gtk/gdk/win32/gdkglcontext-win32-wgl.c
Chun-wei Fan 5d0f188615 GDK-Win32: Reject WGL context if shaders aren't supported
When we initialize OpenGL, check whether we have OpenGL  2.0 or later; if not,
check whether we have the 'GL_ARB_shader_objects' extension, since we must be
able to support shaders if using OpenGL for GTK.

If we don't support shaders, as some Windows graphics drivers do not support
OpenGL adequately, notably older Intel drivers, reject and destroy the GL
context that we created, and so fallback to the Cairo GSK renderer, so that
things continue to run, albeit with an expected warning message that the GL
context cannot be realized.

Also, when we could not make the created dummy WGL context current during
initialization, make sure that we destroy the dummy WGL context as well.

Fixes issue #4165.
2021-08-17 16:25:09 +08:00

747 lines
23 KiB
C

/* GDK - The GIMP Drawing Kit
*
* gdkglcontext-win32.c: Win32 specific OpenGL wrappers
*
* Copyright © 2014 Emmanuele Bassi
* Copyright © 2014 Alexander Larsson
* Copyright © 2014 Chun-wei Fan
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
#include "config.h"
#include "gdkprivate-win32.h"
#include "gdksurface-win32.h"
#include "gdkglcontext-win32.h"
#include "gdkdisplay-win32.h"
#include "gdkwin32display.h"
#include "gdkwin32glcontext.h"
#include "gdkwin32misc.h"
#include "gdkwin32screen.h"
#include "gdkwin32surface.h"
#include "gdkglcontext.h"
#include "gdkprofilerprivate.h"
#include "gdkinternals.h"
#include "gdkintl.h"
#include "gdksurface.h"
#include <cairo.h>
#include <epoxy/wgl.h>
struct _GdkWin32GLContextWGL
{
GdkWin32GLContext parent_instance;
HGLRC wgl_context;
guint do_frame_sync : 1;
};
typedef struct _GdkWin32GLContextClass GdkWin32GLContextWGLClass;
G_DEFINE_TYPE (GdkWin32GLContextWGL, gdk_win32_gl_context_wgl, GDK_TYPE_WIN32_GL_CONTEXT)
static void
gdk_win32_gl_context_wgl_dispose (GObject *gobject)
{
GdkWin32GLContextWGL *context_wgl = GDK_WIN32_GL_CONTEXT_WGL (gobject);
if (context_wgl->wgl_context != NULL)
{
if (wglGetCurrentContext () == context_wgl->wgl_context)
wglMakeCurrent (NULL, NULL);
GDK_NOTE (OPENGL, g_print ("Destroying WGL context\n"));
wglDeleteContext (context_wgl->wgl_context);
context_wgl->wgl_context = NULL;
}
G_OBJECT_CLASS (gdk_win32_gl_context_wgl_parent_class)->dispose (gobject);
}
static void
gdk_win32_gl_context_wgl_end_frame (GdkDrawContext *draw_context,
cairo_region_t *painted)
{
GdkGLContext *context = GDK_GL_CONTEXT (draw_context);
GdkWin32GLContextWGL *context_wgl = GDK_WIN32_GL_CONTEXT_WGL (context);
GdkSurface *surface = gdk_gl_context_get_surface (context);
GdkWin32Display *display_win32 = (GDK_WIN32_DISPLAY (gdk_gl_context_get_display (context)));
cairo_rectangle_int_t whole_window;
gboolean can_wait = display_win32->hasWglOMLSyncControl;
HDC hdc;
GDK_DRAW_CONTEXT_CLASS (gdk_win32_gl_context_wgl_parent_class)->end_frame (draw_context, painted);
gdk_gl_context_make_current (context);
whole_window = (GdkRectangle) { 0, 0, gdk_surface_get_width (surface), gdk_surface_get_height (surface) };
gdk_profiler_add_mark (GDK_PROFILER_CURRENT_TIME, 0, "win32", "swap buffers");
if (surface != NULL)
hdc = GDK_WIN32_SURFACE (surface)->hdc;
else
hdc = display_win32->dummy_context_wgl.hdc;
if (context_wgl->do_frame_sync)
{
glFinish ();
if (can_wait)
{
gint64 ust, msc, sbc;
wglGetSyncValuesOML (hdc, &ust, &msc, &sbc);
wglWaitForMscOML (hdc,
0,
2,
(msc + 1) % 2,
&ust, &msc, &sbc);
}
}
SwapBuffers (hdc);
}
static void
gdk_win32_gl_context_wgl_begin_frame (GdkDrawContext *draw_context,
cairo_region_t *update_area)
{
GdkGLContext *context = GDK_GL_CONTEXT (draw_context);
GdkSurface *surface;
surface = gdk_gl_context_get_surface (context);
gdk_win32_surface_handle_queued_move_resize (draw_context);
GDK_DRAW_CONTEXT_CLASS (gdk_win32_gl_context_wgl_parent_class)->begin_frame (draw_context, update_area);
}
static int
gdk_init_dummy_wgl_context (GdkWin32Display *display_win32);
#define PIXEL_ATTRIBUTES 17
static int
get_wgl_pfd (HDC hdc,
PIXELFORMATDESCRIPTOR *pfd,
GdkWin32Display *display_win32)
{
int best_pf = 0;
pfd->nSize = sizeof (PIXELFORMATDESCRIPTOR);
if (display_win32 != NULL && display_win32->hasWglARBPixelFormat)
{
UINT num_formats;
int colorbits = GetDeviceCaps (hdc, BITSPIXEL);
int i = 0;
int pixelAttribs[PIXEL_ATTRIBUTES];
/* Save up the HDC and HGLRC that we are currently using, to restore back to it when we are done here */
HDC hdc_current = wglGetCurrentDC ();
HGLRC hglrc_current = wglGetCurrentContext ();
/* Update PIXEL_ATTRIBUTES above if any groups are added here! */
pixelAttribs[i] = WGL_DRAW_TO_WINDOW_ARB;
pixelAttribs[i++] = GL_TRUE;
pixelAttribs[i++] = WGL_SUPPORT_OPENGL_ARB;
pixelAttribs[i++] = GL_TRUE;
pixelAttribs[i++] = WGL_DOUBLE_BUFFER_ARB;
pixelAttribs[i++] = GL_TRUE;
pixelAttribs[i++] = WGL_ACCELERATION_ARB;
pixelAttribs[i++] = WGL_FULL_ACCELERATION_ARB;
pixelAttribs[i++] = WGL_PIXEL_TYPE_ARB;
pixelAttribs[i++] = WGL_TYPE_RGBA_ARB;
pixelAttribs[i++] = WGL_COLOR_BITS_ARB;
pixelAttribs[i++] = colorbits;
/* end of "Update PIXEL_ATTRIBUTES above if any groups are added here!" */
if (display_win32->hasWglARBmultisample)
{
pixelAttribs[i++] = WGL_SAMPLE_BUFFERS_ARB;
pixelAttribs[i++] = 1;
pixelAttribs[i++] = WGL_SAMPLES_ARB;
pixelAttribs[i++] = 8;
}
pixelAttribs[i++] = 0; /* end of pixelAttribs */
best_pf = gdk_init_dummy_wgl_context (display_win32);
if (!wglMakeCurrent (display_win32->dummy_context_wgl.hdc,
display_win32->dummy_context_wgl.hglrc))
{
wglMakeCurrent (hdc_current, hglrc_current);
return 0;
}
wglChoosePixelFormatARB (hdc,
pixelAttribs,
NULL,
1,
&best_pf,
&num_formats);
/* Go back to the HDC that we were using, since we are done with the dummy HDC and GL Context */
wglMakeCurrent (hdc_current, hglrc_current);
}
else
{
pfd->nVersion = 1;
pfd->dwFlags = PFD_SUPPORT_OPENGL | PFD_DRAW_TO_WINDOW | PFD_DOUBLEBUFFER;
pfd->iPixelType = PFD_TYPE_RGBA;
pfd->cColorBits = GetDeviceCaps (hdc, BITSPIXEL);
pfd->cAlphaBits = 8;
pfd->dwLayerMask = PFD_MAIN_PLANE;
best_pf = ChoosePixelFormat (hdc, pfd);
}
return best_pf;
}
/* in WGL, for many OpenGL items, we need a dummy WGL context, so create
* one and cache it for later use
*/
static int
gdk_init_dummy_wgl_context (GdkWin32Display *display_win32)
{
PIXELFORMATDESCRIPTOR pfd;
gboolean set_pixel_format_result = FALSE;
int best_idx = 0;
if (display_win32->dummy_context_wgl.hdc == NULL)
display_win32->dummy_context_wgl.hdc = GetDC (display_win32->hwnd);
memset (&pfd, 0, sizeof (PIXELFORMATDESCRIPTOR));
best_idx = get_wgl_pfd (display_win32->dummy_context_wgl.hdc, &pfd, NULL);
if (best_idx != 0)
set_pixel_format_result = SetPixelFormat (display_win32->dummy_context_wgl.hdc,
best_idx,
&pfd);
if (best_idx == 0 || !set_pixel_format_result)
return 0;
display_win32->dummy_context_wgl.hglrc =
wglCreateContext (display_win32->dummy_context_wgl.hdc);
if (display_win32->dummy_context_wgl.hglrc == NULL)
return 0;
return best_idx;
}
gboolean
gdk_win32_display_init_wgl (GdkDisplay *display,
GError **error)
{
int best_idx = 0;
GdkWin32Display *display_win32 = GDK_WIN32_DISPLAY (display);
HDC hdc;
if (display_win32->wgl_pixel_format != 0)
return TRUE;
/* acquire and cache dummy Window (HWND & HDC) and
* dummy GL Context, it is used to query functions
* and used for other stuff as well
*/
best_idx = gdk_init_dummy_wgl_context (display_win32);
hdc = display_win32->dummy_context_wgl.hdc;
if (best_idx == 0 ||
!wglMakeCurrent (hdc, display_win32->dummy_context_wgl.hglrc))
{
if (display_win32->dummy_context_wgl.hglrc != NULL)
wglDeleteContext (display_win32->dummy_context_wgl.hglrc);
g_set_error_literal (error, GDK_GL_ERROR,
GDK_GL_ERROR_NOT_AVAILABLE,
_("No GL implementation is available"));
return FALSE;
}
display_win32->wgl_pixel_format = best_idx;
display_win32->gl_version = epoxy_gl_version ();
/* We must have OpenGL/WGL 2.0 or later, or have the GL_ARB_shader_objects extension */
if (display_win32->gl_version < 20)
{
if (!epoxy_has_gl_extension ("GL_ARB_shader_objects"))
{
wglMakeCurrent (NULL, NULL);
wglDeleteContext (display_win32->dummy_context_wgl.hglrc);
g_set_error_literal (error, GDK_GL_ERROR,
GDK_GL_ERROR_NOT_AVAILABLE,
_("No GL implementation is available"));
return FALSE;
}
}
display_win32->hasWglARBCreateContext =
epoxy_has_wgl_extension (hdc, "WGL_ARB_create_context");
display_win32->hasWglEXTSwapControl =
epoxy_has_wgl_extension (hdc, "WGL_EXT_swap_control");
display_win32->hasWglOMLSyncControl =
epoxy_has_wgl_extension (hdc, "WGL_OML_sync_control");
display_win32->hasWglARBPixelFormat =
epoxy_has_wgl_extension (hdc, "WGL_ARB_pixel_format");
display_win32->hasWglARBmultisample =
epoxy_has_wgl_extension (hdc, "WGL_ARB_multisample");
GDK_NOTE (OPENGL,
g_print ("WGL API version %d.%d found\n"
" - Vendor: %s\n"
" - Checked extensions:\n"
"\t* WGL_ARB_pixel_format: %s\n"
"\t* WGL_ARB_create_context: %s\n"
"\t* WGL_EXT_swap_control: %s\n"
"\t* WGL_OML_sync_control: %s\n"
"\t* WGL_ARB_multisample: %s\n",
display_win32->gl_version / 10,
display_win32->gl_version % 10,
glGetString (GL_VENDOR),
display_win32->hasWglARBPixelFormat ? "yes" : "no",
display_win32->hasWglARBCreateContext ? "yes" : "no",
display_win32->hasWglEXTSwapControl ? "yes" : "no",
display_win32->hasWglOMLSyncControl ? "yes" : "no",
display_win32->hasWglARBmultisample ? "yes" : "no"));
wglMakeCurrent (NULL, NULL);
return TRUE;
}
/* Setup the legacy context after creating it */
static gboolean
ensure_legacy_wgl_context (HDC hdc,
HGLRC hglrc_legacy,
GdkGLContext *share)
{
GdkWin32GLContextWGL *context_wgl;
if (!wglMakeCurrent (hdc, hglrc_legacy))
return FALSE;
if (share != NULL)
{
context_wgl = GDK_WIN32_GL_CONTEXT_WGL (share);
return wglShareLists (hglrc_legacy, context_wgl->wgl_context);
}
return TRUE;
}
static HGLRC
create_wgl_context_with_attribs (HDC hdc,
HGLRC hglrc_base,
GdkGLContext *share,
int flags,
int major,
int minor,
gboolean *is_legacy)
{
HGLRC hglrc;
GdkWin32GLContextWGL *context_wgl;
/* if we have wglCreateContextAttribsARB(), create a
* context with the compatibility profile if a legacy
* context is requested, or when we go into fallback mode
*/
int profile = *is_legacy ? WGL_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB :
WGL_CONTEXT_CORE_PROFILE_BIT_ARB;
int attribs[] = {
WGL_CONTEXT_PROFILE_MASK_ARB, profile,
WGL_CONTEXT_MAJOR_VERSION_ARB, *is_legacy ? 3 : major,
WGL_CONTEXT_MINOR_VERSION_ARB, *is_legacy ? 0 : minor,
WGL_CONTEXT_FLAGS_ARB, flags,
0
};
if (share != NULL)
context_wgl = GDK_WIN32_GL_CONTEXT_WGL (share);
hglrc = wglCreateContextAttribsARB (hdc,
share != NULL ? context_wgl->wgl_context : NULL,
attribs);
return hglrc;
}
static HGLRC
create_wgl_context (HDC hdc,
GdkGLContext *share,
int flags,
int major,
int minor,
gboolean *is_legacy,
gboolean hasWglARBCreateContext)
{
/* We need a legacy context for *all* cases */
HGLRC hglrc_base = wglCreateContext (hdc);
gboolean success = TRUE;
/* Save up the HDC and HGLRC that we are currently using, to restore back to it when we are done here */
HDC hdc_current = wglGetCurrentDC ();
HGLRC hglrc_current = wglGetCurrentContext ();
/* if we have no wglCreateContextAttribsARB(), return the legacy context when all is set */
if (*is_legacy && !hasWglARBCreateContext)
{
if (ensure_legacy_wgl_context (hdc, hglrc_base, share))
{
wglMakeCurrent (hdc_current, hglrc_current);
return hglrc_base;
}
success = FALSE;
goto gl_fail;
}
else
{
HGLRC hglrc = NULL;
if (!wglMakeCurrent (hdc, hglrc_base))
{
success = FALSE;
goto gl_fail;
}
/*
* We need a Core GL 4.1 context in order to use the GL support in
* the GStreamer media widget backend, but wglCreateContextAttribsARB()
* may only give us the GL context version that we ask for here, and
* nothing more. So, if we are asking for a pre-GL 4.1 context,
* try to ask for a 4.1 context explicitly first. If that is not supported,
* then we fall back to whatever version that we were asking for (or, even a
* legacy context if that fails), at a price of not able to have GL support
* for the media GStreamer backend.
*/
if (major < 4 || (major == 4 && minor < 1))
hglrc = create_wgl_context_with_attribs (hdc,
hglrc_base,
share,
flags,
4,
1,
is_legacy);
if (hglrc == NULL)
hglrc = create_wgl_context_with_attribs (hdc,
hglrc_base,
share,
flags,
major,
minor,
is_legacy);
/* return the legacy context we have if it could be setup properly, in case the 3.0+ context creation failed */
if (hglrc == NULL)
{
if (!(*is_legacy))
{
/* If we aren't using a legacy context in the beginning, try again with a compatibility profile 3.0 context */
hglrc = create_wgl_context_with_attribs (hdc,
hglrc_base,
share,
flags,
0, 0,
is_legacy);
*is_legacy = TRUE;
}
if (hglrc == NULL)
{
if (!ensure_legacy_wgl_context (hdc, hglrc_base, share))
success = FALSE;
}
if (success)
GDK_NOTE (OPENGL, g_print ("Using legacy context as fallback\n"));
}
gl_fail:
if (!success)
{
wglMakeCurrent (NULL, NULL);
wglDeleteContext (hglrc_base);
return NULL;
}
wglMakeCurrent (hdc_current, hglrc_current);
if (hglrc != NULL)
{
wglDeleteContext (hglrc_base);
return hglrc;
}
return hglrc_base;
}
}
static gboolean
set_wgl_pixformat_for_hdc (HDC hdc,
int *best_idx,
GdkWin32Display *display_win32)
{
gboolean already_checked = TRUE;
*best_idx = GetPixelFormat (hdc);
/* one is only allowed to call SetPixelFormat(), and so ChoosePixelFormat()
* one single time per window HDC
*/
if (*best_idx == 0)
{
PIXELFORMATDESCRIPTOR pfd;
gboolean set_pixel_format_result = FALSE;
GDK_NOTE (OPENGL, g_print ("requesting pixel format...\n"));
already_checked = FALSE;
*best_idx = get_wgl_pfd (hdc, &pfd, display_win32);
if (*best_idx != 0)
set_pixel_format_result = SetPixelFormat (hdc, *best_idx, &pfd);
/* ChoosePixelFormat() or SetPixelFormat() failed, bail out */
if (*best_idx == 0 || !set_pixel_format_result)
return FALSE;
}
GDK_NOTE (OPENGL, g_print ("%s""requested and set pixel format: %d\n", already_checked ? "already " : "", *best_idx));
return TRUE;
}
static gboolean
gdk_win32_gl_context_wgl_realize (GdkGLContext *context,
GError **error)
{
GdkWin32GLContextWGL *context_wgl = GDK_WIN32_GL_CONTEXT_WGL (context);
gboolean debug_bit, compat_bit, legacy_bit;
/* request flags and specific versions for core (3.2+) WGL context */
int flags = 0;
int major = 0;
int minor = 0;
HGLRC hglrc;
int pixel_format;
HDC hdc;
HWND hwnd;
GdkSurface *surface = gdk_gl_context_get_surface (context);
GdkDisplay *display = gdk_gl_context_get_display (context);
GdkWin32Display *display_win32 = GDK_WIN32_DISPLAY (display);
GdkGLContext *share = gdk_display_get_gl_context (display);
gdk_gl_context_get_required_version (context, &major, &minor);
debug_bit = gdk_gl_context_get_debug_enabled (context);
compat_bit = gdk_gl_context_get_forward_compatible (context);
if (surface != NULL)
hdc = GDK_WIN32_SURFACE (surface)->hdc;
else
hdc = display_win32->dummy_context_wgl.hdc;
/*
* A legacy context cannot be shared with core profile ones, so this means we
* must stick to a legacy context if the shared context is a legacy context
*/
legacy_bit = GDK_DISPLAY_DEBUG_CHECK (display, GL_LEGACY) ?
TRUE :
share != NULL && gdk_gl_context_is_legacy (share);
if (!set_wgl_pixformat_for_hdc (hdc,
&pixel_format,
display_win32))
{
g_set_error_literal (error, GDK_GL_ERROR,
GDK_GL_ERROR_UNSUPPORTED_FORMAT,
_("No available configurations for the given pixel format"));
return FALSE;
}
/* if there isn't wglCreateContextAttribsARB() on WGL, use a legacy context */
if (!legacy_bit)
legacy_bit = !display_win32->hasWglARBCreateContext;
if (debug_bit)
flags |= WGL_CONTEXT_DEBUG_BIT_ARB;
if (compat_bit)
flags |= WGL_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB;
GDK_NOTE (OPENGL,
g_print ("Creating %s WGL context (version:%d.%d, debug:%s, forward:%s, legacy: %s)\n",
compat_bit ? "core" : "compat",
major,
minor,
debug_bit ? "yes" : "no",
compat_bit ? "yes" : "no",
legacy_bit ? "yes" : "no"));
hglrc = create_wgl_context (hdc,
share,
flags,
major,
minor,
&legacy_bit,
display_win32->hasWglARBCreateContext);
if (hglrc == NULL)
{
g_set_error_literal (error, GDK_GL_ERROR,
GDK_GL_ERROR_NOT_AVAILABLE,
_("Unable to create a GL context"));
return FALSE;
}
GDK_NOTE (OPENGL,
g_print ("Created WGL context[%p], pixel_format=%d\n",
hglrc,
pixel_format));
context_wgl->wgl_context = hglrc;
/* No GLES, WGL does not support using EGL contexts */
gdk_gl_context_set_use_es (context, FALSE);
/* Ensure that any other context is created with a legacy bit set */
gdk_gl_context_set_is_legacy (context, legacy_bit);
return TRUE;
}
static gboolean
gdk_win32_gl_context_wgl_clear_current (GdkGLContext *context)
{
return wglMakeCurrent (NULL, NULL);
}
static gboolean
gdk_win32_gl_context_wgl_make_current (GdkGLContext *context,
gboolean surfaceless)
{
GdkWin32GLContextWGL *context_wgl = GDK_WIN32_GL_CONTEXT_WGL (context);
GdkDisplay *display = gdk_gl_context_get_display (context);
GdkWin32Display *display_win32 = GDK_WIN32_DISPLAY (display);
GdkSurface *surface = gdk_gl_context_get_surface (context);
HDC hdc;
if (surfaceless || surface == NULL)
hdc = display_win32->dummy_context_wgl.hdc;
else
hdc = GDK_WIN32_SURFACE (surface)->hdc;
if (!wglMakeCurrent (hdc, context_wgl->wgl_context))
return FALSE;
if (!surfaceless && display_win32->hasWglEXTSwapControl)
{
gboolean do_frame_sync = FALSE;
/* If there is compositing there is no particular need to delay
* the swap when drawing on the offscreen, rendering to the screen
* happens later anyway, and its up to the compositor to sync that
* to the vblank. */
do_frame_sync = ! gdk_display_is_composited (display);
if (do_frame_sync != context_wgl->do_frame_sync)
{
context_wgl->do_frame_sync = do_frame_sync;
wglSwapIntervalEXT (do_frame_sync ? 1 : 0);
}
}
return TRUE;
}
static void
gdk_win32_gl_context_wgl_class_init (GdkWin32GLContextWGLClass *klass)
{
GdkGLContextClass *context_class = GDK_GL_CONTEXT_CLASS (klass);
GdkDrawContextClass *draw_context_class = GDK_DRAW_CONTEXT_CLASS (klass);
GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
context_class->realize = gdk_win32_gl_context_wgl_realize;
context_class->make_current = gdk_win32_gl_context_wgl_make_current;
context_class->clear_current = gdk_win32_gl_context_wgl_clear_current;
draw_context_class->begin_frame = gdk_win32_gl_context_wgl_begin_frame;
draw_context_class->end_frame = gdk_win32_gl_context_wgl_end_frame;
gobject_class->dispose = gdk_win32_gl_context_wgl_dispose;
}
static void
gdk_win32_gl_context_wgl_init (GdkWin32GLContextWGL *wgl_context)
{
}
/**
* gdk_win32_display_get_wgl_version:
* @display: a `GdkDisplay`
* @major: (out): return location for the WGL major version
* @minor: (out): return location for the WGL minor version
*
* Retrieves the version of the WGL implementation.
*
* Returns: %TRUE if WGL is available
*/
gboolean
gdk_win32_display_get_wgl_version (GdkDisplay *display,
int *major,
int *minor)
{
GdkWin32Display *display_win32;
g_return_val_if_fail (GDK_IS_DISPLAY (display), FALSE);
if (!GDK_IS_WIN32_DISPLAY (display))
return FALSE;
display_win32 = GDK_WIN32_DISPLAY (display);
if (display_win32->wgl_pixel_format == 0)
return FALSE;
if (major != NULL)
*major = display_win32->gl_version / 10;
if (minor != NULL)
*minor = display_win32->gl_version % 10;
return TRUE;
}