XNextEvent Blocking At Start of Application - c++

Question

I have the following application.
#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;
}
When I run it it gets stuck on the XNextEvent() because it blocks until it gets the next event from the XServer. What I would like to know, is based on the code below, why is the XNextEvent not getting the ConfigureNotify or Expose events after I am calling XMapWindow(); I have checked to make sure my application provides the right Display based on the address in the watch window of my IDE. What am I missing to get the window to appear?
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

You're not specifying an event mask in your window's attributes, so XNextEvent() won't report any event. You should write something like:
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