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解决Android SurfaceView绘制触摸轨迹闪烁问题的方法

作者:佚名      Android开发编辑:admin      更新时间:2022-07-23

本文分享了解决SurfaceView触摸轨迹闪烁问题的方法,供大家参考,具体内容如下

第一种解决SurfaceView触摸轨迹闪烁问题的方法:

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。

第二种解决SurfaceView触摸轨迹闪烁问题的方法:

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!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){
  }
 }
 
 }
}

以上就是本文的全部内容,希望能够帮助大家轻松解决SurfaceView触摸轨迹闪烁问题。