Disappearing content of QMainWindow

[Antares]

Hello,
I am porting some code from Qt3 to Qt4. I have a form which uses a QtMainWindow, this is showing some canvas obtained with QTRoot (I think this is not important for the bug I am going to explain).
In the constructor the canvas is added to the QtMainWindow, then another class is using this to show some histograms. When I run the executable I see that when I try to plot the histograms, they are correctly showed for a small fraction of second, then they disappear. To show them again I must click inside the QMainWindow where the canvas is put, but if I do something outside then they disappear again. I think this means that the histograms are showed just if the canvas is selected. I tried to solve this with a lot of commands like raise() and so on, but the problem is still occurring.

I can put some simplified code lines to help myself with the explanation:

HistogramView::HistogramView(...) 
:QMainWindow() {
 MyQRootCanvas *my_canvas = new MyQRootCanvas( frame, "my_canvas" );
vboxLayout->addWidget( my_canvas );
}

HistogramView::HistogramView(...) 
:QMainWindow() {
 MyQRootCanvas *my_canvas = new MyQRootCanvas( frame, "my_canvas" );
vboxLayout->addWidget( my_canvas );
}

To copy to clipboard, switch view to plain text mode 

Then the class which calls HistogramView is calling the command:

histogramViewList.push_back(  new HistogramView(...) ) {
histogramViewList.back()->show(); 
}

histogramViewList.push_back(  new HistogramView(...) ) {
histogramViewList.back()->show(); 
}

To copy to clipboard, switch view to plain text mode 

The show() command is showing the QmainWindow, the histogram is showed for a very small time and disappears, and appears again just if I click in the canvas, as I described before.
I did not write the code myself, I am just trying to port it to Qt4.

I really say thank you to anybody who can help me solving this problem or gives me any suggestion.

[anda_skoa]

What widgets is "vboxLayout" managing?
Is it the layout of "frame"?
If so, is frame the main window's central widget or part of another layout?

Cheers,
_

[wysota]

What is the definition of MyQRootCanvas?

[Antares]

Thank you very much for the help

---

Added after 5 minutes:

This code is inside setupUi(QMainWindow* HistogramViewBase):

widget = new QWidget(HistogramViewBase);
        frame = new Q3Frame(widget);
   vboxLayout = new QVBoxLayout(frame);
    my_canvas = new TQRootCanvas(frame);
    sizePolicy4.setHeightForWidth(m_canvas->sizePolicy().hasHeightForWidth());
    my_canvas->setSizePolicy(sizePolicy4);
    vboxLayout->addWidget(m_canvas);

widget = new QWidget(HistogramViewBase);
        frame = new Q3Frame(widget);
   vboxLayout = new QVBoxLayout(frame);
    my_canvas = new TQRootCanvas(frame);
    sizePolicy4.setHeightForWidth(m_canvas->sizePolicy().hasHeightForWidth());
    my_canvas->setSizePolicy(sizePolicy4);
    vboxLayout->addWidget(m_canvas);

To copy to clipboard, switch view to plain text mode 

Hello, here it is the definition,

void MyQRootCanvas::mouseMoveEvent(QMouseEvent *e) {
  TQRootCanvas::mouseMoveEvent(e);
  if (e) {
    TCanvas *the_canvas=::getCanvas(this);
    if (the_canvas) {
      PadRestore save_pad;
      gPad = the_canvas->GetSelectedPad();
      TObject *selected = the_canvas->GetSelected();
      if (selected) {
	const char *message_text = NULL;
	if (!selected->InheritsFrom(TVirtualPad::Class())) {
	  message_text = selected->GetObjectInfo(e->x(), e->y());
	}
	QString message;
	if (selected->InheritsFrom(TNamed::Class())) {
	  //	  message = static_cast<TNamed *>(selected)->GetTitle();
	  //	  message += " [";
	  message += static_cast<TNamed *>(selected)->GetName();
	  message += " : ";
	  //	  message += "] : ";
	}
	if (message_text) {
	  message+=message_text;
	}
	emit statusMessage(message);
      } ...

void MyQRootCanvas::mouseMoveEvent(QMouseEvent *e) {
  TQRootCanvas::mouseMoveEvent(e);
  if (e) {
    TCanvas *the_canvas=::getCanvas(this);
    if (the_canvas) {
      PadRestore save_pad;
      gPad = the_canvas->GetSelectedPad();
      TObject *selected = the_canvas->GetSelected();
      if (selected) {
	const char *message_text = NULL;
	if (!selected->InheritsFrom(TVirtualPad::Class())) {
	  message_text = selected->GetObjectInfo(e->x(), e->y());
	}
	QString message;
	if (selected->InheritsFrom(TNamed::Class())) {
	  //	  message = static_cast<TNamed *>(selected)->GetTitle();
	  //	  message += " [";
	  message += static_cast<TNamed *>(selected)->GetName();
	  message += " : ";
	  //	  message += "] : ";
	}
	if (message_text) {
	  message+=message_text;
	}
	emit statusMessage(message);
      } ...

To copy to clipboard, switch view to plain text mode 

Anyway I don't think the problem is inside here..

[anda_skoa]

This code is inside setupUi(QMainWindow* HistogramViewBase):

widget = new QWidget(HistogramViewBase);
        frame = new Q3Frame(widget);
   vboxLayout = new QVBoxLayout(frame);
    my_canvas = new TQRootCanvas(frame);
    sizePolicy4.setHeightForWidth(m_canvas->sizePolicy().hasHeightForWidth());
    my_canvas->setSizePolicy(sizePolicy4);
    vboxLayout->addWidget(m_canvas);

widget = new QWidget(HistogramViewBase);
        frame = new Q3Frame(widget);
   vboxLayout = new QVBoxLayout(frame);
    my_canvas = new TQRootCanvas(frame);
    sizePolicy4.setHeightForWidth(m_canvas->sizePolicy().hasHeightForWidth());
    my_canvas->setSizePolicy(sizePolicy4);
    vboxLayout->addWidget(m_canvas);

To copy to clipboard, switch view to plain text mode 

The frame has a layout and the canvas was added to it, this is good.
What is missing here is the layout of "widget" and the frame being added to it.

Is that further down in the code of setupUi?
Is widget then set as HistogramViewBase's centralWidget?

Make sure that when you open the .ui file in Qt Designer, that none of the widget that are containers are showing the "broken layout" icon.

Cheers,
_

[Antares]

Thank you very much for your suggestion. Anyway, everything seems to be ok, I can see:

vboxLayout = new QVBoxLayout(widget);
...
HistogramViewBase->setCentralWidget(widget);

vboxLayout = new QVBoxLayout(widget);
...
HistogramViewBase->setCentralWidget(widget);

To copy to clipboard, switch view to plain text mode 

and no broken layouts...
Do you have any other suggestion?

Thank you very much

[anda_skoa]

And the frame has been added to vboxLayout?

Can you attach the .ui file and the generated header?

If you add a label instead of the canvas, does it stay visible?

Cheers,
_

[Antares]

And the frame has been added to vboxLayout?

Can you attach the .ui file and the generated header?

If you add a label instead of the canvas, does it stay visible?

Cheers,
_

I have attached the files. What do you mean to add a label instead of a canvas?
Thank you very much