resizeEvent() only enabled with the window corner

[fem_dev]

I would like to know how to block/filter the vertical and horizontal resize events and call the resizeEvent() when the user try to resize the QMainWindow using the window corner (Image below).

I tried to use the setFixedSize(), but this method blocks ALL resizes events.

void MainWindow::resizeEvent(QResizeEvent *event)
{
    qDebug() << "SIZE = " << event->size();
}

How can I do that?

[SamurayH]

Hi,
I'm not sure you can achieve that with resizeEvent. But I'm certain that it's possible throw the nativeEvent handler..., at least for Windows:

add this:

#include <Windows.h>

and this:

private:
    RECT* m_winRect;

add this, in the constructor:

m_winRect = new RECT;
GetWindowRect((HWND)winId(), m_winRect);

and finally, handle the native resizing event...

bool MyWidget::nativeEvent(const QByteArray &eventType, void *message, long *result)
{
    // for a message coming from Windows
    if(eventType == "windows_generic_MSG"){
        MSG* msg = static_cast<MSG*>(message);
        // the native resizing event
        if(msg->message == WM_SIZING){
            RECT* rect = (RECT*)msg->lParam;
            if(msg->wParam == WMSZ_BOTTOMRIGHT) //bottom right corner resizing...
                *m_winRect = *rect; //allow resize
            else
                *rect = *m_winRect; //block resize    

           *result = true;
            return true;
        }
    }  

    return false;
}

And now the user can resize the window using the bottom right corner only.

You can read more about the Qt native event here, and about WM_SIZING here.

[dheerendra]

Three options.

1. Use windows flags Qt::FramelessWindowHint
2. Use setFixedSize(...)
3. Use event filters to filter the resize event.

[fem_dev]

@dheerendra thank you for your quick answer.

But I want to block ONLY the vertical and horizontal resize, but I want TO ENABLE just the window corner resize, like a proportional image resize keeping the window aspect ratio.

• option 1: blocks all
• option 2: blocks all
• option 3: I have the MainWindow::resizeEvent(QResizeEvent *event) method, but I don't know how to filter this specific window corner resize event. Could you help me?