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don't post WM_NULL if there is already a WM_NULL in the queue to avoid overflowing it (patch 1904771)

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git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@52253 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Vadim Zeitlin
2008-03-02 14:45:41 +00:00
parent 60d02d5637
commit 7f02d57e99
1 changed files with 19 additions and 4 deletions
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23
src/msw/app.cpp
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@@ -539,13 +539,28 @@ void wxApp::WakeUpIdle()
// start up again. Doing it this way ensures that the idle handler
// wakes up in the right thread (see also wxWakeUpMainThread() which does
// the same for the main app thread only)
wxWindow *topWindow = wxTheApp->GetTopWindow();
wxWindow * const topWindow = wxTheApp->GetTopWindow();
if ( topWindow )
{
if ( !::PostMessage(GetHwndOf(topWindow), WM_NULL, 0, 0) )
HWND hwndTop = GetHwndOf(topWindow);
// Do not post WM_NULL if there's already a pending WM_NULL to avoid
// overflowing the message queue.
//
// Notice that due to a limitation of PeekMessage() API (which handles
// 0,0 range specially), we have to check the range from 0-1 instead.
// This still makes it possible to overflow the queue with WM_NULLs by
// interspersing the calles to WakeUpIdle() with windows creation but
// it should be rather hard to do it accidentally.
MSG msg;
if ( !::PeekMessage(&msg, hwndTop, 0, 1, PM_NOREMOVE) ||
::PeekMessage(&msg, hwndTop, 1, 1, PM_NOREMOVE) )
{
// should never happen
wxLogLastError(wxT("PostMessage(WM_NULL)"));
if ( !::PostMessage(hwndTop, WM_NULL, 0, 0) )
{
// should never happen
wxLogLastError(wxT("PostMessage(WM_NULL)"));
}
}
}
}