Android:如果从通知栏恢复应用程序,则绘制的画布油漆消失了

Question

我正在绘制一个绘图应用程序,并希望从通知栏恢复活动.我在研究后添加了代码来自通知栏中的恢复(而不是创建),如下所示.

Doodlz2

@Override
   protected void onCreate(Bundle savedInstanceState) 
   {
      super.onCreate(savedInstanceState);
      this.requestWindowFeature(Window.FEATURE_NO_TITLE);       
      setContentView(R.layout.main); // inflate the layout    
      generateNotification(Doodlz2.this, getResources().getString(R.string.app_name));

      Display display = getWindowManager().getDefaultDisplay(); 
      Constants.SCREEN_W = display.getWidth();  // deprecated
      Constants.SCREEN_H = display.getHeight();  // deprecated

      doodleView = (DoodleView2) findViewById(R.id.doodleView);
      doodleView.setOnTouchListener(this);    
      doodleView.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() 
      {
            @Override
            public void onGlobalLayout() 
            {
                Constants.DRAW_W = doodleView.getWidth(); 
                Constants.DRAW_H = doodleView.getHeight();
            }
      }); 
      OnCreate_NewDialog();
   }

    @Override
    protected void onResume() 
    {
        super.onResume();
    }

   @Override
   protected void onPause()
   {
       super.onPause();
   } 

   @Override
   protected void onDestroy() 
   {
       super.onDestroy();
   }

private static void generateNotification(Context context, String message)
   {
        Intent notificationIntent = new Intent(context, Doodlz2.class);
        notificationIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        PendingIntent intent = PendingIntent.getActivity(context, 0, notificationIntent, 0);

        NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(context)
            .setSmallIcon(R.drawable.logo)
            .setContentTitle(context.getString(R.string.app_name))
            .setContentIntent(intent)
            .setPriority(5) //private static final PRIORITY_HIGH = 5;
            .setContentText(message)
            .setAutoCancel(true)
            .setDefaults(Notification.DEFAULT_LIGHTS);
        NotificationManager mNotificationManager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
        mNotificationManager.notify(0, mBuilder.build());
    }

DoodleView2

public DoodleView2(Context c, AttributeSet attrs) 
   {
       super(c, attrs);
       context_new = c;    
       setFocusable(true);
       setFocusableInTouchMode(true);
       //setLayerType(View.LAYER_TYPE_SOFTWARE, null); // for solely removing the black eraser

       mPath = new Path(); 
       mCanvas = new Canvas();  
       mBitmapPaint = new Paint(Paint.DITHER_FLAG);   

       Constants.mPaint = new Paint();
       Constants.mPaint.setAntiAlias(true); // smooth edges of drawn line
       Constants.mPaint.setDither(true);
       Constants.mPaint.setColor(Color.BLACK); // default color is black
       Constants.mPaint.setStyle(Paint.Style.STROKE); // solid line
       Constants.mPaint.setStrokeJoin(Paint.Join.ROUND);
       Constants.mPaint.setStrokeWidth(5); // set the default line width
       Constants.mPaint.setStrokeCap(Paint.Cap.ROUND); // rounded line ends 
   } 

   @Override
   public void onSizeChanged(int w, int h, int oldW, int oldH)
   {
       super.onSizeChanged(w, h, oldW, oldH);
       mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
       mBitmap = getResizedBitmap(BitmapFactory.decodeResource(getResources(), R.drawable.bdg6),h,w); 
   }   

   @Override
   protected void onDraw(Canvas canvas) 
   {
       canvas.drawBitmap(mBitmap, 0, 0, null); // draw the background screen

       for (Path p : paths)
       {
           Constants.mPaint.setColor(colorsMap.get(p));
           Constants.mPaint.setStrokeWidth(widthMap.get(p));
           canvas.drawPath(p, Constants.mPaint);           
       }       
       Constants.mPaint.setColor(selectedColor);
       Constants.mPaint.setStrokeWidth(selectedWidth);
       canvas.drawPath(mPath, Constants.mPaint);                   
   } 

题:

绘图板正在使用涂料可以绘制.按下主页按钮并从长按主屏幕恢复,线路仍在那里.然而,从通知栏恢复,所有线都消失了,并且再次重新启动绘图板,显示onCreate_NewDialog.

如果从通知栏恢复但是如果从长按主屏幕恢复仍然存在,为什么绘制的线条消失了？

Answer 1

代替：

notificationIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

经过：

notificationIntent.addFlags(Intent.FLAG_ACTIVITY_LAUNCHED_FROM_HISTORY);

现在，您可以从历史记录中调用该活动，而不是创建新类。