WindowProc in a class - function and pointer problem

[Sean Cavanaugh]

On 5/22/2013 8:49 PM, evilrat wrote:
> On Wednesday, 22 May 2013 at 21:42:32 UTC, D-sturbed wrote:
>>
>> Yes I'm in the "multiple Window case", every window is wraped in a
>> class and has its own message handler. I know that Win, in its
>> callback system, often lets you retrieve a pointer to something, and I
>> haven't get it was possible in this case...(which is you seem to
>> describe). I will try this tomorrow.
>
> you can't really make it without static wndproc. if you don't know how
> to do it just go google some wndproc in a class tutors for c++, i can
> even recommend you one(i had used my own port of this in D before i
> switched to crossplatform lib for my needs) -
> http://blogs.msdn.com/b/oldnewthing/archive/2005/04/22/410773.aspx


I had a partial port of WTL over to D which worked well enough for what 
I needed, the core of the WndProc handling is down below.   Each HWND is 
owned by the thread it was created on, so assigning it into D 
associative array (which is thread local) can do the trick.  It involved 
a hack, before any call to the Win32 CreateWindow/CreateWindowEx APIs, 
to capture the association with the new HWND and to remove them when 
they get cleaned up.  There is probably a better way but this worked 
enough to get started, and should work with multiple windows reasonably 
well.






CWindowInterface g_CreatingWindow;
CWindowInterface[HWND] g_HWNDtoObject;


extern (Windows)
int CWindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
     int WindowProcReturnValue = 0;

/*
     auto EventMsg = appender!string();
     formattedWrite(EventMsg, "EventMsg (hWnd=%1$s) (uMsg=%2$s) 
(wParam=%3$s) (lParam=%4$s)\n", cast(DWORD)hWnd, cast(DWORD)uMsg, 
cast(DWORD)wParam, cast(DWORD)lParam);
     OutputDebugString(toUTFz!(const(wchar)*)(EventMsg.data));
*/

     if (g_CreatingWindow)
     {
         g_HWNDtoObject[hWnd] = g_CreatingWindow;
         g_CreatingWindow = null;
     }
     auto Window = g_HWNDtoObject[cast(HANDLE)hWnd];
     if (Window is null)
     {
         WindowProcReturnValue = DefWindowProc(hWnd, uMsg, wParam, lParam);
     }
     else
     {
         WindowProcReturnValue = Window.WindowProc(hWnd, uMsg, wParam, 
lParam);
     }
     if (uMsg == WM_NCDESTROY)
     {
         g_HWNDtoObject.remove(hWnd);
     }
     return WindowProcReturnValue;
}