Overriding paintEvent broke window minimizing from taskbar

loginmen

A round clock example can be used as an example of code. The problem is this, if you override paintEvent then you lose the ability to minimize the window from the start menu (taskbar, not tray) by clicking of progamm icon. When you click on the program icon, nothing happens. At the same time, the folding itself through showMinimized works. And unfolding also works. How to fix? Windows 10, qt 6.1.2

Christian Ehrlicher

I doubt that paintEvent() has something to do with it. Please provide some code - a minimal compilable example would be the best - creating a simply QWidget with an overwritten paintEvent shouldn't be that hard.

jsulm

@loginmen Has nothing to do with paintEvent.
Remove "Qt::FramelessWindowHint | Qt::WindowSystemMenuHint" and you will see that it works.

loginmen

@jsulm

QWidget mainWindow {};
    mainWindow.setWindowFlag(Qt::FramelessWindowHint);

Minimize fine, if do that

Window::Window(QWidget *parent)
: QWidget(parent, Qt::FramelessWindowHint) {
//...
}

not working, but

Window::Window(QWidget *parent)
: QWidget(parent) {
setWindowFlag(Qt::FramelessWindowHint);
//...
}

work fine too, why?

jsulm

@loginmen https://doc.qt.io/qt-5/qt.html#WidgetAttribute-enum
"Qt::WA_TranslucentBackground 120 Indicates that the widget should have a translucent background, i.e., any non-opaque regions of the widgets will be translucent because the widget will have an alpha channel. Setting this flag causes WA_NoSystemBackground to be set. On Windows the widget also needs the Qt::FramelessWindowHint window flag to be set. This flag is set or cleared by the widget's author."

loginmen

@jsulm some error in message Qt::FramelessWindowHint instead of Qt::WA_TranslucentBackground

jsulm

@loginmen What error?

loginmen

@jsulm in the message wrote the wrong flag

jsulm

@loginmen Sorry, I don't understand what you mean. Please rephrase. Show code and exact error message.

loginmen

@jsulm correct message:

QWidget mainWindow {};
    mainWindow.setWindowFlag(Qt::FramelessWindowHint);

Minimize fine, if do that

Window::Window(QWidget *parent)
: QWidget(parent, Qt::FramelessWindowHint) {
//...
}

not working, but

Window::Window(QWidget *parent)
: QWidget(parent) {
setWindowFlag(Qt::FramelessWindowHint);
//...
}

work fine too, why?

J.Hilk

@loginmen

 Window::Window(QWidget *parent)
 : QWidget(parent, Qt::WindowFlags() | Qt::FramelessWindowHint) {
//...
}

loginmen

@J-Hilk still not working

JonB

@loginmen
One thing just to verify: parent is being passed in as nullptr to your constructor, right?

loginmen

@JonB That's right, he is the main widget (window), all his other children

JonB

@loginmen
OK. if you say one works and one does not: on the first line in the constructor-argument one or the line after the setWindowFlag() one try printing out what's in windowFlags() and compare for any differences?

loginmen

@JonB in constructor i have flags:

00000801

and in use function:

8800F801

flags decode:

80000000 WindowFullscreenButtonHint
08000000 WindowCloseButtonHint

00000001 Window
00000800 FramelessWindowHint

0000F000:
00001000 WindowTitleHint
00002000 WindowSystemMenuHint
00004000 WindowMinimizeButtonHint
00008000 WindowMaximizeButtonHint

If i use

Window::Window(QWidget *parent)
: QWidget(parent, Qt::FramelessWindowHint | Qt::WindowMinimizeButtonHint) {
//...
}

Minimize work fine and button not showing