gstreamer/ext/wayland/gstwaylandsink.c

/* GStreamer Wayland video sink
 *
 * Copyright (C) 2011 Intel Corporation
 * Copyright (C) 2011 Sreerenj Balachandran <sreerenj.balachandran@intel.com>
 * Copyright (C) 2012 Wim Taymans <wim.taymans@gmail.com>
 * Copyright (C) 2014 Collabora Ltd.
 *
 * 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 Street, Fifth Floor,
 * Boston, MA 02110-1301 USA.
 */

/**
 * SECTION:element-waylandsink
 *
 *  The waylandsink is creating its own window and render the decoded video frames to that.
 *  Setup the Wayland environment as described in
 *  <ulink url="http://wayland.freedesktop.org/building.html">Wayland</ulink> home page.
 *  The current implementaion is based on weston compositor.
 *
 * <refsect2>
 * <title>Example pipelines</title>
 * |[
 * gst-launch-1.0 -v videotestsrc ! waylandsink
 * ]| test the video rendering in wayland
 * </refsect2>
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "gstwaylandsink.h"
#include "wlvideoformat.h"
#include "wlbuffer.h"
#include "wlshmallocator.h"

#include <gst/wayland/wayland.h>
#include <gst/video/videooverlay.h>

/* signals */
enum
{
  SIGNAL_0,
  LAST_SIGNAL
};

/* Properties */
enum
{
  PROP_0,
  PROP_DISPLAY
};

GST_DEBUG_CATEGORY (gstwayland_debug);
#define GST_CAT_DEFAULT gstwayland_debug

static GstStaticPadTemplate sink_template = GST_STATIC_PAD_TEMPLATE ("sink",
    GST_PAD_SINK,
    GST_PAD_ALWAYS,
    GST_STATIC_CAPS (GST_VIDEO_CAPS_MAKE
        ("{ BGRx, BGRA, RGBx, xBGR, xRGB, RGBA, ABGR, ARGB, RGB, BGR, "
            "RGB16, BGR16, YUY2, YVYU, UYVY, AYUV, NV12, NV21, NV16, "
            "YUV9, YVU9, Y41B, I420, YV12, Y42B, v308 }"))
    );

static void gst_wayland_sink_get_property (GObject * object,
    guint prop_id, GValue * value, GParamSpec * pspec);
static void gst_wayland_sink_set_property (GObject * object,
    guint prop_id, const GValue * value, GParamSpec * pspec);
static void gst_wayland_sink_finalize (GObject * object);

static GstStateChangeReturn gst_wayland_sink_change_state (GstElement * element,
    GstStateChange transition);
static void gst_wayland_sink_set_context (GstElement * element,
    GstContext * context);

static GstCaps *gst_wayland_sink_get_caps (GstBaseSink * bsink,
    GstCaps * filter);
static gboolean gst_wayland_sink_set_caps (GstBaseSink * bsink, GstCaps * caps);
static gboolean
gst_wayland_sink_propose_allocation (GstBaseSink * bsink, GstQuery * query);
static gboolean gst_wayland_sink_show_frame (GstVideoSink * bsink,
    GstBuffer * buffer);

/* VideoOverlay interface */
static void gst_wayland_sink_videooverlay_init (GstVideoOverlayInterface *
    iface);
static void gst_wayland_sink_set_window_handle (GstVideoOverlay * overlay,
    guintptr handle);
static void gst_wayland_sink_set_render_rectangle (GstVideoOverlay * overlay,
    gint x, gint y, gint w, gint h);
static void gst_wayland_sink_expose (GstVideoOverlay * overlay);

/* WaylandVideo interface */
static void gst_wayland_sink_waylandvideo_init (GstWaylandVideoInterface *
    iface);
static void gst_wayland_sink_begin_geometry_change (GstWaylandVideo * video);
static void gst_wayland_sink_end_geometry_change (GstWaylandVideo * video);

#define gst_wayland_sink_parent_class parent_class
G_DEFINE_TYPE_WITH_CODE (GstWaylandSink, gst_wayland_sink, GST_TYPE_VIDEO_SINK,
    G_IMPLEMENT_INTERFACE (GST_TYPE_VIDEO_OVERLAY,
        gst_wayland_sink_videooverlay_init)
    G_IMPLEMENT_INTERFACE (GST_TYPE_WAYLAND_VIDEO,
        gst_wayland_sink_waylandvideo_init));

static void
gst_wayland_sink_class_init (GstWaylandSinkClass * klass)
{
  GObjectClass *gobject_class;
  GstElementClass *gstelement_class;
  GstBaseSinkClass *gstbasesink_class;
  GstVideoSinkClass *gstvideosink_class;

  gobject_class = (GObjectClass *) klass;
  gstelement_class = (GstElementClass *) klass;
  gstbasesink_class = (GstBaseSinkClass *) klass;
  gstvideosink_class = (GstVideoSinkClass *) klass;

  gobject_class->set_property = gst_wayland_sink_set_property;
  gobject_class->get_property = gst_wayland_sink_get_property;
  gobject_class->finalize = GST_DEBUG_FUNCPTR (gst_wayland_sink_finalize);

  gst_element_class_add_static_pad_template (gstelement_class, &sink_template);

  gst_element_class_set_static_metadata (gstelement_class,
      "wayland video sink", "Sink/Video",
      "Output to wayland surface",
      "Sreerenj Balachandran <sreerenj.balachandran@intel.com>, "
      "George Kiagiadakis <george.kiagiadakis@collabora.com>");

  gstelement_class->change_state =
      GST_DEBUG_FUNCPTR (gst_wayland_sink_change_state);
  gstelement_class->set_context =
      GST_DEBUG_FUNCPTR (gst_wayland_sink_set_context);

  gstbasesink_class->get_caps = GST_DEBUG_FUNCPTR (gst_wayland_sink_get_caps);
  gstbasesink_class->set_caps = GST_DEBUG_FUNCPTR (gst_wayland_sink_set_caps);
  gstbasesink_class->propose_allocation =
      GST_DEBUG_FUNCPTR (gst_wayland_sink_propose_allocation);

  gstvideosink_class->show_frame =
      GST_DEBUG_FUNCPTR (gst_wayland_sink_show_frame);

  g_object_class_install_property (gobject_class, PROP_DISPLAY,
      g_param_spec_string ("display", "Wayland Display name", "Wayland "
          "display name to connect to, if not supplied via the GstContext",
          NULL, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
}

static void
gst_wayland_sink_init (GstWaylandSink * sink)
{
  g_mutex_init (&sink->display_lock);
  g_mutex_init (&sink->render_lock);
}

static void
gst_wayland_sink_get_property (GObject * object,
    guint prop_id, GValue * value, GParamSpec * pspec)
{
  GstWaylandSink *sink = GST_WAYLAND_SINK (object);

  switch (prop_id) {
    case PROP_DISPLAY:
      GST_OBJECT_LOCK (sink);
      g_value_set_string (value, sink->display_name);
      GST_OBJECT_UNLOCK (sink);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static void
gst_wayland_sink_set_property (GObject * object,
    guint prop_id, const GValue * value, GParamSpec * pspec)
{
  GstWaylandSink *sink = GST_WAYLAND_SINK (object);

  switch (prop_id) {
    case PROP_DISPLAY:
      GST_OBJECT_LOCK (sink);
      sink->display_name = g_value_dup_string (value);
      GST_OBJECT_UNLOCK (sink);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static void
gst_wayland_sink_finalize (GObject * object)
{
  GstWaylandSink *sink = GST_WAYLAND_SINK (object);

  GST_DEBUG_OBJECT (sink, "Finalizing the sink..");

  if (sink->last_buffer)
    gst_buffer_unref (sink->last_buffer);
  if (sink->display)
    g_object_unref (sink->display);
  if (sink->window)
    g_object_unref (sink->window);
  if (sink->pool)
    gst_object_unref (sink->pool);

  g_free (sink->display_name);

  g_mutex_clear (&sink->display_lock);
  g_mutex_clear (&sink->render_lock);

  G_OBJECT_CLASS (parent_class)->finalize (object);
}

/* must be called with the display_lock */
static void
gst_wayland_sink_set_display_from_context (GstWaylandSink * sink,
    GstContext * context)
{
  struct wl_display *display;
  GError *error = NULL;

  display = gst_wayland_display_handle_context_get_handle (context);
  sink->display = gst_wl_display_new_existing (display, FALSE, &error);

  if (error) {
    GST_ELEMENT_WARNING (sink, RESOURCE, OPEN_READ_WRITE,
        ("Could not set display handle"),
        ("Failed to use the external wayland display: '%s'", error->message));
    g_error_free (error);
  }
}

static gboolean
gst_wayland_sink_find_display (GstWaylandSink * sink)
{
  GstQuery *query;
  GstMessage *msg;
  GstContext *context = NULL;
  GError *error = NULL;
  gboolean ret = TRUE;

  g_mutex_lock (&sink->display_lock);

  if (!sink->display) {
    /* first query upstream for the needed display handle */
    query = gst_query_new_context (GST_WAYLAND_DISPLAY_HANDLE_CONTEXT_TYPE);
    if (gst_pad_peer_query (GST_VIDEO_SINK_PAD (sink), query)) {
      gst_query_parse_context (query, &context);
      gst_wayland_sink_set_display_from_context (sink, context);
    }
    gst_query_unref (query);

    if (G_LIKELY (!sink->display)) {
      /* now ask the application to set the display handle */
      msg = gst_message_new_need_context (GST_OBJECT_CAST (sink),
          GST_WAYLAND_DISPLAY_HANDLE_CONTEXT_TYPE);

      g_mutex_unlock (&sink->display_lock);
      gst_element_post_message (GST_ELEMENT_CAST (sink), msg);
      /* at this point we expect gst_wayland_sink_set_context
       * to get called and fill sink->display */
      g_mutex_lock (&sink->display_lock);

      if (!sink->display) {
        /* if the application didn't set a display, let's create it ourselves */
        GST_OBJECT_LOCK (sink);
        sink->display = gst_wl_display_new (sink->display_name, &error);
        GST_OBJECT_UNLOCK (sink);

        if (error) {
          GST_ELEMENT_WARNING (sink, RESOURCE, OPEN_READ_WRITE,
              ("Could not initialise Wayland output"),
              ("Failed to create GstWlDisplay: '%s'", error->message));
          g_error_free (error);
          ret = FALSE;
        }
      }
    }
  }

  g_mutex_unlock (&sink->display_lock);

  return ret;
}

static GstStateChangeReturn
gst_wayland_sink_change_state (GstElement * element, GstStateChange transition)
{
  GstWaylandSink *sink = GST_WAYLAND_SINK (element);
  GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;

  switch (transition) {
    case GST_STATE_CHANGE_NULL_TO_READY:
      if (!gst_wayland_sink_find_display (sink))
        return GST_STATE_CHANGE_FAILURE;
      break;
    default:
      break;
  }

  ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
  if (ret == GST_STATE_CHANGE_FAILURE)
    return ret;

  switch (transition) {
    case GST_STATE_CHANGE_PAUSED_TO_READY:
      gst_buffer_replace (&sink->last_buffer, NULL);
      if (sink->window) {
        if (gst_wl_window_is_toplevel (sink->window)) {
          g_clear_object (&sink->window);
        } else {
          /* remove buffer from surface, show nothing */
          gst_wl_window_render (sink->window, NULL, NULL);
        }
      }
      break;
    case GST_STATE_CHANGE_READY_TO_NULL:
      g_mutex_lock (&sink->display_lock);
      /* If we had a toplevel window, we most likely have our own connection
       * to the display too, and it is a good idea to disconnect and allow
       * potentially the application to embed us with GstVideoOverlay
       * (which requires to re-use the same display connection as the parent
       * surface). If we didn't have a toplevel window, then the display
       * connection that we have is definitely shared with the application
       * and it's better to keep it around (together with the window handle)
       * to avoid requesting them again from the application if/when we are
       * restarted (GstVideoOverlay behaves like that in other sinks)
       */
      if (sink->display && !sink->window) {     /* -> the window was toplevel */
        g_clear_object (&sink->display);
      }
      g_mutex_unlock (&sink->display_lock);
      g_clear_object (&sink->pool);
      break;
    default:
      break;
  }

  return ret;
}

static void
gst_wayland_sink_set_context (GstElement * element, GstContext * context)
{
  GstWaylandSink *sink = GST_WAYLAND_SINK (element);

  if (gst_context_has_context_type (context,
          GST_WAYLAND_DISPLAY_HANDLE_CONTEXT_TYPE)) {
    g_mutex_lock (&sink->display_lock);
    if (G_LIKELY (!sink->display)) {
      gst_wayland_sink_set_display_from_context (sink, context);
    } else {
      GST_WARNING_OBJECT (element, "changing display handle is not supported");
      g_mutex_unlock (&sink->display_lock);
      return;
    }
    g_mutex_unlock (&sink->display_lock);
  }

  if (GST_ELEMENT_CLASS (parent_class)->set_context)
    GST_ELEMENT_CLASS (parent_class)->set_context (element, context);
}

static GstCaps *
gst_wayland_sink_get_caps (GstBaseSink * bsink, GstCaps * filter)
{
  GstWaylandSink *sink;
  GstCaps *caps;

  sink = GST_WAYLAND_SINK (bsink);

  caps = gst_pad_get_pad_template_caps (GST_VIDEO_SINK_PAD (sink));

  g_mutex_lock (&sink->display_lock);

  if (sink->display) {
    GValue list = G_VALUE_INIT;
    GValue value = G_VALUE_INIT;
    GArray *formats;
    gint i;
    enum wl_shm_format fmt;

    g_value_init (&list, GST_TYPE_LIST);

    formats = sink->display->shm_formats;
    for (i = 0; i < formats->len; i++) {
      g_value_init (&value, G_TYPE_STRING);
      fmt = g_array_index (formats, uint32_t, i);
      g_value_set_static_string (&value, gst_wl_shm_format_to_string (fmt));
      gst_value_list_append_and_take_value (&list, &value);
    }

    caps = gst_caps_make_writable (caps);
    gst_structure_take_value (gst_caps_get_structure (caps, 0), "format",
        &list);

    GST_DEBUG_OBJECT (sink, "display caps: %" GST_PTR_FORMAT, caps);
  }

  g_mutex_unlock (&sink->display_lock);

  if (filter) {
    GstCaps *intersection;

    intersection =
        gst_caps_intersect_full (filter, caps, GST_CAPS_INTERSECT_FIRST);
    gst_caps_unref (caps);
    caps = intersection;
  }

  return caps;
}

static GstBufferPool *
gst_wayland_create_pool (GstWaylandSink * sink, GstCaps * caps)
{
  GstBufferPool *pool = NULL;
  GstStructure *structure;
  gsize size = sink->video_info.size;

  pool = gst_video_buffer_pool_new ();

  structure = gst_buffer_pool_get_config (pool);
  gst_buffer_pool_config_set_params (structure, caps, size, 2, 0);
  gst_buffer_pool_config_set_allocator (structure, gst_wl_shm_allocator_get (),
      NULL);

  if (!gst_buffer_pool_set_config (pool, structure)) {
    g_object_unref (pool);
    pool = NULL;
  }

  return pool;
}

static gboolean
gst_wayland_sink_set_caps (GstBaseSink * bsink, GstCaps * caps)
{
  GstWaylandSink *sink;
  GstBufferPool *newpool;
  GstVideoInfo info;
  enum wl_shm_format format;
  GArray *formats;
  gint i;

  sink = GST_WAYLAND_SINK (bsink);

  GST_DEBUG_OBJECT (sink, "set caps %" GST_PTR_FORMAT, caps);

  /* extract info from caps */
  if (!gst_video_info_from_caps (&info, caps))
    goto invalid_format;

  format = gst_video_format_to_wl_shm_format (GST_VIDEO_INFO_FORMAT (&info));
  if ((gint) format == -1)
    goto invalid_format;

  /* verify we support the requested format */
  formats = sink->display->shm_formats;
  for (i = 0; i < formats->len; i++) {
    if (g_array_index (formats, uint32_t, i) == format)
      break;
  }

  if (i >= formats->len)
    goto unsupported_format;

  /* store the video info */
  sink->video_info = info;
  sink->video_info_changed = TRUE;

  /* create a new pool for the new configuration */
  newpool = gst_wayland_create_pool (sink, caps);
  if (!newpool)
    goto pool_failed;


  gst_object_replace ((GstObject **) & sink->pool, (GstObject *) newpool);
  gst_object_unref (newpool);

  return TRUE;

invalid_format:
  {
    GST_ERROR_OBJECT (sink,
        "Could not locate image format from caps %" GST_PTR_FORMAT, caps);
    return FALSE;
  }
unsupported_format:
  {
    GST_ERROR_OBJECT (sink, "Format %s is not available on the display",
        gst_wl_shm_format_to_string (format));
    return FALSE;
  }
pool_failed:
  {
    GST_ERROR_OBJECT (sink, "Failed to create new pool");
    return FALSE;
  }
}

static gboolean
gst_wayland_sink_propose_allocation (GstBaseSink * bsink, GstQuery * query)
{
  GstWaylandSink *sink = GST_WAYLAND_SINK (bsink);
  GstCaps *caps;
  GstBufferPool *pool = NULL;
  gboolean need_pool;

  gst_query_parse_allocation (query, &caps, &need_pool);

  if (need_pool)
    pool = gst_wayland_create_pool (sink, caps);

  if (pool) {
    gst_query_add_allocation_pool (query, pool, sink->video_info.size, 2, 0);
    g_object_unref (pool);
  }

  gst_query_add_allocation_param (query, gst_wl_shm_allocator_get (), NULL);
  gst_query_add_allocation_meta (query, GST_VIDEO_META_API_TYPE, NULL);

  return TRUE;
}

static void
frame_redraw_callback (void *data, struct wl_callback *callback, uint32_t time)
{
  GstWaylandSink *sink = data;

  GST_LOG ("frame_redraw_cb");

  g_mutex_lock (&sink->render_lock);
  sink->redraw_pending = FALSE;
  g_mutex_unlock (&sink->render_lock);

  wl_callback_destroy (callback);
}

static const struct wl_callback_listener frame_callback_listener = {
  frame_redraw_callback
};

/* must be called with the render lock */
static void
render_last_buffer (GstWaylandSink * sink)
{
  GstWlBuffer *wlbuffer;
  const GstVideoInfo *info = NULL;
  struct wl_surface *surface;
  struct wl_callback *callback;

  wlbuffer = gst_buffer_get_wl_buffer (sink->last_buffer);
  surface = gst_wl_window_get_wl_surface (sink->window);

  sink->redraw_pending = TRUE;
  callback = wl_surface_frame (surface);
  wl_callback_add_listener (callback, &frame_callback_listener, sink);

  if (G_UNLIKELY (sink->video_info_changed)) {
    info = &sink->video_info;
    sink->video_info_changed = FALSE;
  }
  gst_wl_window_render (sink->window, wlbuffer, info);
}

static GstFlowReturn
gst_wayland_sink_show_frame (GstVideoSink * vsink, GstBuffer * buffer)
{
  GstWaylandSink *sink = GST_WAYLAND_SINK (vsink);
  GstBuffer *to_render;
  GstWlBuffer *wlbuffer;
  GstFlowReturn ret = GST_FLOW_OK;

  g_mutex_lock (&sink->render_lock);

  GST_LOG_OBJECT (sink, "render buffer %p", buffer);

  if (G_UNLIKELY (!sink->window)) {
    /* ask for window handle. Unlock render_lock while doing that because
     * set_window_handle & friends will lock it in this context */
    g_mutex_unlock (&sink->render_lock);
    gst_video_overlay_prepare_window_handle (GST_VIDEO_OVERLAY (sink));
    g_mutex_lock (&sink->render_lock);

    if (!sink->window) {
      /* if we were not provided a window, create one ourselves */
      sink->window = gst_wl_window_new_toplevel (sink->display,
          &sink->video_info, &sink->render_lock);
    }
  }

  /* drop buffers until we get a frame callback */
  if (sink->redraw_pending)
    goto done;

  /* make sure that the application has called set_render_rectangle() */
  if (G_UNLIKELY (sink->window->render_rectangle.w == 0))
    goto no_window_size;

  wlbuffer = gst_buffer_get_wl_buffer (buffer);

  if (G_LIKELY (wlbuffer && wlbuffer->display == sink->display)) {
    GST_LOG_OBJECT (sink, "buffer %p has a wl_buffer from our display, "
        "writing directly", buffer);
    to_render = buffer;
  } else {
    GstVideoMeta *vmeta;
    GstMemory *mem;
    struct wl_buffer *wbuf = NULL;

    /* update video info from video meta */
    vmeta = gst_buffer_get_video_meta (buffer);
    if (vmeta) {
      gint i;

      for (i = 0; i < vmeta->n_planes; i++) {
        sink->video_info.offset[i] = vmeta->offset[i];
        sink->video_info.stride[i] = vmeta->stride[i];
      }
    }

    GST_LOG_OBJECT (sink, "buffer %p does not have a wl_buffer from our "
        "display, creating it", buffer);

    /* FIXME check all memory when introducing DMA-Buf */
    mem = gst_buffer_peek_memory (buffer, 0);

    if (gst_is_wl_shm_memory (mem)) {
      wbuf = gst_wl_shm_memory_construct_wl_buffer (mem, sink->display,
          &sink->video_info);
    }

    if (wbuf) {
      gst_buffer_add_wl_buffer (buffer, wbuf, sink->display);
      to_render = buffer;
    } else {
      GstVideoFrame src, dst;
      GstVideoInfo src_info = sink->video_info;

      /* we don't know how to create a wl_buffer directly from the provided
       * memory, so we have to copy the data to a memory that we know how
       * to handle... */

      GST_LOG_OBJECT (sink, "buffer %p cannot have a wl_buffer, "
          "copying to wl_shm memory", buffer);

      /* sink->pool always exists (created in set_caps), but it may not
       * be active if upstream is not using it */
      if (!gst_buffer_pool_is_active (sink->pool)) {
        GstStructure *config;
        GstCaps *caps;
        guint size = sink->video_info.size;

        config = gst_buffer_pool_get_config (sink->pool);
        gst_buffer_pool_config_get_params (config, &caps, &size, NULL, NULL);
        gst_buffer_pool_config_set_params (config, caps, size, 2, 0);

        /* This is a video pool, it should not fail with basic setings */
        if (!gst_buffer_pool_set_config (sink->pool, config) ||
            !gst_buffer_pool_set_active (sink->pool, TRUE))
          goto activate_failed;
      }

      ret = gst_buffer_pool_acquire_buffer (sink->pool, &to_render, NULL);
      if (ret != GST_FLOW_OK)
        goto no_buffer;

      /* the first time we acquire a buffer,
       * we need to attach a wl_buffer on it */
      wlbuffer = gst_buffer_get_wl_buffer (to_render);
      if (G_UNLIKELY (!wlbuffer)) {
        mem = gst_buffer_peek_memory (to_render, 0);
        wbuf = gst_wl_shm_memory_construct_wl_buffer (mem, sink->display,
            &sink->video_info);
        if (G_UNLIKELY (!wbuf))
          goto no_wl_buffer;

        gst_buffer_add_wl_buffer (to_render, wbuf, sink->display);
      }

      if (!gst_video_frame_map (&dst, &sink->video_info, to_render,
              GST_MAP_WRITE))
        goto dst_map_failed;

      if (!gst_video_frame_map (&src, &src_info, buffer, GST_MAP_READ)) {
        gst_video_frame_unmap (&dst);
        goto src_map_failed;
      }

      gst_video_frame_copy (&dst, &src);

      gst_video_frame_unmap (&src);
      gst_video_frame_unmap (&dst);
    }
  }

  /* drop double rendering */
  if (G_UNLIKELY (to_render == sink->last_buffer)) {
    GST_LOG_OBJECT (sink, "Buffer already being rendered");
    goto done;
  }

  gst_buffer_replace (&sink->last_buffer, to_render);
  render_last_buffer (sink);

  if (buffer != to_render)
    gst_buffer_unref (to_render);
  goto done;

no_window_size:
  {
    GST_ELEMENT_ERROR (sink, RESOURCE, WRITE,
        ("Window has no size set"),
        ("Make sure you set the size after calling set_window_handle"));
    ret = GST_FLOW_ERROR;
    goto done;
  }
no_buffer:
  {
    GST_WARNING_OBJECT (sink, "could not create buffer");
    goto done;
  }
no_wl_buffer:
  {
    GST_ERROR_OBJECT (sink, "could not create wl_buffer out of wl_shm memory");
    ret = GST_FLOW_ERROR;
    goto done;
  }
activate_failed:
  {
    GST_ERROR_OBJECT (sink, "failed to activate bufferpool.");
    ret = GST_FLOW_ERROR;
    goto done;
  }
src_map_failed:
  {
    GST_ELEMENT_ERROR (sink, RESOURCE, READ,
        ("Video memory can not be read from userspace."), (NULL));
    ret = GST_FLOW_ERROR;
    goto done;
  }
dst_map_failed:
  {
    GST_ELEMENT_ERROR (sink, RESOURCE, WRITE,
        ("Video memory can not be written from userspace."), (NULL));
    ret = GST_FLOW_ERROR;
    goto done;
  }
done:
  {
    g_mutex_unlock (&sink->render_lock);
    return ret;
  }
}

static void
gst_wayland_sink_videooverlay_init (GstVideoOverlayInterface * iface)
{
  iface->set_window_handle = gst_wayland_sink_set_window_handle;
  iface->set_render_rectangle = gst_wayland_sink_set_render_rectangle;
  iface->expose = gst_wayland_sink_expose;
}

static void
gst_wayland_sink_set_window_handle (GstVideoOverlay * overlay, guintptr handle)
{
  GstWaylandSink *sink = GST_WAYLAND_SINK (overlay);
  struct wl_surface *surface = (struct wl_surface *) handle;

  g_return_if_fail (sink != NULL);

  if (sink->window != NULL) {
    GST_WARNING_OBJECT (sink, "changing window handle is not supported");
    return;
  }

  g_mutex_lock (&sink->render_lock);

  GST_DEBUG_OBJECT (sink, "Setting window handle %" GST_PTR_FORMAT,
      (void *) handle);

  g_clear_object (&sink->window);

  if (handle) {
    if (G_LIKELY (gst_wayland_sink_find_display (sink))) {
      /* we cannot use our own display with an external window handle */
      if (G_UNLIKELY (sink->display->own_display)) {
        GST_ELEMENT_ERROR (sink, RESOURCE, OPEN_READ_WRITE,
            ("Application did not provide a wayland display handle"),
            ("waylandsink cannot use an externally-supplied surface without "
                "an externally-supplied display handle. Consider providing a "
                "display handle from your application with GstContext"));
      } else {
        sink->window = gst_wl_window_new_in_surface (sink->display, surface,
            &sink->render_lock);
      }
    } else {
      GST_ERROR_OBJECT (sink, "Failed to find display handle, "
          "ignoring window handle");
    }
  }

  g_mutex_unlock (&sink->render_lock);
}

static void
gst_wayland_sink_set_render_rectangle (GstVideoOverlay * overlay,
    gint x, gint y, gint w, gint h)
{
  GstWaylandSink *sink = GST_WAYLAND_SINK (overlay);

  g_return_if_fail (sink != NULL);

  g_mutex_lock (&sink->render_lock);
  if (!sink->window) {
    g_mutex_unlock (&sink->render_lock);
    GST_WARNING_OBJECT (sink,
        "set_render_rectangle called without window, ignoring");
    return;
  }

  GST_DEBUG_OBJECT (sink, "window geometry changed to (%d, %d) %d x %d",
      x, y, w, h);
  gst_wl_window_set_render_rectangle (sink->window, x, y, w, h);

  g_mutex_unlock (&sink->render_lock);
}

static void
gst_wayland_sink_expose (GstVideoOverlay * overlay)
{
  GstWaylandSink *sink = GST_WAYLAND_SINK (overlay);

  g_return_if_fail (sink != NULL);

  GST_DEBUG_OBJECT (sink, "expose");

  g_mutex_lock (&sink->render_lock);
  if (sink->last_buffer && !sink->redraw_pending) {
    GST_DEBUG_OBJECT (sink, "redrawing last buffer");
    render_last_buffer (sink);
  }
  g_mutex_unlock (&sink->render_lock);
}

static void
gst_wayland_sink_waylandvideo_init (GstWaylandVideoInterface * iface)
{
  iface->begin_geometry_change = gst_wayland_sink_begin_geometry_change;
  iface->end_geometry_change = gst_wayland_sink_end_geometry_change;
}

static void
gst_wayland_sink_begin_geometry_change (GstWaylandVideo * video)
{
  GstWaylandSink *sink = GST_WAYLAND_SINK (video);
  g_return_if_fail (sink != NULL);

  g_mutex_lock (&sink->render_lock);
  if (!sink->window || !sink->window->area_subsurface) {
    g_mutex_unlock (&sink->render_lock);
    GST_INFO_OBJECT (sink,
        "begin_geometry_change called without window, ignoring");
    return;
  }

  wl_subsurface_set_sync (sink->window->area_subsurface);
  g_mutex_unlock (&sink->render_lock);
}

static void
gst_wayland_sink_end_geometry_change (GstWaylandVideo * video)
{
  GstWaylandSink *sink = GST_WAYLAND_SINK (video);
  g_return_if_fail (sink != NULL);

  g_mutex_lock (&sink->render_lock);
  if (!sink->window || !sink->window->area_subsurface) {
    g_mutex_unlock (&sink->render_lock);
    GST_INFO_OBJECT (sink,
        "end_geometry_change called without window, ignoring");
    return;
  }

  wl_subsurface_set_desync (sink->window->area_subsurface);
  g_mutex_unlock (&sink->render_lock);
}

static gboolean
plugin_init (GstPlugin * plugin)
{
  GST_DEBUG_CATEGORY_INIT (gstwayland_debug, "waylandsink", 0,
      " wayland video sink");

  gst_wl_shm_allocator_register ();

  return gst_element_register (plugin, "waylandsink", GST_RANK_MARGINAL,
      GST_TYPE_WAYLAND_SINK);
}

GST_PLUGIN_DEFINE (GST_VERSION_MAJOR,
    GST_VERSION_MINOR,
    waylandsink,
    "Wayland Video Sink", plugin_init, VERSION, "LGPL", GST_PACKAGE_NAME,
    GST_PACKAGE_ORIGIN)