android画布一闪一闪的,解决Android SurfaceView绘制触摸轨迹闪烁问题的方法
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 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=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
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。
總結
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