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>

注意：图片位置不要设置，表面图片要大于底层图片

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

		// 參数1：res是资源的引用，參数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);

		// 创建能够改动的空白的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

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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