ValueAnimator

 如果你的需求中只需要对View进行移动、缩放、旋转和淡入淡出操作，那么补间动画确实已经足够健全了
补间动画还有一个致命的缺陷，就是它只是改变了View的显示效果而已，而不会真正去改变View的属性。

 

Android:interpolator
     Interpolator 被用来修饰动画效果，定义动画的变化率，可以使存在的动画效果accelerated(加速)，decelerated(减速),repeated(重复),bounced(弹跳)等。
  AccelerateDecelerateInterpolator 在动画开始与结束的地方速率改变比较慢，在中间的时候加速
  AccelerateInterpolator  在动画开始的地方速率改变比较慢，然后开始加速
  AnticipateInterpolator 开始的时候向后然后向前甩
  AnticipateOvershootInterpolator 开始的时候向后然后向前甩一定值后返回最后的值
  BounceInterpolator   动画结束的时候弹起
  CycleInterpolator 动画循环播放特定的次数，速率改变沿着正弦曲线
  DecelerateInterpolator 在动画开始的地方快然后慢
  LinearInterpolator   以常量速率改变
  OvershootInterpolator    向前甩一定值后再回到原来位置
如果android定义的interpolators不符合你的效果也可以自定义interpolators

 

package com.example.xr;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends Activity implements OnClickListener {

    private DrawView drawView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Button startBtn = (Button) findViewById(R.id.start);
        startBtn.setOnClickListener(this);

        drawView = (DrawView) findViewById(R.id.draw);
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.start:
                drawView.startAminator();
                break;
        }

    }
}

 

package com.example.xr;

import android.animation.ValueAnimator;
import android.animation.ValueAnimator.AnimatorUpdateListener;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;

public class DrawView extends View {
    private static final String TAG = "CM-DrawView";
    private int mPointX;
    private int mPointY;
    private Paint mPaint;
    private int mRadius;

    public DrawView(Context context) {
        this(context, null);
    }

    public DrawView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public DrawView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        Log.d(TAG, "DrawView(Context context)");
        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mPaint.setColor(Color.BLUE);
    }

    @Override
    public void draw(Canvas canvas) {
        canvas.drawCircle(mPointX, mPointY, mRadius, mPaint);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        // mPointX = getMeasuredHeight() >> 1;
        // mPointY = getMeasuredWidth() >> 1;
        mPointX = MeasureSpec.getSize(widthMeasureSpec) >> 1;
        mPointY = MeasureSpec.getSize(heightMeasureSpec) >> 1;
    }

    public void startAminator() {
        ValueAnimator animator = ValueAnimator.ofInt(0, 100);

        animator.setDuration(8000);
        animator.addUpdateListener(new AnimatorUpdateListener() {

            @Override
            public void onAnimationUpdate(ValueAnimator animation) {
                mRadius = (int) animation.getAnimatedValue();
                invalidate();
            }
        });

        animator.start();
    }
}

 

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="${relativePackage}.${activityClass}" >

    <Button
        android:id="@+id/start"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/start" />

    <com.example.xr.DrawView
        android:id="@+id/draw"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>