自定义View实现擦除和点击亮灯效果

擦除效果图：

自定义View代码：

package com.example.workday05;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.view.MotionEvent;
import android.view.View;
import android.view.WindowManager;

public class Demo1 extends View {

    private Paint paint;
    private Canvas mycanvas;
    private Context context;
    private int width;
    private int height;
    private Bitmap fgbitmap;
    private Bitmap bgbitmap;
    private Path path;
    private WindowManager manager;

    public Demo1(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.context = context;
        initPaint();
    }

    private void initPaint() {
        paint = new Paint();
        //获取窗口的大小
        manager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
        DisplayMetrics displayMetrics = new DisplayMetrics();
        manager.getDefaultDisplay().getMetrics(displayMetrics);
        //获取到宽高
        width = displayMetrics.widthPixels;
        height = displayMetrics.heightPixels;
        //设置画笔的属性
        paint.setAntiAlias(true);//抗锯齿
        paint.setDither(true);//抗抖动
        //设置透明度
        paint.setARGB(128,255,0,0);
        //设置混合模式
        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));
        //设置 描边
        paint.setStyle(Paint.Style.STROKE);
        //设置宽度
        paint.setStrokeWidth(40);
        //设置路径结合处样式
        paint.setStrokeJoin(Paint.Join.ROUND);
        //设置笔触类型
        paint.setStrokeCap(Paint.Cap.ROUND);
        //生成灰色前景
        fgbitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        //将其注入画布
        mycanvas = new Canvas(fgbitmap);
        //设置画布为灰色
        mycanvas.drawColor(Color.GRAY);
        //生成背景图片
        bgbitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.demo1);
        //剪切成屏幕大小
        bgbitmap = Bitmap.createScaledBitmap(bgbitmap,width,height,true);
        //创建path对象
        path = new Path();
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch(event.getAction()){
            case MotionEvent.ACTION_DOWN:
                path.reset();//清除之前的路径
                path.moveTo(event.getX(),event.getY());
                break;
            case MotionEvent.ACTION_MOVE:
                path.lineTo(event.getX(),event.getY());
                break;
            case MotionEvent.ACTION_UP:
                path.lineTo(event.getX(),event.getY());
                break;
        }
        invalidate();
        return true;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        //设置背景图片
        canvas.drawBitmap(bgbitmap,0,0,null);
        //设置前景灰色背景
        canvas.drawBitmap(fgbitmap,0,0,null);
        //手指划过的路径
        mycanvas.drawPath(path,paint);
    }



}

布局代码：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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=".workday5"
    android:orientation="vertical"
    >
    <com.example.workday05.Demo1
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/demo1"
        />

</LinearLayout>

点击亮灯效果：

java代码：

package com.example.day05;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Point;
import android.graphics.RectF;
import android.graphics.Region;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.view.MotionEvent;
import android.view.View;
import android.view.WindowManager;

public class MyView2 extends View {
    private Paint paint;
    private Paint paint1;
    private Paint paint2;
    private Paint paint3;

    private Path path;
    private Path path1;
    private Path path2;
    private Path path3;
    private Context context;
    public MyView2(Context context,AttributeSet attrs) {
        super(context, attrs);
        this.context = context;
        initPaint();
    }

    private void initPaint() {
        //四个画笔
        paint = new Paint();
        paint1 = new Paint();
        paint2 = new Paint();
        paint3 = new Paint();
        //四个路径
        path = new Path();
        path1 = new Path();
        path2 = new Path();
        path3 = new Path();
        //第一个画笔
        paint.setColor(Color.RED);
        paint.setStrokeWidth(2);
        paint.setStrokeWidth(5);
        paint.setStyle(Paint.Style.STROKE);
        //第二个画笔
        paint1.setColor(Color.BLUE);
        paint1.setStrokeWidth(2);
        paint1.setStrokeWidth(5);
        paint1.setStyle(Paint.Style.STROKE);
        //第三个画笔
        paint2.setColor(Color.GREEN);
        paint2.setStrokeWidth(2);
        paint2.setStrokeWidth(5);
        paint2.setStyle(Paint.Style.STROKE);
        //第四个画笔
        paint3.setColor(Color.GRAY);
        paint3.setStrokeWidth(2);
        paint3.setStrokeWidth(5);
        paint3.setStyle(Paint.Style.STROKE);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);

    }
    int height;
    int width;
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        path.moveTo(0,0);
         WindowManager manager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
        DisplayMetrics displayMetrics = new DisplayMetrics();
        manager.getDefaultDisplay().getMetrics(displayMetrics);
        //获取主屏幕的宽与高
        height = displayMetrics.heightPixels;
        width = displayMetrics.widthPixels;
        path.lineTo(width/2,height/2);
        path.lineTo(width,0);
        canvas.drawPath(path,paint);

        path1.moveTo(width,height);
        path1.lineTo(width/2,height/2);
        path1.lineTo(width,0);
        canvas.drawPath(path1,paint1);

        path2.moveTo(width,height);
        path2.lineTo(width/2,height/2);
        path2.lineTo(0,height);
        canvas.drawPath(path2,paint2);

        path3.moveTo(0,height);
        path3.lineTo(width/2,height/2);
        path3.lineTo(0,0);
        canvas.drawPath(path3,paint3);
    }
    float x;
    float y;
    private int PicX;
    private int PicY;

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        //获取XY的坐标
        x = event.getX();
        y = event.getY();
        switch (event.getAction()){
            case MotionEvent.ACTION_DOWN:
                //点击区域的判断方法
                ClickRegion();
                break;
            case MotionEvent.ACTION_MOVE:
                break;
            case MotionEvent.ACTION_UP:
                break;
        }
        invalidate();
        return true;
    }

    private void ClickRegion() {
        PicX = (int) x;
        PicY = (int) y;
        //创建一个矩形
        RectF rectF = new RectF();
        path.computeBounds(rectF,true);//用path分割成矩形
        Region region = new Region();//区域
        //构造新区域
        region.setPath(path,new Region((int) rectF.left,(int)rectF.top,(int)rectF.right,(int)rectF.bottom));
        boolean b = region.contains(PicX, PicY);
        if(b){
            paint.setStyle(Paint.Style.FILL);
        }

        //创建一个矩形
        RectF rectF1 = new RectF();
        path1.computeBounds(rectF1,true);//用path分割成矩形
        Region region1 = new Region();//区域
        //构造新区域
        region1.setPath(path1,new Region((int) rectF1.left,(int)rectF1.top,(int)rectF1.right,(int)rectF1.bottom));
        boolean b1 = region1.contains(PicX, PicY);
        if(b1){
            paint1.setStyle(Paint.Style.FILL);
        }

        //创建一个矩形
        RectF rectF2 = new RectF();
        path2.computeBounds(rectF2,true);//用path分割成矩形
        Region region2 = new Region();//区域
        //构造新区域
        region2.setPath(path2,new Region((int) rectF2.left,(int)rectF2.top,(int)rectF2.right,(int)rectF2.bottom));
        boolean b2 = region2.contains(PicX, PicY);
        if(b2){
            paint2.setStyle(Paint.Style.FILL);
        }

        //创建一个矩形
        RectF rectF3 = new RectF();
        path3.computeBounds(rectF3,true);//用path分割成矩形
        Region region3 = new Region();//区域
        //构造新区域
        region3.setPath(path3,new Region((int) rectF3.left,(int)rectF3.top,(int)rectF3.right,(int)rectF3.bottom));
        boolean b3 = region3.contains(PicX, PicY);
        if(b3){
            paint3.setStyle(Paint.Style.FILL);
        }
    }
}

这里的代码全是复制粘贴，如有更简单的方法欢迎私信。

布局代码：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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=".day05">
    <com.example.day05.MyView2
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/myview"
        />


</RelativeLayout>

主类引用：

package com.example.workday05;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class Activity_second extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
        Demo2 demo2 = findViewById(R.id.demo2);
    }
}