1 /* GStreamer Video Overlay interface
2 * Copyright (C) 2003 Ronald Bultje <rbultje@ronald.bitfreak.net>
3 * Copyright (C) 2011 Tim-Philipp Müller <tim@centricular.net>
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Library General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Library General Public License for more details.
15 * You should have received a copy of the GNU Library General Public
16 * License along with this library; if not, write to the
17 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 * Boston, MA 02111-1307, USA.
21 * SECTION:gstvideooverlay
22 * @short_description: Interface for setting/getting a window system resource
23 * on elements supporting it to configure a window into which to render a
28 * The #GstVideoOverlay interface is used for 2 main purposes :
32 * To get a grab on the Window where the video sink element is going to render.
33 * This is achieved by either being informed about the Window identifier that
34 * the video sink element generated, or by forcing the video sink element to use
35 * a specific Window identifier for rendering.
40 * To force a redrawing of the latest video frame the video sink element
41 * displayed on the Window. Indeed if the #GstPipeline is in #GST_STATE_PAUSED
42 * state, moving the Window around will damage its content. Application
43 * developers will want to handle the Expose events themselves and force the
44 * video sink element to refresh the Window's content.
50 * Using the Window created by the video sink is probably the simplest scenario,
51 * in some cases, though, it might not be flexible enough for application
52 * developers if they need to catch events such as mouse moves and button
56 * Setting a specific Window identifier on the video sink element is the most
57 * flexible solution but it has some issues. Indeed the application needs to set
58 * its Window identifier at the right time to avoid internal Window creation
59 * from the video sink element. To solve this issue a #GstMessage is posted on
60 * the bus to inform the application that it should set the Window identifier
61 * immediately. Here is an example on how to do that correctly:
63 * static GstBusSyncReply
64 * create_window (GstBus * bus, GstMessage * message, GstPipeline * pipeline)
66 * // ignore anything but 'prepare-window-handle' element messages
67 * if (!gst_is_video_overlay_prepare_window_handle_message (message))
68 * return GST_BUS_PASS;
70 * win = XCreateSimpleWindow (disp, root, 0, 0, 320, 240, 0, 0, 0);
72 * XSetWindowBackgroundPixmap (disp, win, None);
74 * XMapRaised (disp, win);
76 * XSync (disp, FALSE);
78 * gst_video_overlay_set_window_handle (GST_VIDEO_OVERLAY (GST_MESSAGE_SRC (message)),
81 * gst_message_unref (message);
83 * return GST_BUS_DROP;
87 * main (int argc, char **argv)
90 * bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
91 * gst_bus_set_sync_handler (bus, (GstBusSyncHandler) create_window, pipeline);
98 * <title>Two basic usage scenarios</title>
100 * There are two basic usage scenarios: in the simplest case, the application
101 * knows exactly what particular element is used for video output, which is
102 * usually the case when the application creates the videosink to use
103 * (e.g. #xvimagesink, #ximagesink, etc.) itself; in this case, the application
104 * can just create the videosink element, create and realize the window to
105 * render the video on and then call gst_video_overlay_set_window_handle() directly
106 * with the XID or native window handle, before starting up the pipeline.
109 * In the other and more common case, the application does not know in advance
110 * what GStreamer video sink element will be used for video output. This is
111 * usually the case when an element such as #autovideosink or #gconfvideosink
112 * is used. In this case, the video sink element itself is created
113 * asynchronously from a GStreamer streaming thread some time after the
114 * pipeline has been started up. When that happens, however, the video sink
115 * will need to know right then whether to render onto an already existing
116 * application window or whether to create its own window. This is when it
117 * posts a prepare-window-handle message, and that is also why this message needs
118 * to be handled in a sync bus handler which will be called from the streaming
119 * thread directly (because the video sink will need an answer right then).
122 * As response to the prepare-window-handle element message in the bus sync
123 * handler, the application may use gst_video_overlay_set_window_handle() to tell
124 * the video sink to render onto an existing window surface. At this point the
125 * application should already have obtained the window handle / XID, so it
126 * just needs to set it. It is generally not advisable to call any GUI toolkit
127 * functions or window system functions from the streaming thread in which the
128 * prepare-window-handle message is handled, because most GUI toolkits and
129 * windowing systems are not thread-safe at all and a lot of care would be
130 * required to co-ordinate the toolkit and window system calls of the
131 * different threads (Gtk+ users please note: prior to Gtk+ 2.18
132 * GDK_WINDOW_XID() was just a simple structure access, so generally fine to do
133 * within the bus sync handler; this macro was changed to a function call in
134 * Gtk+ 2.18 and later, which is likely to cause problems when called from a
135 * sync handler; see below for a better approach without GDK_WINDOW_XID()
136 * used in the callback).
140 * <title>GstVideoOverlay and Gtk+</title>
143 * #include <gst/video/xoverlay.h>
144 * #include <gtk/gtk.h>
145 * #ifdef GDK_WINDOWING_X11
146 * #include <gdk/gdkx.h> // for GDK_WINDOW_XID
148 * #ifdef GDK_WINDOWING_WIN32
149 * #include <gdk/gdkwin32.h> // for GDK_WINDOW_HWND
152 * static guintptr video_window_handle = 0;
154 * static GstBusSyncReply
155 * bus_sync_handler (GstBus * bus, GstMessage * message, gpointer user_data)
157 * // ignore anything but 'prepare-window-handle' element messages
158 * if (!gst_is_video_overlay_prepare_window_handle_message (message))
159 * return GST_BUS_PASS;
161 * if (video_window_handle != 0) {
162 * GstXOverlay *xoverlay;
164 * // GST_MESSAGE_SRC (message) will be the video sink element
165 * xoverlay = GST_X_OVERLAY (GST_MESSAGE_SRC (message));
166 * gst_x_overlay_set_window_handle (xoverlay, video_window_handle);
168 * g_warning ("Should have obtained video_window_handle by now!");
171 * gst_message_unref (message);
172 * return GST_BUS_DROP;
176 * video_widget_realize_cb (GtkWidget * widget, gpointer data)
178 * #if GTK_CHECK_VERSION(2,18,0)
179 * // Tell Gtk+/Gdk to create a native window for this widget instead of
180 * // drawing onto the parent widget.
181 * // This is here just for pedagogical purposes, GDK_WINDOW_XID will call
182 * // it as well in newer Gtk versions
183 * if (!gdk_window_ensure_native (widget->window))
184 * g_error ("Couldn't create native window needed for GstVideoOverlay!");
187 * #ifdef GDK_WINDOWING_X11
189 * gulong xid = GDK_WINDOW_XID (gtk_widget_get_window (video_window));
190 * video_window_handle = xid;
193 * #ifdef GDK_WINDOWING_WIN32
195 * HWND wnd = GDK_WINDOW_HWND (gtk_widget_get_window (video_window));
196 * video_window_handle = (guintptr) wnd;
202 * main (int argc, char **argv)
204 * GtkWidget *video_window;
205 * GtkWidget *app_window;
207 * app_window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
209 * video_window = gtk_drawing_area_new ();
210 * g_signal_connect (video_window, "realize",
211 * G_CALLBACK (video_widget_realize_cb), NULL);
212 * gtk_widget_set_double_buffered (video_window, FALSE);
214 * // usually the video_window will not be directly embedded into the
215 * // application window like this, but there will be many other widgets
216 * // and the video window will be embedded in one of them instead
217 * gtk_container_add (GTK_CONTAINER (ap_window), video_window);
220 * gtk_widget_show_all (app_window);
222 * // realize window now so that the video window gets created and we can
223 * // obtain its XID/HWND before the pipeline is started up and the videosink
224 * // asks for the XID/HWND of the window to render onto
225 * gtk_widget_realize (video_window);
227 * // we should have the XID/HWND now
228 * g_assert (video_window_handle != 0);
230 * // set up sync handler for setting the xid once the pipeline is started
231 * bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
232 * gst_bus_set_sync_handler (bus, (GstBusSyncHandler) bus_sync_handler, NULL);
233 * gst_object_unref (bus);
235 * gst_element_set_state (pipeline, GST_STATE_PLAYING);
242 * <title>GstVideoOverlay and Qt</title>
245 * #include <glib.h>
246 * #include <gst/gst.h>
247 * #include <gst/video/videooverlay.h>
249 * #include <QApplication>
250 * #include <QTimer>
251 * #include <QWidget>
253 * int main(int argc, char *argv[])
255 * if (!g_thread_supported ())
256 * g_thread_init (NULL);
258 * gst_init (&argc, &argv);
259 * QApplication app(argc, argv);
260 * app.connect(&app, SIGNAL(lastWindowClosed()), &app, SLOT(quit ()));
262 * // prepare the pipeline
264 * GstElement *pipeline = gst_pipeline_new ("xvoverlay");
265 * GstElement *src = gst_element_factory_make ("videotestsrc", NULL);
266 * GstElement *sink = gst_element_factory_make ("xvimagesink", NULL);
267 * gst_bin_add_many (GST_BIN (pipeline), src, sink, NULL);
268 * gst_element_link (src, sink);
273 * window.resize(320, 240);
276 * WId xwinid = window.winId();
277 * gst_video_overlay_set_window_handle (GST_VIDEO_OVERLAY (sink), xwinid);
279 * // run the pipeline
281 * GstStateChangeReturn sret = gst_element_set_state (pipeline,
282 * GST_STATE_PLAYING);
283 * if (sret == GST_STATE_CHANGE_FAILURE) {
284 * gst_element_set_state (pipeline, GST_STATE_NULL);
285 * gst_object_unref (pipeline);
286 * // Exit application
287 * QTimer::singleShot(0, QApplication::activeWindow(), SLOT(quit()));
290 * int ret = app.exec();
293 * gst_element_set_state (pipeline, GST_STATE_NULL);
294 * gst_object_unref (pipeline);
307 #include "videooverlay.h"
310 gst_video_overlay_get_type (void)
312 static GType gst_video_overlay_type = 0;
314 if (!gst_video_overlay_type) {
315 static const GTypeInfo gst_video_overlay_info = {
316 sizeof (GstVideoOverlayInterface),
327 gst_video_overlay_type = g_type_register_static (G_TYPE_INTERFACE,
328 "GstVideoOverlay", &gst_video_overlay_info, 0);
331 return gst_video_overlay_type;
335 * gst_video_overlay_set_window_handle:
336 * @overlay: a #GstVideoOverlay to set the window on.
337 * @handle: a handle referencing the window.
339 * This will call the video overlay's set_window_handle method. You
340 * should use this method to tell to a XOverlay to display video output to a
341 * specific window (e.g. an XWindow on X11). Passing 0 as the @handle will
342 * tell the overlay to stop using that window and create an internal one.
347 gst_video_overlay_set_window_handle (GstVideoOverlay * overlay, guintptr handle)
349 GstVideoOverlayInterface *iface;
351 g_return_if_fail (overlay != NULL);
352 g_return_if_fail (GST_IS_VIDEO_OVERLAY (overlay));
354 iface = GST_VIDEO_OVERLAY_GET_INTERFACE (overlay);
356 if (iface->set_window_handle) {
357 iface->set_window_handle (overlay, handle);
362 * gst_video_overlay_got_window_handle:
363 * @overlay: a #GstVideoOverlay which got a window
364 * @handle: a platform-specific handle referencing the window
366 * This will post a "have-window-handle" element message on the bus.
368 * This function should only be used by video overlay plugin developers.
371 gst_video_overlay_got_window_handle (GstVideoOverlay * overlay, guintptr handle)
376 g_return_if_fail (overlay != NULL);
377 g_return_if_fail (GST_IS_VIDEO_OVERLAY (overlay));
379 GST_LOG_OBJECT (GST_OBJECT (overlay), "window_handle = %p", (gpointer)
381 s = gst_structure_new ("have-window-handle",
382 "window-handle", G_TYPE_UINT64, (guint64) handle, NULL);
383 msg = gst_message_new_element (GST_OBJECT (overlay), s);
384 gst_element_post_message (GST_ELEMENT (overlay), msg);
388 * gst_video_overlay_prepare_window_handle:
389 * @overlay: a #GstVideoOverlay which does not yet have an Window handle set
391 * This will post a "prepare-window-handle" element message on the bus
392 * to give applications an opportunity to call
393 * gst_video_overlay_set_window_handle() before a plugin creates its own
396 * This function should only be used by video overlay plugin developers.
399 gst_video_overlay_prepare_window_handle (GstVideoOverlay * overlay)
404 g_return_if_fail (overlay != NULL);
405 g_return_if_fail (GST_IS_VIDEO_OVERLAY (overlay));
407 GST_LOG_OBJECT (GST_OBJECT (overlay), "prepare window handle");
408 s = gst_structure_new_empty ("prepare-window-handle");
409 msg = gst_message_new_element (GST_OBJECT (overlay), s);
410 gst_element_post_message (GST_ELEMENT (overlay), msg);
414 * gst_video_overlay_expose:
415 * @overlay: a #GstVideoOverlay to expose.
417 * Tell an overlay that it has been exposed. This will redraw the current frame
418 * in the drawable even if the pipeline is PAUSED.
421 gst_video_overlay_expose (GstVideoOverlay * overlay)
423 GstVideoOverlayInterface *iface;
425 g_return_if_fail (overlay != NULL);
426 g_return_if_fail (GST_IS_VIDEO_OVERLAY (overlay));
428 iface = GST_VIDEO_OVERLAY_GET_INTERFACE (overlay);
431 iface->expose (overlay);
436 * gst_video_overlay_handle_events:
437 * @overlay: a #GstVideoOverlay to expose.
438 * @handle_events: a #gboolean indicating if events should be handled or not.
440 * Tell an overlay that it should handle events from the window system. These
441 * events are forwarded upstream as navigation events. In some window system,
442 * events are not propagated in the window hierarchy if a client is listening
443 * for them. This method allows you to disable events handling completely
449 gst_video_overlay_handle_events (GstVideoOverlay * overlay,
450 gboolean handle_events)
452 GstVideoOverlayInterface *iface;
454 g_return_if_fail (overlay != NULL);
455 g_return_if_fail (GST_IS_VIDEO_OVERLAY (overlay));
457 iface = GST_VIDEO_OVERLAY_GET_INTERFACE (overlay);
459 if (iface->handle_events) {
460 iface->handle_events (overlay, handle_events);
465 * gst_video_overlay_set_render_rectangle:
466 * @overlay: a #GstVideoOverlay
467 * @x: the horizontal offset of the render area inside the window
468 * @y: the vertical offset of the render area inside the window
469 * @width: the width of the render area inside the window
470 * @height: the height of the render area inside the window
472 * Configure a subregion as a video target within the window set by
473 * gst_video_overlay_set_window_handle(). If this is not used or not supported
474 * the video will fill the area of the window set as the overlay to 100%.
475 * By specifying the rectangle, the video can be overlayed to a specific region
476 * of that window only. After setting the new rectangle one should call
477 * gst_video_overlay_expose() to force a redraw. To unset the region pass -1 for
478 * the @width and @height parameters.
480 * This method is needed for non fullscreen video overlay in UI toolkits that
481 * do not support subwindows.
483 * Returns: %FALSE if not supported by the sink.
488 gst_video_overlay_set_render_rectangle (GstVideoOverlay * overlay,
489 gint x, gint y, gint width, gint height)
491 GstVideoOverlayInterface *iface;
493 g_return_val_if_fail (overlay != NULL, FALSE);
494 g_return_val_if_fail (GST_IS_VIDEO_OVERLAY (overlay), FALSE);
495 g_return_val_if_fail ((width == -1 && height == -1) ||
496 (width > 0 && height > 0), FALSE);
498 iface = GST_VIDEO_OVERLAY_GET_INTERFACE (overlay);
500 if (iface->set_render_rectangle) {
501 iface->set_render_rectangle (overlay, x, y, width, height);
508 * gst_is_video_overlay_prepare_window_handle_message:
509 * @msg: a #GstMessage
511 * Convenience function to check if the given message is a
512 * "prepare-window-handle" message from a #GstVideoOverlay.
516 * Returns: whether @msg is a "prepare-window-handle" message
519 gst_is_video_overlay_prepare_window_handle_message (GstMessage * msg)
521 g_return_val_if_fail (msg != NULL, FALSE);
523 if (GST_MESSAGE_TYPE (msg) != GST_MESSAGE_ELEMENT)
526 return gst_message_has_name (msg, "prepare-window-handle");