Add gst_vaapi_display_lookup_downstream() helper.

gst-libs/gst/vaapi/Makefile.am

@@ -37,6 +37,7 @@ libgstvaapi_source_c =				\
 	gstvaapisurfacepool.c			\
 	gstvaapisurfaceproxy.c			\
 	gstvaapiutils.c				\
+	gstvaapiutils_gst.c			\
 	gstvaapivalue.c				\
 	gstvaapivideobuffer.c			\
 	gstvaapivideopool.c			\
@@ -75,6 +76,7 @@ libgstvaapi_source_priv_h =			\
 	gstvaapidisplay_priv.h			\
 	gstvaapiobject_priv.h			\
 	gstvaapiutils.h				\
+	gstvaapiutils_gst.h			\
 	gstvaapi_priv.h				\
 	$(libgst_vaapi_ffmpeg_source_priv_h)	\
 	$(NULL)

gst-libs/gst/vaapi/gstvaapiutils_gst.c

@@ -0,0 +1,108 @@
+/*
+ *  gstvaapiutils_gst.c - GST utilties
+ *
+ *  gstreamer-vaapi (C) 2010 Splitted-Desktop Systems
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public License
+ *  as published by the Free Software Foundation; either version 2.1
+ *  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
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free
+ *  Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ *  Boston, MA 02110-1301 USA
+ */
+
+#include "config.h"
+#include "gstvaapiutils_gst.h"
+#include "gstvaapivideosink.h"
+#include "gstvaapivideobuffer.h"
+
+#define DEBUG 1
+#include "gstvaapidebug.h"
+
+static GstVaapiDisplay *
+lookup_through_vaapisink_iface(GstElement *element)
+{
+    GstVaapiDisplay *display;
+    GstVaapiVideoSink *sink;
+
+    GST_DEBUG("looking for a downstream vaapisink");
+
+    /* Look for a downstream vaapisink */
+    sink = gst_vaapi_video_sink_lookup(element);
+    if (!sink)
+        return NULL;
+
+    display = gst_vaapi_video_sink_get_display(sink);
+    GST_DEBUG("  found display %p", display);
+    return display;
+}
+
+static GstVaapiDisplay *
+lookup_through_peer_buffer(GstElement *element)
+{
+    GstVaapiDisplay *display;
+    GstPad *pad;
+    GstBuffer *buffer;
+    GstFlowReturn ret;
+
+    GST_DEBUG("looking for a GstVaapiVideoBuffer from peer");
+
+    /* Lookup for a GstVaapiVideoBuffer from peer */
+    pad = gst_element_get_static_pad(element, "src");
+    if (!pad)
+        return NULL;
+
+    buffer = NULL;
+    ret = gst_pad_alloc_buffer(pad, 0, 0, GST_PAD_CAPS(pad), &buffer);
+    g_object_unref(pad);
+    if (ret != GST_FLOW_OK || !buffer)
+        return NULL;
+
+    display = GST_VAAPI_IS_VIDEO_BUFFER(buffer) ?
+        gst_vaapi_video_buffer_get_display(GST_VAAPI_VIDEO_BUFFER(buffer)) :
+        NULL;
+    gst_buffer_unref(buffer);
+
+    GST_DEBUG("  found display %p", display);
+    return display;
+}
+
+/**
+ * gst_vaapi_display_lookup_downstream:
+ * @element: a #GstElement
+ *
+ * Finds a suitable #GstVaapiDisplay downstream from @element.
+ *
+ *   1. Check whether a downstream element implements the
+ *      #GstVaapiVideoSinkInterface interface.
+ *
+ *   2. Check whether the @element peer implements a custom
+ *      buffer_alloc() function that allocates #GstVaapiVideoBuffer
+ *      buffers.
+ *
+ * Return value: a downstream allocated #GstVaapiDisplay object, or
+ *   %NULL if none was found
+ */
+GstVaapiDisplay *
+gst_vaapi_display_lookup_downstream(GstElement *element)
+{
+    GstVaapiDisplay *display;
+
+    display = lookup_through_vaapisink_iface(element);
+    if (display)
+        return display;
+
+    display = lookup_through_peer_buffer(element);
+    if (display)
+        return display;
+
+    return NULL;
+}

gst-libs/gst/vaapi/gstvaapiutils_gst.h

@@ -0,0 +1,31 @@
+/*
+ *  gstvaapiutils_gst.h - GST utilties
+ *
+ *  gstreamer-vaapi (C) 2010 Splitted-Desktop Systems
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public License
+ *  as published by the Free Software Foundation; either version 2.1
+ *  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
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free
+ *  Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ *  Boston, MA 02110-1301 USA
+ */
+
+#ifndef GST_VAAPI_UTILS_GST_H
+#define GST_VAAPI_UTILS_GST_H
+
+#include <gst/gst.h>
+#include <gst/vaapi/gstvaapidisplay.h>
+
+GstVaapiDisplay *
+gst_vaapi_display_lookup_downstream(GstElement *element);
+
+#endif /* GST_VAAPI_UTILS_GST_H */