撕衣服图片效果的实现

package com.gyarmy.setcloth;

import android.os.Bundle;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.view.Menu;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.ImageView;

public class MainActivity extends Activity implements OnTouchListener {
	
	private ImageView iv_pre;
	private ImageView iv_after;
	
	private Bitmap copyBitmap;
	
	Paint paint ;
	
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        iv_after = (ImageView) findViewById(R.id.iv_after);
        iv_pre = (ImageView) findViewById(R.id.iv_pre);
        
        iv_after.setImageResource(R.drawable.after14);
        iv_pre.setImageResource(R.drawable.pre14);
        
        iv_pre.setOnTouchListener(this);
        
        Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.pre14);
        copyBitmap = bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Config.ARGB_8888);
        Canvas canvas = new Canvas(copyBitmap);
        paint = new Paint();
        //paint.setStrokeWidth(10);
        
        Matrix matrix = new Matrix();
        
        //绘制图片
        canvas.drawBitmap(bitmap, matrix, paint);
        
    }

    
    
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }



	@Override
	public boolean onTouch(View v, MotionEvent event) {
		// TODO Auto-generated method stub
		
		switch (event.getAction()) {
		case MotionEvent.ACTION_DOWN:
			System.out.println("按下.............");
			int downX = (int) (event.getX()+0.5f);
			int downY = (int) (event.getY()+0.5f);
			clearPicture(downX,downY);
			
			break;

		case MotionEvent.ACTION_MOVE:
			//设置透明色
			int	moveX = (int) (event.getX()+0.5f);
			int moveY = (int) (event.getY()+0.5f);
			clearPicture(moveX,moveY);
			
			break;
			
		case MotionEvent.ACTION_UP:
			System.out.println("UP UP UP.............");
			break;
			
		default:
			break;
		}
		
		
		
		
		return true;
	}
    
	
	
	public void clearPicture(int x,int y){
		//设置新图片
		for(int i=-10;i<=10;i++)
		{
			for(int j=-10;j<=10;j++){
				
				//要求圆形，并且不报错
				try {
					
					if((i*i+j*j)<=100){
						copyBitmap.setPixel(x+i, y+j, Color.TRANSPARENT);
					}
				} catch (Exception e) {
					// TODO: handle exception
				}
				
				
			}
			
		}
		
		
		
		iv_pre.setImageBitmap(copyBitmap);
		
	}
	
}