[Qt-interest] missing double click event when using native win32 window

[Christopher Lux]

Hi,
you can find attached a simple reproduction case for my problem.

I create a custom widget using a native win32 window (simplified for
the demonstration). The custom widget gets all mouse events except the
double click event. You can disable the native widget using the macro
on top of the demo file, then the double click event is fired as
expected.

I was testing this using Qt 4.7.0b2 and rc1 with Visual Studio 2010
and 2008 x64 with the same results. When implementing this under X11
the mouse events fire also as expected, so this might be a Windows
problem.

I hope this example helps to solve the problem.

Regards
-chris

/////////////////////////////////////////////////////////
// code

#define QT_TEST_NATIVE_WND 1
//#undef QT_TEST_NATIVE_WND

#include <iostream>
#include <string>

#include <QtGui/QApplication>
#include <QtGui/QDialog>

#include <Windows.h>

class my_native_window
{
public:
    my_native_window(HWND p)
    {
        HINSTANCE   inst = ::GetModuleHandle(0);
        std::string class_name("native_wnd_test");

        WNDCLASSEX wnd_class;
        ::ZeroMemory(&wnd_class, sizeof(WNDCLASSEX));
        wnd_class.cbSize        = sizeof(WNDCLASSEX);
        wnd_class.lpfnWndProc   = &DefWindowProc;
        wnd_class.style         = CS_OWNDC;
        wnd_class.hInstance     = inst;
        wnd_class.hbrBackground = 0;//(HBRUSH)::GetStockObject(DKGRAY_BRUSH);
        wnd_class.lpszClassName = class_name.c_str();

        _window_class = ::RegisterClassEx(&wnd_class);

        DWORD wnd_style     = 0;
        DWORD wnd_style_ex  = 0;
        HWND  parent_wnd    = ::GetDesktopWindow();

        if (0 != p) {
            parent_wnd = p;
            wnd_style  = WS_CLIPCHILDREN | WS_CLIPSIBLINGS | WS_CHILD;
        }
        else {
            wnd_style  = WS_CLIPCHILDREN | WS_CLIPSIBLINGS | WS_POPUP;
        }
        wnd_style_ex = 0;

        _hwnd = ::CreateWindowEx(wnd_style_ex,
reinterpret_cast<LPCSTR>(_window_class),
                                 class_name.c_str(),
                                 wnd_style,
                                 0, 0,
                                 50, 50,
                                 parent_wnd, 0,
                                 inst, 0);
        _hdc = ::GetDC(_hwnd);

    }
    virtual ~my_native_window()
    {
        if (_hdc) {
            ::ReleaseDC(_hwnd, _hdc);
        }
        if (_hwnd) {
            ::DestroyWindow(_hwnd);
        }
    }

public:
    HWND        _hwnd;
    HDC         _hdc;
    ATOM        _window_class;

}; // class my_native_window

class my_widget : public QWidget
{
    my_native_window* _native_wnd;

public:
    my_widget(QWidget* p)
      : QWidget(p, Qt::MSWindowsOwnDC),
        _native_wnd(0)
    {
        setMouseTracking(true);
        setFocusPolicy(Qt::StrongFocus);

        setAttribute(Qt::WA_NativeWindow, true);
        //setAttribute(Qt::WA_DontCreateNativeAncestors, false);
        setAttribute(Qt::WA_PaintOnScreen, true); // disables qt
double buffering (seems X11 only since qt4.5, ...)
        //setAttribute(Qt::WA_OpaquePaintEvent, true);
        setAttribute(Qt::WA_NoSystemBackground, true);
        //setAttribute(Qt::WA_ForceUpdatesDisabled, true);
        //setAttribute(Qt::WA_PaintUnclipped, true);
        setAutoFillBackground(false);

#if QT_TEST_NATIVE_WND
        _native_wnd = new my_native_window(p->winId());
        // ok set the native window as this widgets window...and hold thumbs
        this->create(_native_wnd->_hwnd, true, true);
#endif
    }
    virtual ~my_widget()
    {
        if (_native_wnd) {
            delete _native_wnd;
        }
    }

    void                        mouseDoubleClickEvent(QMouseEvent* mouse_event)
    {
        std::cout << "my_widget::mouseDoubleClickEvent() fired" << std::endl;
    }
    void                        mousePressEvent(QMouseEvent* mouse_event)
    {
        std::cout << "my_widget::mousePressEvent() fired" << std::endl;
    }
    void                        mouseMoveEvent(QMouseEvent* mouse_event)
    {
        std::cout << "my_widget::mouseMoveEvent() fired" << std::endl;
    }
    void                        mouseReleaseEvent(QMouseEvent* mouse_event)
    {
        std::cout << "my_widget::mouseReleaseEvent() fired" << std::endl;
    }

}; // my_widget

class qt_test : public QDialog
{
    my_widget*  _widget;

public:
    qt_test(unsigned w, unsigned h)
      : QDialog(0, Qt::Dialog | Qt::MSWindowsFixedSizeDialogHint)
    {
        // because we have no parent
        setAttribute(Qt::WA_DeleteOnClose);

        _widget = new my_widget(this);
        _widget->setFixedSize(w, h);
    }
}; // class qt_test

int main(int argc, char **argv)
{
    ///////////////////////////////////////////////////////////////////////////////////////////////
    QApplication     app(argc, argv);
    qt_test* qt_test_instance(new qt_test(200, 100));

    qt_test_instance->setWindowTitle("qt native widget test");
    qt_test_instance->show();

    return app.exec();
}
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