android animator

参考
属性动画
Android源码分析—属性动画的工作原理

一、view动画

• TranslateAnimation
• ScaleAnimation
• RotateAnimation
• AlphaAnimation

建议使用XML来定义动画，可读性比较好

//res/anim/animation_test.xml
...

如何应用上面的动画呢

Button mButton = (Button)findViewById(R.id.buttton1);
Animation animation = AnimationUtils.
loadAnimation(this,R.anim.animation_test);
mButton.startAnimation(animation);

• view动画只能控制view对象
• view动画只有平移缩放旋转淡入淡出效果
• view动画只是对影像做动画 交互事件容易出问题

二、帧动画

使用AnimationDrawable。帧动画容易引起OOM，尽量避免使用过多尺寸较大的图片

//res/drawable/frame_animation.xml
...


...
Button mButton = (Button)findViewById(R.id.button1);
mButton.setBackgroundResource(R.drawable.frame_animation);
AnimationDrawable drawable = (AnimationDrawable) mButton.getBackground();
drawable.start();

三、属性动画

android3.0,api11之后才有属性动画。默认帧率10ms/帧，动画默认时间间隔300ms。

• ValueAnimator

//三秒内颜色渐变，无限循环且反复
ValueAnimator colorAnim = ObjectAnimator.ofInt(this,
"backgroundColor",/\*Red\*/0xffff8080,/\*Blue\*/0xff8080ff);
colorAnim.setDuration(3000);
colorAnim.setEvaluator(new ArgbEvaluator());
colorAnim.setRepeatCount(ValueAnimator.INFINITE);
colorAnim.setRepeatMode(ValueAnimator.REVERSE);
colorAnim.start();
//测试数值0到1的变化
ValueAnimator anim = ValueAnimator.ofFloat(0f, 1f);  
anim.setDuration(300);  
anim.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {  
    @Override  
    public void onAnimationUpdate(ValueAnimator animation) {  
        float currentValue = (float) animation.getAnimatedValue();  
        Log.d("TAG", "cuurent value is " + currentValue);  
    }  
});  
anim.start();  

• 继承自ValueAnimator的ObjectAnimator

ObjectAnimator.ofFloat(myObject,"translationY",
-myObject.getHeight()).start();//向上平移他的高度

• AnimatorSet 动画集合
  5秒内对view的旋转、平移、缩放和透明度都进行了改变。

AnimatorSet set = new AnimatorSet();
set.playTogether(
   ObjectAnimator.ofFloat(myView,"rotationX",0,360),
   ObjectAnimator.ofFloat(myView,"rotationY",0,180),
   ObjectAnimator.ofFloat(myView,"rotation",0,-90),
   ObjectAnimator.ofFloat(myView,"translationX",0,90),
   ObjectAnimator.ofFloat(myView,"translationY",0,90),
   ObjectAnimator.ofFloat(myView,"scaleX",1,1.5f),
   ObjectAnimator.ofFloat(myView,"scaleY",1,1.5f),
   ObjectAnimator.ofFloat(myView,"alpha",1,0.25f,1)
);
set.setDuration(5*1000).start();

四、让一个Button宽度从当前宽度增加到500px

• 方式一：使用view动画，拉伸的只是影像，背景图和文字都会变形。
• 方式二：
  

  
   public void onClick(View v){
   if(v == Button){
   performAnimate();
   }
   }
   private void performAnimate(){
   ObjectAnimator.ofInt(mButton,"width",500).setDuration(5000).start();
   }
   

  
  这样是无效的,object会不停地调用set方法，但是button的setWidth由于继承自TextView，其设置的是最大宽度和最小宽度，真正起作用的是width.
• 方式三：
  将方式二包装一下
  

  
   private static class ViewWrapper{
   private View mTarget;
   public ViewWrapper(View target){
   mTarget = target;
   }
   public int getWidth(){
   return mTarget.getLayoutParams().width;
   }
   public void setWidth(int width){
   mTarget.getLayoutParams().width = width;
   mTarget.requestLayout();
   }
   private void performAnimate(){
   ViewWrapper wrapper = new ViewWrapper(mButton);
   ObjectAnimator.ofInt(wrapper,"width",500).setDuration(5000).start();
   }
   }
   

• 方式四：
  使用ValueAnimator

private void performAnimate(final View target,final int start,final int end){
   ValueAnimator valueAnimator = ValueAnimator.ofInt(1,100);//动画过程中从1变成100
   valueAnimator.addUpdateListener(
      new AnimatorUpdateListener(){
         //持有一个IntEvaluator对象，方便下面估值时使用
         private IntEvalluator mEvaluaotr = new IntEvalluator();
         
         public void onAnimationUpdate(ValueAnimator animation){
            int currentValue = (Integer)animator.getAnimatedValue();//1~100间
            float fraction = animator.getAnimatedFraction();//当前进度，0~1间
            target.getLayoutParams().width = mEvaluaotr.
            evaluate(fraction,start,end);
            target.requestLayout();
        }
      }
   );
   valueAnimator.setDuration(5000).start();
}
performAnimate(mButton,mButton.getWidth(),500);