gconf: Add GstSwitchSrc base class

ext/gconf/Makefile.am

@@ -7,6 +7,7 @@ libgstgconfelements_la_SOURCES = \
 	gstgconfvideosink.c \
 	gstgconfvideosrc.c \
 	gstswitchsink.c \
+	gstswitchsrc.c \
 	gstgconf.c
 
 DIR_CFLAGS = -DGST_GCONF_DIR=\"/system/gstreamer/@GST_MAJORMINOR@\"
@@ -22,4 +23,5 @@ noinst_HEADERS = \
 	gstgconfvideosink.h \
 	gstgconfvideosrc.h \
 	gstswitchsink.h \
+	gstswitchsrc.h \
 	gstgconf.h

ext/gconf/gstswitchsrc.c

@@ -0,0 +1,266 @@
+/* GStreamer
+ * Copyright (c) 2005 Ronald S. Bultje <rbultje@ronald.bitfreak.net>
+ * Copyright (c) 2006 Jürg Billeter <j@bitron.ch>
+ * Copyright (c) 2007 Jan Schmidt <thaytan@noraisin.net>
+ * Copyright (c) 2010 Sebastian Dröge <sebastian.droege@collabora.co.uk>
+ *
+ * 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., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <string.h>
+
+#include "gstswitchsrc.h"
+
+GST_DEBUG_CATEGORY_STATIC (switch_debug);
+#define GST_CAT_DEFAULT switch_debug
+
+static void gst_switch_src_dispose (GObject * object);
+static GstStateChangeReturn
+gst_switch_src_change_state (GstElement * element, GstStateChange transition);
+
+GST_BOILERPLATE (GstSwitchSrc, gst_switch_src, GstBin, GST_TYPE_BIN);
+
+static void
+gst_switch_src_base_init (gpointer klass)
+{
+  GST_DEBUG_CATEGORY_INIT (switch_debug, "switchsrc", 0, "switchsrc element");
+}
+
+static void
+gst_switch_src_class_init (GstSwitchSrcClass * klass)
+{
+  GObjectClass *oklass = G_OBJECT_CLASS (klass);
+  GstElementClass *eklass = GST_ELEMENT_CLASS (klass);
+  static GstStaticPadTemplate src_template = GST_STATIC_PAD_TEMPLATE ("src",
+      GST_PAD_SRC,
+      GST_PAD_ALWAYS,
+      GST_STATIC_CAPS_ANY);
+  GstPadTemplate *child_pad_templ;
+
+  oklass->dispose = gst_switch_src_dispose;
+  eklass->change_state = gst_switch_src_change_state;
+
+  /* Provide a default pad template if the child didn't */
+  child_pad_templ = gst_element_class_get_pad_template (eklass, "src");
+  if (child_pad_templ == NULL) {
+    gst_element_class_add_pad_template (eklass,
+        gst_static_pad_template_get (&src_template));
+  }
+}
+
+static gboolean
+gst_switch_src_reset (GstSwitchSrc * src)
+{
+  /* this will install fakesrc if no other child has been set,
+   * otherwise we rely on the subclass to know when to unset its
+   * custom kid */
+  if (src->kid == NULL) {
+    return gst_switch_src_set_child (src, NULL);
+  }
+
+  return TRUE;
+}
+
+static void
+gst_switch_src_init (GstSwitchSrc * src, GstSwitchSrcClass * g_class)
+{
+  GstElementClass *eklass = GST_ELEMENT_GET_CLASS (src);
+  GstPadTemplate *templ;
+
+  templ = gst_element_class_get_pad_template (eklass, "src");
+  src->pad = gst_ghost_pad_new_no_target_from_template ("src", templ);
+  gst_element_add_pad (GST_ELEMENT (src), src->pad);
+
+  gst_switch_src_reset (src);
+}
+
+static void
+gst_switch_src_dispose (GObject * object)
+{
+  GstSwitchSrc *src = GST_SWITCH_SRC (object);
+  GstObject *new_kid, *kid;
+
+  GST_OBJECT_LOCK (src);
+  new_kid = GST_OBJECT_CAST (src->new_kid);
+  src->new_kid = NULL;
+
+  kid = GST_OBJECT_CAST (src->kid);
+  src->kid = NULL;
+  GST_OBJECT_UNLOCK (src);
+
+  gst_object_replace (&new_kid, NULL);
+  gst_object_replace (&kid, NULL);
+
+  GST_CALL_PARENT (G_OBJECT_CLASS, dispose, (object));
+}
+
+static gboolean
+gst_switch_commit_new_kid (GstSwitchSrc * src)
+{
+  GstPad *targetpad;
+  GstState kid_state;
+  GstElement *new_kid, *old_kid;
+  gboolean is_fakesrc = FALSE;
+  GstBus *bus;
+
+  /* need locking around member accesses */
+  GST_OBJECT_LOCK (src);
+  /* If we're currently changing state, set the child to the next state
+   * we're transitioning too, rather than our current state which is 
+   * about to change */
+  if (GST_STATE_NEXT (src) != GST_STATE_VOID_PENDING)
+    kid_state = GST_STATE_NEXT (src);
+  else
+    kid_state = GST_STATE (src);
+
+  new_kid = src->new_kid;
+  src->new_kid = NULL;
+  GST_OBJECT_UNLOCK (src);
+
+  /* Fakesrc by default if NULL is passed as the new child */
+  if (new_kid == NULL) {
+    GST_DEBUG_OBJECT (src, "Replacing kid with fakesrc");
+    new_kid = gst_element_factory_make ("fakesrc", "testsrc");
+    if (new_kid == NULL) {
+      GST_ERROR_OBJECT (src, "Failed to create fakesrc");
+      return FALSE;
+    }
+    /* Add a reference, as it would if the element came from src->new_kid */
+    gst_object_ref (new_kid);
+    is_fakesrc = TRUE;
+  } else {
+    GST_DEBUG_OBJECT (src, "Setting new kid");
+  }
+
+  /* set temporary bus of our own to catch error messages from the child
+   * (could we just set our own bus on it, or would the state change messages
+   * from the not-yet-added element confuse the state change algorithm? Let's
+   * play it safe for now) */
+  bus = gst_bus_new ();
+  gst_element_set_bus (new_kid, bus);
+  gst_object_unref (bus);
+
+  if (gst_element_set_state (new_kid, kid_state) == GST_STATE_CHANGE_FAILURE) {
+    GstMessage *msg;
+
+    /* check if child posted an error message and if so re-post it on our bus
+     * so that the application gets to see a decent error and not our generic
+     * fallback error message which is completely indecipherable to the user */
+    msg = gst_bus_pop_filtered (GST_ELEMENT_BUS (new_kid), GST_MESSAGE_ERROR);
+    if (msg) {
+      GST_INFO_OBJECT (src, "Forwarding kid error: %" GST_PTR_FORMAT, msg);
+      gst_element_post_message (GST_ELEMENT (src), msg);
+    }
+    /* FIXME: need a translated error message that tells the user to check
+     * her GConf audio/video settings */
+    GST_ELEMENT_ERROR (src, CORE, STATE_CHANGE, (NULL),
+        ("Failed to set state on new child."));
+    gst_element_set_bus (new_kid, NULL);
+    gst_object_unref (new_kid);
+    return FALSE;
+  }
+  gst_element_set_bus (new_kid, NULL);
+  gst_bin_add (GST_BIN (src), new_kid);
+
+  /* Now, replace the existing child */
+  GST_OBJECT_LOCK (src);
+  old_kid = src->kid;
+  src->kid = new_kid;
+  /* Mark whether a custom kid or fakesrc has been installed */
+  src->have_kid = !is_fakesrc;
+  GST_OBJECT_UNLOCK (src);
+
+  /* kill old element */
+  if (old_kid) {
+    GST_DEBUG_OBJECT (src, "Removing old kid %" GST_PTR_FORMAT, old_kid);
+    gst_element_set_state (old_kid, GST_STATE_NULL);
+    gst_bin_remove (GST_BIN (src), old_kid);
+    gst_object_unref (old_kid);
+    /* Don't lose the SINK flag */
+    GST_OBJECT_FLAG_SET (src, GST_ELEMENT_IS_SINK);
+  }
+
+  /* re-attach ghostpad */
+  GST_DEBUG_OBJECT (src, "Creating new ghostpad");
+  targetpad = gst_element_get_static_pad (src->kid, "src");
+  gst_ghost_pad_set_target (GST_GHOST_PAD (src->pad), targetpad);
+  gst_object_unref (targetpad);
+  GST_DEBUG_OBJECT (src, "done changing child of switchsrc");
+
+  /* Unblock the target pad if necessary */
+  if (src->awaiting_block) {
+    gst_pad_set_blocked (src->pad, FALSE);
+    src->awaiting_block = FALSE;
+  }
+
+  return TRUE;
+}
+
+gboolean
+gst_switch_src_set_child (GstSwitchSrc * src, GstElement * new_kid)
+{
+  GstState cur, next;
+  GstElement **p_kid;
+
+  /* Nothing to do if clearing the child and we've already installed fakesrc */
+  if (new_kid == NULL && src->kid != NULL && src->have_kid == FALSE)
+    return TRUE;
+
+  /* Store the new kid to be committed later */
+  GST_OBJECT_LOCK (src);
+  cur = GST_STATE (src);
+  next = GST_STATE_NEXT (src);
+  p_kid = &src->new_kid;
+  gst_object_replace ((GstObject **) p_kid, (GstObject *) new_kid);
+  GST_OBJECT_UNLOCK (src);
+
+  /* Sometime, it would be lovely to allow src changes even when
+   * already running */
+  /* FIXME: Block the pad and replace the kid when it completes */
+  if (cur > GST_STATE_READY || next == GST_STATE_PAUSED) {
+    GST_DEBUG_OBJECT (src,
+        "Switch-src is already running. Ignoring change of child.");
+    gst_object_unref (new_kid);
+    return TRUE;
+  }
+
+  return gst_switch_commit_new_kid (src);
+}
+
+static GstStateChangeReturn
+gst_switch_src_change_state (GstElement * element, GstStateChange transition)
+{
+  GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
+  GstSwitchSrc *src = GST_SWITCH_SRC (element);
+
+  ret = GST_CALL_PARENT_WITH_DEFAULT (GST_ELEMENT_CLASS, change_state,
+      (element, transition), GST_STATE_CHANGE_SUCCESS);
+
+  switch (transition) {
+    case GST_STATE_CHANGE_READY_TO_NULL:
+      if (!gst_switch_src_reset (src))
+        ret = GST_STATE_CHANGE_FAILURE;
+      break;
+    default:
+      break;
+  }
+
+  return ret;
+}

ext/gconf/gstswitchsrc.h

@@ -0,0 +1,60 @@
+/* GStreamer
+ *
+ * Copyright (c) 2005 Ronald S. Bultje <rbultje@ronald.bitfreak.net>
+ * Copyright (c) 2005 Tim-Philipp Müller <tim centricular net>
+ * Copyright (c) 2007 Jan Schmidt <thaytan@mad.scientist.com>
+ * Copyright (c) 2010 Sebastian Dröge <sebastian.droege@collabora.co.uk>
+ *
+ * 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., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifndef __GST_SWITCH_SRC_H__
+#define __GST_SWITCH_SRC_H__
+
+#include <gst/gst.h>
+
+G_BEGIN_DECLS
+
+#define GST_TYPE_SWITCH_SRC            (gst_switch_src_get_type ())
+#define GST_SWITCH_SRC(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GST_TYPE_SWITCH_SRC, GstSwitchSrc))
+#define GST_SWITCH_SRC_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GST_TYPE_SWITCH_SRC, GstSwitchSrcClass))
+#define GST_IS_SWITCH_SRC(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GST_TYPE_SWITCH_SRC))
+#define GST_IS_SWITCH_SRC_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GST_TYPE_SWITCH_SRC))
+
+typedef struct _GstSwitchSrc {
+  GstBin parent;
+
+  GstElement *kid;
+  GstElement *new_kid;
+  GstPad *pad;
+
+  /* If a custom child has been set... */
+  gboolean have_kid;
+
+  /* If waiting for a pad block to complete on the ghost pad */
+  gboolean awaiting_block;
+} GstSwitchSrc;
+
+typedef struct _GstSwitchSrcClass {
+  GstBinClass parent_class;
+} GstSwitchSrcClass;
+
+GType     gst_switch_src_get_type   (void);
+gboolean  gst_switch_src_set_child  (GstSwitchSrc *ssrc, GstElement *new_kid);
+
+G_END_DECLS
+
+#endif /* __GST_SWITCH_SRC_H__ */