android view实现一张图片的渐隐效果

package liu.com.kiexun;
 
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
 
public class SimpleTestActivity extends Activity {
  /** Called when the activity is first created. */
 SimpleFlash simpleFlash;
 boolean flag=true;
 private Handler handler=new Handler()
 {
  public void handleMessage(Message msg)
  {
  switch(msg.what)
  {
   case 1:
   if (flag)
   {
    try
    {
    Thread.sleep(1000);//第一张图片时间显示为1秒
    } catch (InterruptedException e)
    {
    // TODO Auto-generated catch block
    e.printStackTrace();
    }
    flag=false;
   }  
   simpleFlash.invalidate(); 
   break;  
   default:
   break;  
  }  
  }; 
 };
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    //在这里才产生contex，才可以对view进行初始化
    simpleFlash=new SimpleFlash(this,handler);
    setContentView(simpleFlash);
  }
}

package liu.com.kiexun;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.os.Handler;
import android.os.Message;
import android.view.MotionEvent;
import android.view.View;
public class SimpleFlash extends View
{
int index=0;
int size=480*800;
Bitmap firstBitmap,secondBitmap;
Canvas canvas=null;
int pixels[]=new int[size];
Handler handler ;
int changeArrary[]=
{
(1<<31)-1,
(1<<30)-1,
(1<<29)-1,
(1<<28)-1,
(1<<27)-1,
(1<<26)-1,
(1<<25)-1,
(1<<24)-1
};
int changeArrary2[]={
/*  11111110   
11111100  
11111000 
11110000 
11100000   
11000000   
10000000   
01111111
00111111
00011111
00001111
00000111
00000011
00000001
00000000
1<<32 相当于没有进行移位  =32位的时候与移的为数是与32的余数
*/
( ( (1<<31)-1 )+(1<<31)-(1<<24) ),
( ( (1<<31)-1 )+(1<<31)-(1<<24)-(1<<25) ),
( ( (1<<31)-1 )+(1<<31)-(1<<24)-(1<<25)-(1<<26) ),
( ( (1<<31)-1 )+(1<<31)- (1<<24)-(1<<25)-(1<<26)-(1<<27)),
( ( (1<<24)-1 )+(1<<31)+(1<<30)+(1<<29)),
( ( (1<<24)-1 )+(1<<31)+(1<<30)),
( ( (1<<24)-1 )+(1<<31)),
(1<<31)-1,
(1<<30)-1,
(1<<29)-1,
(1<<28)-1,
(1<<27)-1,
(1<<26)-1,
(1<<25)-1,
(1<<24)-1
};
public SimpleFlash(Context context,Handler handler)
{
super(context);
this.handler=handler;
// TODO Auto-generated constructor stub
firstBitmap=BitmapFactory.decodeResource(getResources(), R.drawable.about);
secondBitmap=BitmapFactory.decodeResource(getResources(), R.drawable.help);
firstBitmap.getPixels(pixels, 0, 480, 0, 0, 480, 800);
}
/*
* (non-Javadoc)
* @see android.view.View#onDraw(android.graphics.Canvas)
* draw函数执行完毕才能显示出图片，应该是执行完毕后才能提交绘画消息
*/
public void onDraw(Canvas canvas)
{
this.canvas=canvas;
canvas.drawBitmap(secondBitmap, 0, 0, null);
/*
* 不会先显示第二个图片，5秒后在显示第一个图片
*/
firstBitmap=Bitmap.createBitmap(pixels, 480, 800,Config.ARGB_8888);
canvas.drawBitmap(firstBitmap, 0, 0, null); 
changePixels();
try
{
Thread.sleep(100);
} catch (InterruptedException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void changePixels()
{
if (index<8)
{
for (int i = 1; i < pixels.length; i++)
{
pixels[i]=pixels[i]&changeArrary[index];
}
index++;
Message changeMessage=new Message();
changeMessage.what=1;
handler.sendMessage(changeMessage); 
}
}
}