GDK/Win32: Use dummy WGL contexts more

... for creating the actual WGL contexts, so that we can cut down on the
number of times where we need to create the base, legacy WGL contexts in
order to create the WGL contexts with attributes.  We could just use the
dummy context that we have to make it current to create the needed
WGL contexts.

1 files changed, 66 insertions, 26 deletions

diff --git a/gdk/win32/gdkglcontext-win32-wgl.c b/gdk/win32/gdkglcontext-win32-wgl.c
index 02a4b1f47f..cc3c3097a9 100644
--- a/gdk/win32/gdkglcontext-win32-wgl.c
+++ b/gdk/win32/gdkglcontext-win32-wgl.c
@@ -430,7 +430,6 @@ ensure_legacy_wgl_context (HDC            hdc,
 
 static HGLRC
 create_wgl_context_with_attribs (HDC           hdc,
-                                 HGLRC         hglrc_base,
                                  GdkGLContext *share,
                                  int           flags,
                                  gboolean      is_legacy,
@@ -484,36 +483,63 @@ create_wgl_context_with_attribs (HDC           hdc,
 }
 
 static HGLRC
-create_wgl_context (GdkGLContext  *context,
-                    HDC            hdc,
-                    gboolean       hasWglARBCreateContext,
-                    GdkGLContext  *share,
-                    int            flags,
-                    gboolean       legacy,
-                    GError       **error)
+create_base_wgl_context (GdkWin32Display *display_win32,
+                         HDC              hdc,
+                         gboolean         force_create_base_context,
+                         gboolean        *remove_base_context)
 {
-  /* We need a legacy context for *all* cases */
+  HGLRC hglrc_base = NULL;
+
+  if (force_create_base_context || display_win32->dummy_context_wgl.hglrc == NULL)
+    {
+      hglrc_base = wglCreateContext (hdc);
+
+      if (hglrc_base == NULL)
+        return NULL;
+
+      *remove_base_context = !force_create_base_context;
+    }
+  else
+    hglrc_base = display_win32->dummy_context_wgl.hglrc;
+
+  return hglrc_base;
+}
+
+static HGLRC
+create_wgl_context (GdkGLContext    *context,
+                    GdkWin32Display *display_win32,
+                    HDC              hdc,
+                    GdkGLContext    *share,
+                    int              flags,
+                    gboolean         legacy,
+                    GError         **error)
+{
+  /* We need a legacy context for *all* cases, if no WGL contexts are created */
   HGLRC hglrc_base, hglrc;
   GdkGLVersion version;
+  gboolean remove_base_context = FALSE;
   /* 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 ();
 
-  hglrc_base = wglCreateContext (hdc);
-  if (hglrc_base == NULL ||
-      !wglMakeCurrent (hdc, hglrc_base))
-    {
-      g_clear_pointer (&hglrc_base, gdk_win32_private_wglDeleteContext);
-      g_set_error_literal (error, GDK_GL_ERROR,
-                           GDK_GL_ERROR_NOT_AVAILABLE,
-                           _("Unable to create a GL context"));
-      return 0;
-    }
-
   hglrc = NULL;
 
-  if (hasWglARBCreateContext)
+  if (display_win32->hasWglARBCreateContext)
     {
+      hglrc_base = create_base_wgl_context (display_win32,
+                                            hdc,
+                                            FALSE,
+                                           &remove_base_context);
+
+      if (hglrc_base == NULL || !wglMakeCurrent (hdc, hglrc_base))
+        {
+          g_clear_pointer (&hglrc_base, gdk_win32_private_wglDeleteContext);
+          g_set_error_literal (error, GDK_GL_ERROR,
+                               GDK_GL_ERROR_NOT_AVAILABLE,
+                               _("Unable to create a GL context"));
+          return 0;
+        }
+
       if (!legacy)
         {
           gdk_gl_context_get_matching_version (context,
@@ -521,7 +547,6 @@ create_wgl_context (GdkGLContext  *context,
                                                FALSE,
                                                &version);
           hglrc = create_wgl_context_with_attribs (hdc,
-                                                   hglrc_base,
                                                    share,
                                                    flags,
                                                    FALSE,
@@ -535,7 +560,6 @@ create_wgl_context (GdkGLContext  *context,
                                                TRUE,
                                                &version);
           hglrc = create_wgl_context_with_attribs (hdc,
-                                                   hglrc_base,
                                                    share,
                                                    flags,
                                                    TRUE,
@@ -546,6 +570,20 @@ create_wgl_context (GdkGLContext  *context,
   if (hglrc == NULL)
     {
       legacy = TRUE;
+      hglrc_base = create_base_wgl_context (display_win32,
+                                            hdc,
+                                            TRUE,
+                                           &remove_base_context);
+
+      if (hglrc_base == NULL || !wglMakeCurrent (hdc, hglrc_base))
+        {
+          g_clear_pointer (&hglrc_base, gdk_win32_private_wglDeleteContext);
+          g_set_error_literal (error, GDK_GL_ERROR,
+                               GDK_GL_ERROR_NOT_AVAILABLE,
+                               _("Unable to create a GL context"));
+          return 0;
+        }
+
       gdk_gl_context_get_matching_version (context,
                                            GDK_GL_API_GL,
                                            TRUE,
@@ -560,7 +598,8 @@ create_wgl_context (GdkGLContext  *context,
       gdk_gl_context_set_is_legacy (context, legacy);
     }
 
-  g_clear_pointer (&hglrc_base, gdk_win32_private_wglDeleteContext);
+  if (remove_base_context)
+    g_clear_pointer (&hglrc_base, gdk_win32_private_wglDeleteContext);
 
   wglMakeCurrent (hdc_current, hglrc_current);
 
@@ -591,6 +630,7 @@ set_wgl_pixformat_for_hdc (GdkWin32Display *display_win32,
        * also use for our new dummy HDC will have the correct pixel format set
        */
       wglDeleteContext (display_win32->dummy_context_wgl.hglrc);
+      display_win32->dummy_context_wgl.hglrc = NULL;
       display_win32->dummy_context_wgl.hdc = GetDC (display_win32->hwnd);
       *hdc = display_win32->dummy_context_wgl.hdc;
       *recreate_dummy_context = TRUE;
@@ -676,8 +716,8 @@ gdk_win32_gl_context_wgl_realize (GdkGLContext *context,
     flags |= WGL_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB;
 
   hglrc = create_wgl_context (context,
+                              display_win32,
                               hdc,
-                              display_win32->hasWglARBCreateContext,
                               share,
                               flags,
                               legacy_bit,
@@ -687,8 +727,8 @@ gdk_win32_gl_context_wgl_realize (GdkGLContext *context,
     {
       display_win32->dummy_context_wgl.hglrc =
         create_wgl_context (context,
+                            display_win32,
                             display_win32->dummy_context_wgl.hdc,
-                            display_win32->hasWglARBCreateContext,
                             NULL,
                             flags,
                             legacy_bit,