[gtk/wip.win32.fixes] GDK/Win32: Try to fix intializing GLES contexts

[Chun-wei Fan <fanchunwei src gnome org>]

commit c4cf2e5db952f0559c53a58aae5e09676acd5bed
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Mon Jan 17 16:11:27 2022 +0800

    GDK/Win32: Try to fix intializing GLES contexts
    
    We are now able to create EGL contexts properly on Windows, but not GLES.  This
    tries to fix things by doing the following:
    
    *  Record the GL context type in a more proper fashion, using an Enum.  This
       makes things a bit cleaner.
    *  Force GLES-3.0+ contexts, since libANGLE requires this to properly work with
       the shaders-its 2.0 contexts don't work well with our shaders.

 gdk/win32/gdkdisplay-win32.c       | 38 +++++++++++++++++++++++++++++---------
 gdk/win32/gdkdisplay-win32.h       |  9 ++++++++-
 gdk/win32/gdkglcontext-win32-wgl.c |  9 ++++-----
 3 files changed, 41 insertions(+), 15 deletions(-)
---
diff --git a/gdk/win32/gdkdisplay-win32.c b/gdk/win32/gdkdisplay-win32.c
index 675e1af5e2..14de69ff7b 100644
--- a/gdk/win32/gdkdisplay-win32.c
+++ b/gdk/win32/gdkdisplay-win32.c
@@ -1181,6 +1181,7 @@ gdk_win32_display_init_gl_backend (GdkDisplay  *display,
 {
   gboolean result = FALSE;
   GdkWin32Display *display_win32 = GDK_WIN32_DISPLAY (display);
+  GdkWin32GLType gl_type = GDK_WIN32_GL_TYPE_NONE;
 
   if (display_win32->dummy_context_wgl.hdc == NULL)
     display_win32->dummy_context_wgl.hdc = GetDC (display_win32->hwnd);
@@ -1196,20 +1197,29 @@ gdk_win32_display_init_gl_backend (GdkDisplay  *display,
    * usage against libANGLE EGL.  EGL is used more as a compatibility layer
    * on Windows rather than being a native citizen on Windows
    */
-  if (_gdk_debug_flags & GDK_DEBUG_GL_EGL)
-    result = gdk_display_init_egl (display,
-                                   EGL_PLATFORM_ANGLE_ANGLE,
-                                   display_win32->dummy_context_wgl.hdc,
-                                   FALSE,
-                                   error);
+  if (GDK_DEBUG_CHECK (GL_EGL) || GDK_DEBUG_CHECK (GL_GLES))
+    {
+      result = gdk_display_init_egl (display,
+                                     EGL_PLATFORM_ANGLE_ANGLE,
+                                     display_win32->dummy_context_wgl.hdc,
+                                     FALSE,
+                                     error);
+
+      if (result)
+        gl_type = GDK_WIN32_GL_TYPE_EGL;
+    }
 #endif
 
   if (!result)
     {
       g_clear_error (error);
       result = gdk_win32_display_init_wgl (display, error);
+
+      if (result)
+        gl_type = GDK_WIN32_GL_TYPE_WGL;
     }
 
+
 #ifdef HAVE_EGL
   if (!result)
     {
@@ -1219,9 +1229,13 @@ gdk_win32_display_init_gl_backend (GdkDisplay  *display,
                                      display_win32->dummy_context_wgl.hdc,
                                      TRUE,
                                      error);
+
+      if (result)
+        gl_type = GDK_WIN32_GL_TYPE_EGL;
     }
 #endif
 
+  display_win32->gl_type = gl_type;
   return result;
 }
 
@@ -1235,11 +1249,17 @@ gdk_win32_display_init_gl (GdkDisplay  *display,
   if (!gdk_win32_display_init_gl_backend (display, error))
     return NULL;
 
-  if (display_win32->wgl_pixel_format != 0)
+  if (display_win32->gl_type == GDK_WIN32_GL_TYPE_WGL)
     gl_context = g_object_new (GDK_TYPE_WIN32_GL_CONTEXT_WGL, "display", display, NULL);
 #ifdef HAVE_EGL
-  else if (gdk_display_get_egl_display (display))
-    gl_context = g_object_new (GDK_TYPE_WIN32_GL_CONTEXT_EGL, "display", display, NULL);
+  else if (display_win32->gl_type == GDK_WIN32_GL_TYPE_EGL)
+    {
+      gl_context = g_object_new (GDK_TYPE_WIN32_GL_CONTEXT_EGL, "display", display, NULL);
+
+      /* We want to use a GLES 3.0+ context */
+      gdk_gl_context_set_allowed_apis (gl_context, GDK_GL_API_GLES);
+      gdk_gl_context_set_required_version (gl_context, 3, 0);
+    }
 #endif
 
   g_return_val_if_fail (gl_context != NULL, NULL);
diff --git a/gdk/win32/gdkdisplay-win32.h b/gdk/win32/gdkdisplay-win32.h
index 3b746bbe1b..88757e03e0 100644
--- a/gdk/win32/gdkdisplay-win32.h
+++ b/gdk/win32/gdkdisplay-win32.h
@@ -105,6 +105,13 @@ typedef enum {
   GDK_WIN32_TABLET_INPUT_API_WINPOINTER
 } GdkWin32TabletInputAPI;
 
+typedef enum
+{
+  GDK_WIN32_GL_TYPE_NONE,
+  GDK_WIN32_GL_TYPE_WGL,
+  GDK_WIN32_GL_TYPE_EGL,
+} GdkWin32GLType;
+
 typedef struct
 {
   HDC hdc;
@@ -125,7 +132,7 @@ struct _GdkWin32Display
 
   /* WGL/OpenGL Items */
   GdkWin32GLDummyContextWGL dummy_context_wgl;
-  int wgl_pixel_format;
+  GdkWin32GLType gl_type;
   guint gl_version;
 
   GListModel *monitors;
diff --git a/gdk/win32/gdkglcontext-win32-wgl.c b/gdk/win32/gdkglcontext-win32-wgl.c
index d443a2c7ff..41aed57d1f 100644
--- a/gdk/win32/gdkglcontext-win32-wgl.c
+++ b/gdk/win32/gdkglcontext-win32-wgl.c
@@ -258,7 +258,7 @@ gdk_win32_display_init_wgl (GdkDisplay  *display,
   if (!gdk_gl_backend_can_be_used (GDK_GL_WGL, error))
     return FALSE;
 
-  if (display_win32->wgl_pixel_format != 0)
+  if (display_win32->gl_type == GDK_WIN32_GL_TYPE_WGL)
     return TRUE;
 
   /* acquire and cache dummy Window (HWND & HDC) and
@@ -299,8 +299,6 @@ gdk_win32_display_init_wgl (GdkDisplay  *display,
         }
     }
 
-  display_win32->wgl_pixel_format = best_idx;
-
   display_win32->hasWglARBCreateContext =
     epoxy_has_wgl_extension (hdc, "WGL_ARB_create_context");
   display_win32->hasWglEXTSwapControl =
@@ -728,10 +726,11 @@ gdk_win32_display_get_wgl_version (GdkDisplay *display,
   if (!GDK_IS_WIN32_DISPLAY (display))
     return FALSE;
 
-  display_win32 = GDK_WIN32_DISPLAY (display);
-  if (display_win32->wgl_pixel_format == 0)
+  if (!gdk_win32_display_init_wgl (display, NULL))
     return FALSE;
 
+  display_win32 = GDK_WIN32_DISPLAY (display);
+
   if (major != NULL)
     *major = display_win32->gl_version / 10;
   if (minor != NULL)