c++ - XNextEvent 在应用程序开始时阻塞

Question

我有以下应用程序。

#include <FWWindow.h>
#include <FWApplication.h>

int main(int /*argc*/, char */*argv*/[])
{
    FWApplication::Initialize();
    FWWindow *win = new FWWindow(800, 600);
    win->Show();
    FWApplication::Run();
    delete win;
}

当我运行它时，它会卡在 XNextEvent() 上，因为它会阻塞，直到它从 XServer 获取下一个事件。我想知道的是，基于下面的代码，为什么 XNextEvent 在我调用 XMapWindow() 后没有获得 ConfigureNotify 或 Expose 事件；我已检查以确保我的应用程序根据我的 IDE 监 window 口中的地址提供正确的 Display。我缺少什么才能让窗口出现？

---

Initialize() does the following

-

FWApplication *FWApplication::Initialize()
{
    if (!_instance)
    {
        _xDisplay = XOpenDisplay(NULL);
        if (_xDisplay == NULL)
            throw "Failed to get XDisplay";
        _initialized = true;
        _instance = new FWApplication(); // Calls an empty ctor
    }
    return _instance;
}

---

FWWindow *win = new FWWindow(800, 600); does the following

-

FWWindow::FWWindow(int width, int height) :
        clientWidth(width),
        clientHeight(height)
{
    // These are all member variables
    xDisplay = FWApplication::GetMainDisplay();
    xScreen = DefaultScreen(xDisplay);
    xDepth  = DefaultDepth(xDisplay, xScreen);
    xVisual = DefaultVisual(xDisplay,xScreen);
    xAttributes.background_pixel = XWhitePixel(xDisplay, xScreen);
    xAttributes.border_pixel = XBlackPixel(xDisplay, xScreen);
    xAttributes.override_redirect = 0;
    xWindow = XCreateWindow(
                             xDisplay,
                             RootWindow(xDisplay, xScreen),
                             0, 0,
                             width, height,
                             0,
                             xDepth,
                             InputOutput,
                             xVisual,
                             CWBorderPixel | CWColormap | CWEventMask,
                             &xAttributes
                           );

      XSetStandardProperties(
                             xDisplay,
                             xWindow,
                             "glxsimple",
                             "glxsimple",
                             None,
                             NULL,
                             0,
                             NULL
                            );
}

---

win->Show(); does the following

-

void FWWindow::Show()
{                                   
    XMapWindow(xDisplay, xWindow); // xWindow and xDisplay defined in ctor above
}

---

And finaly FWApplication::Run(); does the following

-

int FWApplication::Run()
{
    if (!_initialized)
        return -1;
    static bool run = true;
    static Display *lDisplay = _xDisplay;
    XEvent xEvent;
    while (run)
    {
        do
        {
            XNextEvent(lDisplay, &xEvent);
            switch (xEvent.type)
            {
            case ConfigureNotify:
                {
                    unsigned int w = xEvent.xconfigure.width;
                    unsigned int h = xEvent.xconfigure.height;
                    // Do something to main widget
                }
            case Expose:
                break;
            }
        } while (XPending(GetMainDisplay()));
    }
    return EXIT_SUCCESS;
}

Answer 1

您没有在窗口的属性中指定事件掩码，因此 XNextEvent() 不会报告任何事件。你应该这样写:

xAttributes.background_pixel = XWhitePixel(xDisplay, xScreen);
xAttributes.border_pixel = XBlackPixel(xDisplay, xScreen);
xAttributes.override_redirect = 0;
xAttributes.event_mask = StructureNotifyMask  // for ConfigureNotify
                       | ExposureMask;        // for Expose