representation
         * @return a String with the following format: output +
         *         "ViewGroup.LayoutParams={ width=WIDTH, height=HEIGHT }"
         *
         * @hide
         */
        public String debug(String output) {
            return output + "ViewGroup.LayoutParams={ width="
                    + sizeToString(width) + ", height=" + sizeToString(height) + " }";
        }

        /**
         * Converts the specified size to a readable String.
         *
         * @param size the size to convert
         * @return a String instance representing the supplied size
         *
         * @hide
         */
        protected static String sizeToString(int size) {
            if (size == WRAP_CONTENT) {
                return "wrap-content";
            }
            if (size == MATCH_PARENT) {
                return "match-parent";
            }
            return String.valueOf(size);
        }
    }

    /**
     * Per-child layout information for layouts that support margins.
     * See
     * {@link android.R.styleable#ViewGroup_MarginLayout ViewGroup Margin Layout Attributes}
     * for a list of all child view attributes that this class supports.
     */
    public static class MarginLayoutParams extends ViewGroup.LayoutParams {
        /**
         * The left margin in pixels of the child.
         */
        @ViewDebug.ExportedProperty
        public int leftMargin;

        /**
         * The top margin in pixels of the child.
         */
        @ViewDebug.ExportedProperty
        public int topMargin;

        /**
         * The right margin in pixels of the child.
         */
        @ViewDebug.ExportedProperty
        public int rightMargin;

        /**
         * The bottom margin in pixels of the child.
         */
        @ViewDebug.ExportedProperty
        public int bottomMargin;

        /**
         * Creates a new set of layout parameters. The values are extracted from
         * the supplied attributes set and context.
         *
         * @param c the application environment
         * @param attrs the set of attributes from which to extract the layout
         *              parameters' values
         */
        public MarginLayoutParams(Context c, AttributeSet attrs) {
            super();

            TypedArray a = c.obtainStyledAttributes(attrs, R.styleable.ViewGroup_MarginLayout);
            setBaseAttributes(a,
                    R.styleable.ViewGroup_MarginLayout_layout_width,
                    R.styleable.ViewGroup_MarginLayout_layout_height);

            int margin = a.getDimensionPixelSize(
                    com.android.internal.R.styleable.ViewGroup_MarginLayout_layout_margin, -1);
            if (margin >= 0) {
                leftMargin = margin;
                topMargin = margin;
                rightMargin= margin;
                bottomMargin = margin;
            } else {
                leftMargin = a.getDimensionPixelSize(
                        R.styleable.ViewGroup_MarginLayout_layout_marginLeft, 0);
                topMargin = a.getDimensionPixelSize(
                        R.styleable.ViewGroup_MarginLayout_layout_marginTop, 0);
                rightMargin = a.getDimensionPixelSize(
                        R.styleable.ViewGroup_MarginLayout_layout_marginRight, 0);
                bottomMargin = a.getDimensionPixelSize(
                        R.styleable.ViewGroup_MarginLayout_layout_marginBottom, 0);
            }

            a.recycle();
        }

        /**
         * {@inheritDoc}
         */
        public MarginLayoutParams(int width, int height) {
            super(width, height);
        }

        /**
         * Copy constructor. Clones the width, height and margin values of the source.
         *
         * @param source The layout params to copy from.
         */
        public MarginLayoutParams(MarginLayoutParams source) {
            this.width = source.width;
            this.height = source.height;

            this.leftMargin = source.leftMargin;
            this.topMargin = source.topMargin;
            this.rightMargin = source.rightMargin;
            this.bottomMargin = source.bottomMargin;
        }

        /**
         * {@inheritDoc}
         */
        public MarginLayoutParams(LayoutParams source) {
            super(source);
        }

        /**
         * Sets the margins, in pixels.
         *
         * @param left the left margin size
         * @param top the top margin size
         * @param right the right margin size
         * @param bottom the bottom margin size
         *
         * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginLeft
         * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginTop
         * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginRight
         * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginBottom
         */
        public void setMargins(int left, int top, int right, int bottom) {
            leftMargin = left;
            topMargin = top;
            rightMargin = right;
            bottomMargin = bottom;
        }
    }
}

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