[gegl] buffer-source: Handle the 'changed' signal on input buffer correctly

[Jon Nordby <jonnor src gnome org>]

commit 937e609532a5bdba8ff547bb456a01f64885d798
Author: Jon Nordby <jononor gmail com>
Date:   Sat May 5 23:25:04 2012 +0200

    buffer-source: Handle the 'changed' signal on input buffer correctly
    
    Connetion needs to be done when the buffer is set, not in process.
    Since buffers might be long lives we also need to disconnect our
    handler correctly.

 operations/common/buffer-source.c |   64 +++++++++++++++++++++++++++++++++---
 1 files changed, 58 insertions(+), 6 deletions(-)
---
diff --git a/operations/common/buffer-source.c b/operations/common/buffer-source.c
index 82eb83e..03f5822 100644
--- a/operations/common/buffer-source.c
+++ b/operations/common/buffer-source.c
@@ -34,6 +34,24 @@ gegl_chant_object(buffer, _("Input buffer"),
 #include <gegl.h>
 #include "graph/gegl-node.h"
 
+typedef struct
+{
+  gulong buffer_changed_handler;
+} Priv;
+
+static Priv *
+get_priv (GeglChantO *o)
+{
+  Priv *priv = (Priv*)o->chant_data;
+  if (priv == NULL) {
+    priv = g_new0 (Priv, 1);
+    o->chant_data = (void*) priv;
+
+    priv->buffer_changed_handler = 0;
+  }
+  return priv;
+}
+
 static void buffer_changed (GeglBuffer          *buffer,
                             const GeglRectangle *rect,
                             gpointer             userdata)
@@ -56,6 +74,37 @@ get_bounding_box (GeglOperation *operation)
   return result;
 }
 
+static void
+my_set_property (GObject  *gobject,
+                          guint         property_id,
+                          const GValue *value,
+                          GParamSpec   *pspec)
+{
+  GeglOperation *operation = GEGL_OPERATION (gobject);
+  GeglChantO *o = GEGL_CHANT_PROPERTIES (operation);
+  Priv *p = get_priv(o);
+  GObject *buffer = NULL;
+
+  switch (property_id)
+  {
+    case PROP_buffer:
+      if (o->buffer) {
+        g_signal_handler_disconnect (o->buffer, p->buffer_changed_handler);
+      }
+      buffer = G_OBJECT (g_value_get_object (value));
+      if (buffer) {
+        g_signal_connect (buffer, "changed", G_CALLBACK(buffer_changed), operation);
+      }
+      break;
+    default:
+      break;
+  }
+
+  /* The set_property provided by the chant system does the
+   * storing and reffing/unreffing of the input properties */
+  set_property(gobject, property_id, value, pspec);
+}
+
 static gboolean
 process (GeglOperation        *operation,
          GeglOperationContext *context,
@@ -67,12 +116,6 @@ process (GeglOperation        *operation,
 
   if (o->buffer)
     {
-      if (!o->chant_data)
-        {
-          o->chant_data = (void*)0xf00;
-          g_signal_connect (o->buffer, "changed",
-                            G_CALLBACK(buffer_changed), operation);
-        }
       g_object_ref (o->buffer); /* Add an extra reference, since
 				     * gegl_operation_set_data is
 				     * stealing one.
@@ -93,13 +136,20 @@ static void
 dispose (GObject *object)
 {
   GeglChantO *o = GEGL_CHANT_PROPERTIES (object);
+  Priv *p = get_priv(o);
 
   if (o->buffer)
     {
+      g_signal_handler_disconnect (o->buffer, p->buffer_changed_handler);
       g_object_unref (o->buffer);
       o->buffer = NULL;
     }
 
+  if (p) {
+    g_free(p);
+    o->chant_data = NULL;
+  }
+
   G_OBJECT_CLASS (gegl_chant_parent_class)->dispose (object);
 }
 
@@ -114,6 +164,7 @@ gegl_chant_class_init (GeglChantClass *klass)
   operation_class->process = process;
   operation_class->get_bounding_box = get_bounding_box;
 
+  G_OBJECT_CLASS (klass)->set_property = my_set_property;
   G_OBJECT_CLASS (klass)->dispose = dispose;
 
   gegl_operation_class_set_keys (operation_class,
@@ -126,3 +177,4 @@ gegl_chant_class_init (GeglChantClass *klass)
 }
 
 #endif
+