Android中属性动画Property Animation使用示例(二)

MainActivity如下:

package cc.cn;

import android.animation.ValueAnimator;
import android.animation.ValueAnimator.AnimatorUpdateListener;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup.MarginLayoutParams;
import android.widget.Button;
/**
 * Demo描述:
 * 属性动画中ValueAnimator使用实例
 * 利用ValueAnimator使控件发生位移(变化Margin值)
 * 
 * ValueAnimator是Property Animation很重要的一个类
 * ValueAnimator可跟踪记录对象属性已经变化的时间及当前这个时间点的值
 * 
 * 参考资料:
 * 1 http://blog.csdn.net/linmiansheng/article/details/18716841
 * 2 http://blog.csdn.net/linmiansheng/article/details/18763987
 * 3 关于属性动画的中文文档,请参见:
 *   http://blog.csdn.net/think_soft/article/details/7703684
 *   http://wiki.eoeandroid.com/Property_Animation
 *   Thank you very much
 *
 */
public class MainActivity extends Activity {
	private Button mValueAnimatorButton;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        init();
    }
    
    private void init(){
    	mValueAnimatorButton=(Button) findViewById(R.id.valueAnimatorButton);
    	//ValueAnimator.ofInt(int,int)设定了值的变化范围
    	final ValueAnimator valueAnimator=ValueAnimator.ofInt(20,100);
    	//利用AnimatorUpdateListener监听动画的执行
    	valueAnimator.addUpdateListener(new AnimatorUpdateListener() {	
			@Override
			public void onAnimationUpdate(ValueAnimator va) {
				//得到动画当前执行的值
				//这些值均在(20,100)之间
				Integer animatedValue = (Integer)va.getAnimatedValue();
				System.out.println("animatedValue="+animatedValue);
				MarginLayoutParams marginLayoutParams = (MarginLayoutParams) mValueAnimatorButton.getLayoutParams(); 
				marginLayoutParams.leftMargin = animatedValue;
				//不断修改Button的Margin值
				mValueAnimatorButton.setLayoutParams(marginLayoutParams);
			}
		});			
    	valueAnimator.setDuration(2000);
    	//valueAnimator.setRepeatCount(1);
    	//valueAnimator.setRepeatMode(ValueAnimator.REVERSE);
    	valueAnimator.setTarget(mValueAnimatorButton);
    	
    	mValueAnimatorButton.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				valueAnimator.start();
			}
		});
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <Button
        android:id="@+id/valueAnimatorButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="ValueAnimatorButton" />

</LinearLayout>