controllers: add new proxy control binding

Allows proxying the control interface from one property on one GstObject
to another property (of the same type) in another GstObject.

E.g. in a parent-child relationship, one may need to
gst_object_sync_values() on the child and have a binding (set elsewhere)
on the parent update the value.

Note: that this doesn't solve GObject property forwarding and must be
taken care of by the implementation manually or using GBinding.

https://bugzilla.gnome.org/show_bug.cgi?id=774657

4 files changed, 286 insertions, 0 deletions

diff --git a/libs/gst/controller/Makefile.am b/libs/gst/controller/Makefile.am
index 5016ea62b..b20a8e7d9 100644
--- a/libs/gst/controller/Makefile.am
+++ b/libs/gst/controller/Makefile.am
@@ -7,6 +7,7 @@ libgstcontroller_@GST_API_VERSION@_include_HEADERS = \
 	gstdirectcontrolbinding.h \
 	gsttimedvaluecontrolsource.h \
 	gstinterpolationcontrolsource.h \
+	gstproxycontrolbinding.h \
 	gsttriggercontrolsource.h \
 	gstlfocontrolsource.h
 
@@ -15,6 +16,7 @@ libgstcontroller_@GST_API_VERSION@_la_SOURCES = \
 	gstdirectcontrolbinding.c \
 	gsttimedvaluecontrolsource.c \
 	gstinterpolationcontrolsource.c \
+	gstproxycontrolbinding.c \
 	gsttriggercontrolsource.c \
 	gstlfocontrolsource.c
 
diff --git a/libs/gst/controller/gstproxycontrolbinding.c b/libs/gst/controller/gstproxycontrolbinding.c
new file mode 100644
index 000000000..ce5cad5d8
--- /dev/null
+++ b/libs/gst/controller/gstproxycontrolbinding.c
@@ -0,0 +1,199 @@
+/*
+ * GStreamer
+ * Copyright (C) 2016 Matthew Waters <matthew@centricular.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+/**
+ * SECTION:gstproxycontrolbinding
+ * @short_description: attachment for forwarding control sources
+ * @see_also: #GstControlBinding
+ *
+ * A #GstControlBinding that forwards requests to another #GstControlBinding
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "gstproxycontrolbinding.h"
+
+G_DEFINE_TYPE (GstProxyControlBinding,
+    gst_proxy_control_binding, GST_TYPE_CONTROL_BINDING);
+
+static void
+gst_proxy_control_binding_init (GstProxyControlBinding * self)
+{
+  g_weak_ref_init (&self->ref_object, NULL);
+}
+
+static void
+gst_proxy_control_binding_finalize (GObject * object)
+{
+  GstProxyControlBinding *self = (GstProxyControlBinding *) object;
+
+  g_weak_ref_clear (&self->ref_object);
+  g_free (self->property_name);
+
+  G_OBJECT_CLASS (gst_proxy_control_binding_parent_class)->finalize (object);
+}
+
+static gboolean
+gst_proxy_control_binding_sync_values (GstControlBinding * binding,
+    GstObject * object, GstClockTime timestamp, GstClockTime last_sync)
+{
+  GstProxyControlBinding *self = (GstProxyControlBinding *)
+      binding;
+  gboolean ret = TRUE;
+  GstObject *ref_object;
+
+  ref_object = g_weak_ref_get (&self->ref_object);
+  if (ref_object) {
+    GstControlBinding *ref_binding =
+        gst_object_get_control_binding (ref_object, self->property_name);
+    if (ref_binding) {
+      ret = gst_control_binding_sync_values (ref_binding, ref_object,
+          timestamp, last_sync);
+      gst_object_unref (ref_binding);
+    }
+    gst_object_unref (ref_object);
+  }
+
+  return ret;
+}
+
+static GValue *
+gst_proxy_control_binding_get_value (GstControlBinding * binding,
+    GstClockTime timestamp)
+{
+  GstProxyControlBinding *self = (GstProxyControlBinding *)
+      binding;
+  GValue *ret = NULL;
+  GstObject *ref_object;
+
+  ref_object = g_weak_ref_get (&self->ref_object);
+  if (ref_object) {
+    GstControlBinding *ref_binding =
+        gst_object_get_control_binding (ref_object, self->property_name);
+    if (ref_binding) {
+      ret = gst_control_binding_get_value (ref_binding, timestamp);
+      gst_object_unref (ref_binding);
+    }
+    gst_object_unref (ref_object);
+  }
+
+  return ret;
+}
+
+static gboolean
+gst_proxy_control_binding_get_value_array (GstControlBinding * binding,
+    GstClockTime timestamp, GstClockTime interval, guint n_values,
+    gpointer values)
+{
+  GstProxyControlBinding *self = (GstProxyControlBinding *)
+      binding;
+  gboolean ret = FALSE;
+  GstObject *ref_object;
+
+  ref_object = g_weak_ref_get (&self->ref_object);
+  if (ref_object) {
+    GstControlBinding *ref_binding =
+        gst_object_get_control_binding (ref_object, self->property_name);
+    if (ref_binding) {
+      ret = gst_control_binding_get_value_array (ref_binding, timestamp,
+          interval, n_values, values);
+      gst_object_unref (ref_binding);
+    }
+    gst_object_unref (ref_object);
+  }
+
+  return ret;
+}
+
+static gboolean
+gst_proxy_control_binding_get_g_value_array (GstControlBinding *
+    binding, GstClockTime timestamp, GstClockTime interval, guint n_values,
+    GValue * values)
+{
+  GstProxyControlBinding *self = (GstProxyControlBinding *) binding;
+  gboolean ret = FALSE;
+  GstObject *ref_object;
+
+  ref_object = g_weak_ref_get (&self->ref_object);
+  if (ref_object) {
+    GstControlBinding *ref_binding =
+        gst_object_get_control_binding (ref_object, self->property_name);
+    if (ref_binding) {
+      ret = gst_control_binding_get_g_value_array (ref_binding, timestamp,
+          interval, n_values, values);
+      gst_object_unref (ref_binding);
+    }
+    gst_object_unref (ref_object);
+  }
+
+  return ret;
+}
+
+static void
+gst_proxy_control_binding_class_init (GstProxyControlBindingClass * klass)
+{
+  GstControlBindingClass *cb_class = GST_CONTROL_BINDING_CLASS (klass);
+  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
+
+  cb_class->sync_values = gst_proxy_control_binding_sync_values;
+  cb_class->get_value = gst_proxy_control_binding_get_value;
+  cb_class->get_value_array = gst_proxy_control_binding_get_value_array;
+  cb_class->get_g_value_array = gst_proxy_control_binding_get_g_value_array;
+
+  gobject_class->finalize = gst_proxy_control_binding_finalize;
+}
+
+/**
+ * gst_proxy_control_binding_new:
+ * @object: (transfer none): a #GstObject
+ * @property_name: the property name in @object to control
+ * @ref_object: (transfer none): a #GstObject to forward all
+ *              #GstControlBinding requests to
+ * @ref_property_name: the property_name in @ref_object to control
+ *
+ * #GstProxyControlBinding forwards all access to data or sync_values()
+ * requests from @property_name on @object to the control binding at
+ * @ref_property_name on @ref_object.
+ *
+ * Returns: a new #GstControlBinding that proxies the control interface between
+ * properties on different #GstObject's
+ *
+ * Since: 1.12
+ */
+GstControlBinding *
+gst_proxy_control_binding_new (GstObject * object, const gchar * property_name,
+    GstObject * ref_object, const gchar * ref_property_name)
+{
+  GstProxyControlBinding *cb;
+
+  g_return_val_if_fail (GST_IS_OBJECT (object), NULL);
+  g_return_val_if_fail (property_name != NULL, NULL);
+  g_return_val_if_fail (GST_IS_OBJECT (ref_object), NULL);
+  g_return_val_if_fail (ref_property_name != NULL, NULL);
+
+  cb = g_object_new (GST_TYPE_PROXY_CONTROL_BINDING, "object", object,
+      "name", property_name, NULL);
+
+  g_weak_ref_set (&cb->ref_object, ref_object);
+  cb->property_name = g_strdup (ref_property_name);
+
+  return (GstControlBinding *) cb;
+}
diff --git a/libs/gst/controller/gstproxycontrolbinding.h b/libs/gst/controller/gstproxycontrolbinding.h
new file mode 100644
index 000000000..096712d9d
--- /dev/null
+++ b/libs/gst/controller/gstproxycontrolbinding.h
@@ -0,0 +1,83 @@
+/*
+ * GStreamer
+ * Copyright (C) 2016 Matthew Waters <matthew@centricular.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifndef __GST_PROXY_CONTROL_BINDING_H__
+#define __GST_PROXY_CONTROL_BINDING_H__
+
+#include <gst/gst.h>
+
+G_BEGIN_DECLS
+
+GType gst_proxy_control_binding_get_type (void);
+#define GST_TYPE_PROXY_CONTROL_BINDING  (gst_proxy_control_binding_get_type())
+#define GST_PROXY_CONTROL_BINDING(obj) \
+  (G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_PROXY_CONTROL_BINDING,GstProxyControlBinding))
+#define GST_PROXY_CONTROL_BINDING_CLASS(klass) \
+  (G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_PROXY_CONTROL_BINDING,GstProxyControlBindingClass))
+#define GST_IS_PROXY_CONTROL_BINDING(obj) \
+  (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_PROXY_CONTROL_BINDING))
+#define GST_IS_PROXY_CONTROL_BINDING_CLASS(klass) \
+  (G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_PROXY_CONTROL_BINDING))
+#define GST_PROXY_CONTROL_BINDING_GET_CLASS(obj) \
+  (G_TYPE_INSTANCE_GET_CLASS ((obj), GST_TYPE_CONTOL_SOURCE, GstProxyControlBindingClass))
+
+typedef struct _GstProxyControlBinding GstProxyControlBinding;
+typedef struct _GstProxyControlBindingClass GstProxyControlBindingClass;
+
+/**
+ * GstProxyControlBinding:
+ *
+ * Opaque #GstProxyControlBinding struct
+ */
+struct _GstProxyControlBinding
+{
+  /* <private> */
+  GstControlBinding parent;
+
+  GWeakRef ref_object;
+  gchar *property_name;
+
+  gpointer _padding[GST_PADDING];
+};
+
+/**
+ * GstProxyControlBindingClass:
+ *
+ * Opaque #GstProxyControlBindingClass struct
+ */
+struct _GstProxyControlBindingClass
+{
+  /* <private> */
+  GstControlBindingClass parent_class;
+
+  gpointer _padding[GST_PADDING];
+};
+
+GstControlBinding *     gst_proxy_control_binding_new               (GstObject * object,
+                                                                     const gchar * property_name,
+                                                                     GstObject * ref_object,
+                                                                     const gchar * ref_property_name);
+
+#ifdef G_DEFINE_AUTOPTR_CLEANUP_FUNC
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GstProxyControlBinding, gst_object_unref)
+#endif
+G_END_DECLS
+
+#endif /* __GST_PROXY_CONTROL_BINDING_H__ */
diff --git a/libs/gst/controller/meson.build b/libs/gst/controller/meson.build
index c3c784393..861ada525 100644
--- a/libs/gst/controller/meson.build
+++ b/libs/gst/controller/meson.build
@@ -3,6 +3,7 @@ gst_controller_sources = [
   'gstdirectcontrolbinding.c',
   'gsttimedvaluecontrolsource.c',
   'gstinterpolationcontrolsource.c',
+  'gstproxycontrolbinding.c',
   'gsttriggercontrolsource.c',
   'gstlfocontrolsource.c',
 ]
@@ -12,6 +13,7 @@ gst_controller_headers = [
   'gstdirectcontrolbinding.h',
   'gsttimedvaluecontrolsource.h',
   'gstinterpolationcontrolsource.h',
+  'gstproxycontrolbinding.h',
   'gsttriggercontrolsource.h',
   'gstlfocontrolsource.h',
   'controller.h',