android图片_刮刮乐

一、项目目录结构

二、activity_main.xml代码

<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"
    tools:context=".MainActivity" >

    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/after19" />

    <ImageView
        android:id="@+id/iv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
       />

</RelativeLayout>

三、MainActivity.java代码

package com.zgs.ggl;

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;

public class MainActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		//[1]找到iv 显示我们操作的图片 
		final ImageView iv = (ImageView) findViewById(R.id.iv);
		//[2]把我们要操作的图片转换成bitmap
		Bitmap srcBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.pre19);
		//[3]创建原图的副本  
		//[3.1]创建模板
		final Bitmap alterbBitmap = Bitmap.createBitmap(srcBitmap.getWidth(), srcBitmap.getHeight(), srcBitmap.getConfig());
		//[3.2]以alterbBitmap bitmap为模板创建一个画布 
		Canvas canvas = new Canvas(alterbBitmap);
		//[3.3]创建一个画笔 
		Paint paint = new Paint();
		//[3.4]开始作画 
		canvas.drawBitmap(srcBitmap, new Matrix(), paint);
		//[4]把alterbitmap显示到iv上 
		iv.setImageBitmap(alterbBitmap);
		//[5]给iv设置一个触摸事件 
		iv.setOnTouchListener(new OnTouchListener() {
			@Override
			public boolean onTouch(View v, MotionEvent event) {
				//[6]获取触摸事件的类型 
				int action = event.getAction();
				switch (action) {
				case MotionEvent.ACTION_MOVE: //移动  
					for (int i = -7; i < 7; i++) {  //改变x 
						for (int j = -7; j <7; j++) {
							//为了 良好的用户体验 撕一个圆 
							if (Math.sqrt(i*i+j*j)<7) {
								//一次修改一个像素 
								try {
									alterbBitmap.setPixel((int)event.getX()+i, (int)event.getY()+j, Color.TRANSPARENT);
								} catch (Exception e) {
								}
							}
						}
					}
					//一定要记得更新iv
					iv.setImageBitmap(alterbBitmap);
					break;
				}
				return true;
			}
		});
	}
}