定义

通过不断控制值的变化，再不断手动赋给对象的属性，从而实现动画效果

使用

已有属性动画

palpha.gif

objectAnimator = ObjectAnimator.ofFloat(mPropertyIv, "alpha", 1.0f, 0.1f)
objectAnimator.apply {
   duration = 5000
   repeatCount = -1
   repeatMode = ObjectAnimator.REVERSE
}
objectAnimator.start()

pscale.gif

 mScaleXAnimator = ObjectAnimator.ofFloat(mPropertyIv, "scaleX", 1.0f,0.3f)

 mScaleYAnimator = ObjectAnimator.ofFloat(mPropertyIv, "scaleY", 1.0f,0.3f)
 mScaleYAnimator.repeatCount = -1
 mScaleYAnimator.repeatMode = ObjectAnimator.REVERSE
 val set = AnimatorSet()
 set.playTogether(mScaleXAnimator,mScaleYAnimator)
 set.duration = 5000
 set.start()

protate.gif

  mRotationAnimator = ObjectAnimator.ofFloat(mPropertyIv, "rotation", 0f,100f,200f,300f)
  mRotationAnimator.duration = 5000
  mRotationAnimator.repeatCount= 3
  mRotationAnimator.repeatMode = ObjectAnimator.REVERSE
  mRotationAnimator.start()

ptranlate.gif

 mTranslateXAnimator = ObjectAnimator.ofFloat(mPropertyIv, "translationX", 0f,100f,200f,300f)
 mTranslateYAnimator = ObjectAnimator.ofFloat(mPropertyIv, "translationY", 0f,100f)
 mTranslateYAnimator.repeatCount = -1
 mTranslateYAnimator.repeatMode = ObjectAnimator.REVERSE
 val set = AnimatorSet()
 set.playTogether(mTranslateXAnimator,mTranslateYAnimator)
 set.duration = 5000
 set.start()

组合属性动画

 ObjectAnimator alphaAnim = ObjectAnimator.ofFloat(myView, "alpha", 1.0f, 0.5f, 0.8f, 1.0f);
 ObjectAnimator scaleXAnim = ObjectAnimator.ofFloat(myView, "scaleX", 0.0f, 1.0f);
 ObjectAnimator scaleYAnim = ObjectAnimator.ofFloat(myView, "scaleY", 0.0f, 2.0f);
 ObjectAnimator rotateAnim = ObjectAnimator.ofFloat(myView, "rotation", 0, 360);
 ObjectAnimator transXAnim = ObjectAnimator.ofFloat(myView, "translationX", 100, 400);
 ObjectAnimator transYAnim = ObjectAnimator.ofFloat(myView, "tranlsationY", 100, 750);
 AnimatorSet set = new AnimatorSet();
 set.playTogether(alphaAnim, scaleXAnim, scaleYAnim, rotateAnim,transXAnim, transYAnim);
// set.playSequentially(alphaAnim, scaleXAnim, scaleYAnim, rotateAnim, transXAnim, transYAnim);
 set.setDuration(3000);
 set.start();

可以看到这些动画可以同时播放，或者是按序播放。

自定义属性动画

如果是自定义控件，需要添加 setter / getter 方法；
用 ObjectAnimator.ofXXX() 创建 ObjectAnimator 对象；
用 start() 方法执行动画。

public class SportsView extends View {
    float progress = 0;

    ......

    // 创建 getter 方法
    public float getProgress() {
        return progress;
    }

    // 创建 setter 方法
    public void setProgress(float progress) {
        this.progress = progress;
        invalidate();
    }

    @Override
    public void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        ......

        canvas.drawArc(arcRectF, 135, progress * 2.7f, false, paint);

        ......
    }
}

......

// 创建 ObjectAnimator 对象
ObjectAnimator animator = ObjectAnimator.ofFloat(view, "progress", 0, 65);
// 执行动画
animator.start();