贝济埃曲线quadTo与传统的手势轨迹平滑度对比分析

package com.loaderman.customviewdemo;

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

public class NormalGestureTrackView extends View {
    private Path mPath = new Path();
    private Paint mPaint;

    public NormalGestureTrackView(Context context, AttributeSet attrs) {
        super(context, attrs);

        mPaint = new Paint();
        mPaint.setColor(Color.BLACK);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeWidth(5);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN: {
                mPath.moveTo(event.getX(), event.getY());
                return true;//代表消费了触摸事件
            }
            case MotionEvent.ACTION_MOVE:
                mPath.lineTo(event.getX(), event.getY());//曲线转折处不够平滑
                postInvalidate();
                break;
            default:
                break;
        }
        return super.onTouchEvent(event);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawColor(Color.WHITE);
        canvas.drawPath(mPath, mPaint);
    }
}

package com.loaderman.customviewdemo;

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

public class BezierGestureTrackView extends View {
    private Path mPath = new Path();
    private Paint mPaint;
    private float mPreX,mPreY;

    public BezierGestureTrackView(Context context, AttributeSet attrs) {
        super(context, attrs);

        mPaint = new Paint();
        mPaint.setColor(Color.BLACK);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeWidth(5);
    }

    @Override
public boolean onTouchEvent(MotionEvent event) {
    switch (event.getAction()){
        case MotionEvent.ACTION_DOWN:{
            mPath.moveTo(event.getX(),event.getY());
            mPreX = event.getX();
            mPreY = event.getY();
            return true;
        }
        case MotionEvent.ACTION_MOVE:{
            float endX = (mPreX+event.getX())/2;
            float endY = (mPreY+event.getY())/2;
            mPath.quadTo(mPreX,mPreY,endX,endY);//实现手势平滑过渡
            mPreX = event.getX();
            mPreY =event.getY();
            invalidate();
        }
        break;
        default:
            break;
    }
    return super.onTouchEvent(event);
}

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawColor(Color.WHITE);
        canvas.drawPath(mPath,mPaint);
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <com.loaderman.customviewdemo.NormalGestureTrackView
        android:layout_width="match_parent"

        android:layout_height="300dp" />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="5dp"
        android:background="@color/colorPrimary" />

    <com.loaderman.customviewdemo.BezierGestureTrackView
        android:layout_width="match_parent"
        android:layout_height="300dp" />
</LinearLayout>

效果图