[gtk: 1/3] Fixed OpenGL extension detection for extensions promoted to OpenGL core.

[Emmanuele Bassi <ebassi src gnome org>]

commit c4111dad314848fee057344026e87dfa64755bb6
Author: David Hogan <david q hogan gmail com>
Date:   Thu Feb 13 06:52:24 2020 +1100

    Fixed OpenGL extension detection for extensions promoted to OpenGL core.
    
    For a given OpenGL context, macOS in particular does not support enumeration / detection of OpenGL 
features that have been promoted to core OpenGL functionality. It is possible other drivers are the same. 
This change assumes support for GL_ARB_texture_non_power_of_two with OpenGL 2.0+, GL_ARB_texture_rectangle 
with OpenGL 3.1+ and GL_EXT_framebuffer_blit with OpenGL 3.0+. I failed to find definitive information on 
whether GL_GREMEDY_frame_terminator has been promoted to OpenGL core, or whether GL_ANGLE_framebuffer_blit or 
GL_EXT_unpack_subimage have been promoted to core in OpenGL ES. This change results in a significant 
GtkGLArea performance boost on macOS.
    
    Closes #2428

 gdk/gdkglcontext.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/gdk/gdkglcontext.c b/gdk/gdkglcontext.c
index 4a01b2bab9..5ab960335b 100644
--- a/gdk/gdkglcontext.c
+++ b/gdk/gdkglcontext.c
@@ -1007,10 +1007,10 @@ gdk_gl_context_check_extensions (GdkGLContext *context)
     }
   else
     {
-      has_npot = epoxy_has_gl_extension ("GL_ARB_texture_non_power_of_two");
-      has_texture_rectangle = epoxy_has_gl_extension ("GL_ARB_texture_rectangle");
+      has_npot = priv->gl_version >= 20 || epoxy_has_gl_extension ("GL_ARB_texture_non_power_of_two");
+      has_texture_rectangle = priv->gl_version >= 31 || epoxy_has_gl_extension ("GL_ARB_texture_rectangle");
 
-      priv->has_gl_framebuffer_blit = epoxy_has_gl_extension ("GL_EXT_framebuffer_blit");
+      priv->has_gl_framebuffer_blit = priv->gl_version >= 30 || epoxy_has_gl_extension 
("GL_EXT_framebuffer_blit");
       priv->has_frame_terminator = epoxy_has_gl_extension ("GL_GREMEDY_frame_terminator");
       priv->has_unpack_subimage = TRUE;
       priv->has_khr_debug = epoxy_has_gl_extension ("GL_KHR_debug");