- "There are 5 common DCs available in Win95. These are aquired when you call
- GetDC or GetDCEx from a window that does _not_ have the OWNDC flag.
- OWNDC flagged windows do not get their DC from the common DC pool, the issue
- is they require 800 bytes each from the limited 64Kb local heap for GDI."
-
- "The deal is, if you hold onto one of the 5 shared DC's too long (as GL apps
- do), Win95 will actually "steal" it from you. MakeCurrent fails,
- apparently, because Windows re-assigns the HDC to a different window. The
- only way to prevent this, the only reliable means, is to set CS_OWNDC."
- */
-
- if (!s_registeredGLCanvasClass)
- {
- WNDCLASS wndclass;
-
- // the fields which are common to all classes
- wndclass.lpfnWndProc = (WNDPROC)wxWndProc;
- wndclass.cbClsExtra = 0;
- wndclass.cbWndExtra = sizeof( DWORD ); // VZ: what is this DWORD used for?
- wndclass.hInstance = wxhInstance;
- wndclass.hIcon = (HICON) NULL;
- wndclass.hCursor = ::LoadCursor((HINSTANCE)NULL, IDC_ARROW);
- wndclass.lpszMenuName = NULL;
-
- // Register the GLCanvas class name
- wndclass.hbrBackground = (HBRUSH)NULL;
- wndclass.lpszClassName = wxGLCanvasClassName;
- wndclass.style = CS_HREDRAW | CS_VREDRAW | CS_DBLCLKS | CS_OWNDC;
-
- if ( !::RegisterClass(&wndclass) )
- {
- wxLogLastError(wxT("RegisterClass(wxGLCanvasClass)"));
- return FALSE;
- }
-
- // Register the GLCanvas class name for windows which don't do full repaint
- // on resize
- wndclass.lpszClassName = wxGLCanvasClassNameNoRedraw;
- wndclass.style &= ~(CS_HREDRAW | CS_VREDRAW);
-
- if ( !::RegisterClass(&wndclass) )