[gtk+/gtk-3-16] demo/glarea: Check errors on GtkGLArea

[Emmanuele Bassi <ebassi src gnome org>]

commit a7f06d2ae672b3eac9202ad72c0472b8b80e221b
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Wed Mar 25 15:20:36 2015 +0000

    demo/glarea: Check errors on GtkGLArea
    
    We should not call OpenGL API if GtkGLArea is in an error state.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=746746

 demos/gtk-demo/glarea.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)
---
diff --git a/demos/gtk-demo/glarea.c b/demos/gtk-demo/glarea.c
index ed87ef0..613c2c9 100644
--- a/demos/gtk-demo/glarea.c
+++ b/demos/gtk-demo/glarea.c
@@ -220,6 +220,9 @@ realize (GtkWidget *widget)
 {
   gtk_gl_area_make_current (GTK_GL_AREA (widget));
 
+  if (gtk_gl_area_get_error (GTK_GL_AREA (widget)) != NULL)
+    return;
+
   init_buffers (&position_buffer, NULL);
   init_shaders (&program, &mvp_location);
 }
@@ -230,6 +233,9 @@ unrealize (GtkWidget *widget)
 {
   gtk_gl_area_make_current (GTK_GL_AREA (widget));
 
+  if (gtk_gl_area_get_error (GTK_GL_AREA (widget)) != NULL)
+    return;
+
   glDeleteBuffers (1, &position_buffer);
   glDeleteProgram (program);
 }
@@ -271,6 +277,9 @@ static gboolean
 render (GtkGLArea    *area,
         GdkGLContext *context)
 {
+  if (gtk_gl_area_get_error (area) != NULL)
+    return FALSE;
+
   /* Clear the viewport */
   glClearColor (0.5, 0.5, 0.5, 1.0);
   glClear (GL_COLOR_BUFFER_BIT);