Animation

android上X、Y上坐标

　　手机屏幕的左上角为原心，分别向右和向下为正方向。由此为各种animation方向的标准

总的来说Animation分为两类：

• Tweened Animations
  • TranslateAnimation类，移动效果

    • /**
           * Constructor to use when building a TranslateAnimation from code
           * 
           * @param fromXType Specifies how fromXValue should be interpreted. One of
           *        Animation.ABSOLUTE, Animation.RELATIVE_TO_SELF, or
           *        Animation.RELATIVE_TO_PARENT.
           * @param fromXValue Change in X coordinate to apply at the start of the
           *        animation. This value can either be an absolute number if fromXType
           *        is ABSOLUTE, or a percentage (where 1.0 is 100%) otherwise.
           * @param toXType Specifies how toXValue should be interpreted. One of
           *        Animation.ABSOLUTE, Animation.RELATIVE_TO_SELF, or
           *        Animation.RELATIVE_TO_PARENT.
           * @param toXValue Change in X coordinate to apply at the end of the
           *        animation. This value can either be an absolute number if toXType
           *        is ABSOLUTE, or a percentage (where 1.0 is 100%) otherwise.
           * @param fromYType Specifies how fromYValue should be interpreted. One of
           *        Animation.ABSOLUTE, Animation.RELATIVE_TO_SELF, or
           *        Animation.RELATIVE_TO_PARENT.
           * @param fromYValue Change in Y coordinate to apply at the start of the
           *        animation. This value can either be an absolute number if fromYType
           *        is ABSOLUTE, or a percentage (where 1.0 is 100%) otherwise.
           * @param toYType Specifies how toYValue should be interpreted. One of
           *        Animation.ABSOLUTE, Animation.RELATIVE_TO_SELF, or
           *        Animation.RELATIVE_TO_PARENT.
           * @param toYValue Change in Y coordinate to apply at the end of the
           *        animation. This value can either be an absolute number if toYType
           *        is ABSOLUTE, or a percentage (where 1.0 is 100%) otherwise.
           */
          public TranslateAnimation(int fromXType, float fromXValue, int toXType, float toXValue,
                  int fromYType, float fromYValue, int toYType, float toYValue) {
      
              mFromXValue = fromXValue;
              mToXValue = toXValue;
              mFromYValue = fromYValue;
              mToYValue = toYValue;
      
              mFromXType = fromXType;
              mToXType = toXType;
              mFromYType = fromYType;
              mToYType = toYType;
          }

  • RotateAnimation类，旋转效果。

  • /**
         * Constructor to use when building a RotateAnimation from code
         * 
         * @param fromDegrees Rotation offset to apply at the start of the
         *        animation.
         * 
         * @param toDegrees Rotation offset to apply at the end of the animation.
         * 
         * @param pivotX The X coordinate of the point about which the object is
         *        being rotated, specified as an absolute number where 0 is the left
         *        edge.
         * @param pivotY The Y coordinate of the point about which the object is
         *        being rotated, specified as an absolute number where 0 is the top
         *        edge.
         */
    　　　//旋转表示一个控件绕着一个点做旋转（平面旋转）。这个旋转是围绕一个点，而这个点是由百分比决定的，比如相对于自身时x为0.5，y为0.5，那么这个点就是该控件的中心；如果x为1，y为1，那么这个点就是控件的右下角；相对父控件时x为0.5，y为0.5，那么这个点就是该父控件的中心。
    
        public RotateAnimation(float fromDegrees, float toDegrees, float pivotX, float pivotY) {
            mFromDegrees = fromDegrees;
            mToDegrees = toDegrees;
    
            mPivotXType = ABSOLUTE;
            mPivotYType = ABSOLUTE;
            mPivotXValue = pivotX;
            mPivotYValue = pivotY;
            initializePivotPoint();
        }

  • ScaleAnimation类，缩放效果

    • /**
           * 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;
          }

  • AlphaAnimation类，透明度变化效果

    •  /**
           * Constructor to use when building an AlphaAnimation from code
           * 
           * @param fromAlpha Starting alpha value for the animation, where 1.0 means
           *        fully opaque and 0.0 means fully transparent.
           * @param toAlpha Ending alpha value for the animation.
           */
           //fromAlpha：开始时刻的透明度，取值范围0~1。
           //toAlpha：结束时刻的透明度，取值范围0~1。

          public AlphaAnimation(float fromAlpha, float toAlpha) {
              mFromAlpha = fromAlpha;
              mToAlpha = toAlpha;
          }

• Frame-by-Frame Animations,创建一个Drawable序列，通过按照一定的顺序轮换达到动画的效果

四个TweenAnimation的通用方法

• setDuration(long durationMills) 设置动画的持续时间
• setFillAfter(Boolean fillAfter) ，如果设为true，则动画执行结束完，控件停留在执行结束的状态
• setFillBefore(Boolean fillAfter)，如果设为true，则动画执行结束后，控件回到动画执行前的状态
• setStartOffSet(long startOffSet) ，设置动画开始前等待的时间
• setRepeatCount(int repeatCount)，设置动画重复的次数

当然以上的动画都是单个的效果，如果想要混合两个以上的动画效果，就要用到AnimationSet