problems with stacked widgets

[django.Reinhard]

Hi,

I have some problems with stacked widgets.
I tried QStackedLayout and selfwritten widget with QGridLayout.
No matter what I do, the visual "defect" is always the same:

First time I switch through the pages, everything looks fine. But second time I select a page, only some child-widgets repaint itself.
QTreeView and QTableView don't repaint itself.
I tried to add widget->update and widget->repaint - it makes no difference. QTreeView and QTableView don't respond to mouseclicks / focus change.
QPlainTextEdit, QLineEdit, QSplitter and QPushbutton always repaint itself.
I tried to change size of mainwindow, but that does not change anything either.

From java I know invalidate() for this sitation. Does Qt have something similar?

[Pl45m4]

@django-Reinhard

Do you have a QStackedWidget or a QStackedLayout ? (or both?!)

Show what you did, so we can understand better.

[django.Reinhard]

Hi,

as written - I tried QStackedLayout and own widget subclass with QGridLayout.
Both showed the same behaviour.
But I can only show the latter:

MainView::MainView(QWidget* parent)
 : QWidget(parent) {
  setLayout(new QGridLayout);
  }


void MainView::activatePage(const QString& name) {
  if (pages.contains(name)) {
     QWidget*     w  = pages[name];
     QGridLayout* gl = static_cast<QGridLayout*>(layout());

     if (gl) {
        w->setVisible(true);
        for (auto k = pages.keyBegin(); k != pages.keyEnd(); ++k) {
            if (!k->compare(name)) continue;
            pages[*k]->setVisible(false);
            }
        w->repaint();
        }
     }
  }


void MainView::addPage(const QString& name, QWidget *page) {
  pages.insert(name, page);
  QGridLayout* gl = static_cast<QGridLayout*>(layout());

  if (gl) gl->addWidget(page, 0, 0);
  activatePage(name);
  }

and this class was used like this:

void MainWindow::createMainWidgets() {
  mainView = new MainView(this);
  view3D = new View(doc3D->getContext(), this);
  doc3D->setView(view3D);
  mainView->addPage("FileManager", new FileManager(QDir(QDir::homePath() + "/linuxcnc"), mainView));
  mainView->addPage("ToolManager", new ToolManager(mainView));
  mainView->addPage("Settings", new SettingsEditor("../QtUi/src/UI/Settings.ui", mainView));
  mainView->addPage("Preview", new PreViewEditor("../QtUi/src/UI/GCodeEditor.ui", view3D, mainView));
  this->setCentralWidget(mainView);
  }


void MainWindow::selectPage(const QString& name) {
  qDebug() << "page to select: " << name;
  mainView->activatePage(name);
  }

selectPage() is a public slot connected to different menue actions.

Some additional tests showed, that the problems may be caused by View-class, which is borrowed from opencascade Qt-Samples and is an opengl window.

[JoeCFD]

@django-Reinhard said in problems with stacked widgets:

if (!k->compare(name)) continue

try this out:
if ( 0 != k->compare(name)) continue;

k->compare(name) does not return true or false;
when two strings are same, it returns 0;
https://doc.qt.io/qt-5/qstring.html#compare

[Pl45m4]

@JoeCFD said in problems with stacked widgets:

k->compare(name) does not return true or false;
when two strings are same, it returns 0;

True and false are considered as 0 and 1 when using them in if-clauses.

e.g.:

if(0) // forever false

if(1) // forever true

[JoeCFD]

@Pl45m4 The problem here is
when two strings are same, compare returns 0 which is false( do you like it?); False means they are not same in common logic.
I would prefer to use 0 in the code instead of true or false to make sure I know what I am doing.

[JonB]

@JoeCFD
QString::compare() returns 0/negative/positive a la strcmp(). While I personally, like you, do not write !string.compare() others do use that idiom, and the OP's

if (!k->compare(name)) continue;

behaves exactly the same as your

if ( 0 != k->compare(name)) continue;

Whatever the OP's problem elsewhere, this code is correct.

[SGaist]

@django-Reinhard hi,

Which version of Qt are you using ?
On which OS ?
Can you provide a minimal compilable example that shows this behaviour ?

[JoeCFD]

@JonB I think his logic might be

if ( 0 == k->compare(name)) { /* if the name is the same, show it */
    continue;
}
else { /* if the name is different, hide it  */
   pages[*k]->setVisible(false);
}

The coders can easily get confused with true and false here. I never use true and false for string compare().

[django.Reinhard]

@SGaist said in problems with stacked widgets:

Which version of Qt are you using ?
On which OS ?

I was on the way to switch all my projects to Qt6.2 but on recompiling latest opencascade I had to realize, that occ is not ready for Qt6xx - so I turned everything back to Qt5.15

My OS is still debian 11

@SGaist said in problems with stacked widgets:

Can you provide a minimal compilable example that shows this behaviour ?

Sorry, guess I can't do that. Each page is a single prototype and on merging all prototypes into the final app this issue came up. Its my first project using Qt and the first using occ - so most of all, I'm stumbling around ...

[django.Reinhard]

Just to close this ...

... I got help from occ forum.
... adding

  setAttribute(Qt::WA_NativeWindow);

to the View-Constructor changed behaviour of the View-class - which now works as expected :)