SurfaceView绘制触摸轨迹闪烁问题的最终解决方案

来源：互联网发布：淘宝延长收货是几天编辑：程序博客网时间：2024/06/16 17:00

由于SurfaceView使用双缓存机制，两张画布轮流显示到屏幕上。那么，要存储触摸轨迹并避免两张画布内容不一致造成的闪烁问题，完全可以利用保存绘制过程并不断重新绘制的方法解决闪烁，而且这样还顺带解决了多次试验中偶尔出现的因为moveTo（）函数不能读取到参数执行默认设置（参数设为上次的触摸点）而出现的断线连接闪烁问题，详细代码如下：

package com.tobacco.touchdraw;

import java.util.ArrayList;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.SurfaceHolder.Callback;
import android.view.View.OnTouchListener;

public class LSurfaceView extends SurfaceView implements Callback,OnTouchListener,Runnable{
private SurfaceHolder sfh;
private Canvas canvas;
private Paint paint;
private Path path;
private ArrayList<Path> paths;
private boolean flag;

public LSurfaceView(Context context) {
  super(context);
  sfh=this.getHolder();
  sfh.addCallback(this);
  paint=new Paint();
  paint.setColor(Color.RED);
  paint.setAntiAlias(true);
  paint.setStrokeWidth(4);
  paint.setStyle(Paint.Style.STROKE);
  paint.setStrokeCap(Paint.Cap.ROUND);
  paths=new ArrayList<Path>();
  path=new Path();
}
public void myDraw(MotionEvent e){
  int action=e.getAction();
  switch(action){
  case MotionEvent.ACTION_DOWN:
   path.moveTo(e.getX(),e.getY());
   break;
  case MotionEvent.ACTION_MOVE:
   path.lineTo(e.getX(),e.getY());
   break;
  case MotionEvent.ACTION_UP:
   //path.close();
   Path path1=new Path(path);
   paths.add(path1);
   path.reset();
   break;
  }


}

@Override
public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) {

}

@Override
public void surfaceCreated(SurfaceHolder holder) {
  flag=true;
  setOnTouchListener(this);
  new Thread(this).start();

}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
flag=false;
}

@Override
public boolean onTouch(View v, MotionEvent event) {
  myDraw(event);
  return true;
}
@Override
public void run() {
  while(flag){
   long start=System.currentTimeMillis();
   canvas=sfh.lockCanvas();
   if(canvas!=null){
    canvas.drawColor(Color.BLACK);
    for(int i=0;i<paths.size();i++)
     canvas.drawPath(paths.get(i),paint);
    canvas.drawPath(path,paint);
    sfh.unlockCanvasAndPost(canvas);
   }
   long end=System.currentTimeMillis();
   try{
    if(end-start<30){
     Thread.sleep(30-(end-start));
    }
   }
   catch(Exception e){
   }
  }

}

}
这里还要注意的是：ArrayList保存的是对象的引用，所以要在每次添加时都新建一个对象实体。

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