Android自定义Animation

先呈上我测试动画的界面：

布局文件main.xml为：

<?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" >

    <ImageView
        android:id="@+id/image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_marginTop="30dp"
        android:src="@drawable/naruto" /> 

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_marginTop="30dp"
        android:text="click me to show" />

</LinearLayout>

接下来自定义动画，新建一个类CustomAnimation继承自Animation，需要重写applyTransformation和initialize方法，具体解释就在代码中给出了，所以呢，在这里就不重复说了吧O(∩_∩)O。自定义类CustomAnimation代码如下：

package com.android.animation;

import android.graphics.Matrix;
import android.view.animation.Animation;
import android.view.animation.AnticipateOvershootInterpolator;
import android.view.animation.Transformation;

public class CustomAnimation extends Animation {
    int centerX, centerY;

    public CustomAnimation() {
        
    }

    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t) {
        // TODO Auto-generated method stub
        super.applyTransformation(interpolatedTime, t);
        Matrix matrix = t.getMatrix();
        //通过interpolatedTime设置矩阵缩放
        matrix.setScale(interpolatedTime, interpolatedTime);
        matrix.preTranslate(-centerX, -centerY);
        matrix.postTranslate(centerX, centerY);
    }

    //初始化动画
    @Override
    public void initialize(int width, int height, int parentWidth,
            int parentHeight) {
        // TODO Auto-generated method stub
        super.initialize(width, height, parentWidth, parentHeight);
        // 初始化中点坐标
        centerX = width / 2;
        centerY = height / 2;
        //动画持续的时间
        setDuration(2000);
        //设置动画结束后是否保留在终止的位置
        setFillAfter(true);
        /**
         * 设置动画的加速度曲线，传入参数Interpolator的简介子类有：
         * AnticipateOvershootInterpolator 改变开始向后然后向前射出超出屏幕
         * AccelerateDecelerateInterpolator 变化的速度开始和结束缓慢但中间加速穿过
         * AccelerateInterpolator 变化的速度开始慢慢,然后加速
         * AnticipateInterpolator 改变开始向后然后向前射出
         * BounceInterpolator 变化到最后时反弹
         * CycleInterpolator 重复动画指定数量的周期CycleInterpolator(float cycles)需传入周期数
         * DecelerateInterpolator 开始变化的速度很快,然后开始减速
         * LinearInterpolator 线性变化
         * OvershootInterpolator 射出向前,超过屏幕然后回来
         * 
         * pS->文字功底欠佳，描述的不是很准确哈，见谅，见谅o(╯□╰)o具体效果还是要自己动手试试
         */
        setInterpolator(new AnticipateOvershootInterpolator());
    }

}

最后在主Activity中使用自定义的Animation：

package com.android.animation;

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

public class CustomAnimationActivity extends Activity {
    /** Called when the activity is first created. */
    private CustomAnimation animation;
    private ImageView image;
    private Button button;
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        //实例化
        animation = new CustomAnimation();
        
        image = (ImageView)findViewById(R.id.image);
        button = (Button)findViewById(R.id.button);
        button.setOnClickListener(new OnClickListener(){
            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                //为图片设置动画效果
                image.setAnimation(animation);
            }
        });
    }
}