Android实现缩放动画

public void startAnimation(Animation animation)

/**
 * Constructor to use when building a ScaleAnimation from code
 * 
 * @param fromX Horizontal scaling factor to apply at the start of the animation
 * @param toX Horizontal scaling factor to apply at the end of the animation
 * @param fromY Vertical scaling factor to apply at the start of the animation
 * @param toY Vertical scaling factor to apply at the end of the animation
 */
public ScaleAnimation(float fromX, float toX, float fromY, float toY) {
    mResources = null;
    mFromX = fromX;
    mToX = toX;
    mFromY = fromY;
    mToY = toY;
    mPivotX = 0;
    mPivotY = 0;
}

public void scale(View view) {
    // 创建缩放的动画对象
    ScaleAnimation sa = new ScaleAnimation(0f,1.0f,0f,1.0f);
    // 设置动画播放的时间
    sa.setDuration(1000);
    // 开始播放动画
    iv.startAnimation(sa);
}

/**
    * Constructor to use when building a ScaleAnimation from code
    * 
    * @param fromX Horizontal scaling factor to apply at the start of the animation
    * @param toX Horizontal scaling factor to apply at the end of the animation
    * @param fromY Vertical scaling factor to apply at the start of the animation
    * @param toY Vertical scaling factor to apply at the end of the animation
    * @param pivotX The X coordinate of the point about which the object is being scaled, specified as an absolute number where 0 is the left edge. (This point remains fixed while the object changes size.)
    * @param pivotY The Y coordinate of the point about which the object is being scaled, specified as an absolute number where 0 is the top edge. (This point remains fixed while the object changes size.)
    */
   public ScaleAnimation(float fromX, float toX, float fromY, float toY, float pivotX, float pivotY) {
       mResources = null;
       mFromX = fromX;
       mToX = toX;
       mFromY = fromY;
       mToY = toY;

       mPivotXType = ABSOLUTE;
       mPivotYType = ABSOLUTE;
       mPivotXValue = pivotX;
       mPivotYValue = pivotY;
       initializePivotPoint();
   }

ScaleAnimation sa = new ScaleAnimation(0f, 1.0f, 0f, 1.0f, iv.getWidth() / 2, iv.getHeight() / 2);
// 设置动画播放的时间
sa.setDuration(1000);
// 开始播放动画
iv.startAnimation(sa);

/**
    * Constructor to use when building a ScaleAnimation from code
    * 
    * @param fromX Horizontal scaling factor to apply at the start of the animation
    * @param toX Horizontal scaling factor to apply at the end of the animation
    * @param fromY Vertical scaling factor to apply at the start of the animation
    * @param toY Vertical scaling factor to apply at the end of the animation
    * @param pivotXType Specifies how pivotXValue should be interpreted. One of Animation.ABSOLUTE, Animation.RELATIVE_TO_SELF, or Animation.RELATIVE_TO_PARENT.
    * @param pivotXValue The X coordinate of the point about which the object is being scaled, specified as an absolute number where 0 is the left edge. (This point remains fixed while the object changes size.) This value can either be an absolute number if pivotXType is ABSOLUTE, or a percentage (where 1.0 is 100%) otherwise.
    * @param pivotYType Specifies how pivotYValue should be interpreted. One of Animation.ABSOLUTE, Animation.RELATIVE_TO_SELF, or Animation.RELATIVE_TO_PARENT.
    * @param pivotYValue The Y coordinate of the point about which the object is being scaled, specified as an absolute number where 0 is the top edge. (This point remains fixed while the object changes size.) This value can either be an absolute number if pivotYType is ABSOLUTE, or a percentage (where 1.0 is 100%) otherwise.
    */
   public ScaleAnimation(float fromX, float toX, float fromY, float toY, int pivotXType, float pivotXValue, int pivotYType, float pivotYValue) {
       mResources = null;
       mFromX = fromX;
       mToX = toX;
       mFromY = fromY;
       mToY = toY;

       mPivotXValue = pivotXValue;
       mPivotXType = pivotXType;
       mPivotYValue = pivotYValue;
       mPivotYType = pivotYType;
       initializePivotPoint();
   }

// 创建缩放的动画对象
ScaleAnimation sa = new ScaleAnimation(0f, 1.0f, 0f, 1.0f, ScaleAnimation.RELATIVE_TO_SELF, 0.5f, ScaleAnimation.RELATIVE_TO_SELF, 0.5f);
// 设置动画播放的时间
sa.setDuration(1000);
// 开始播放动画
iv.startAnimation(sa);

/**
 * 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;
}

sa.setRepeatCount(2);

/**
 * 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;
}

sa.setRepeatMode(ScaleAnimation.REVERSE);