Error after putting in QGraphicView Codes

[020394]

terminate called after throwing an instance of 'std::bad_alloc'
  what():  std::bad_alloc
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D:\project1\Qt\build-QtCreatorMP-Desktop-Debug\debug\QtCreatorMP exited with code 3

terminate called after throwing an instance of 'std::bad_alloc'
  what():  std::bad_alloc
terminate called recursively
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D:\project1\Qt\build-QtCreatorMP-Desktop-Debug\debug\QtCreatorMP exited with code 3

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I am getting this errors after putting QGraphicsView code into it

h file

private:  
 QGraphicsScene *scene;
    QGraphicsRectItem*rectangle;
    QGraphicsLineItem*line;

private:  
 QGraphicsScene *scene;
    QGraphicsRectItem*rectangle;
    QGraphicsLineItem*line;

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cpp file

scene=new QGraphicsScene(this);
   ui->graphicsView->setScene(scene);
           QBrush yelloBrush(Qt::yellow);
           QBrush magentaBrush(Qt::magenta);
   QBrush greenBrush(Qt::green);
 
   QPen Linepen(Qt::black);
   Linepen.setWidth(2);
 
 
 
 
   //BASAL
   rectangle=scene->addRect(50,220,100,-50,Linepen,magentaBrush);//LAST 1st HOUR BAR CHART
   rectangle=scene->addRect(200,220,100,-50,Linepen,magentaBrush);//LAST 2nd HOUR BAR CHART
   rectangle=scene->addRect(350,220,100,-50,Linepen,magentaBrush);//LAST 3th HOUR BAR CHART
   rectangle=scene->addRect(500,220,100,-50,Linepen,magentaBrush);//LAST 4TH HOUR BAR CHART
   rectangle=scene->addRect(650,220,100,-50,Linepen,magentaBrush);//LAST 5th HOUR BAR CHART
  //BASAL
 
   //PATIENT
   //TO ADD ON TOP OF THE GRAPH ,BREAL Y +Y OF BASAL
   rectangle=scene->addRect(50,220-50,100,-50,Linepen,yelloBrush);//LAST 1st HOUR BAR CHART
   rectangle=scene->addRect(200,220-50,100,-50,Linepen,yelloBrush);//LAST 2nd HOUR BAR CHART
   rectangle=scene->addRect(350,220-50,100,-50,Linepen,yelloBrush);//LAST 3th HOUR BAR CHART
   rectangle=scene->addRect(500,220-50,100,-50,Linepen,yelloBrush);//LAST 4TH HOUR BAR CHART
   rectangle=scene->addRect(650,220-50,100,-50,Linepen,yelloBrush);//LAST 5th HOUR BAR CHART
   //PATIENT
 
   //CLINICIAN
               //TO ADD ON TOP OF THE GRAPH ,BREAL Y +Y OF BASAL AND CLINICIAN
   rectangle=scene->addRect(50,220-50-50,100,-50,Linepen,greenBrush);//LAST 1st HOUR BAR CHART
   rectangle=scene->addRect(200,220-50-50,100,-50,Linepen,greenBrush);//LAST 2nd HOUR BAR CHART
   rectangle=scene->addRect(350,220-50-50,100,-50,Linepen,greenBrush);//LAST 3th HOUR BAR CHART
   rectangle=scene->addRect(500,220-50-50,100,-50,Linepen,greenBrush);//LAST 4TH HOUR BAR CHART
   rectangle=scene->addRect(650,220-50-50,100,-50,Linepen,greenBrush);//LAST 5th HOUR BAR CHART
   //CLINICIAN
    line=scene->addLine(0,220,790,220,Linepen);//x axis
    line=scene->addLine(790,220,780,215,Linepen);//> for x axis
    line=scene->addLine(790,220,780,225,Linepen);//> for x axis
 
    line=scene->addLine( 20,0,20,240,Linepen);//y axis
    line=scene->addLine(20,0,15,10,Linepen);//> for y axis
    line=scene->addLine(20,0,25,10,Linepen);//> for y axis
 
 
    line=scene->addLine( 15,215,25,215,Linepen);//y Coordinate (1)
    line=scene->addLine( 15,210,25,210,Linepen);//y Coordinate (2
    line=scene->addLine( 15,205,25,205,Linepen);//y Coordinate (3)
    line=scene->addLine( 15,200,25,200,Linepen);//y Coordinate (4)
    line=scene->addLine( 15,195,25,195,Linepen);//y Coordinate (5)
    line=scene->addLine( 15,190,25,190,Linepen);//y Coordinate (6)
    line=scene->addLine( 15,185,25,185,Linepen);//y Coordinate (7)
    line=scene->addLine( 15,180,25,180,Linepen);//y Coordinate (8)
    line=scene->addLine( 15,175,25,175,Linepen);//y Coordinate (9)
 
    line=scene->addLine( 10,170,30,170,Linepen);//y Coordinate (10)
    line=scene->addLine( 15,165,25,165,Linepen);//y Coordinate (11)
    line=scene->addLine( 15,160,25,160,Linepen);//y Coordinate (12
    line=scene->addLine( 15,155,25,155,Linepen);//y Coordinate (13)
    line=scene->addLine( 15,150,25,150,Linepen);//y Coordinate (14)
    line=scene->addLine( 15,145,25,145,Linepen);//y Coordinate (15)
    line=scene->addLine( 15,140,25,140,Linepen);//y Coordinate (16)
    line=scene->addLine( 15,135,25,135,Linepen);//y Coordinate (17)
    line=scene->addLine( 15,130,25,130,Linepen);//y Coordinate (18)
    line=scene->addLine( 15,125,25,125,Linepen);//y Coordinate (19)
 
    line=scene->addLine( 10,120,30,120,Linepen);//y Coordinate (20)
    line=scene->addLine( 15,115,25,115,Linepen);//y Coordinate (21)
    line=scene->addLine( 15,110,25,110,Linepen);//y Coordinate (22)
    line=scene->addLine( 15,105,25,105,Linepen);//y Coordinate (23)
    line=scene->addLine( 15,100,25,100,Linepen);//y Coordinate (24)
    line=scene->addLine( 15,95,25,95,Linepen);  //y Coordinate (25)
    line=scene->addLine( 15,90,25,90,Linepen);  //y Coordinate (26)
    line=scene->addLine( 15,85,25,85,Linepen);  //y Coordinate (27)
    line=scene->addLine( 15,80,25,80,Linepen);  //y Coordinate (28)
    line=scene->addLine( 15,75,25,75,Linepen);  //y Coordinate (29)
    line=scene->addLine( 10,70,30,70,Linepen);  //y Coordinate (30)
 
    line=scene->addLine( 15,65,25,65,Linepen); //y Coordinate (31)
    line=scene->addLine( 15,60,25,60,Linepen); //y Coordinate (32)
    line=scene->addLine( 15,55,25,55,Linepen); //y Coordinate (33)
    line=scene->addLine( 15,50,25,50,Linepen); //y Coordinate (34)
    line=scene->addLine( 15,45,25,45,Linepen); //y Coordinate (35)
    line=scene->addLine( 15,40,25,40,Linepen); //y Coordinate (36)
    line=scene->addLine( 15,35,25,35,Linepen); //y Coordinate (37)
    line=scene->addLine( 15,30,25,30,Linepen); //y Coordinate (38)
    line=scene->addLine( 15,25,25,25,Linepen); //y Coordinate (39)
    line=scene->addLine( 10,20,30,20,Linepen); //y Coordinate (40)
 
 
    yText0=scene->addText("0");
    yText0->setPos(7,215);

scene=new QGraphicsScene(this);
   ui->graphicsView->setScene(scene);
           QBrush yelloBrush(Qt::yellow);
           QBrush magentaBrush(Qt::magenta);
   QBrush greenBrush(Qt::green);

   QPen Linepen(Qt::black);
   Linepen.setWidth(2);




   //BASAL
   rectangle=scene->addRect(50,220,100,-50,Linepen,magentaBrush);//LAST 1st HOUR BAR CHART
   rectangle=scene->addRect(200,220,100,-50,Linepen,magentaBrush);//LAST 2nd HOUR BAR CHART
   rectangle=scene->addRect(350,220,100,-50,Linepen,magentaBrush);//LAST 3th HOUR BAR CHART
   rectangle=scene->addRect(500,220,100,-50,Linepen,magentaBrush);//LAST 4TH HOUR BAR CHART
   rectangle=scene->addRect(650,220,100,-50,Linepen,magentaBrush);//LAST 5th HOUR BAR CHART
  //BASAL

   //PATIENT
   //TO ADD ON TOP OF THE GRAPH ,BREAL Y +Y OF BASAL
   rectangle=scene->addRect(50,220-50,100,-50,Linepen,yelloBrush);//LAST 1st HOUR BAR CHART
   rectangle=scene->addRect(200,220-50,100,-50,Linepen,yelloBrush);//LAST 2nd HOUR BAR CHART
   rectangle=scene->addRect(350,220-50,100,-50,Linepen,yelloBrush);//LAST 3th HOUR BAR CHART
   rectangle=scene->addRect(500,220-50,100,-50,Linepen,yelloBrush);//LAST 4TH HOUR BAR CHART
   rectangle=scene->addRect(650,220-50,100,-50,Linepen,yelloBrush);//LAST 5th HOUR BAR CHART
   //PATIENT

   //CLINICIAN
               //TO ADD ON TOP OF THE GRAPH ,BREAL Y +Y OF BASAL AND CLINICIAN
   rectangle=scene->addRect(50,220-50-50,100,-50,Linepen,greenBrush);//LAST 1st HOUR BAR CHART
   rectangle=scene->addRect(200,220-50-50,100,-50,Linepen,greenBrush);//LAST 2nd HOUR BAR CHART
   rectangle=scene->addRect(350,220-50-50,100,-50,Linepen,greenBrush);//LAST 3th HOUR BAR CHART
   rectangle=scene->addRect(500,220-50-50,100,-50,Linepen,greenBrush);//LAST 4TH HOUR BAR CHART
   rectangle=scene->addRect(650,220-50-50,100,-50,Linepen,greenBrush);//LAST 5th HOUR BAR CHART
   //CLINICIAN
    line=scene->addLine(0,220,790,220,Linepen);//x axis
    line=scene->addLine(790,220,780,215,Linepen);//> for x axis
    line=scene->addLine(790,220,780,225,Linepen);//> for x axis

    line=scene->addLine( 20,0,20,240,Linepen);//y axis
    line=scene->addLine(20,0,15,10,Linepen);//> for y axis
    line=scene->addLine(20,0,25,10,Linepen);//> for y axis


    line=scene->addLine( 15,215,25,215,Linepen);//y Coordinate (1)
    line=scene->addLine( 15,210,25,210,Linepen);//y Coordinate (2
    line=scene->addLine( 15,205,25,205,Linepen);//y Coordinate (3)
    line=scene->addLine( 15,200,25,200,Linepen);//y Coordinate (4)
    line=scene->addLine( 15,195,25,195,Linepen);//y Coordinate (5)
    line=scene->addLine( 15,190,25,190,Linepen);//y Coordinate (6)
    line=scene->addLine( 15,185,25,185,Linepen);//y Coordinate (7)
    line=scene->addLine( 15,180,25,180,Linepen);//y Coordinate (8)
    line=scene->addLine( 15,175,25,175,Linepen);//y Coordinate (9)

    line=scene->addLine( 10,170,30,170,Linepen);//y Coordinate (10)
    line=scene->addLine( 15,165,25,165,Linepen);//y Coordinate (11)
    line=scene->addLine( 15,160,25,160,Linepen);//y Coordinate (12
    line=scene->addLine( 15,155,25,155,Linepen);//y Coordinate (13)
    line=scene->addLine( 15,150,25,150,Linepen);//y Coordinate (14)
    line=scene->addLine( 15,145,25,145,Linepen);//y Coordinate (15)
    line=scene->addLine( 15,140,25,140,Linepen);//y Coordinate (16)
    line=scene->addLine( 15,135,25,135,Linepen);//y Coordinate (17)
    line=scene->addLine( 15,130,25,130,Linepen);//y Coordinate (18)
    line=scene->addLine( 15,125,25,125,Linepen);//y Coordinate (19)

    line=scene->addLine( 10,120,30,120,Linepen);//y Coordinate (20)
    line=scene->addLine( 15,115,25,115,Linepen);//y Coordinate (21)
    line=scene->addLine( 15,110,25,110,Linepen);//y Coordinate (22)
    line=scene->addLine( 15,105,25,105,Linepen);//y Coordinate (23)
    line=scene->addLine( 15,100,25,100,Linepen);//y Coordinate (24)
    line=scene->addLine( 15,95,25,95,Linepen);  //y Coordinate (25)
    line=scene->addLine( 15,90,25,90,Linepen);  //y Coordinate (26)
    line=scene->addLine( 15,85,25,85,Linepen);  //y Coordinate (27)
    line=scene->addLine( 15,80,25,80,Linepen);  //y Coordinate (28)
    line=scene->addLine( 15,75,25,75,Linepen);  //y Coordinate (29)
    line=scene->addLine( 10,70,30,70,Linepen);  //y Coordinate (30)

    line=scene->addLine( 15,65,25,65,Linepen); //y Coordinate (31)
    line=scene->addLine( 15,60,25,60,Linepen); //y Coordinate (32)
    line=scene->addLine( 15,55,25,55,Linepen); //y Coordinate (33)
    line=scene->addLine( 15,50,25,50,Linepen); //y Coordinate (34)
    line=scene->addLine( 15,45,25,45,Linepen); //y Coordinate (35)
    line=scene->addLine( 15,40,25,40,Linepen); //y Coordinate (36)
    line=scene->addLine( 15,35,25,35,Linepen); //y Coordinate (37)
    line=scene->addLine( 15,30,25,30,Linepen); //y Coordinate (38)
    line=scene->addLine( 15,25,25,25,Linepen); //y Coordinate (39)
    line=scene->addLine( 10,20,30,20,Linepen); //y Coordinate (40)


    yText0=scene->addText("0");
    yText0->setPos(7,215);

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I Put the above cpp codes inside a timer(1000) which runs every sec . I am doing this as in the future i am going to change the height to a variable which will get data from a database and set the height of it . That why i use the timer so it can keep updating . Anyway to solve this ?

[ChrisW67]

Your program is exhausting your system's memory. Start with the observation that you are creating a whole graphics scene repeatedly and this is not being cleaned up.

[020394]

I see so what should i do ? Does the problem lies with the QGraphicView ?

[ChrisW67]

No, the problem is not in Qt. Fix your code. We cannot see that, you can.

[020394]

I check the processes my program took up 1.6++ gb mem . I check my codes. I implemented the graphic view in a timer. guess that causes it to keep running and adding to the memory . Is there a way to like reset the graphic view and call it back again ?

---

Added after 6 minutes:

infusion.cppinfusion.h


The above are my codes, feel free to take a look .

[ChrisW67]

Your program is creating a new scene graph every millisecond (or thereabouts) as a result of the timer expiring. You never delete the old one... you exhaust system memory rather quickly.

The other timer (the one that actually updates a clock display) is probably pegging your CPU at about 100% busy-polling when that is entirely unnecessary.

[020394]

I see , I tried using a 1sec timer , The memory is increasing slower than before . It is ok to put the QGraphic codes in a timer right ? Is it ok to keep creating a new scene graph using a timer ? How to delete the old one ?

[ChrisW67]

Is it ok to keep creating a new scene graph using a timer ?

Technically fine. Probably not sane though. Ask yourself, "Why am I creating a whole new graphical display every second?" Typical usage would be to construct the scene once and manipulate it as time goes by.

How to delete the old one ?

The C++ delete operator or scene->deleteLater(). Fix the busy polling if you want deleteLater() to function well.

[020394]

I see . i was thinking of that too , but i tried to put it out of the timer but the graph would not update efficiently , need to switch to another tab and back in order to see the change . For the deleteLater(), should i put it in another timer to delete the scene every 2-5 sec ?

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Added after 1 46 minutes:

Ok i tried to solve it , not sure whether it is the right way . I added a scene->update() inside the same timer and create the new scene graph outside the timer .

[020394]

The C++ delete operator or scene->deleteLater(). Fix the busy polling if you want deleteLater() to function well.

I tried using deletelater() but it seems there is a problem , the program seems to stop working . You said about Busy polling , how to do that? I tried to use destroyed() on my scene/ui->graphicview but it seems that it does not work as the memory of the process is still running .

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Added after 1 15 minutes:

Besides using the deletelater(), I seem to find another method not sure whether I did it correctly . I used scene->clear() and put it in the timer . then later sceneupdate() after that to update the ones i need to show .