main widget geometry width ...

[1XU7]

hello!
there is somethng really strange while reading this->geometry().width(),

from constructor, it returns 640 (i think this is the default width main widget value..)

MyWidget::MyWidget(){
     qDebug() << this->geometry().width();      // returns 640 even with full screen browser
}

from void resizeEvent(QResizeEvent*) it returns real browser width.

void MyWidget::resizeEvent(QResizeEvent* _e){
     qDebug() << this->geometry().width();      // returns 1930, real browser width.
}

as you can see, i need to adjust in constructor some parameters:

MyWidget::MyWidget(){
     //create a button as long as browser width...
     myButton->setGeometry(0, 0, this->geometry().width(), 30);
}

but that will create a button with geometry 0, 0, 640, 30.

well, i thought i could do this to fix it, since i noticed resizeEvent is executing very early but not enought sure earliest than constructor..

//MyWidget.h
private: 
     int PageWidth {0};

//MyWidget.cpp
MyWidget::MyWidget(){
     myButton->setGeometry(0, 0, PageWidth, 30);
}

void MyWidget::resizeEvent(QResizeEvent* _e){
     PageWidth = this->geometry().width();
}

but myButton geometry was 0, 0, 0, 30 ...

possible scenarios for this:

1. constructor is executing before resizeEvent
2. resizeEvent is executing before constructor but is not assigning PageWidth var. (this is less probable).

i don´t get what else can try.. this only happens on Qt webassembly.

My specs:
Qt 6.5.2
Emscripten 3.1.25

Thanks in advance.

[JonB]

@1XU7 said in main widget geometry width ...:

this only happens on Qt webassembly.

I have not used WASM. But for a Qt widgets application at least basically you cannot call/rely on the return value for "visual" things like size until the widget has been shown. So it's OK in, say, resizeEvent() but not in a constructor since the widget has not been shown yet at that time and so has no proper visual dimensions calculated.

If you subclass a widget you get a showEvent() when it is first shown, which is when the dimensions are first made valid. I don't know whether you also get a resizeEvent() at that point too.

See if the above applies in a Qt WASM application?

[1XU7]

@JonB i Will give a try to showEvent and comment

Thanks!