Android之Canvas撕衣服

<RelativeLayout 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"
>
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/after"
android:layout_centerInParent="true"/>
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:src="@drawable/pre"
android:id="@+id/iv"/>

</RelativeLayout>

public class MainActivity extends Activity {

private ImageView iv;
private Bitmap baseBitmap,copyBitmap;
private Canvas canvas;
private Paint paint;
private Matrix matrix;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
iv=(ImageView) findViewById(R.id.iv);
baseBitmap=BitmapFactory.decodeResource(getResources(), R.drawable.pre);
copyBitmap=Bitmap.createBitmap(baseBitmap.getWidth(), baseBitmap.getHeight(), baseBitmap.getConfig());
canvas=new Canvas(copyBitmap);
matrix=new Matrix();
paint=new Paint();
canvas.drawBitmap(baseBitmap, matrix, paint);
iv.setImageBitmap(copyBitmap);
//imageView所在区域被触摸的时候回调
iv.setOnTouchListener(new OnTouchListener() {

@Override
public boolean onTouch(View v, MotionEvent event) {
// TODO Auto-generated method stub
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
//按下  1次

break;
case MotionEvent.ACTION_MOVE:
//移动  0-N次
//getX和getY是以控件左上角为原点的
//getRawX和getRawY是以屏幕左上角为原点的
int moveX=(int)event.getX();
int moveY=(int)event.getY();
//					event.getRawX();
//					event.getRawY();
//针对单个像素点去说的
try {
for(int i=-20;i<21;i++){
for(int j=-20;j<21;j++){
copyBitmap.setPixel(moveX+i, moveY+j, Color.TRANSPARENT);
}
}
//TRANSPARENT是透明
//copyBitmap.setPixel(moveX, moveY, Color.TRANSPARENT);
iv.setImageBitmap(copyBitmap);
} catch (Exception e) {
// TODO: handle exception
}
break;
case MotionEvent.ACTION_UP:
//抬起  1次
break;
default:
break;
}
return true;//方法被消费
}
});

}

}