市场上撕衣服案例的解析，两张图片，设置屏幕触摸事件，触摸的时候把范围内的元素设为透明。

效果掩饰

项目结构

代码

• MainActivity

package com.example.www.ripclose;

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.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;

public class MainActivity extends AppCompatActivity {

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

        //用来显示 操作后的图片
        final ImageView iv = (ImageView) findViewById(R.id.imageView2);

        //[1]获取要操作图片 原图
        Bitmap srcBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.background);

        //[2]创建一个副本   相当于有一个和原图大小的白纸
        final Bitmap alterBitmap = Bitmap.createBitmap(srcBitmap.getWidth(), srcBitmap.getHeight(), srcBitmap.getConfig());
        //创建画笔
        Paint paint = new Paint();
        //创建画布   把白纸铺到画布上
        Canvas canvas = new Canvas(alterBitmap);
        //开始作画
        canvas.drawBitmap(srcBitmap, new Matrix(), paint);

        iv.setImageBitmap(alterBitmap);

        //[3]给vi设置一个触摸事件
        iv.setOnTouchListener(new View.OnTouchListener() {

            @Override
            public boolean onTouch(View v, MotionEvent event) {
                //[4]具体判断一下触摸事件
                switch (event.getAction()) {

                    case MotionEvent.ACTION_MOVE://移动事件

                        for (int i = -7; i < 70; i++) { //增加X轴坐标

                            for (int j = -7; j < 70; j++) {
                                //增加Y轴坐标

                                //为了良好的用户体验  撕一个圆
                                if (Math.sqrt(i*i+j*j)<70) {

                                    try {
                                        alterBitmap.setPixel((int)event.getX()+i, (int)event.getY()+j, Color.TRANSPARENT);
                                    } catch (Exception e) {
                                    }
                                }

                            }
                        }

                        //更新一下iv
                        iv.setImageBitmap(alterBitmap);
                        break;

                }

                return true;
            }
        });





    }
}

• activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">


    <ImageView
        android:id="@+id/imageView"
        android:layout_width="0dp"
        android:layout_height="389dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="152dp"
        android:layout_marginEnd="8dp"
        android:layout_marginBottom="8dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.552"
        android:src="@drawable/a123"/>

    <ImageView
        android:id="@+id/imageView2"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginBottom="8dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>