[gtk+/wip/gl-texture] wip: convert gtkglarea to use snapshots

[Matthias Clasen <matthiasc src gnome org>]

commit 9abe8ea25c33ffd4a57b41216fd7b67321ad18ac
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Jan 17 07:25:51 2018 -0500

    wip: convert gtkglarea to use snapshots
    
    Just append a texture node.

 gtk/gtkglarea.c |   42 ++++++++++++++++++++++++++++--------------
 1 files changed, 28 insertions(+), 14 deletions(-)
---
diff --git a/gtk/gtkglarea.c b/gtk/gtkglarea.c
index 27157a0..9074a23 100644
--- a/gtk/gtkglarea.c
+++ b/gtk/gtkglarea.c
@@ -27,6 +27,7 @@
 #include "gtkmarshalers.h"
 #include "gtkprivate.h"
 #include "gtkrender.h"
+#include "gtksnapshot.h"
 
 #include <epoxy/gl.h>
 
@@ -144,6 +145,7 @@
 typedef struct {
   GdkGLContext *context;
   GError *error;
+  GdkTexture *gdk_texture;
 
   gboolean have_buffers;
 
@@ -381,7 +383,13 @@ gtk_gl_area_ensure_buffers (GtkGLArea *area)
     {
       /* For alpha we use textures as that is required for blending to work */
       if (priv->texture == 0)
-        glGenTextures (1, &priv->texture);
+        {
+          glGenTextures (1, &priv->texture);
+          priv->gdk_texture = gdk_texture_new_for_gl (priv->context,
+                                                      priv->texture,
+                                                      gtk_widget_get_width (widget),
+                                                      gtk_widget_get_height (widget));
+        }
 
       /* Delete old render buffer if any */
       if (priv->render_buffer != 0)
@@ -399,6 +407,7 @@ gtk_gl_area_ensure_buffers (GtkGLArea *area)
       /* Delete old texture if any */
       if (priv->texture != 0)
         {
+          g_clear_object (&priv->gdk_texture);
           glDeleteTextures(1, &priv->texture);
           priv->texture = 0;
         }
@@ -537,6 +546,7 @@ gtk_gl_area_delete_buffers (GtkGLArea *area)
 
   if (priv->texture != 0)
     {
+      g_clear_object (&priv->gdk_texture);
       glDeleteTextures(1, &priv->texture);
       priv->texture = 0;
     }
@@ -618,9 +628,9 @@ gtk_gl_area_draw_error_screen (GtkGLArea *area,
   g_object_unref (layout);
 }
 
-static gboolean
-gtk_gl_area_draw (GtkWidget *widget,
-                  cairo_t   *cr)
+static void
+gtk_gl_area_snapshot (GtkWidget   *widget,
+                      GtkSnapshot *snapshot)
 {
   GtkGLArea *area = GTK_GL_AREA (widget);
   GtkGLAreaPrivate *priv = gtk_gl_area_get_instance_private (area);
@@ -628,6 +638,7 @@ gtk_gl_area_draw (GtkWidget *widget,
   int w, h, scale;
   GLenum status;
 
+#if 0
   if (priv->error != NULL)
     {
       gtk_gl_area_draw_error_screen (area,
@@ -636,9 +647,10 @@ gtk_gl_area_draw (GtkWidget *widget,
                                      gtk_widget_get_height (widget));
       return FALSE;
     }
+#endif
 
   if (priv->context == NULL)
-    return FALSE;
+    return;
 
   gtk_gl_area_make_current (area);
 
@@ -669,19 +681,17 @@ gtk_gl_area_draw (GtkWidget *widget,
 
       priv->needs_render = FALSE;
 
-      gdk_cairo_draw_from_gl (cr,
-                              gtk_widget_get_window (widget),
-                              priv->texture ? priv->texture : priv->render_buffer,
-                              priv->texture ? GL_TEXTURE : GL_RENDERBUFFER,
-                              scale, 0, 0, w, h);
-      gtk_gl_area_make_current (area);
+      gtk_snapshot_append_texture (snapshot,
+                                   priv->gdk_texture,
+                                   &GRAPHENE_RECT_INIT (0, 0,
+                                                        gtk_widget_get_width (widget),
+                                                        gtk_widget_get_height (widget)),
+                                   "GL Area");
     }
   else
     {
       g_warning ("fb setup not supported");
     }
-
-  return TRUE;
 }
 
 static gboolean
@@ -708,7 +718,7 @@ gtk_gl_area_class_init (GtkGLAreaClass *klass)
   widget_class->realize = gtk_gl_area_realize;
   widget_class->unrealize = gtk_gl_area_unrealize;
   widget_class->size_allocate = gtk_gl_area_size_allocate;
-  widget_class->draw = gtk_gl_area_draw;
+  widget_class->snapshot = gtk_gl_area_snapshot;
 
   gtk_widget_class_set_accessible_role (widget_class, ATK_ROLE_DRAWING_AREA);
 
@@ -929,6 +939,8 @@ gtk_gl_area_init (GtkGLArea *area)
   priv->auto_render = TRUE;
   priv->needs_render = TRUE;
   priv->required_gl_version = 0;
+
+  priv->has_alpha = 1;
 }
 
 /**
@@ -1138,6 +1150,8 @@ gtk_gl_area_set_has_alpha (GtkGLArea *area,
 
   has_alpha = !!has_alpha;
 
+  has_alpha = 1;
+
   if (priv->has_alpha != has_alpha)
     {
       priv->has_alpha = has_alpha;