qt5 widgetHandle -> SFML2.0

[uGhster]

Hi I am trying to setup a QTSFMLCanvas as seen in eg: http://becomingindiedev.blogspot.se/2013/10/qt-5-and-sfml-20-integration.html

Qt5-widget has a winId() method that is supposed to return the native handler for the widget. On my platform (linux Arch 64bit) it is a long long unsigned int and RenderWindow seems to want a long unsigned int.

hence,
RenderWindow::create(reinterpret_cast<sf::WindowHandle>(winId()));

fails with: invalid cast from type 'WId {aka long long unsigned int}' to type 'sf::WindowHandle {aka long unsigned int}'

Is there a workaround or a way to convert the handle? I have been giving google hard time with this one and have found nothing.

static_cast just hangs the application.

Any ideas?

[korczurekk]

RenderWindow::create((sf::WindowHandle) winId());

In my case it worked fine. If you want to use Qt&SFML without implementing everything on your own you can use my library – QSFML. https://github.com/KoczurekK/QSFML

[uGhster]

Belive me, I have tried this but there seems to be something changed. I have had Qt wrap up SFML nicely before.
Please try your lib, which seems to do a just that with Qt 5.7 and SFML 2.4 on a linux system and if that works then I'll be the first to confess that your lib has some vodoo-magic involved

[korczurekk]

I've just recompiled library and it worked fine.  Do you have C++11 enabled? And what is your compiler version?

[uGhster]

There IS magic involved
This is weird, I looked into SFML headers and this is how a WindowHandle is defined on my setup:

#elif defined(SFML_SYSTEM_LINUX) || defined(SFML_SYSTEM_FREEBSD)

    // Window handle is Window (unsigned long) on Unix - X11
    typedef unsigned long WindowHandle;


and a WinId() returns a WId which is defined as a long long unsigned int.
static_cast fails aswell as reinterpret_cast.

I am running C++11 enabled on a gcc 6.2.1. on a 64bit system.

[eXpl0it3r]

long long unsigned int is implicitly convertible to long unsigned int (aka unsigned long), it may only show a warning due to potential type narrowing. So unless you want to remove the warning a cast is not needed and when you do use a cast, static_cast should be used.

This test code works fine on Ideone.

#include <iostream>

int main() {
        unsigned long ul = 10;
        long long unsigned int llui = 20;
       
        std::cout << ul << " " << llui << "\n";
       
        ul = llui;
        ul = static_cast<long unsigned int>(llui);
       
        std::cout << ul << " " << llui << "\n";
}

My guess is that because there was an issue ("hanging"?) when using an implicit cast or a static_cast, you assumed that this must be the origin of the issue, while it actually might be somewhere else entirely  (see also XY Problem).
So what exactly is your problem with an implicit cast?

[uGhster]

exactly, my guess is that WinId from QtWidget is not a handle but something else completely.
Seems that I am not the only one with this problem.
But what bothers me is that it works with some configurations.

[eXpl0it3r]

Well don't just guess. Use your debugger or compile some test code and find out what is going on.

[uGhster]

Wow, that is why I asked the question here... to hopefully save the time and effort.
But you sir, seem to have time on your hand to go overboard to explain casting \o/ yaay!

[eXpl0it3r]

So instead of spending your own time on the problem you waste other people's time by not actually trying to figure out the problem and enjoy doing so. Thanks.

[uGhster]

Wasting your time?.. someone else might actually hold an answer to the problem instead of boosting their ego by posting how it in fact is possible to cast a long to a bool or whatnot. Well now your postcount went ++.