实现效果

主要代码

<FrameLayout 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:id="@+id/img_info"  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:src="@drawable/b" />  
  
    <ImageView  
        android:id="@+id/img_surface"  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:src="@drawable/a" />  
  
</FrameLayout>  

MainActivity.java

package com.example.guaguale;

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

/**
 * 刮刮乐
 * 
 * @author zhaoyazhi
 * 
 *         2014-6-18
 */
public class MainActivity extends Activity implements OnTouchListener {

	private Canvas canvas;
	private Paint paint;
	private Bitmap bitmap;
	private ImageView imgInfo;
	private ImageView imgSurface;
	private Bitmap bSurface;// 没有刮开的表面图片
	private Bitmap bInfo;// 刮开后的显示内容

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

		imgSurface = (ImageView) findViewById(R.id.img_surface);
		imgInfo = (ImageView) findViewById(R.id.img_info);

		// 获得图片
		// 参数1：res是资源的引用，参数2：id是图片的id
		bSurface = BitmapFactory.decodeResource(getResources(), R.drawable.a);
		bInfo = BitmapFactory.decodeResource(getResources(), R.drawable.b);

		// 设置图片
		imgSurface.setImageBitmap(bSurface);
		imgInfo.setImageBitmap(bInfo);

		// 创建可以修改的空白的bitmap
		bitmap = Bitmap.createBitmap(bSurface.getWidth(), bSurface.getHeight(),
				bSurface.getConfig());

		// 设置屏幕触摸事件
		imgSurface.setOnTouchListener(this);

		// 创建画笔
		paint = new Paint();

		// 创建画布
		canvas = new Canvas(bitmap);
		canvas.drawBitmap(bSurface, new Matrix(), paint);
	}

	/**
	 * 用户触摸屏幕时候的事件
	 */
	@Override
	public boolean onTouch(View view, MotionEvent event) {
		switch (event.getAction()) {
		case MotionEvent.ACTION_MOVE:
			int newX = (int) event.getX();
			int newY = (int) event.getY();
			// i ，j每一个透明单位的大小
			for (int i = -10; i < 10; i++) {
				for (int j = -10; j < 10; j++) {
					//图片之外的区域
					if ((i + newX) >= bSurface.getWidth()
							|| j + newY >= bSurface.getHeight() || i + newX < 0
							|| j + newY < 0) {
						return false;
					}
					//将滑过的地方变为透明
					bitmap.setPixel(i + newX, j + newY, Color.TRANSPARENT);
				}
			}
			//设置透明区域
			imgSurface.setImageBitmap(bitmap);
			break;
		}
		return true;
	}
}

涉及知识点

getResources()

http://blog.csdn.net/zhaoyazhi2129/article/details/32077513

setImageBitmap

http://blog.csdn.net/zhaoyazhi2129/article/details/32080827

paint画笔

http://blog.csdn.net/zhaoyazhi2129/article/details/32090187

canvas画布

http://blog.csdn.net/zhaoyazhi2129/article/details/32098477

bitmap

http://blog.csdn.net/zhaoyazhi2129/article/details/32136179

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赵雅智_Android案例_刮刮乐