[gtk+/wip/gdk-gl: 14/31] gdk: Rework the GL context update

[Emmanuele Bassi <ebassi src gnome org>]

commit a71cec0119ed720bd725dddb621f794458034817
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Tue Aug 12 11:51:45 2014 +0100

    gdk: Rework the GL context update
    
    Ensure that gdk_gl_context_update() schedules an update of the viewport,
    and then perform the actual update when the backend says it should. This
    makes the code a bit more readable, and we can keep asking the user to
    call gdk_gl_context_update() after gdk_window_move_resize() without
    having to care about asynchronous updates.

 gdk/gdkglcontext.c         |   45 +++++++++++++++++++++++++++++++++++++++++++-
 gdk/gdkglcontextprivate.h  |   16 +++++++++++---
 gdk/x11/gdkdisplay-x11.c   |   11 +++++++++-
 gdk/x11/gdkglcontext-x11.c |   25 ++++++++++++-----------
 4 files changed, 79 insertions(+), 18 deletions(-)
---
diff --git a/gdk/gdkglcontext.c b/gdk/gdkglcontext.c
index 08c6956..dfecfa0 100644
--- a/gdk/gdkglcontext.c
+++ b/gdk/gdkglcontext.c
@@ -54,6 +54,8 @@ typedef struct {
   GdkVisual *visual;
 
   gboolean swap_interval;
+
+  gboolean needs_update;
 } GdkGLContextPrivate;
 
 enum {
@@ -453,9 +455,50 @@ gdk_gl_context_get_window (GdkGLContext *context)
 void
 gdk_gl_context_update (GdkGLContext *context)
 {
+  GdkGLContextPrivate *priv = gdk_gl_context_get_instance_private (context);
+
   g_return_if_fail (GDK_IS_GL_CONTEXT (context));
 
-  GDK_GL_CONTEXT_GET_CLASS (context)->update (context);
+  if (priv->needs_update)
+    return;
+
+  priv->needs_update = TRUE;
+}
+
+/*< private >
+ * gdk_gl_context_needs_update:
+ * @context: a #GdkGLContext
+ *
+ * Checks whether gdk_gl_context_update() was called on @context.
+ *
+ * Platform-specific code may need to be executed to update the
+ * viewport in case the context requested an update.
+ */
+gboolean
+gdk_gl_context_needs_update (GdkGLContext *context)
+{
+  GdkGLContextPrivate *priv = gdk_gl_context_get_instance_private (context);
+
+  return priv->needs_update;
+}
+
+/*< private >*
+ * gdk_gl_context_update_viewport:
+ * @context: a #GdkGLContext
+ * @window: a #GdkWindow
+ * @width: width of the viewport
+ * @height: height of the viewport
+ *
+ * Updates the viewport of @context in response to a size change
+ * of the given @window.
+ */
+void
+gdk_gl_context_update_viewport (GdkGLContext *context,
+                                GdkWindow    *window,
+                                int           width,
+                                int           height)
+{
+  GDK_GL_CONTEXT_GET_CLASS (context)->update_viewport (context, window, width, height);
 }
 
 /**
diff --git a/gdk/gdkglcontextprivate.h b/gdk/gdkglcontextprivate.h
index 74450b2..412c5f9 100644
--- a/gdk/gdkglcontextprivate.h
+++ b/gdk/gdkglcontextprivate.h
@@ -40,13 +40,21 @@ struct _GdkGLContextClass
 {
   GObjectClass parent_class;
 
-  void (* set_window)   (GdkGLContext *context,
-                         GdkWindow    *window);
-  void (* update)       (GdkGLContext *context);
-  void (* flush_buffer) (GdkGLContext *context);
+  void (* set_window)      (GdkGLContext *context,
+                            GdkWindow    *window);
+  void (* update_viewport) (GdkGLContext *context,
+                            GdkWindow    *window,
+                            int           width,
+                            int           height);
+  void (* flush_buffer)    (GdkGLContext *context);
 };
 
 gboolean        gdk_gl_context_get_swap_interval        (GdkGLContext *context);
+gboolean        gdk_gl_context_needs_update             (GdkGLContext *context);
+void            gdk_gl_context_update_viewport          (GdkGLContext *context,
+                                                         GdkWindow    *window,
+                                                         int           width,
+                                                         int           height);
 
 G_END_DECLS
 
diff --git a/gdk/x11/gdkdisplay-x11.c b/gdk/x11/gdkdisplay-x11.c
index f6ba01a..29cd960 100644
--- a/gdk/x11/gdkdisplay-x11.c
+++ b/gdk/x11/gdkdisplay-x11.c
@@ -798,7 +798,16 @@ gdk_x11_display_translate_event (GdkEventTranslator *translator,
             {
               GdkGLContext *context = gdk_window_get_gl_context (window);
 
-              gdk_gl_context_update (context);
+              /* only update the viewport if the context asked for it */
+              if (gdk_gl_context_needs_update (context))
+                {
+                  GDK_NOTE (OPENGL,
+                            g_print ("Updating viewport after a ConfigureNotify on window %lu\n",
+                                     (unsigned long) xevent->xconfigure.window));
+                  gdk_gl_context_update_viewport (context, window,
+                                                  xevent->xconfigure.width,
+                                                  xevent->xconfigure.height);
+                }
             }
 
           return_val = FALSE;
diff --git a/gdk/x11/gdkglcontext-x11.c b/gdk/x11/gdkglcontext-x11.c
index f8d6302..8394eee 100644
--- a/gdk/x11/gdkglcontext-x11.c
+++ b/gdk/x11/gdkglcontext-x11.c
@@ -10,6 +10,8 @@
 #include "gdkx11window.h"
 #include "gdkx11visual.h"
 
+#include "gdkinternals.h"
+
 #include "gdkintl.h"
 
 #include <GL/glx.h>
@@ -98,18 +100,13 @@ gdk_x11_gl_context_set_window (GdkGLContext *context,
 }
 
 static void
-gdk_x11_gl_context_update (GdkGLContext *context)
+gdk_x11_gl_context_update_viewport (GdkGLContext *context,
+                                    GdkWindow    *window,
+                                    int           width,
+                                    int           height)
 {
-  GdkWindow *window = gdk_gl_context_get_window (context);
-  int x, y, width, height;
-
-  if (window == NULL)
-    return;
+  GDK_NOTE (OPENGL, g_print ("Updating viewport to { 0, 0, %d, %d }\n", width, height));
 
-  if (!gdk_gl_context_make_current (context))
-    return;
-
-  gdk_window_get_geometry (window, &x, &y, &width, &height);
   glViewport (0, 0, width, height);
 }
 
@@ -157,7 +154,11 @@ gdk_x11_gl_context_flush_buffer (GdkGLContext *context)
   else
     drawable = gdk_x11_window_get_xid (window);
 
-  GDK_NOTE (OPENGL, g_print ("Flushing GLX buffers for %lu\n", (unsigned long) drawable));
+  GDK_NOTE (OPENGL,
+            g_print ("Flushing GLX buffers for %s drawable %lu (window: %lu)\n",
+                     drawable == info->drawable ? "GLX" : "X11",
+                     (unsigned long) drawable,
+                     (unsigned long) gdk_x11_window_get_xid (window)));
 
   /* if we are going to wait for the vertical refresh manually
    * we need to flush pending redraws, and we also need to wait
@@ -204,7 +205,7 @@ gdk_x11_gl_context_class_init (GdkX11GLContextClass *klass)
   GdkGLContextClass *context_class = GDK_GL_CONTEXT_CLASS (klass);
 
   context_class->set_window = gdk_x11_gl_context_set_window;
-  context_class->update = gdk_x11_gl_context_update;
+  context_class->update_viewport = gdk_x11_gl_context_update_viewport;
   context_class->flush_buffer = gdk_x11_gl_context_flush_buffer;
 }