[mutter] MetaEgl: Add EGL extensions support

[Jonas Ådahl <jadahl src gnome org>]

commit 80c61c4b3bc6d7354911b3afcf223ca2fc4640ae
Author: Jonas Ådahl <jadahl gmail com>
Date:   Thu Aug 18 11:05:20 2016 +0800

    MetaEgl: Add EGL extensions support
    
    Add proc symbol loading and helper functions for calling them, dealing
    with errors etc. So far no extension symbols are loaded, only the
    infrastructure is there.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=773629

 src/backends/meta-egl.c |   90 +++++++++++++++++++++++++++++++++++++++++++++++
 src/backends/meta-egl.h |    7 ++++
 2 files changed, 97 insertions(+), 0 deletions(-)
---
diff --git a/src/backends/meta-egl.c b/src/backends/meta-egl.c
index a5dd14f..f15c082 100644
--- a/src/backends/meta-egl.c
+++ b/src/backends/meta-egl.c
@@ -109,6 +109,76 @@ set_egl_error (GError **error)
                error_str);
 }
 
+static gboolean
+extensions_string_has_extensions_valist (const char *extensions_str,
+                                         char     ***missing_extensions,
+                                         char       *first_extension,
+                                         va_list     var_args)
+{
+  char **extensions;
+  char *extension;
+  size_t num_missing_extensions = 0;
+
+  if (missing_extensions)
+    *missing_extensions = NULL;
+
+  extensions = g_strsplit (extensions_str, " ", -1);
+
+  extension = first_extension;
+  while (extension)
+    {
+      if (!g_strv_contains ((const char * const *) extensions, extension))
+        {
+          num_missing_extensions++;
+          if (missing_extensions)
+            {
+              *missing_extensions = g_realloc_n (*missing_extensions,
+                                                 num_missing_extensions + 1,
+                                                 sizeof (const char *));
+              (*missing_extensions)[num_missing_extensions - 1] = extension;
+              (*missing_extensions)[num_missing_extensions] = NULL;
+            }
+          else
+            {
+              break;
+            }
+        }
+      extension = va_arg (var_args, char *);
+    }
+
+  g_strfreev (extensions);
+
+  return num_missing_extensions == 0;
+}
+
+gboolean
+meta_egl_has_extensions (MetaEgl   *egl,
+                         EGLDisplay display,
+                         char    ***missing_extensions,
+                         char      *first_extension,
+                         ...)
+{
+  va_list var_args;
+  const char *extensions_str;
+  gboolean has_extensions;
+
+  extensions_str = (const char *) eglQueryString (display, EGL_EXTENSIONS);
+  if (!extensions_str)
+    {
+      g_warning ("Failed to query string: %s", get_egl_error_str ());
+      return FALSE;
+    }
+
+  va_start (var_args, first_extension);
+  has_extensions = extensions_string_has_extensions_valist (extensions_str,
+                                                            missing_extensions,
+                                                            first_extension,
+                                                            var_args);
+  va_end (var_args);
+
+  return has_extensions;
+}
+
 EGLDisplay
 meta_egl_get_display (MetaEgl             *egl,
                       EGLNativeDisplayType display_id,
@@ -126,6 +196,23 @@ meta_egl_get_display (MetaEgl             *egl,
   return display;
 }
 
+#define GET_EGL_PROC_ADDR(proc) \
+  egl->proc = (void *) eglGetProcAddress (#proc);
+
+#define GET_EGL_PROC_ADDR_REQUIRED(proc) \
+  GET_EGL_PROC_ADDR(proc) \
+  if (!egl->proc) \
+    { \
+      meta_fatal ("Failed to get proc address for '%s'\n", #proc); \
+    }
+
+static void
+meta_egl_constructed (GObject *object)
+{
+}
+
+#undef GET_EGL_PROC_ADDR
+
 static void
 meta_egl_init (MetaEgl *egl)
 {
@@ -134,4 +221,7 @@ meta_egl_init (MetaEgl *egl)
 static void
 meta_egl_class_init (MetaEglClass *klass)
 {
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->constructed = meta_egl_constructed;
 }
diff --git a/src/backends/meta-egl.h b/src/backends/meta-egl.h
index 0762c04..c2b3e2f 100644
--- a/src/backends/meta-egl.h
+++ b/src/backends/meta-egl.h
@@ -26,11 +26,18 @@
 #define META_EGL_H
 
 #include <EGL/egl.h>
+#include <EGL/eglext.h>
 #include <glib-object.h>
 
 #define META_TYPE_EGL (meta_egl_get_type ())
 G_DECLARE_FINAL_TYPE (MetaEgl, meta_egl, META, EGL, GObject)
 
+gboolean meta_egl_has_extensions (MetaEgl   *egl,
+                                  EGLDisplay display,
+                                  char    ***missing_extensions,
+                                  char      *first_extension,
+                                  ...);
+
 EGLDisplay meta_egl_get_display (MetaEgl             *egl,
                                  EGLNativeDisplayType display_id,
                                  GError             **error);