Android example source code file (Animation.java)

This example Android source code file (Animation.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

absolute, android, animation, animationlistener, content, description, drawing, infinite, interpolator, rectf, relative_to_parent, relative_to_self, restart, reverse, transformation, util, utilities, utils, zorder_bottom, zorder_normal

The Animation.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.animation;

import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.graphics.RectF;

/**
 * Abstraction for an Animation that can be applied to Views, Surfaces, or
 * other objects. See the {@link android.view.animation animation package
 * description file}.
 */
public abstract class Animation implements Cloneable {
    /**
     * Repeat the animation indefinitely.
     */
    public static final int INFINITE = -1;

    /**
     * When the animation reaches the end and the repeat count is INFINTE_REPEAT
     * or a positive value, the animation restarts from the beginning.
     */
    public static final int RESTART = 1;

    /**
     * When the animation reaches the end and the repeat count is INFINTE_REPEAT
     * or a positive value, the animation plays backward (and then forward again).
     */
    public static final int REVERSE = 2;

    /**
     * Can be used as the start time to indicate the start time should be the current
     * time when {@link #getTransformation(long, Transformation)} is invoked for the
     * first animation frame. This can is useful for short animations.
     */
    public static final int START_ON_FIRST_FRAME = -1;

    /**
     * The specified dimension is an absolute number of pixels.
     */
    public static final int ABSOLUTE = 0;

    /**
     * The specified dimension holds a float and should be multiplied by the
     * height or width of the object being animated.
     */
    public static final int RELATIVE_TO_SELF = 1;

    /**
     * The specified dimension holds a float and should be multiplied by the
     * height or width of the parent of the object being animated.
     */
    public static final int RELATIVE_TO_PARENT = 2;

    /**
     * Requests that the content being animated be kept in its current Z
     * order.
     */
    public static final int ZORDER_NORMAL = 0;
    
    /**
     * Requests that the content being animated be forced on top of all other
     * content for the duration of the animation.
     */
    public static final int ZORDER_TOP = 1;
    
    /**
     * Requests that the content being animated be forced under all other
     * content for the duration of the animation.
     */
    public static final int ZORDER_BOTTOM = -1;
    
    /**
     * Set by {@link #getTransformation(long, Transformation)} when the animation ends.
     */
    boolean mEnded = false;

    /**
     * Set by {@link #getTransformation(long, Transformation)} when the animation starts.
     */
    boolean mStarted = false;

    /**
     * Set by {@link #getTransformation(long, Transformation)} when the animation repeats
     * in REVERSE mode.
     */
    boolean mCycleFlip = false;

    /**
     * This value must be set to true by {@link #initialize(int, int, int, int)}. It
     * indicates the animation was successfully initialized and can be played.
     */
    boolean mInitialized = false;

    /**
     * Indicates whether the animation transformation should be applied before the
     * animation starts.
     */
    boolean mFillBefore = true;

    /**
     * Indicates whether the animation transformation should be applied after the
     * animation ends.
     */
    boolean mFillAfter = false;

    /**
     * Indicates whether fillAfter should be taken into account.
     */
    boolean mFillEnabled = false;    

    /**
     * The time in milliseconds at which the animation must start;
     */
    long mStartTime = -1;

    /**
     * The delay in milliseconds after which the animation must start. When the
     * start offset is > 0, the start time of the animation is startTime + startOffset.
     */
    long mStartOffset;

    /**
     * The duration of one animation cycle in milliseconds.
     */
    long mDuration;

    /**
     * The number of times the animation must repeat. By default, an animation repeats
     * indefinitely.
     */
    int mRepeatCount = 0;

    /**
     * Indicates how many times the animation was repeated.
     */
    int mRepeated = 0;

    /**
     * The behavior of the animation when it repeats. The repeat mode is either
     * {@link #RESTART} or {@link #REVERSE}.
     *
     */
    int mRepeatMode = RESTART;

    /**
     * The interpolator used by the animation to smooth the movement.
     */
    Interpolator mInterpolator;

    /**
     * The animation listener to be notified when the animation starts, ends or repeats.
     */
    AnimationListener mListener;

    /**
     * Desired Z order mode during animation.
     */
    private int mZAdjustment;
    
    /**
     * Don't animate the wallpaper.
     */
    private boolean mDetachWallpaper = false;

    private boolean mMore = true;
    private boolean mOneMoreTime = true;

    RectF mPreviousRegion = new RectF();
    RectF mRegion = new RectF();
    Transformation mTransformation = new Transformation();
    Transformation mPreviousTransformation = new Transformation();

    /**
     * Creates a new animation with a duration of 0ms, the default interpolator, with
     * fillBefore set to true and fillAfter set to false
     */
    public Animation() {
        ensureInterpolator();
    }

    /**
     * Creates a new animation whose parameters come from the specified context and
     * attributes set.
     *
     * @param context the application environment
     * @param attrs the set of attributes holding the animation parameters
     */
    public Animation(Context context, AttributeSet attrs) {
        TypedArray a = context.obtainStyledAttributes(attrs, com.android.internal.R.styleable.Animation);

        setDuration((long) a.getInt(com.android.internal.R.styleable.Animation_duration, 0));
        setStartOffset((long) a.getInt(com.android.internal.R.styleable.Animation_startOffset, 0));
        
        setFillEnabled(a.getBoolean(com.android.internal.R.styleable.Animation_fillEnabled, mFillEnabled));
        setFillBefore(a.getBoolean(com.android.internal.R.styleable.Animation_fillBefore, mFillBefore));
        setFillAfter(a.getBoolean(com.android.internal.R.styleable.Animation_fillAfter, mFillAfter));

        final int resID = a.getResourceId(com.android.internal.R.styleable.Animation_interpolator, 0);
        if (resID > 0) {
            setInterpolator(context, resID);
        }

        setRepeatCount(a.getInt(com.android.internal.R.styleable.Animation_repeatCount, mRepeatCount));
        setRepeatMode(a.getInt(com.android.internal.R.styleable.Animation_repeatMode, RESTART));

        setZAdjustment(a.getInt(com.android.internal.R.styleable.Animation_zAdjustment, ZORDER_NORMAL));
        
        setDetachWallpaper(a.getBoolean(com.android.internal.R.styleable.Animation_detachWallpaper, false));
        
        ensureInterpolator();

        a.recycle();
    }

    @Override
    protected Animation clone() throws CloneNotSupportedException {
        final Animation animation = (Animation) super.clone();
        animation.mPreviousRegion = new RectF();
        animation.mRegion = new RectF();
        animation.mTransformation = new Transformation();
        animation.mPreviousTransformation = new Transformation();
        return animation;
    }

    /**
     * Reset the initialization state of this animation.
     *
     * @see #initialize(int, int, int, int)
     */
    public void reset() {
        mPreviousRegion.setEmpty();
        mPreviousTransformation.clear();
        mInitialized = false;
        mCycleFlip = false;
        mRepeated = 0;
        mMore = true;
        mOneMoreTime = true;
    }

    /**
     * Cancel the animation. Cancelling an animation invokes the animation
     * listener, if set, to notify the end of the animation.
     * 
     * If you cancel an animation manually, you must call {@link #reset()}
     * before starting the animation again.
     * 
     * @see #reset() 
     * @see #start() 
     * @see #startNow() 
     */
    public void cancel() {
        if (mStarted && !mEnded) {
            if (mListener != null) mListener.onAnimationEnd(this);
            mEnded = true;
        }
        // Make sure we move the animation to the end
        mStartTime = Long.MIN_VALUE;
        mMore = mOneMoreTime = false;
    }

    /**
     * @hide
     */
    public void detach() {
        if (mStarted && !mEnded) {
            mEnded = true;
            if (mListener != null) mListener.onAnimationEnd(this);
        }
    }

    /**
     * Whether or not the animation has been initialized.
     *
     * @return Has this animation been initialized.
     * @see #initialize(int, int, int, int)
     */
    public boolean isInitialized() {
        return mInitialized;
    }

    /**
     * Initialize this animation with the dimensions of the object being
     * animated as well as the objects parents. (This is to support animation
     * sizes being specifed relative to these dimensions.)
     *
     * <p>Objects that interpret a Animations should call this method when
     * the sizes of the object being animated and its parent are known, and
     * before calling {@link #getTransformation}.
     *
     *
     * @param width Width of the object being animated
     * @param height Height of the object being animated
     * @param parentWidth Width of the animated object's parent
     * @param parentHeight Height of the animated object's parent
     */
    public void initialize(int width, int height, int parentWidth, int parentHeight) {
        reset();
        mInitialized = true;
    }

    /**
     * Sets the acceleration curve for this animation. The interpolator is loaded as
     * a resource from the specified context.
     *
     * @param context The application environment
     * @param resID The resource identifier of the interpolator to load
     * @attr ref android.R.styleable#Animation_interpolator
     */
    public void setInterpolator(Context context, int resID) {
        setInterpolator(AnimationUtils.loadInterpolator(context, resID));
    }

    /**
     * Sets the acceleration curve for this animation. Defaults to a linear
     * interpolation.
     *
     * @param i The interpolator which defines the acceleration curve
     * @attr ref android.R.styleable#Animation_interpolator
     */
    public void setInterpolator(Interpolator i) {
        mInterpolator = i;
    }

    /**
     * When this animation should start relative to the start time. This is most
     * useful when composing complex animations using an {@link AnimationSet }
     * where some of the animations components start at different times.
     *
     * @param startOffset When this Animation should start, in milliseconds from
     *                    the start time of the root AnimationSet.
     * @attr ref android.R.styleable#Animation_startOffset
     */
    public void setStartOffset(long startOffset) {
        mStartOffset = startOffset;
    }

    /**
     * How long this animation should last. The duration cannot be negative.
     * 
     * @param durationMillis Duration in milliseconds
     *
     * @throws java.lang.IllegalArgumentException if the duration is < 0
     *
     * @attr ref android.R.styleable#Animation_duration
     */
    public void setDuration(long durationMillis) {
        if (durationMillis < 0) {
            throw new IllegalArgumentException("Animation duration cannot be negative");
        }
        mDuration = durationMillis;
    }

    /**
     * Ensure that the duration that this animation will run is not longer
     * than <var>durationMillis.  In addition to adjusting the duration
     * itself, this ensures that the repeat count also will not make it run
     * longer than the given time.
     * 
     * @param durationMillis The maximum duration the animation is allowed
     * to run.
     */
    public void restrictDuration(long durationMillis) {
        // If we start after the duration, then we just won't run.
        if (mStartOffset > durationMillis) {
            mStartOffset = durationMillis;
            mDuration = 0;
            mRepeatCount = 0;
            return;
        }
        
        long dur = mDuration + mStartOffset;
        if (dur > durationMillis) {
            mDuration = durationMillis-mStartOffset;
            dur = durationMillis;
        }
        // If the duration is 0 or less, then we won't run.
        if (mDuration <= 0) {
            mDuration = 0;
            mRepeatCount = 0;
            return;
        }
        // Reduce the number of repeats to keep below the maximum duration.
        // The comparison between mRepeatCount and duration is to catch
        // overflows after multiplying them.
        if (mRepeatCount < 0 || mRepeatCount > durationMillis
                || (dur*mRepeatCount) > durationMillis) {
            // Figure out how many times to do the animation.  Subtract 1 since
            // repeat count is the number of times to repeat so 0 runs once.
            mRepeatCount = (int)(durationMillis/dur) - 1;
            if (mRepeatCount < 0) {
                mRepeatCount = 0;
            }
        }
    }
    
    /**
     * How much to scale the duration by.
     *
     * @param scale The amount to scale the duration.
     */
    public void scaleCurrentDuration(float scale) {
        mDuration = (long) (mDuration * scale);
    }

    /**
     * When this animation should start. When the start time is set to
     * {@link #START_ON_FIRST_FRAME}, the animation will start the first time
     * {@link #getTransformation(long, Transformation)} is invoked. The time passed
     * to this method should be obtained by calling
     * {@link AnimationUtils#currentAnimationTimeMillis()} instead of
     * {@link System#currentTimeMillis()}.
     *
     * @param startTimeMillis the start time in milliseconds
     */
    public void setStartTime(long startTimeMillis) {
        mStartTime = startTimeMillis;
        mStarted = mEnded = false;
        mCycleFlip = false;
        mRepeated = 0;
        mMore = true;
    }

    /**
     * Convenience method to start the animation the first time
     * {@link #getTransformation(long, Transformation)} is invoked.
     */
    public void start() {
        setStartTime(-1);
    }

    /**
     * Convenience method to start the animation at the current time in
     * milliseconds.
     */
    public void startNow() {
        setStartTime(AnimationUtils.currentAnimationTimeMillis());
    }

    /**
     * Defines what this animation should do when it reaches the end. This
     * setting is applied only when the repeat count is either greater than
     * 0 or {@link #INFINITE}. Defaults to {@link #RESTART}. 
     *
     * @param repeatMode {@link #RESTART} or {@link #REVERSE}
     * @attr ref android.R.styleable#Animation_repeatMode
     */
    public void setRepeatMode(int repeatMode) {
        mRepeatMode = repeatMode;
    }

    /**
     * Sets how many times the animation should be repeated. If the repeat
     * count is 0, the animation is never repeated. If the repeat count is
     * greater than 0 or {@link #INFINITE}, the repeat mode will be taken
     * into account. The repeat count is 0 by default.
     *
     * @param repeatCount the number of times the animation should be repeated
     * @attr ref android.R.styleable#Animation_repeatCount
     */
    public void setRepeatCount(int repeatCount) {
        if (repeatCount < 0) {
            repeatCount = INFINITE;
        }
        mRepeatCount = repeatCount;
    }

    /**
     * If fillEnabled is true, this animation will apply fillBefore and fillAfter.
     *
     * @return true if the animation will take fillBefore and fillAfter into account
     * @attr ref android.R.styleable#Animation_fillEnabled
     */
    public boolean isFillEnabled() {
        return mFillEnabled;
    }

    /**
     * If fillEnabled is true, the animation will apply the value of fillBefore and
     * fillAfter. Otherwise, fillBefore and fillAfter are ignored and the animation
     * transformation is always applied.
     *
     * @param fillEnabled true if the animation should take fillBefore and fillAfter into account
     * @attr ref android.R.styleable#Animation_fillEnabled
     *
     * @see #setFillBefore(boolean)
     * @see #setFillAfter(boolean)
     */
    public void setFillEnabled(boolean fillEnabled) {
        mFillEnabled = fillEnabled;
    }

    /**
     * If fillBefore is true, this animation will apply its transformation
     * before the start time of the animation. Defaults to true if not set.
     * Note that this applies when using an {@link
     * android.view.animation.AnimationSet AnimationSet} to chain
     * animations. The transformation is not applied before the AnimationSet
     * itself starts.
     *
     * @param fillBefore true if the animation should apply its transformation before it starts
     * @attr ref android.R.styleable#Animation_fillBefore
     *
     * @see #setFillEnabled(boolean)
     */
    public void setFillBefore(boolean fillBefore) {
        mFillBefore = fillBefore;
    }

    /**
     * If fillAfter is true, the transformation that this animation performed
     * will persist when it is finished. Defaults to false if not set.
     * Note that this applies when using an {@link
     * android.view.animation.AnimationSet AnimationSet} to chain
     * animations. The transformation is not applied before the AnimationSet
     * itself starts.
     *
     * @param fillAfter true if the animation should apply its transformation after it ends
     * @attr ref android.R.styleable#Animation_fillAfter
     *
     * @see #setFillEnabled(boolean) 
     */
    public void setFillAfter(boolean fillAfter) {
        mFillAfter = fillAfter;
    }

    /**
     * Set the Z ordering mode to use while running the animation.
     * 
     * @param zAdjustment The desired mode, one of {@link #ZORDER_NORMAL},
     * {@link #ZORDER_TOP}, or {@link #ZORDER_BOTTOM}.
     * @attr ref android.R.styleable#Animation_zAdjustment
     */
    public void setZAdjustment(int zAdjustment) {
        mZAdjustment = zAdjustment;
    }
    
    /**
     * If detachWallpaper is true, and this is a window animation of a window
     * that has a wallpaper background, then the window will be detached from
     * the wallpaper while it runs.  That is, the animation will only be applied
     * to the window, and the wallpaper behind it will remain static.
     *
     * @param detachWallpaper true if the wallpaper should be detached from the animation
     * @attr ref android.R.styleable#Animation_detachWallpaper
     */
    public void setDetachWallpaper(boolean detachWallpaper) {
        mDetachWallpaper = detachWallpaper;
    }

    /**
     * Gets the acceleration curve type for this animation.
     *
     * @return the {@link Interpolator} associated to this animation
     * @attr ref android.R.styleable#Animation_interpolator
     */
    public Interpolator getInterpolator() {
        return mInterpolator;
    }

    /**
     * When this animation should start. If the animation has not startet yet,
     * this method might return {@link #START_ON_FIRST_FRAME}.
     *
     * @return the time in milliseconds when the animation should start or
     *         {@link #START_ON_FIRST_FRAME}
     */
    public long getStartTime() {
        return mStartTime;
    }

    /**
     * How long this animation should last
     *
     * @return the duration in milliseconds of the animation
     * @attr ref android.R.styleable#Animation_duration
     */
    public long getDuration() {
        return mDuration;
    }

    /**
     * When this animation should start, relative to StartTime
     *
     * @return the start offset in milliseconds
     * @attr ref android.R.styleable#Animation_startOffset
     */
    public long getStartOffset() {
        return mStartOffset;
    }

    /**
     * Defines what this animation should do when it reaches the end.
     *
     * @return either one of {@link #REVERSE} or {@link #RESTART}
     * @attr ref android.R.styleable#Animation_repeatMode
     */
    public int getRepeatMode() {
        return mRepeatMode;
    }

    /**
     * Defines how many times the animation should repeat. The default value
     * is 0.
     *
     * @return the number of times the animation should repeat, or {@link #INFINITE}
     * @attr ref android.R.styleable#Animation_repeatCount
     */
    public int getRepeatCount() {
        return mRepeatCount;
    }

    /**
     * If fillBefore is true, this animation will apply its transformation
     * before the start time of the animation.
     *
     * @return true if the animation applies its transformation before it starts
     * @attr ref android.R.styleable#Animation_fillBefore
     */
    public boolean getFillBefore() {
        return mFillBefore;
    }

    /**
     * If fillAfter is true, this animation will apply its transformation
     * after the end time of the animation.
     *
     * @return true if the animation applies its transformation after it ends
     * @attr ref android.R.styleable#Animation_fillAfter
     */
    public boolean getFillAfter() {
        return mFillAfter;
    }

    /**
     * Returns the Z ordering mode to use while running the animation as
     * previously set by {@link #setZAdjustment}.
     * 
     * @return Returns one of {@link #ZORDER_NORMAL},
     * {@link #ZORDER_TOP}, or {@link #ZORDER_BOTTOM}.
     * @attr ref android.R.styleable#Animation_zAdjustment
     */
    public int getZAdjustment() {
        return mZAdjustment;
    }

    /**
     * Return value of {@link #setDetachWallpaper(boolean)}.
     * @attr ref android.R.styleable#Animation_detachWallpaper
     */
    public boolean getDetachWallpaper() {
        return mDetachWallpaper;
    }

    /**
     * <p>Indicates whether or not this animation will affect the transformation
     * matrix. For instance, a fade animation will not affect the matrix whereas
     * a scale animation will.</p>
     *
     * @return true if this animation will change the transformation matrix
     */
    public boolean willChangeTransformationMatrix() {
        // assume we will change the matrix
        return true;
    }

    /**
     * <p>Indicates whether or not this animation will affect the bounds of the
     * animated view. For instance, a fade animation will not affect the bounds
     * whereas a 200% scale animation will.</p>
     *
     * @return true if this animation will change the view's bounds
     */
    public boolean willChangeBounds() {
        // assume we will change the bounds
        return true;
    }

    /**
     * <p>Binds an animation listener to this animation. The animation listener
     * is notified of animation events such as the end of the animation or the
     * repetition of the animation.</p>
     *
     * @param listener the animation listener to be notified
     */
    public void setAnimationListener(AnimationListener listener) {
        mListener = listener;
    }

    /**
     * Gurantees that this animation has an interpolator. Will use
     * a AccelerateDecelerateInterpolator is nothing else was specified.
     */
    protected void ensureInterpolator() {
        if (mInterpolator == null) {
            mInterpolator = new AccelerateDecelerateInterpolator();
        }
    }

    /**
     * Compute a hint at how long the entire animation may last, in milliseconds.
     * Animations can be written to cause themselves to run for a different
     * duration than what is computed here, but generally this should be
     * accurate.
     */
    public long computeDurationHint() {
        return (getStartOffset() + getDuration()) * (getRepeatCount() + 1);
    }
    
    /**
     * Gets the transformation to apply at a specified point in time. Implementations of this
     * method should always replace the specified Transformation or document they are doing
     * otherwise.
     *
     * @param currentTime Where we are in the animation. This is wall clock time.
     * @param outTransformation A tranformation object that is provided by the
     *        caller and will be filled in by the animation.
     * @return True if the animation is still running
     */
    public boolean getTransformation(long currentTime, Transformation outTransformation) {
        if (mStartTime == -1) {
            mStartTime = currentTime;
        }

        final long startOffset = getStartOffset();
        final long duration = mDuration;
        float normalizedTime;
        if (duration != 0) {
            normalizedTime = ((float) (currentTime - (mStartTime + startOffset))) /
                    (float) duration;
        } else {
            // time is a step-change with a zero duration
            normalizedTime = currentTime < mStartTime ? 0.0f : 1.0f;
        }

        final boolean expired = normalizedTime >= 1.0f;
        mMore = !expired;

        if (!mFillEnabled) normalizedTime = Math.max(Math.min(normalizedTime, 1.0f), 0.0f);

        if ((normalizedTime >= 0.0f || mFillBefore) && (normalizedTime <= 1.0f || mFillAfter)) {
            if (!mStarted) {
                if (mListener != null) {
                    mListener.onAnimationStart(this);
                }
                mStarted = true;
            }

            if (mFillEnabled) normalizedTime = Math.max(Math.min(normalizedTime, 1.0f), 0.0f);

            if (mCycleFlip) {
                normalizedTime = 1.0f - normalizedTime;
            }

            final float interpolatedTime = mInterpolator.getInterpolation(normalizedTime);
            applyTransformation(interpolatedTime, outTransformation);
        }

        if (expired) {
            if (mRepeatCount == mRepeated) {
                if (!mEnded) {
                    mEnded = true;
                    if (mListener != null) {
                        mListener.onAnimationEnd(this);
                    }
                }
            } else {
                if (mRepeatCount > 0) {
                    mRepeated++;
                }

                if (mRepeatMode == REVERSE) {
                    mCycleFlip = !mCycleFlip;
                }

                mStartTime = -1;
                mMore = true;

                if (mListener != null) {
                    mListener.onAnimationRepeat(this);
                }
            }
        }

        if (!mMore && mOneMoreTime) {
            mOneMoreTime = false;
            return true;
        }

        return mMore;
    }

    /**
     * <p>Indicates whether this animation has started or not.

     *
     * @return true if the animation has started, false otherwise
     */
    public boolean hasStarted() {
        return mStarted;
    }

    /**
     * <p>Indicates whether this animation has ended or not.

     *
     * @return true if the animation has ended, false otherwise
     */
    public boolean hasEnded() {
        return mEnded;
    }

    /**
     * Helper for getTransformation. Subclasses should implement this to apply
     * their transforms given an interpolation value.  Implementations of this
     * method should always replace the specified Transformation or document
     * they are doing otherwise.
     * 
     * @param interpolatedTime The value of the normalized time (0.0 to 1.0)
     *        after it has been run through the interpolation function.
     * @param t The Transofrmation object to fill in with the current
     *        transforms.
     */
    protected void applyTransformation(float interpolatedTime, Transformation t) {
    }

    /**
     * Convert the information in the description of a size to an actual
     * dimension
     *
     * @param type One of Animation.ABSOLUTE, Animation.RELATIVE_TO_SELF, or
     *             Animation.RELATIVE_TO_PARENT.
     * @param value The dimension associated with the type parameter
     * @param size The size of the object being animated
     * @param parentSize The size of the parent of the object being animated
     * @return The dimension to use for the animation
     */
    protected float resolveSize(int type, float value, int size, int parentSize) {
        switch (type) {
            case ABSOLUTE:
                return value;
            case RELATIVE_TO_SELF:
                return size * value;
            case RELATIVE_TO_PARENT:
                return parentSize * value;
            default:
                return value;
        }
    }

    /**
     * @param left
     * @param top
     * @param right
     * @param bottom
     * @param invalidate
     * @param transformation
     * 
     * @hide
     */
    public void getInvalidateRegion(int left, int top, int right, int bottom,
            RectF invalidate, Transformation transformation) {

        final RectF tempRegion = mRegion;
        final RectF previousRegion = mPreviousRegion;

        invalidate.set(left, top, right, bottom);
        transformation.getMatrix().mapRect(invalidate);
        // Enlarge the invalidate region to account for rounding errors
        invalidate.inset(-1.0f, -1.0f);
        tempRegion.set(invalidate);
        invalidate.union(previousRegion);

        previousRegion.set(tempRegion);

        final Transformation tempTransformation = mTransformation;
        final Transformation previousTransformation = mPreviousTransformation;

        tempTransformation.set(transformation);
        transformation.set(previousTransformation);
        previousTransformation.set(tempTransformation);
    }

    /**
     * @param left
     * @param top
     * @param right
     * @param bottom
     *
     * @hide
     */
    public void initializeInvalidateRegion(int left, int top, int right, int bottom) {
        final RectF region = mPreviousRegion;
        region.set(left, top, right, bottom);
        // Enlarge the invalidate region to account for rounding errors
        region.inset(-1.0f, -1.0f);
        if (mFillBefore) {
            final Transformation previousTransformation = mPreviousTransformation;
            applyTransformation(mInterpolator.getInterpolation(0.0f), previousTransformation);
        }
    }

    /**
     * Utility class to parse a string description of a size.
     */
    protected static class Description {
        /**
         * One of Animation.ABSOLUTE, Animation.RELATIVE_TO_SELF, or
         * Animation.RELATIVE_TO_PARENT.
         */
        public int type;

        /**
         * The absolute or relative dimension for this Description.
         */
        public float value;

        /**
         * Size descriptions can appear inthree forms:
         * <ol>
         * <li>An absolute size. This is represented by a number.
         * <li>A size relative to the size of the object being animated. This
         * is represented by a number followed by "%".</li> *
         * <li>A size relative to the size of the parent of object being
         * animated. This is represented by a number followed by "%p".</li>
         * </ol>
         * @param value The typed value to parse
         * @return The parsed version of the description
         */
        static Description parseValue(TypedValue value) {
            Description d = new Description();
            if (value == null) {
                d.type = ABSOLUTE;
                d.value = 0;
            } else {
                if (value.type == TypedValue.TYPE_FRACTION) {
                    d.type = (value.data & TypedValue.COMPLEX_UNIT_MASK) ==
                            TypedValue.COMPLEX_UNIT_FRACTION_PARENT ?
                                    RELATIVE_TO_PARENT : RELATIVE_TO_SELF;
                    d.value = TypedValue.complexToFloat(value.data);
                    return d;
                } else if (value.type == TypedValue.TYPE_FLOAT) {
                    d.type = ABSOLUTE;
                    d.value = value.getFloat();
                    return d;
                } else if (value.type >= TypedValue.TYPE_FIRST_INT &&
                        value.type <= TypedValue.TYPE_LAST_INT) {
                    d.type = ABSOLUTE;
                    d.value = value.data;
                    return d;
                }
            }

            d.type = ABSOLUTE;
            d.value = 0.0f;

            return d;
        }
    }

    /**
     * <p>An animation listener receives notifications from an animation.
     * Notifications indicate animation related events, such as the end or the
     * repetition of the animation.</p>
     */
    public static interface AnimationListener {
        /**
         * <p>Notifies the start of the animation.

         *
         * @param animation The started animation.
         */
        void onAnimationStart(Animation animation);

        /**
         * <p>Notifies the end of the animation. This callback is not invoked
         * for animations with repeat count set to INFINITE.</p>
         *
         * @param animation The animation which reached its end.
         */
        void onAnimationEnd(Animation animation);

        /**
         * <p>Notifies the repetition of the animation.

         *
         * @param animation The animation which was repeated.
         */
        void onAnimationRepeat(Animation animation);
    }
}