本文分享了解決SurfaceView觸摸軌跡閃爍問題的方法,供大家參考,具體內容如下
第一種解決SurfaceView觸摸軌跡閃爍問題的方法:
由于SurfaceView使用雙緩存機制,兩張畫布輪流顯示到屏幕上。那么,要存儲觸摸軌跡并避免兩張畫布內容不一致造成的閃爍問題,完全可以利用保存繪制過程并不斷重新繪制的方法解決閃爍,而且這樣還順帶解決了多次試驗中偶爾出現的因為moveTo()函數不能讀取到參數執行默認設置(參數設為上次的觸摸點)而出現的斷線連接閃爍問題,詳細代碼如下:
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){  } }  }}這里還要注意的是:ArrayList保存的是對象的引用,所以要在每次添加時都新建一個對象實體。
第二種解決SurfaceView觸摸軌跡閃爍問題的方法:
處理觸屏軌跡的繪制時,用到了SurfaceView,建立Path對象,在點擊時開始設置Path對象,滑動過程中記錄觸摸點,離開后重新設置Path對象,因不能阻塞主線程,所以新建了一個子線程來不斷刷新屏幕,也就是將path不斷繪制。但是,接著就出現了一個問題:屏幕中每條軌跡線的終點都會有一小段直線段不斷閃爍。猜測可能是lockCanvas()獲取的對象區域不一樣,就試著使用了lockCanvas(Rect re),但是,運行后發現還是沒有解決問題;接著想到可能是因為每次lockCanvas()后獲取的對象不同,就在主線程中添加了一個Canvas對象,每次都在Canvas對象中修改畫面,然后提交顯示,但是,程序運行后效果絲毫沒有改變!程序代碼如下:
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內容,希望能夠幫助大家輕松解決SurfaceView觸摸軌跡閃爍問題。
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