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Android example source code file (Drawable.java)

This example Android source code file (Drawable.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, attributeset, bitmapdrawable, constantstate, content, drawable, inputstream, io, ioexception, ninepatchdrawable, rect, runnable, string, typedarray, typedvalue, util, utilities, utils, xmlpullparserexception, zero_bounds_rect

The Drawable.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.graphics.drawable;

import java.io.InputStream;
import java.io.IOException;
import java.util.Arrays;

import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;

import android.content.res.Resources;
import android.content.res.TypedArray;
import android.graphics.*;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.StateSet;
import android.util.Xml;
import android.util.TypedValue;

/**
 * A Drawable is a general abstraction for "something that can be drawn."  Most
 * often you will deal with Drawable as the type of resource retrieved for
 * drawing things to the screen; the Drawable class provides a generic API for
 * dealing with an underlying visual resource that may take a variety of forms.
 * Unlike a {@link android.view.View}, a Drawable does not have any facility to
 * receive events or otherwise interact with the user.
 *
 * <p>In addition to simple drawing, Drawable provides a number of generic
 * mechanisms for its client to interact with what is being drawn:
 *
 * <ul>
 *     <li> The {@link #setBounds} method must be called to tell the
 *     Drawable where it is drawn and how large it should be.  All Drawables
 *     should respect the requested size, often simply by scaling their
 *     imagery.  A client can find the preferred size for some Drawables with
 *     the {@link #getIntrinsicHeight} and {@link #getIntrinsicWidth} methods.
 *
 *     <li> The {@link #getPadding} method can return from some Drawables
 *     information about how to frame content that is placed inside of them.
 *     For example, a Drawable that is intended to be the frame for a button
 *     widget would need to return padding that correctly places the label
 *     inside of itself.
 *
 *     <li> The {@link #setState} method allows the client to tell the Drawable
 *     in which state it is to be drawn, such as "focused", "selected", etc.
 *     Some drawables may modify their imagery based on the selected state.
 *
 *     <li> The {@link #setLevel} method allows the client to supply a single
 *     continuous controller that can modify the Drawable is displayed, such as
 *     a battery level or progress level.  Some drawables may modify their
 *     imagery based on the current level.
 *
 *     <li> A Drawable can perform animations by calling back to its client
 *     through the {@link Callback} interface.  All clients should support this
 *     interface (via {@link #setCallback}) so that animations will work.  A
 *     simple way to do this is through the system facilities such as
 *     {@link android.view.View#setBackgroundDrawable(Drawable)} and
 *     {@link android.widget.ImageView}.
 * </ul>
 *
 * Though usually not visible to the application, Drawables may take a variety
 * of forms:
 *
 * <ul>
 *     <li> Bitmap: the simplest Drawable, a PNG or JPEG image.
 *     <li> Nine Patch: an extension to the PNG format allows it to
 *     specify information about how to stretch it and place things inside of
 *     it.
 *     <li> Shape: contains simple drawing commands instead of a raw
 *     bitmap, allowing it to resize better in some cases.
 *     <li> Layers: a compound drawable, which draws multiple underlying
 *     drawables on top of each other.
 *     <li> States: a compound drawable that selects one of a set of
 *     drawables based on its state.
 *     <li> Levels: a compound drawable that selects one of a set of
 *     drawables based on its level.
 *     <li> Scale: a compound drawable with a single child drawable,
 *     whose overall size is modified based on the current level.
 * </ul>
 * <p>For information and examples of creating drawable resources (XML or bitmap files that
 * can be loaded in code), see <a href="{@docRoot}guide/topics/resources/resources-i18n.html">Resources
 * and Internationalization</a>.
 */
public abstract class Drawable {
    private static final Rect ZERO_BOUNDS_RECT = new Rect();

    private int[] mStateSet = StateSet.WILD_CARD;
    private int mLevel = 0;
    private int mChangingConfigurations = 0;
    private Rect mBounds = ZERO_BOUNDS_RECT;  // lazily becomes a new Rect()
    /*package*/ Callback mCallback = null;
    private boolean mVisible = true;

    /**
     * Draw in its bounds (set via setBounds) respecting optional effects such
     * as alpha (set via setAlpha) and color filter (set via setColorFilter).
     *
     * @param canvas The canvas to draw into
     */
    public abstract void draw(Canvas canvas);

    /**
     * Specify a bounding rectangle for the Drawable. This is where the drawable
     * will draw when its draw() method is called.
     */
    public void setBounds(int left, int top, int right, int bottom) {
        Rect oldBounds = mBounds;

        if (oldBounds == ZERO_BOUNDS_RECT) {
            oldBounds = mBounds = new Rect();
        }

        if (oldBounds.left != left || oldBounds.top != top ||
                oldBounds.right != right || oldBounds.bottom != bottom) {
            mBounds.set(left, top, right, bottom);
            onBoundsChange(mBounds);
        }
    }

    /**
     * Specify a bounding rectangle for the Drawable. This is where the drawable
     * will draw when its draw() method is called.
     */
    public void setBounds(Rect bounds) {
        setBounds(bounds.left, bounds.top, bounds.right, bounds.bottom);
    }

    /**
     * Return a copy of the drawable's bounds in the specified Rect (allocated
     * by the caller). The bounds specify where this will draw when its draw()
     * method is called.
     *
     * @param bounds Rect to receive the drawable's bounds (allocated by the
     *               caller).
     */
    public final void copyBounds(Rect bounds) {
        bounds.set(mBounds);
    }

    /**
     * Return a copy of the drawable's bounds in a new Rect. This returns the
     * same values as getBounds(), but the returned object is guaranteed to not
     * be changed later by the drawable (i.e. it retains no reference to this
     * rect). If the caller already has a Rect allocated, call copyBounds(rect).
     *
     * @return A copy of the drawable's bounds
     */
    public final Rect copyBounds() {
        return new Rect(mBounds);
    }

    /**
     * Return the drawable's bounds Rect. Note: for efficiency, the returned
     * object may be the same object stored in the drawable (though this is not
     * guaranteed), so if a persistent copy of the bounds is needed, call
     * copyBounds(rect) instead.
     * You should also not change the object returned by this method as it may
     * be the same object stored in the drawable.
     *
     * @return The bounds of the drawable (which may change later, so caller
     *         beware). DO NOT ALTER the returned object as it may change the
     *         stored bounds of this drawable.
     *
     * @see #copyBounds()
     * @see #copyBounds(android.graphics.Rect) 
     */
    public final Rect getBounds() {
        if (mBounds == ZERO_BOUNDS_RECT) {
            mBounds = new Rect();
        }

        return mBounds;
    }

    /**
     * Set a mask of the configuration parameters for which this drawable
     * may change, requiring that it be re-created.
     *
     * @param configs A mask of the changing configuration parameters, as
     * defined by {@link android.content.res.Configuration}.
     *
     * @see android.content.res.Configuration
     */
    public void setChangingConfigurations(int configs) {
        mChangingConfigurations = configs;
    }

    /**
     * Return a mask of the configuration parameters for which this drawable
     * mau change, requiring that it be re-created.  The default implementation
     * returns whatever was provided through
     * {@link #setChangingConfigurations(int)} or 0 by default.  Subclasses
     * may extend this to or in the changing configurations of any other
     * drawables they hold.
     *
     * @return Returns a mask of the changing configuration parameters, as
     * defined by {@link android.content.res.Configuration}.
     *
     * @see android.content.res.Configuration
     */
    public int getChangingConfigurations() {
        return mChangingConfigurations;
    }

    /**
     * Set to true to have the drawable dither its colors when drawn to a device
     * with fewer than 8-bits per color component. This can improve the look on
     * those devices, but can also slow down the drawing a little.
     */
    public void setDither(boolean dither) {}

    /**
     * Set to true to have the drawable filter its bitmap when scaled or rotated
     * (for drawables that use bitmaps). If the drawable does not use bitmaps,
     * this call is ignored. This can improve the look when scaled or rotated,
     * but also slows down the drawing.
     */
    public void setFilterBitmap(boolean filter) {}

    /**
     * Implement this interface if you want to create an animated drawable that
     * extends {@link android.graphics.drawable.Drawable Drawable}.
     * Upon retrieving a drawable, use
     * {@link Drawable#setCallback(android.graphics.drawable.Drawable.Callback)}
     * to supply your implementation of the interface to the drawable; it uses
     * this interface to schedule and execute animation changes.
     */
    public static interface Callback {
        /**
         * Called when the drawable needs to be redrawn.  A view at this point
         * should invalidate itself (or at least the part of itself where the
         * drawable appears).
         *
         * @param who The drawable that is requesting the update.
         */
        public void invalidateDrawable(Drawable who);

        /**
         * A Drawable can call this to schedule the next frame of its
         * animation.  An implementation can generally simply call
         * {@link android.os.Handler#postAtTime(Runnable, Object, long)} with
         * the parameters <var>(what, who, when) to perform the
         * scheduling.
         *
         * @param who The drawable being scheduled.
         * @param what The action to execute.
         * @param when The time (in milliseconds) to run.  The timebase is
         *             {@link android.os.SystemClock#uptimeMillis}
         */
        public void scheduleDrawable(Drawable who, Runnable what, long when);

        /**
         * A Drawable can call this to unschedule an action previously
         * scheduled with {@link #scheduleDrawable}.  An implementation can
         * generally simply call
         * {@link android.os.Handler#removeCallbacks(Runnable, Object)} with
         * the parameters <var>(what, who) to unschedule the drawable.
         *
         * @param who The drawable being unscheduled.
         * @param what The action being unscheduled.
         */
        public void unscheduleDrawable(Drawable who, Runnable what);
    }

    /**
     * Bind a {@link Callback} object to this Drawable.  Required for clients
     * that want to support animated drawables.
     *
     * @param cb The client's Callback implementation.
     */
    public final void setCallback(Callback cb) {
        mCallback = cb;
    }

    /**
     * Use the current {@link Callback} implementation to have this Drawable
     * redrawn.  Does nothing if there is no Callback attached to the
     * Drawable.
     *
     * @see Callback#invalidateDrawable
     */
    public void invalidateSelf()
    {
        if (mCallback != null) {
            mCallback.invalidateDrawable(this);
        }
    }

    /**
     * Use the current {@link Callback} implementation to have this Drawable
     * scheduled.  Does nothing if there is no Callback attached to the
     * Drawable.
     *
     * @param what The action being scheduled.
     * @param when The time (in milliseconds) to run.
     *
     * @see Callback#scheduleDrawable
     */
    public void scheduleSelf(Runnable what, long when)
    {
        if (mCallback != null) {
            mCallback.scheduleDrawable(this, what, when);
        }
    }

    /**
     * Use the current {@link Callback} implementation to have this Drawable
     * unscheduled.  Does nothing if there is no Callback attached to the
     * Drawable.
     *
     * @param what The runnable that you no longer want called.
     *
     * @see Callback#unscheduleDrawable
     */
    public void unscheduleSelf(Runnable what)
    {
        if (mCallback != null) {
            mCallback.unscheduleDrawable(this, what);
        }
    }

    /**
     * Specify an alpha value for the drawable. 0 means fully transparent, and
     * 255 means fully opaque.
     */
    public abstract void setAlpha(int alpha);

    /**
     * Specify an optional colorFilter for the drawable. Pass null to remove
     * any filters.
    */
    public abstract void setColorFilter(ColorFilter cf);

    /**
     * Specify a color and porterduff mode to be the colorfilter for this
     * drawable.
     */
    public void setColorFilter(int color, PorterDuff.Mode mode) {
        setColorFilter(new PorterDuffColorFilter(color, mode));
    }

    public void clearColorFilter() {
        setColorFilter(null);
    }

    /**
     * Indicates whether this view will change its appearance based on state.
     * Clients can use this to determine whether it is necessary to calculate
     * their state and call setState.
     *
     * @return True if this view changes its appearance based on state, false
     *         otherwise.
     *
     * @see #setState(int[])
     */
    public boolean isStateful() {
        return false;
    }

    /**
     * Specify a set of states for the drawable. These are use-case specific,
     * so see the relevant documentation. As an example, the background for
     * widgets like Button understand the following states:
     * [{@link android.R.attr#state_focused},
     *  {@link android.R.attr#state_pressed}].
     *
     * <p>If the new state you are supplying causes the appearance of the
     * Drawable to change, then it is responsible for calling
     * {@link #invalidateSelf} in order to have itself redrawn, <em>and
     * true will be returned from this function.
     *
     * <p>Note: The Drawable holds a reference on to stateSet
     * until a new state array is given to it, so you must not modify this
     * array during that time.</p>
     *
     * @param stateSet The new set of states to be displayed.
     *
     * @return Returns true if this change in state has caused the appearance
     * of the Drawable to change (hence requiring an invalidate), otherwise
     * returns false.
     */
    public boolean setState(final int[] stateSet) {
        if (!Arrays.equals(mStateSet, stateSet)) {
            mStateSet = stateSet;
            return onStateChange(stateSet);
        }
        return false;
    }

    /**
     * Describes the current state, as a union of primitve states, such as
     * {@link android.R.attr#state_focused},
     * {@link android.R.attr#state_selected}, etc.
     * Some drawables may modify their imagery based on the selected state.
     * @return An array of resource Ids describing the current state.
     */
    public int[] getState() {
        return mStateSet;
    }

    /**
     * @return The current drawable that will be used by this drawable. For simple drawables, this
     *         is just the drawable itself. For drawables that change state like
     *         {@link StateListDrawable} and {@link LevelListDrawable} this will be the child drawable
     *         currently in use.
     */
    public Drawable getCurrent() {
        return this;
    }

    /**
     * Specify the level for the drawable.  This allows a drawable to vary its
     * imagery based on a continuous controller, for example to show progress
     * or volume level.
     *
     * <p>If the new level you are supplying causes the appearance of the
     * Drawable to change, then it is responsible for calling
     * {@link #invalidateSelf} in order to have itself redrawn, <em>and
     * true will be returned from this function.
     *
     * @param level The new level, from 0 (minimum) to 10000 (maximum).
     *
     * @return Returns true if this change in level has caused the appearance
     * of the Drawable to change (hence requiring an invalidate), otherwise
     * returns false.
     */
    public final boolean setLevel(int level) {
        if (mLevel != level) {
            mLevel = level;
            return onLevelChange(level);
        }
        return false;
    }

    /**
     * Retrieve the current level.
     *
     * @return int Current level, from 0 (minimum) to 10000 (maximum).
     */
    public final int getLevel() {
        return mLevel;
    }

    /**
     * Set whether this Drawable is visible.  This generally does not impact
     * the Drawable's behavior, but is a hint that can be used by some
     * Drawables, for example, to decide whether run animations.
     *
     * @param visible Set to true if visible, false if not.
     * @param restart You can supply true here to force the drawable to behave
     *                as if it has just become visible, even if it had last
     *                been set visible.  Used for example to force animations
     *                to restart.
     *
     * @return boolean Returns true if the new visibility is different than
     *         its previous state.
     */
    public boolean setVisible(boolean visible, boolean restart) {
        boolean changed = mVisible != visible;
        mVisible = visible;
        return changed;
    }

    public final boolean isVisible() {
        return mVisible;
    }

    /**
     * Return the opacity/transparency of this Drawable.  The returned value is
     * one of the abstract format constants in
     * {@link android.graphics.PixelFormat}:
     * {@link android.graphics.PixelFormat#UNKNOWN},
     * {@link android.graphics.PixelFormat#TRANSLUCENT},
     * {@link android.graphics.PixelFormat#TRANSPARENT}, or
     * {@link android.graphics.PixelFormat#OPAQUE}.
     *
     * <p>Generally a Drawable should be as conservative as possible with the
     * value it returns.  For example, if it contains multiple child drawables
     * and only shows one of them at a time, if only one of the children is
     * TRANSLUCENT and the others are OPAQUE then TRANSLUCENT should be
     * returned.  You can use the method {@link #resolveOpacity} to perform a
     * standard reduction of two opacities to the appropriate single output.
     *
     * <p>Note that the returned value does not take into account a
     * custom alpha or color filter that has been applied by the client through
     * the {@link #setAlpha} or {@link #setColorFilter} methods.
     *
     * @return int The opacity class of the Drawable.
     *
     * @see android.graphics.PixelFormat
     */
    public abstract int getOpacity();

    /**
     * Return the appropriate opacity value for two source opacities.  If
     * either is UNKNOWN, that is returned; else, if either is TRANSLUCENT,
     * that is returned; else, if either is TRANSPARENT, that is returned;
     * else, OPAQUE is returned.
     *
     * <p>This is to help in implementing {@link #getOpacity}.
     *
     * @param op1 One opacity value.
     * @param op2 Another opacity value.
     *
     * @return int The combined opacity value.
     *
     * @see #getOpacity
     */
    public static int resolveOpacity(int op1, int op2) {
        if (op1 == op2) {
            return op1;
        }
        if (op1 == PixelFormat.UNKNOWN || op2 == PixelFormat.UNKNOWN) {
            return PixelFormat.UNKNOWN;
        }
        if (op1 == PixelFormat.TRANSLUCENT || op2 == PixelFormat.TRANSLUCENT) {
            return PixelFormat.TRANSLUCENT;
        }
        if (op1 == PixelFormat.TRANSPARENT || op2 == PixelFormat.TRANSPARENT) {
            return PixelFormat.TRANSPARENT;
        }
        return PixelFormat.OPAQUE;
    }

    /**
     * Returns a Region representing the part of the Drawable that is completely
     * transparent.  This can be used to perform drawing operations, identifying
     * which parts of the target will not change when rendering the Drawable.
     * The default implementation returns null, indicating no transparent
     * region; subclasses can optionally override this to return an actual
     * Region if they want to supply this optimization information, but it is
     * not required that they do so.
     *
     * @return Returns null if the Drawables has no transparent region to
     * report, else a Region holding the parts of the Drawable's bounds that
     * are transparent.
     */
    public Region getTransparentRegion() {
        return null;
    }

    /**
     * Override this in your subclass to change appearance if you recognize the
     * specified state.
     *
     * @return Returns true if the state change has caused the appearance of
     * the Drawable to change (that is, it needs to be drawn), else false
     * if it looks the same and there is no need to redraw it since its
     * last state.
     */
    protected boolean onStateChange(int[] state) { return false; }
    /** Override this in your subclass to change appearance if you vary based
     *  on level.
     * @return Returns true if the level change has caused the appearance of
     * the Drawable to change (that is, it needs to be drawn), else false
     * if it looks the same and there is no need to redraw it since its
     * last level.
     */
    protected boolean onLevelChange(int level) { return false; }
    /**
     * Override this in your subclass to change appearance if you recognize the
     * specified state.
     */
    protected void onBoundsChange(Rect bounds) {}

    /**
     * Return the intrinsic width of the underlying drawable object.  Returns
     * -1 if it has no intrinsic width, such as with a solid color.
     */
    public int getIntrinsicWidth() {
        return -1;
    }

    /**
     * Return the intrinsic height of the underlying drawable object. Returns
     * -1 if it has no intrinsic height, such as with a solid color.
     */
    public int getIntrinsicHeight() {
        return -1;
    }

    /**
     * Returns the minimum width suggested by this Drawable. If a View uses this
     * Drawable as a background, it is suggested that the View use at least this
     * value for its width. (There will be some scenarios where this will not be
     * possible.) This value should INCLUDE any padding.
     *
     * @return The minimum width suggested by this Drawable. If this Drawable
     *         doesn't have a suggested minimum width, 0 is returned.
     */
    public int getMinimumWidth() {
        final int intrinsicWidth = getIntrinsicWidth();
        return intrinsicWidth > 0 ? intrinsicWidth : 0;
    }

    /**
     * Returns the minimum height suggested by this Drawable. If a View uses this
     * Drawable as a background, it is suggested that the View use at least this
     * value for its height. (There will be some scenarios where this will not be
     * possible.) This value should INCLUDE any padding.
     *
     * @return The minimum height suggested by this Drawable. If this Drawable
     *         doesn't have a suggested minimum height, 0 is returned.
     */
    public int getMinimumHeight() {
        final int intrinsicHeight = getIntrinsicHeight();
        return intrinsicHeight > 0 ? intrinsicHeight : 0;
    }

    /**
     * Return in padding the insets suggested by this Drawable for placing
     * content inside the drawable's bounds. Positive values move toward the
     * center of the Drawable (set Rect.inset). Returns true if this drawable
     * actually has a padding, else false. When false is returned, the padding
     * is always set to 0.
     */
    public boolean getPadding(Rect padding) {
        padding.set(0, 0, 0, 0);
        return false;
    }

    /**
     * Make this drawable mutable. This operation cannot be reversed. A mutable
     * drawable is guaranteed to not share its state with any other drawable.
     * This is especially useful when you need to modify properties of drawables
     * loaded from resources. By default, all drawables instances loaded from
     * the same resource share a common state; if you modify the state of one
     * instance, all the other instances will receive the same modification.
     *
     * Calling this method on a mutable Drawable will have no effect.
     *
     * @return This drawable.
     */
    public Drawable mutate() {
        return this;
    }

    /**
     * Create a drawable from an inputstream
     */
    public static Drawable createFromStream(InputStream is, String srcName) {
        return createFromResourceStream(null, null, is, srcName, null);
    }

    /**
     * Create a drawable from an inputstream, using the given resources and
     * value to determine density information.
     */
    public static Drawable createFromResourceStream(Resources res, TypedValue value,
            InputStream is, String srcName) {
        return createFromResourceStream(res, value, is, srcName, null);
    }

    /**
     * Create a drawable from an inputstream, using the given resources and
     * value to determine density information.
     */
    public static Drawable createFromResourceStream(Resources res, TypedValue value,
            InputStream is, String srcName, BitmapFactory.Options opts) {

        if (is == null) {
            return null;
        }

        /*  ugh. The decodeStream contract is that we have already allocated
            the pad rect, but if the bitmap does not had a ninepatch chunk,
            then the pad will be ignored. If we could change this to lazily
            alloc/assign the rect, we could avoid the GC churn of making new
            Rects only to drop them on the floor.
        */
        Rect pad = new Rect();
        
        // Special stuff for compatibility mode: if the target density is not
        // the same as the display density, but the resource -is- the same as
        // the display density, then don't scale it down to the target density.
        // This allows us to load the system's density-correct resources into
        // an application in compatibility mode, without scaling those down
        // to the compatibility density only to have them scaled back up when
        // drawn to the screen.
        if (opts == null) opts = new BitmapFactory.Options();
        opts.inScreenDensity = DisplayMetrics.DENSITY_DEVICE;
        Bitmap  bm = BitmapFactory.decodeResourceStream(res, value, is, pad, opts);
        if (bm != null) {
            byte[] np = bm.getNinePatchChunk();
            if (np == null || !NinePatch.isNinePatchChunk(np)) {
                np = null;
                pad = null;
            }
            return drawableFromBitmap(res, bm, np, pad, srcName);
        }
        return null;
    }

    /**
     * Create a drawable from an XML document. For more information on how to
     * create resources in XML, see
     * <a href="{@docRoot}guide/topics/resources/resources-i18n.html">Resources and
     * Internationalization</a>.
     */
    public static Drawable createFromXml(Resources r, XmlPullParser parser)
            throws XmlPullParserException, IOException {
        AttributeSet attrs = Xml.asAttributeSet(parser);

        int type;
        while ((type=parser.next()) != XmlPullParser.START_TAG &&
                type != XmlPullParser.END_DOCUMENT) {
            // Empty loop
        }

        if (type != XmlPullParser.START_TAG) {
            throw new XmlPullParserException("No start tag found");
        }

        Drawable drawable = createFromXmlInner(r, parser, attrs);

        if (drawable == null) {
            throw new RuntimeException("Unknown initial tag: " + parser.getName());
        }

        return drawable;
    }

    /**
     * Create from inside an XML document.  Called on a parser positioned at
     * a tag in an XML document, tries to create a Drawable from that tag.
     * Returns null if the tag is not a valid drawable.
     */
    public static Drawable createFromXmlInner(Resources r, XmlPullParser parser, AttributeSet attrs)
    throws XmlPullParserException, IOException {
        Drawable drawable;

        final String name = parser.getName();

        if (name.equals("selector")) {
            drawable = new StateListDrawable();
        } else if (name.equals("level-list")) {
            drawable = new LevelListDrawable();
        } else if (name.equals("layer-list")) {
            drawable = new LayerDrawable();
        } else if (name.equals("transition")) {
            drawable = new TransitionDrawable();
        } else if (name.equals("color")) {
            drawable = new ColorDrawable();
        } else if (name.equals("shape")) {
            drawable = new GradientDrawable();
        } else if (name.equals("scale")) {
            drawable = new ScaleDrawable();
        } else if (name.equals("clip")) {
            drawable = new ClipDrawable();
        } else if (name.equals("rotate")) {
            drawable = new RotateDrawable();
        } else if (name.equals("animated-rotate")) {
            drawable = new AnimatedRotateDrawable();            
        } else if (name.equals("animation-list")) {
            drawable = new AnimationDrawable();
        } else if (name.equals("inset")) {
            drawable = new InsetDrawable();
        } else if (name.equals("bitmap")) {
            drawable = new BitmapDrawable();
            if (r != null) {
               ((BitmapDrawable) drawable).setTargetDensity(r.getDisplayMetrics());
            }
        } else if (name.equals("nine-patch")) {
            drawable = new NinePatchDrawable();
            if (r != null) {
                ((NinePatchDrawable) drawable).setTargetDensity(r.getDisplayMetrics());
             }
        } else {
            throw new XmlPullParserException(parser.getPositionDescription() +
                    ": invalid drawable tag " + name);
        }

        drawable.inflate(r, parser, attrs);
        return drawable;
    }


    /**
     * Create a drawable from file path name.
     */
    public static Drawable createFromPath(String pathName) {
        if (pathName == null) {
            return null;
        }

        Bitmap bm = BitmapFactory.decodeFile(pathName);
        if (bm != null) {
            return drawableFromBitmap(null, bm, null, null, pathName);
        }

        return null;
    }

    public void inflate(Resources r, XmlPullParser parser, AttributeSet attrs)
            throws XmlPullParserException, IOException {

        TypedArray a = r.obtainAttributes(attrs, com.android.internal.R.styleable.Drawable);
        inflateWithAttributes(r, parser, a, com.android.internal.R.styleable.Drawable_visible);
        a.recycle();
    }

    void inflateWithAttributes(Resources r, XmlPullParser parser,
            TypedArray attrs, int visibleAttr)
            throws XmlPullParserException, IOException {

        mVisible = attrs.getBoolean(visibleAttr, mVisible);
    }

    public static abstract class ConstantState {
        /**
         * Create a new drawable without supplying resources the caller
         * is running in.  Note that using this means the density-dependent
         * drawables (like bitmaps) will not be able to update their target
         * density correctly.
         */
        public abstract Drawable newDrawable();
        /**
         * Create a new Drawable instance from its constant state.  This
         * must be implemented for drawables that change based on the target
         * density of their caller (that is depending on whether it is
         * in compatibility mode).
         */
        public Drawable newDrawable(Resources res) {
            return newDrawable();
        }
        /**
         * Return a bit mask of configuration changes that will impact
         * this drawable (and thus require completely reloading it).
         */
        public abstract int getChangingConfigurations();
    }

    public ConstantState getConstantState() {
        return null;
    }

    private static Drawable drawableFromBitmap(Resources res, Bitmap bm, byte[] np,
            Rect pad, String srcName) {

        if (np != null) {
            return new NinePatchDrawable(res, bm, np, pad, srcName);
        }

        return new BitmapDrawable(res, bm);
    }
}

Other Android examples (source code examples)

Here is a short list of links related to this Android Drawable.java source code file:

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