Android中SurfaceView绘制触摸轨迹时出现的闪烁有关问题
Android中SurfaceView绘制触摸轨迹时出现的闪烁问题
今天在处理触屏轨迹的绘制时，用到了SurfaceView，建立Path对象，在点击时开始设置Path对象，滑动过程中记录触摸点，离开后重新设置Path对象，因不能阻塞主线程，所以新建了一个子线程来不断刷新屏幕，也就是将path不断绘制。但是，接着就出现了一个问题：屏幕中每条轨迹线的终点都会有一小段直线段不断闪烁。猜测可能是lockCanvas（）获取的对象区域不一样，就试着使用了lockCanvas（Rect re），但是，运行后发现还是没有解决问题；接着想到可能是因为每次lockCanvas（）后获取的对象不同，就在主线程中添加了一个Canvas对象，每次都在Canvas对象中修改画面，然后提交显示，但是，程序运行后效果丝毫没有改变！shit！程序代码如下：
package com.tobacco.touchdraw;
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 MySurfaceView extends SurfaceView implements Callback,OnTouchListener,Runnable{ private SurfaceHolder sfh; private Canvas canvas; private Paint paint; private float lastX,lastY; private Path path; private boolean flag; public MySurfaceView(Context context) { super(context); sfh=this.getHolder(); sfh.addCallback(this); paint=new Paint(); paint.setColor(Color.RED); paint.setAntiAlias(true); paint.setStrokeWidth(5); paint.setStyle(Paint.Style.STROKE); paint.setStrokeCap(Paint.Cap.ROUND); path=new Path(); } public void myDraw(MotionEvent e){ int action=e.getAction(); switch(action){ case MotionEvent.ACTION_DOWN: path.moveTo(e.getX(),e.getY()); lastX=e.getX(); lastY=e.getY(); break; case MotionEvent.ACTION_MOVE: path.quadTo(lastX,lastY,e.getX(),e.getY()); lastX=e.getX(); lastY=e.getY(); break; case MotionEvent.ACTION_UP: //path.quadTo(lastX,lastY,e.getX(),e.getY()); 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.drawPath(path,paint); sfh.unlockCanvasAndPost(canvas); } long end=System.currentTimeMillis(); try{ if(end-start<100){ Thread.sleep(100-(end-start)); } } catch(Exception e){ } } }}
今天在处理触屏轨迹的绘制时，用到了SurfaceView，建立Path对象，在点击时开始设置Path对象，滑动过程中记录触摸点，离开后重新设置Path对象，因不能阻塞主线程，所以新建了一个子线程来不断刷新屏幕，也就是将path不断绘制。但是，接着就出现了一个问题：屏幕中每条轨迹线的终点都会有一小段直线段不断闪烁。猜测可能是lockCanvas（）获取的对象区域不一样，就试着使用了lockCanvas（Rect re），但是，运行后发现还是没有解决问题；接着想到可能是因为每次lockCanvas（）后获取的对象不同，就在主线程中添加了一个Canvas对象，每次都在Canvas对象中修改画面，然后提交显示，但是，程序运行后效果丝毫没有改变！shit！程序代码如下：
package com.tobacco.touchdraw;
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 MySurfaceView extends SurfaceView implements Callback,OnTouchListener,Runnable{ private SurfaceHolder sfh; private Canvas canvas; private Paint paint; private float lastX,lastY; private Path path; private boolean flag; public MySurfaceView(Context context) { super(context); sfh=this.getHolder(); sfh.addCallback(this); paint=new Paint(); paint.setColor(Color.RED); paint.setAntiAlias(true); paint.setStrokeWidth(5); paint.setStyle(Paint.Style.STROKE); paint.setStrokeCap(Paint.Cap.ROUND); path=new Path(); } public void myDraw(MotionEvent e){ int action=e.getAction(); switch(action){ case MotionEvent.ACTION_DOWN: path.moveTo(e.getX(),e.getY()); lastX=e.getX(); lastY=e.getY(); break; case MotionEvent.ACTION_MOVE: path.quadTo(lastX,lastY,e.getX(),e.getY()); lastX=e.getX(); lastY=e.getY(); break; case MotionEvent.ACTION_UP: //path.quadTo(lastX,lastY,e.getX(),e.getY()); 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.drawPath(path,paint); sfh.unlockCanvasAndPost(canvas); } long end=System.currentTimeMillis(); try{ if(end-start<100){ Thread.sleep(100-(end-start)); } } catch(Exception e){ } } }}