一个简单的Android 自定义view,实现手指划线

package com.minibox.mycpp.view;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

import java.util.ArrayList;
import java.util.List;

import androidx.annotation.Nullable;

/**
 * Created by lingbeijing on 2020/8/18.
 */
public class RandomBoll extends View {
     

    public RandomBoll(Context context) {
     
        super(context);
        init();
    }

    private Paint mPaint;
    private Paint paintS;
    private float touchX;
    private float touchY;
    private List<Path> multiPath = new ArrayList<>();
    private Canvas myCanvas;
    public RandomBoll(Context context, @Nullable AttributeSet attrs) {
     
        super(context, attrs);
        init();
    }

    public RandomBoll(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
     
        super(context, attrs, defStyleAttr);
        init();
    }

    public RandomBoll(Context context, @Nullable AttributeSet attrs, int defStyleAttr, int defStyleRes) {
     
        super(context, attrs, defStyleAttr, defStyleRes);
        init();
    }

    private void init(){
     
        mPaint = new Paint();
        mPaint.setARGB(0xff, 0x23, 0x23,0xad);
        mPaint.setTextSize(59);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setAntiAlias(true);
        mPaint.setStrokeWidth(1f);

        paintS = new Paint(Paint.ANTI_ALIAS_FLAG);
        paintS.setStyle(Paint.Style.STROKE);
        paintS.setStrokeWidth(2f);
        paintS.setColor(Color.BLUE);
    }

    @Override
    public void draw(Canvas canvas) {
     
        super.draw(canvas);
        canvas.drawText("I Love You",200,60,mPaint);
        RectF rect = new RectF(180, 10, 180 + 320, 80);
        canvas.drawRoundRect(rect,51f,51f, paintS);
        drawMultiPath(canvas);
    }

    Path pathNew;
    @Override
    public boolean onTouchEvent(MotionEvent event) {
     
        touchX = event.getX();
        touchY = event.getY();
        if (event.getAction() == MotionEvent.ACTION_DOWN) {
     
            pathNew = new Path();
            pathNew.reset();
            pathNew.moveTo(touchX, touchY);
            multiPath.add(pathNew);
        }
        if (Math.abs(touchX + touchY) > 20) {
     
            pathNew.lineTo(touchX, touchY);
        }
        invalidate();
        return true;
    }

    private void drawMultiPath(Canvas c) {
     
        if (c == null) {
     
            return;
        }
        for (Path p : multiPath)
            c.drawPath(p, paintS);
    }
}