[gnome-session] check-accelerated: Print the renderer under Wayland as well

[Bastien Nocera <hadess src gnome org>]

commit 6e474f979da2f6502f820ec652da11bc683ff344
Author: Bastien Nocera <hadess hadess net>
Date:   Tue Oct 11 12:53:11 2016 +0200

    check-accelerated: Print the renderer under Wayland as well
    
    Based on sample code by Matthias Clasen <mclasen redhat com>
    
    We'll use this in gnome-control-center when gnome-session cannot provide
    a renderer, under Wayland, as the Wayland compositor runs after
    gnome-session's startup.
    
    If OpenGL 3 is not supported (which is required for GTK+'s GL support),
    then nothing is output.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=756914

 configure.ac                            |    2 +-
 tools/Makefile.am                       |    6 ++++--
 tools/gnome-session-check-accelerated.c |   27 +++++++++++++++++++++++++--
 3 files changed, 30 insertions(+), 5 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index fb71383..d357e8a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -85,7 +85,7 @@ PKG_CHECK_MODULES(SM, sm)
 PKG_CHECK_MODULES(ICE, ice)
 PKG_CHECK_MODULES(XEXT, xext xau)
 
-PKG_CHECK_MODULES(GL_TEST, xcomposite gl glib-2.0)
+PKG_CHECK_MODULES(GL_TEST, xcomposite gl glib-2.0 epoxy)
 PKG_CHECK_MODULES(GLES_TEST, egl glesv2)
 
 dnl ====================================================================
diff --git a/tools/Makefile.am b/tools/Makefile.am
index 23cafc9..d3b8bf3 100644
--- a/tools/Makefile.am
+++ b/tools/Makefile.am
@@ -77,11 +77,13 @@ gnome_session_check_accelerated_SOURCES =           \
 gnome_session_check_accelerated_CPPFLAGS =      \
        -DLIBEXECDIR=\""$(libexecdir)"\"        \
        $(AM_CPPFLAGS)                          \
-       $(GTK3_CFLAGS)
+       $(GTK3_CFLAGS)                          \
+       $(GL_TEST_CFLAGS)
 
 gnome_session_check_accelerated_LDADD =         \
        $(GTK3_LIBS)                            \
-       $(X11_LIBS)
+       $(X11_LIBS)                             \
+       $(GL_TEST_LIBS)
 
 if BUILD_SESSION_SELECTOR
 gnome_session_selector_CPPFLAGS =              \
diff --git a/tools/gnome-session-check-accelerated.c b/tools/gnome-session-check-accelerated.c
index 810478c..a54a34b 100644
--- a/tools/gnome-session-check-accelerated.c
+++ b/tools/gnome-session-check-accelerated.c
@@ -26,6 +26,7 @@
 #include <stdlib.h>
 
 #include <gtk/gtk.h>
+#include <epoxy/gl.h>
 #include <gdk/gdkx.h>
 #include <X11/Xatom.h>
 #include <sys/wait.h>
@@ -91,6 +92,26 @@ wait_for_property_notify (void)
         return property_changed;
 }
 
+static char *
+get_gtk_gles_renderer (void)
+{
+        GtkWidget *win;
+        GdkGLContext *context;
+        char *renderer = NULL;
+
+        win = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+        gtk_widget_realize (win);
+        context = gdk_window_create_gl_context (gtk_widget_get_window (win), NULL);
+        if (!context)
+                return NULL;
+        gdk_gl_context_make_current (context);
+        renderer = g_strdup ((char *) glGetString (GL_RENDERER));
+        gdk_gl_context_clear_current ();
+        g_object_unref (context);
+
+        return renderer;
+}
+
 int
 main (int argc, char **argv)
 {
@@ -103,16 +124,18 @@ main (int argc, char **argv)
         glong is_accelerated, is_software_rendering;
         GError *gl_error = NULL, *gles_error = NULL;
 
+        gtk_init (NULL, NULL);
+
         /* gnome-session-check-accelerated gets run before X is started in the wayland
          * case, and it currently requires X. Until we have that working, just always
          * assume wayland will work
          */
         if (g_strcmp0 (g_getenv ("XDG_SESSION_TYPE"), "x11") != 0) {
+                renderer_string = get_gtk_gles_renderer ();
+                g_print ("%s", renderer_string);
                 return 0;
         }
 
-        gtk_init (NULL, NULL);
-
         display = gdk_display_get_default ();
         rootwin = gdk_x11_get_default_root_xwindow ();