Activity瓦解坠落退出效果

代码如下

package com.example.fall;

import com.example.fall.BlocksFall.OnFallFinishListener;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.KeyEvent;

public class MainActivity extends Activity {

	 

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

	}

	
	@Override
	public boolean onKeyDown(int keyCode, KeyEvent event) {
		// TODO Auto-generated method stub
		if (keyCode==KeyEvent.KEYCODE_BACK) {
			
			AlertDialog.Builder builder = new AlertDialog.Builder(this); 
			builder.setMessage("Are you sure you want to exit?") 
			       .setCancelable(false) 
			        
			       .setPositiveButton("YES", new DialogInterface.OnClickListener() { 
			           public void onClick(DialogInterface dialog, int id) { 
			                dialog.cancel(); 

			              exitClick();
			           } 
			       }); 
			AlertDialog alert = builder.create(); 
			alert.show();
			
		}
		return true;
	}


	protected void exitClick() {
		  BlocksFall blocksFall=new BlocksFall();
          blocksFall.setFallFinishListener(new OnFallFinishListener() {
				
				@Override
				public void OnFallFinish(Activity act) {
					finish();
				}
			});
          
          blocksFall.startFall(MainActivity.this);
	}
}

<pre style="font-family: 宋体; font-size: 9pt; background-color: rgb(255, 255, 255);"><pre name="code" class="java">package com.example.fall;


import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.ValueAnimator;
import android.animation.ValueAnimator.AnimatorUpdateListener;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Camera;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.provider.Settings;
import android.view.View;
import android.view.animation.LinearInterpolator;
import android.widget.FrameLayout;

import java.util.Random;

/**
 * 注意， startFall(final Activity act)中的activity要在AndroidManifest文件中声明为透明，
 * 例如   android:theme="@android:style/Theme.Translucent.NoTitleBar"
 * @author Young
 *
 */
public class BlocksFall {

	private Block[][] blocks;
	/**
	 * blocks列数
	 */
	private int COL = 5;
	/**
	 * blocks行数
	 */
	private int ROW = 20;
	/**
	 * 动画持续时间 毫秒
	 */
	private int DURING=1200;

	private Activity act=null;

	private OnFallFinishListener fallFinishListener;

	private  FallView fallView;
	public void setFallFinishListener(OnFallFinishListener fallFinishListener) {
		this.fallFinishListener=fallFinishListener;
	}
	public void startFall(final Activity act) {
		this.act=act;

		FrameLayout rootViewGroup=(FrameLayout) act.getWindow().getDecorView();

		rootViewGroup.getChildAt(0).setDrawingCacheEnabled(true);
		//获取屏幕中显示的内容
		Bitmap screenBitmap=rootViewGroup.getChildAt(0).getDrawingCache();
		//创建一张RGB565图片，并把屏幕内容绘制在上面，然后调用System.gc()可以减少20M内存开销
		final Bitmap bitmap = Bitmap.createBitmap(screenBitmap.getWidth(),screenBitmap.getHeight(), Bitmap.Config.RGB_565);
		Canvas canvas=new Canvas(bitmap);
		canvas.drawBitmap(screenBitmap,0,0,null);
		screenBitmap=null;

		rootViewGroup.getChildAt(0).setDrawingCacheEnabled(false);
		System.gc();

		rootViewGroup.getChildAt(0).setVisibility(View.INVISIBLE);

		fallView=new FallView(act);

		rootViewGroup.addView(fallView);
		blocks = new Block[ROW][COL];
		int blockW = bitmap.getWidth() / COL;
		final int blockH = bitmap.getHeight() / ROW;

		for (int i = 0; i < ROW; i++) {
			for (int j = 0; j < COL; j++) {

				Block block = new Block();
				// 2 、4  控制blocks间缝隙
				block.bitmap  = Bitmap.createBitmap(bitmap, j * blockW+2, i * blockH+2, blockW-4, blockH-4);
				block.startY = i * blockH;
				block.currentY =block.startY;
				block.x = j * blockW;

				blocks[i][j] = block;
			}
		}

		final Random random=new Random(System.currentTimeMillis());
		//保证前一半时间所有的block都已经开始坠落
		ValueAnimator animator = ValueAnimator.ofInt( ROW-1,-ROW).setDuration(DURING);
		animator.setInterpolator(new LinearInterpolator());
		animator.addUpdateListener(new AnimatorUpdateListener() {
			int y = 0;
			@SuppressLint("NewApi")
			@Override
			public void onAnimationUpdate(ValueAnimator animation) {
				int value=(Integer) animation.getAnimatedValue();
				if (value!=y&&value>-1) {
					y=value;
					for (int j=y;j<ROW;j++){//如果没有该层for，可能导致某一层blocks一直停留在屏幕上
						if (blocks[j][0].isFalling==false){
							for (int i = 0; i < COL; i++) {
								blocks[j][i].isFalling = true;
								blocks[j][i].startTime = System.currentTimeMillis();
								Matrix matrix=new Matrix();
								Camera camera=new Camera();
								camera.rotateZ(random.nextFloat()*360);
								camera.getMatrix(matrix);
								Bitmap tmp=blocks[j][i].bitmap;
								blocks[j][i].bitmap=Bitmap.createBitmap(tmp,0,0,tmp.getWidth(),tmp.getHeight(),matrix,false);

								tmp.recycle();
								//	System.gc();
							}
						}else
							break;
					}

				}

				for (int i = 0; i < ROW; i++) {
					for (int j = 0; j < COL; j++) {
						//更新已经开始坠落的blocks的y轴距离
						if (blocks[i][j].isFalling) {
							float t =2.0f* (System.currentTimeMillis() - blocks[i][j].startTime) / animation.getDuration();
							blocks[i][j].currentY = blocks[i][j].startY +bitmap.getHeight() * t *t;
						}
					}
				}

				fallView.invalidate();

			}
		});


		animator.addListener(new AnimatorListenerAdapter() {
			@Override
			public void onAnimationEnd(Animator animation) {

				super.onAnimationEnd(animation);
				blocks=null;
				fallView=null;
				System.gc();
				if (fallFinishListener!=null) {
					fallFinishListener.OnFallFinish(act);
				}
			}
		});
		animator.start();

	}
	/**
	 * 用于绘制blocks，覆盖在用户控件的上方
	 * @author Young
	 *
	 */
	private class FallView extends View {

		public FallView(Context context) {
			super(context);
		}


		@Override
		protected void onDraw(Canvas canvas) {
			super.onDraw(canvas);
			if (blocks == null) {
				return;
			}
			for (int i = 0; i < blocks.length; i++) {
				for (int j = 0; j < blocks[0].length; j++) {
					canvas.drawBitmap(blocks[i][j].bitmap, blocks[i][j].x, blocks[i][j].currentY, null);
				}
			}
		}
	}


	public interface OnFallFinishListener {
		public void OnFallFinish(Activity act);
	}
	private class Block {
		Bitmap bitmap;

		float startY;
		float x;
		float currentY;

		long startTime;
		boolean isFalling;

	}
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.fall"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="11"
        android:targetSdkVersion="23" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.fall.MainActivity"
            android:label="@string/app_name" 
            android:theme="@android:style/Theme.Translucent.NoTitleBar">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>