Android example source code file (Gallery.java)
The Gallery.java Android example source code/*
* Copyright (C) 2007 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.widget;
import com.android.internal.R;
import android.annotation.Widget;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.util.Log;
import android.view.GestureDetector;
import android.view.Gravity;
import android.view.HapticFeedbackConstants;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.view.SoundEffectConstants;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.animation.Transformation;
/**
* A view that shows items in a center-locked, horizontally scrolling list.
* <p>
* The default values for the Gallery assume you will be using
* {@link android.R.styleable#Theme_galleryItemBackground} as the background for
* each View given to the Gallery from the Adapter. If you are not doing this,
* you may need to adjust some Gallery properties, such as the spacing.
* <p>
* Views given to the Gallery should use {@link Gallery.LayoutParams} as their
* layout parameters type.
*
* @attr ref android.R.styleable#Gallery_animationDuration
* @attr ref android.R.styleable#Gallery_spacing
* @attr ref android.R.styleable#Gallery_gravity
*/
@Widget
public class Gallery extends AbsSpinner implements GestureDetector.OnGestureListener {
private static final String TAG = "Gallery";
private static final boolean localLOGV = false;
/**
* Duration in milliseconds from the start of a scroll during which we're
* unsure whether the user is scrolling or flinging.
*/
private static final int SCROLL_TO_FLING_UNCERTAINTY_TIMEOUT = 250;
/**
* Horizontal spacing between items.
*/
private int mSpacing = 0;
/**
* How long the transition animation should run when a child view changes
* position, measured in milliseconds.
*/
private int mAnimationDuration = 400;
/**
* The alpha of items that are not selected.
*/
private float mUnselectedAlpha;
/**
* Left most edge of a child seen so far during layout.
*/
private int mLeftMost;
/**
* Right most edge of a child seen so far during layout.
*/
private int mRightMost;
private int mGravity;
/**
* Helper for detecting touch gestures.
*/
private GestureDetector mGestureDetector;
/**
* The position of the item that received the user's down touch.
*/
private int mDownTouchPosition;
/**
* The view of the item that received the user's down touch.
*/
private View mDownTouchView;
/**
* Executes the delta scrolls from a fling or scroll movement.
*/
private FlingRunnable mFlingRunnable = new FlingRunnable();
/**
* Sets mSuppressSelectionChanged = false. This is used to set it to false
* in the future. It will also trigger a selection changed.
*/
private Runnable mDisableSuppressSelectionChangedRunnable = new Runnable() {
public void run() {
mSuppressSelectionChanged = false;
selectionChanged();
}
};
/**
* When fling runnable runs, it resets this to false. Any method along the
* path until the end of its run() can set this to true to abort any
* remaining fling. For example, if we've reached either the leftmost or
* rightmost item, we will set this to true.
*/
private boolean mShouldStopFling;
/**
* The currently selected item's child.
*/
private View mSelectedChild;
/**
* Whether to continuously callback on the item selected listener during a
* fling.
*/
private boolean mShouldCallbackDuringFling = true;
/**
* Whether to callback when an item that is not selected is clicked.
*/
private boolean mShouldCallbackOnUnselectedItemClick = true;
/**
* If true, do not callback to item selected listener.
*/
private boolean mSuppressSelectionChanged;
/**
* If true, we have received the "invoke" (center or enter buttons) key
* down. This is checked before we action on the "invoke" key up, and is
* subsequently cleared.
*/
private boolean mReceivedInvokeKeyDown;
private AdapterContextMenuInfo mContextMenuInfo;
/**
* If true, this onScroll is the first for this user's drag (remember, a
* drag sends many onScrolls).
*/
private boolean mIsFirstScroll;
public Gallery(Context context) {
this(context, null);
}
public Gallery(Context context, AttributeSet attrs) {
this(context, attrs, R.attr.galleryStyle);
}
public Gallery(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mGestureDetector = new GestureDetector(context, this);
mGestureDetector.setIsLongpressEnabled(true);
TypedArray a = context.obtainStyledAttributes(
attrs, com.android.internal.R.styleable.Gallery, defStyle, 0);
int index = a.getInt(com.android.internal.R.styleable.Gallery_gravity, -1);
if (index >= 0) {
setGravity(index);
}
int animationDuration =
a.getInt(com.android.internal.R.styleable.Gallery_animationDuration, -1);
if (animationDuration > 0) {
setAnimationDuration(animationDuration);
}
int spacing =
a.getDimensionPixelOffset(com.android.internal.R.styleable.Gallery_spacing, 0);
setSpacing(spacing);
float unselectedAlpha = a.getFloat(
com.android.internal.R.styleable.Gallery_unselectedAlpha, 0.5f);
setUnselectedAlpha(unselectedAlpha);
a.recycle();
// We draw the selected item last (because otherwise the item to the
// right overlaps it)
mGroupFlags |= FLAG_USE_CHILD_DRAWING_ORDER;
mGroupFlags |= FLAG_SUPPORT_STATIC_TRANSFORMATIONS;
}
/**
* Whether or not to callback on any {@link #getOnItemSelectedListener()}
* while the items are being flinged. If false, only the final selected item
* will cause the callback. If true, all items between the first and the
* final will cause callbacks.
*
* @param shouldCallback Whether or not to callback on the listener while
* the items are being flinged.
*/
public void setCallbackDuringFling(boolean shouldCallback) {
mShouldCallbackDuringFling = shouldCallback;
}
/**
* Whether or not to callback when an item that is not selected is clicked.
* If false, the item will become selected (and re-centered). If true, the
* {@link #getOnItemClickListener()} will get the callback.
*
* @param shouldCallback Whether or not to callback on the listener when a
* item that is not selected is clicked.
* @hide
*/
public void setCallbackOnUnselectedItemClick(boolean shouldCallback) {
mShouldCallbackOnUnselectedItemClick = shouldCallback;
}
/**
* Sets how long the transition animation should run when a child view
* changes position. Only relevant if animation is turned on.
*
* @param animationDurationMillis The duration of the transition, in
* milliseconds.
*
* @attr ref android.R.styleable#Gallery_animationDuration
*/
public void setAnimationDuration(int animationDurationMillis) {
mAnimationDuration = animationDurationMillis;
}
/**
* Sets the spacing between items in a Gallery
*
* @param spacing The spacing in pixels between items in the Gallery
*
* @attr ref android.R.styleable#Gallery_spacing
*/
public void setSpacing(int spacing) {
mSpacing = spacing;
}
/**
* Sets the alpha of items that are not selected in the Gallery.
*
* @param unselectedAlpha the alpha for the items that are not selected.
*
* @attr ref android.R.styleable#Gallery_unselectedAlpha
*/
public void setUnselectedAlpha(float unselectedAlpha) {
mUnselectedAlpha = unselectedAlpha;
}
@Override
protected boolean getChildStaticTransformation(View child, Transformation t) {
t.clear();
t.setAlpha(child == mSelectedChild ? 1.0f : mUnselectedAlpha);
return true;
}
@Override
protected int computeHorizontalScrollExtent() {
// Only 1 item is considered to be selected
return 1;
}
@Override
protected int computeHorizontalScrollOffset() {
// Current scroll position is the same as the selected position
return mSelectedPosition;
}
@Override
protected int computeHorizontalScrollRange() {
// Scroll range is the same as the item count
return mItemCount;
}
@Override
protected boolean checkLayoutParams(ViewGroup.LayoutParams p) {
return p instanceof LayoutParams;
}
@Override
protected ViewGroup.LayoutParams generateLayoutParams(ViewGroup.LayoutParams p) {
return new LayoutParams(p);
}
@Override
public ViewGroup.LayoutParams generateLayoutParams(AttributeSet attrs) {
return new LayoutParams(getContext(), attrs);
}
@Override
protected ViewGroup.LayoutParams generateDefaultLayoutParams() {
/*
* Gallery expects Gallery.LayoutParams.
*/
return new Gallery.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,
ViewGroup.LayoutParams.WRAP_CONTENT);
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
super.onLayout(changed, l, t, r, b);
/*
* Remember that we are in layout to prevent more layout request from
* being generated.
*/
mInLayout = true;
layout(0, false);
mInLayout = false;
}
@Override
int getChildHeight(View child) {
return child.getMeasuredHeight();
}
/**
* Tracks a motion scroll. In reality, this is used to do just about any
* movement to items (touch scroll, arrow-key scroll, set an item as selected).
*
* @param deltaX Change in X from the previous event.
*/
void trackMotionScroll(int deltaX) {
if (getChildCount() == 0) {
return;
}
boolean toLeft = deltaX < 0;
int limitedDeltaX = getLimitedMotionScrollAmount(toLeft, deltaX);
if (limitedDeltaX != deltaX) {
// The above call returned a limited amount, so stop any scrolls/flings
mFlingRunnable.endFling(false);
onFinishedMovement();
}
offsetChildrenLeftAndRight(limitedDeltaX);
detachOffScreenChildren(toLeft);
if (toLeft) {
// If moved left, there will be empty space on the right
fillToGalleryRight();
} else {
// Similarly, empty space on the left
fillToGalleryLeft();
}
// Clear unused views
mRecycler.clear();
setSelectionToCenterChild();
invalidate();
}
int getLimitedMotionScrollAmount(boolean motionToLeft, int deltaX) {
int extremeItemPosition = motionToLeft ? mItemCount - 1 : 0;
View extremeChild = getChildAt(extremeItemPosition - mFirstPosition);
if (extremeChild == null) {
return deltaX;
}
int extremeChildCenter = getCenterOfView(extremeChild);
int galleryCenter = getCenterOfGallery();
if (motionToLeft) {
if (extremeChildCenter <= galleryCenter) {
// The extreme child is past his boundary point!
return 0;
}
} else {
if (extremeChildCenter >= galleryCenter) {
// The extreme child is past his boundary point!
return 0;
}
}
int centerDifference = galleryCenter - extremeChildCenter;
return motionToLeft
? Math.max(centerDifference, deltaX)
: Math.min(centerDifference, deltaX);
}
/**
* Offset the horizontal location of all children of this view by the
* specified number of pixels.
*
* @param offset the number of pixels to offset
*/
private void offsetChildrenLeftAndRight(int offset) {
for (int i = getChildCount() - 1; i >= 0; i--) {
getChildAt(i).offsetLeftAndRight(offset);
}
}
/**
* @return The center of this Gallery.
*/
private int getCenterOfGallery() {
return (getWidth() - mPaddingLeft - mPaddingRight) / 2 + mPaddingLeft;
}
/**
* @return The center of the given view.
*/
private static int getCenterOfView(View view) {
return view.getLeft() + view.getWidth() / 2;
}
/**
* Detaches children that are off the screen (i.e.: Gallery bounds).
*
* @param toLeft Whether to detach children to the left of the Gallery, or
* to the right.
*/
private void detachOffScreenChildren(boolean toLeft) {
int numChildren = getChildCount();
int firstPosition = mFirstPosition;
int start = 0;
int count = 0;
if (toLeft) {
final int galleryLeft = mPaddingLeft;
for (int i = 0; i < numChildren; i++) {
final View child = getChildAt(i);
if (child.getRight() >= galleryLeft) {
break;
} else {
count++;
mRecycler.put(firstPosition + i, child);
}
}
} else {
final int galleryRight = getWidth() - mPaddingRight;
for (int i = numChildren - 1; i >= 0; i--) {
final View child = getChildAt(i);
if (child.getLeft() <= galleryRight) {
break;
} else {
start = i;
count++;
mRecycler.put(firstPosition + i, child);
}
}
}
detachViewsFromParent(start, count);
if (toLeft) {
mFirstPosition += count;
}
}
/**
* Scrolls the items so that the selected item is in its 'slot' (its center
* is the gallery's center).
*/
private void scrollIntoSlots() {
if (getChildCount() == 0 || mSelectedChild == null) return;
int selectedCenter = getCenterOfView(mSelectedChild);
int targetCenter = getCenterOfGallery();
int scrollAmount = targetCenter - selectedCenter;
if (scrollAmount != 0) {
mFlingRunnable.startUsingDistance(scrollAmount);
} else {
onFinishedMovement();
}
}
private void onFinishedMovement() {
if (mSuppressSelectionChanged) {
mSuppressSelectionChanged = false;
// We haven't been callbacking during the fling, so do it now
super.selectionChanged();
}
invalidate();
}
@Override
void selectionChanged() {
if (!mSuppressSelectionChanged) {
super.selectionChanged();
}
}
/**
* Looks for the child that is closest to the center and sets it as the
* selected child.
*/
private void setSelectionToCenterChild() {
View selView = mSelectedChild;
if (mSelectedChild == null) return;
int galleryCenter = getCenterOfGallery();
// Common case where the current selected position is correct
if (selView.getLeft() <= galleryCenter && selView.getRight() >= galleryCenter) {
return;
}
// TODO better search
int closestEdgeDistance = Integer.MAX_VALUE;
int newSelectedChildIndex = 0;
for (int i = getChildCount() - 1; i >= 0; i--) {
View child = getChildAt(i);
if (child.getLeft() <= galleryCenter && child.getRight() >= galleryCenter) {
// This child is in the center
newSelectedChildIndex = i;
break;
}
int childClosestEdgeDistance = Math.min(Math.abs(child.getLeft() - galleryCenter),
Math.abs(child.getRight() - galleryCenter));
if (childClosestEdgeDistance < closestEdgeDistance) {
closestEdgeDistance = childClosestEdgeDistance;
newSelectedChildIndex = i;
}
}
int newPos = mFirstPosition + newSelectedChildIndex;
if (newPos != mSelectedPosition) {
setSelectedPositionInt(newPos);
setNextSelectedPositionInt(newPos);
checkSelectionChanged();
}
}
/**
* Creates and positions all views for this Gallery.
* <p>
* We layout rarely, most of the time {@link #trackMotionScroll(int)} takes
* care of repositioning, adding, and removing children.
*
* @param delta Change in the selected position. +1 means the selection is
* moving to the right, so views are scrolling to the left. -1
* means the selection is moving to the left.
*/
@Override
void layout(int delta, boolean animate) {
int childrenLeft = mSpinnerPadding.left;
int childrenWidth = mRight - mLeft - mSpinnerPadding.left - mSpinnerPadding.right;
if (mDataChanged) {
handleDataChanged();
}
// Handle an empty gallery by removing all views.
if (mItemCount == 0) {
resetList();
return;
}
// Update to the new selected position.
if (mNextSelectedPosition >= 0) {
setSelectedPositionInt(mNextSelectedPosition);
}
// All views go in recycler while we are in layout
recycleAllViews();
// Clear out old views
//removeAllViewsInLayout();
detachAllViewsFromParent();
/*
* These will be used to give initial positions to views entering the
* gallery as we scroll
*/
mRightMost = 0;
mLeftMost = 0;
// Make selected view and center it
/*
* mFirstPosition will be decreased as we add views to the left later
* on. The 0 for x will be offset in a couple lines down.
*/
mFirstPosition = mSelectedPosition;
View sel = makeAndAddView(mSelectedPosition, 0, 0, true);
// Put the selected child in the center
int selectedOffset = childrenLeft + (childrenWidth / 2) - (sel.getWidth() / 2);
sel.offsetLeftAndRight(selectedOffset);
fillToGalleryRight();
fillToGalleryLeft();
// Flush any cached views that did not get reused above
mRecycler.clear();
invalidate();
checkSelectionChanged();
mDataChanged = false;
mNeedSync = false;
setNextSelectedPositionInt(mSelectedPosition);
updateSelectedItemMetadata();
}
private void fillToGalleryLeft() {
int itemSpacing = mSpacing;
int galleryLeft = mPaddingLeft;
// Set state for initial iteration
View prevIterationView = getChildAt(0);
int curPosition;
int curRightEdge;
if (prevIterationView != null) {
curPosition = mFirstPosition - 1;
curRightEdge = prevIterationView.getLeft() - itemSpacing;
} else {
// No children available!
curPosition = 0;
curRightEdge = mRight - mLeft - mPaddingRight;
mShouldStopFling = true;
}
while (curRightEdge > galleryLeft && curPosition >= 0) {
prevIterationView = makeAndAddView(curPosition, curPosition - mSelectedPosition,
curRightEdge, false);
// Remember some state
mFirstPosition = curPosition;
// Set state for next iteration
curRightEdge = prevIterationView.getLeft() - itemSpacing;
curPosition--;
}
}
private void fillToGalleryRight() {
int itemSpacing = mSpacing;
int galleryRight = mRight - mLeft - mPaddingRight;
int numChildren = getChildCount();
int numItems = mItemCount;
// Set state for initial iteration
View prevIterationView = getChildAt(numChildren - 1);
int curPosition;
int curLeftEdge;
if (prevIterationView != null) {
curPosition = mFirstPosition + numChildren;
curLeftEdge = prevIterationView.getRight() + itemSpacing;
} else {
mFirstPosition = curPosition = mItemCount - 1;
curLeftEdge = mPaddingLeft;
mShouldStopFling = true;
}
while (curLeftEdge < galleryRight && curPosition < numItems) {
prevIterationView = makeAndAddView(curPosition, curPosition - mSelectedPosition,
curLeftEdge, true);
// Set state for next iteration
curLeftEdge = prevIterationView.getRight() + itemSpacing;
curPosition++;
}
}
/**
* Obtain a view, either by pulling an existing view from the recycler or by
* getting a new one from the adapter. If we are animating, make sure there
* is enough information in the view's layout parameters to animate from the
* old to new positions.
*
* @param position Position in the gallery for the view to obtain
* @param offset Offset from the selected position
* @param x X-coordintate indicating where this view should be placed. This
* will either be the left or right edge of the view, depending on
* the fromLeft paramter
* @param fromLeft Are we posiitoning views based on the left edge? (i.e.,
* building from left to right)?
* @return A view that has been added to the gallery
*/
private View makeAndAddView(int position, int offset, int x,
boolean fromLeft) {
View child;
if (!mDataChanged) {
child = mRecycler.get(position);
if (child != null) {
// Can reuse an existing view
int childLeft = child.getLeft();
// Remember left and right edges of where views have been placed
mRightMost = Math.max(mRightMost, childLeft
+ child.getMeasuredWidth());
mLeftMost = Math.min(mLeftMost, childLeft);
// Position the view
setUpChild(child, offset, x, fromLeft);
return child;
}
}
// Nothing found in the recycler -- ask the adapter for a view
child = mAdapter.getView(position, null, this);
// Position the view
setUpChild(child, offset, x, fromLeft);
return child;
}
/**
* Helper for makeAndAddView to set the position of a view and fill out its
* layout paramters.
*
* @param child The view to position
* @param offset Offset from the selected position
* @param x X-coordintate indicating where this view should be placed. This
* will either be the left or right edge of the view, depending on
* the fromLeft paramter
* @param fromLeft Are we posiitoning views based on the left edge? (i.e.,
* building from left to right)?
*/
private void setUpChild(View child, int offset, int x, boolean fromLeft) {
// Respect layout params that are already in the view. Otherwise
// make some up...
Gallery.LayoutParams lp = (Gallery.LayoutParams)
child.getLayoutParams();
if (lp == null) {
lp = (Gallery.LayoutParams) generateDefaultLayoutParams();
}
addViewInLayout(child, fromLeft ? -1 : 0, lp);
child.setSelected(offset == 0);
// Get measure specs
int childHeightSpec = ViewGroup.getChildMeasureSpec(mHeightMeasureSpec,
mSpinnerPadding.top + mSpinnerPadding.bottom, lp.height);
int childWidthSpec = ViewGroup.getChildMeasureSpec(mWidthMeasureSpec,
mSpinnerPadding.left + mSpinnerPadding.right, lp.width);
// Measure child
child.measure(childWidthSpec, childHeightSpec);
int childLeft;
int childRight;
// Position vertically based on gravity setting
int childTop = calculateTop(child, true);
int childBottom = childTop + child.getMeasuredHeight();
int width = child.getMeasuredWidth();
if (fromLeft) {
childLeft = x;
childRight = childLeft + width;
} else {
childLeft = x - width;
childRight = x;
}
child.layout(childLeft, childTop, childRight, childBottom);
}
/**
* Figure out vertical placement based on mGravity
*
* @param child Child to place
* @return Where the top of the child should be
*/
private int calculateTop(View child, boolean duringLayout) {
int myHeight = duringLayout ? mMeasuredHeight : getHeight();
int childHeight = duringLayout ? child.getMeasuredHeight() : child.getHeight();
int childTop = 0;
switch (mGravity) {
case Gravity.TOP:
childTop = mSpinnerPadding.top;
break;
case Gravity.CENTER_VERTICAL:
int availableSpace = myHeight - mSpinnerPadding.bottom
- mSpinnerPadding.top - childHeight;
childTop = mSpinnerPadding.top + (availableSpace / 2);
break;
case Gravity.BOTTOM:
childTop = myHeight - mSpinnerPadding.bottom - childHeight;
break;
}
return childTop;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
// Give everything to the gesture detector
boolean retValue = mGestureDetector.onTouchEvent(event);
int action = event.getAction();
if (action == MotionEvent.ACTION_UP) {
// Helper method for lifted finger
onUp();
} else if (action == MotionEvent.ACTION_CANCEL) {
onCancel();
}
return retValue;
}
/**
* {@inheritDoc}
*/
public boolean onSingleTapUp(MotionEvent e) {
if (mDownTouchPosition >= 0) {
// An item tap should make it selected, so scroll to this child.
scrollToChild(mDownTouchPosition - mFirstPosition);
// Also pass the click so the client knows, if it wants to.
if (mShouldCallbackOnUnselectedItemClick || mDownTouchPosition == mSelectedPosition) {
performItemClick(mDownTouchView, mDownTouchPosition, mAdapter
.getItemId(mDownTouchPosition));
}
return true;
}
return false;
}
/**
* {@inheritDoc}
*/
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
if (!mShouldCallbackDuringFling) {
// We want to suppress selection changes
// Remove any future code to set mSuppressSelectionChanged = false
removeCallbacks(mDisableSuppressSelectionChangedRunnable);
// This will get reset once we scroll into slots
if (!mSuppressSelectionChanged) mSuppressSelectionChanged = true;
}
// Fling the gallery!
mFlingRunnable.startUsingVelocity((int) -velocityX);
return true;
}
/**
* {@inheritDoc}
*/
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
if (localLOGV) Log.v(TAG, String.valueOf(e2.getX() - e1.getX()));
/*
* Now's a good time to tell our parent to stop intercepting our events!
* The user has moved more than the slop amount, since GestureDetector
* ensures this before calling this method. Also, if a parent is more
* interested in this touch's events than we are, it would have
* intercepted them by now (for example, we can assume when a Gallery is
* in the ListView, a vertical scroll would not end up in this method
* since a ListView would have intercepted it by now).
*/
mParent.requestDisallowInterceptTouchEvent(true);
// As the user scrolls, we want to callback selection changes so related-
// info on the screen is up-to-date with the gallery's selection
if (!mShouldCallbackDuringFling) {
if (mIsFirstScroll) {
/*
* We're not notifying the client of selection changes during
* the fling, and this scroll could possibly be a fling. Don't
* do selection changes until we're sure it is not a fling.
*/
if (!mSuppressSelectionChanged) mSuppressSelectionChanged = true;
postDelayed(mDisableSuppressSelectionChangedRunnable, SCROLL_TO_FLING_UNCERTAINTY_TIMEOUT);
}
} else {
if (mSuppressSelectionChanged) mSuppressSelectionChanged = false;
}
// Track the motion
trackMotionScroll(-1 * (int) distanceX);
mIsFirstScroll = false;
return true;
}
/**
* {@inheritDoc}
*/
public boolean onDown(MotionEvent e) {
// Kill any existing fling/scroll
mFlingRunnable.stop(false);
// Get the item's view that was touched
mDownTouchPosition = pointToPosition((int) e.getX(), (int) e.getY());
if (mDownTouchPosition >= 0) {
mDownTouchView = getChildAt(mDownTouchPosition - mFirstPosition);
mDownTouchView.setPressed(true);
}
// Reset the multiple-scroll tracking state
mIsFirstScroll = true;
// Must return true to get matching events for this down event.
return true;
}
/**
* Called when a touch event's action is MotionEvent.ACTION_UP.
*/
void onUp() {
if (mFlingRunnable.mScroller.isFinished()) {
scrollIntoSlots();
}
dispatchUnpress();
}
/**
* Called when a touch event's action is MotionEvent.ACTION_CANCEL.
*/
void onCancel() {
onUp();
}
/**
* {@inheritDoc}
*/
public void onLongPress(MotionEvent e) {
if (mDownTouchPosition < 0) {
return;
}
performHapticFeedback(HapticFeedbackConstants.LONG_PRESS);
long id = getItemIdAtPosition(mDownTouchPosition);
dispatchLongPress(mDownTouchView, mDownTouchPosition, id);
}
// Unused methods from GestureDetector.OnGestureListener below
/**
* {@inheritDoc}
*/
public void onShowPress(MotionEvent e) {
}
// Unused methods from GestureDetector.OnGestureListener above
private void dispatchPress(View child) {
if (child != null) {
child.setPressed(true);
}
setPressed(true);
}
private void dispatchUnpress() {
for (int i = getChildCount() - 1; i >= 0; i--) {
getChildAt(i).setPressed(false);
}
setPressed(false);
}
@Override
public void dispatchSetSelected(boolean selected) {
/*
* We don't want to pass the selected state given from its parent to its
* children since this widget itself has a selected state to give to its
* children.
*/
}
@Override
protected void dispatchSetPressed(boolean pressed) {
// Show the pressed state on the selected child
if (mSelectedChild != null) {
mSelectedChild.setPressed(pressed);
}
}
@Override
protected ContextMenuInfo getContextMenuInfo() {
return mContextMenuInfo;
}
@Override
public boolean showContextMenuForChild(View originalView) {
final int longPressPosition = getPositionForView(originalView);
if (longPressPosition < 0) {
return false;
}
final long longPressId = mAdapter.getItemId(longPressPosition);
return dispatchLongPress(originalView, longPressPosition, longPressId);
}
@Override
public boolean showContextMenu() {
if (isPressed() && mSelectedPosition >= 0) {
int index = mSelectedPosition - mFirstPosition;
View v = getChildAt(index);
return dispatchLongPress(v, mSelectedPosition, mSelectedRowId);
}
return false;
}
private boolean dispatchLongPress(View view, int position, long id) {
boolean handled = false;
if (mOnItemLongClickListener != null) {
handled = mOnItemLongClickListener.onItemLongClick(this, mDownTouchView,
mDownTouchPosition, id);
}
if (!handled) {
mContextMenuInfo = new AdapterContextMenuInfo(view, position, id);
handled = super.showContextMenuForChild(this);
}
if (handled) {
performHapticFeedback(HapticFeedbackConstants.LONG_PRESS);
}
return handled;
}
@Override
public boolean dispatchKeyEvent(KeyEvent event) {
// Gallery steals all key events
return event.dispatch(this, null, null);
}
/**
* Handles left, right, and clicking
* @see android.view.View#onKeyDown
*/
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
switch (keyCode) {
case KeyEvent.KEYCODE_DPAD_LEFT:
if (movePrevious()) {
playSoundEffect(SoundEffectConstants.NAVIGATION_LEFT);
}
return true;
case KeyEvent.KEYCODE_DPAD_RIGHT:
if (moveNext()) {
playSoundEffect(SoundEffectConstants.NAVIGATION_RIGHT);
}
return true;
case KeyEvent.KEYCODE_DPAD_CENTER:
case KeyEvent.KEYCODE_ENTER:
mReceivedInvokeKeyDown = true;
// fallthrough to default handling
}
return super.onKeyDown(keyCode, event);
}
@Override
public boolean onKeyUp(int keyCode, KeyEvent event) {
switch (keyCode) {
case KeyEvent.KEYCODE_DPAD_CENTER:
case KeyEvent.KEYCODE_ENTER: {
if (mReceivedInvokeKeyDown) {
if (mItemCount > 0) {
dispatchPress(mSelectedChild);
postDelayed(new Runnable() {
public void run() {
dispatchUnpress();
}
}, ViewConfiguration.getPressedStateDuration());
int selectedIndex = mSelectedPosition - mFirstPosition;
performItemClick(getChildAt(selectedIndex), mSelectedPosition, mAdapter
.getItemId(mSelectedPosition));
}
}
// Clear the flag
mReceivedInvokeKeyDown = false;
return true;
}
}
return super.onKeyUp(keyCode, event);
}
boolean movePrevious() {
if (mItemCount > 0 && mSelectedPosition > 0) {
scrollToChild(mSelectedPosition - mFirstPosition - 1);
return true;
} else {
return false;
}
}
boolean moveNext() {
if (mItemCount > 0 && mSelectedPosition < mItemCount - 1) {
scrollToChild(mSelectedPosition - mFirstPosition + 1);
return true;
} else {
return false;
}
}
private boolean scrollToChild(int childPosition) {
View child = getChildAt(childPosition);
if (child != null) {
int distance = getCenterOfGallery() - getCenterOfView(child);
mFlingRunnable.startUsingDistance(distance);
return true;
}
return false;
}
@Override
void setSelectedPositionInt(int position) {
super.setSelectedPositionInt(position);
// Updates any metadata we keep about the selected item.
updateSelectedItemMetadata();
}
private void updateSelectedItemMetadata() {
View oldSelectedChild = mSelectedChild;
View child = mSelectedChild = getChildAt(mSelectedPosition - mFirstPosition);
if (child == null) {
return;
}
child.setSelected(true);
child.setFocusable(true);
if (hasFocus()) {
child.requestFocus();
}
// We unfocus the old child down here so the above hasFocus check
// returns true
if (oldSelectedChild != null) {
// Make sure its drawable state doesn't contain 'selected'
oldSelectedChild.setSelected(false);
// Make sure it is not focusable anymore, since otherwise arrow keys
// can make this one be focused
oldSelectedChild.setFocusable(false);
}
}
/**
* Describes how the child views are aligned.
* @param gravity
*
* @attr ref android.R.styleable#Gallery_gravity
*/
public void setGravity(int gravity)
{
if (mGravity != gravity) {
mGravity = gravity;
requestLayout();
}
}
@Override
protected int getChildDrawingOrder(int childCount, int i) {
int selectedIndex = mSelectedPosition - mFirstPosition;
// Just to be safe
if (selectedIndex < 0) return i;
if (i == childCount - 1) {
// Draw the selected child last
return selectedIndex;
} else if (i >= selectedIndex) {
// Move the children to the right of the selected child earlier one
return i + 1;
} else {
// Keep the children to the left of the selected child the same
return i;
}
}
@Override
protected void onFocusChanged(boolean gainFocus, int direction, Rect previouslyFocusedRect) {
super.onFocusChanged(gainFocus, direction, previouslyFocusedRect);
/*
* The gallery shows focus by focusing the selected item. So, give
* focus to our selected item instead. We steal keys from our
* selected item elsewhere.
*/
if (gainFocus && mSelectedChild != null) {
mSelectedChild.requestFocus(direction);
}
}
/**
* Responsible for fling behavior. Use {@link #startUsingVelocity(int)} to
* initiate a fling. Each frame of the fling is handled in {@link #run()}.
* A FlingRunnable will keep re-posting itself until the fling is done.
*
*/
private class FlingRunnable implements Runnable {
/**
* Tracks the decay of a fling scroll
*/
private Scroller mScroller;
/**
* X value reported by mScroller on the previous fling
*/
private int mLastFlingX;
public FlingRunnable() {
mScroller = new Scroller(getContext());
}
private void startCommon() {
// Remove any pending flings
removeCallbacks(this);
}
public void startUsingVelocity(int initialVelocity) {
if (initialVelocity == 0) return;
startCommon();
int initialX = initialVelocity < 0 ? Integer.MAX_VALUE : 0;
mLastFlingX = initialX;
mScroller.fling(initialX, 0, initialVelocity, 0,
0, Integer.MAX_VALUE, 0, Integer.MAX_VALUE);
post(this);
}
public void startUsingDistance(int distance) {
if (distance == 0) return;
startCommon();
mLastFlingX = 0;
mScroller.startScroll(0, 0, -distance, 0, mAnimationDuration);
post(this);
}
public void stop(boolean scrollIntoSlots) {
removeCallbacks(this);
endFling(scrollIntoSlots);
}
private void endFling(boolean scrollIntoSlots) {
/*
* Force the scroller's status to finished (without setting its
* position to the end)
*/
mScroller.forceFinished(true);
if (scrollIntoSlots) scrollIntoSlots();
}
public void run() {
if (mItemCount == 0) {
endFling(true);
return;
}
mShouldStopFling = false;
final Scroller scroller = mScroller;
boolean more = scroller.computeScrollOffset();
final int x = scroller.getCurrX();
// Flip sign to convert finger direction to list items direction
// (e.g. finger moving down means list is moving towards the top)
int delta = mLastFlingX - x;
// Pretend that each frame of a fling scroll is a touch scroll
if (delta > 0) {
// Moving towards the left. Use first view as mDownTouchPosition
mDownTouchPosition = mFirstPosition;
// Don't fling more than 1 screen
delta = Math.min(getWidth() - mPaddingLeft - mPaddingRight - 1, delta);
} else {
// Moving towards the right. Use last view as mDownTouchPosition
int offsetToLast = getChildCount() - 1;
mDownTouchPosition = mFirstPosition + offsetToLast;
// Don't fling more than 1 screen
delta = Math.max(-(getWidth() - mPaddingRight - mPaddingLeft - 1), delta);
}
trackMotionScroll(delta);
if (more && !mShouldStopFling) {
mLastFlingX = x;
post(this);
} else {
endFling(true);
}
}
}
/**
* Gallery extends LayoutParams to provide a place to hold current
* Transformation information along with previous position/transformation
* info.
*
*/
public static class LayoutParams extends ViewGroup.LayoutParams {
public LayoutParams(Context c, AttributeSet attrs) {
super(c, attrs);
}
public LayoutParams(int w, int h) {
super(w, h);
}
public LayoutParams(ViewGroup.LayoutParams source) {
super(source);
}
}
}
Other Android examples (source code examples)Here is a short list of links related to this Android Gallery.java source code file: |
The search page
Other Android source code examples at this package level
Click here to learn more about this project
