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>
4 *
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.
9 *
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.
14 *
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., 51 Franklin St, Fifth Floor,
18 * Boston, MA 02110-1301, USA.
19 */
20 /**
21 * SECTION:gstvideooverlay
22 * @title: GstVideoOverlay
23 * @short_description: Interface for setting/getting a window system resource
24 * on elements supporting it to configure a window into which to render a
25 * video.
26 *
27 * The #GstVideoOverlay interface is used for 2 main purposes :
28 *
29 * * To get a grab on the Window where the video sink element is going to render.
30 * This is achieved by either being informed about the Window identifier that
31 * the video sink element generated, or by forcing the video sink element to use
32 * a specific Window identifier for rendering.
33 * * To force a redrawing of the latest video frame the video sink element
34 * displayed on the Window. Indeed if the #GstPipeline is in #GST_STATE_PAUSED
35 * state, moving the Window around will damage its content. Application
36 * developers will want to handle the Expose events themselves and force the
37 * video sink element to refresh the Window's content.
38 *
39 * Using the Window created by the video sink is probably the simplest scenario,
40 * in some cases, though, it might not be flexible enough for application
41 * developers if they need to catch events such as mouse moves and button
42 * clicks.
43 *
44 * Setting a specific Window identifier on the video sink element is the most
45 * flexible solution but it has some issues. Indeed the application needs to set
46 * its Window identifier at the right time to avoid internal Window creation
47 * from the video sink element. To solve this issue a #GstMessage is posted on
48 * the bus to inform the application that it should set the Window identifier
49 * immediately. Here is an example on how to do that correctly:
50 * |[
51 * static GstBusSyncReply
52 * create_window (GstBus * bus, GstMessage * message, GstPipeline * pipeline)
53 * {
54 * // ignore anything but 'prepare-window-handle' element messages
55 * if (!gst_is_video_overlay_prepare_window_handle_message (message))
56 * return GST_BUS_PASS;
57 *
58 * win = XCreateSimpleWindow (disp, root, 0, 0, 320, 240, 0, 0, 0);
59 *
60 * XSetWindowBackgroundPixmap (disp, win, None);
61 *
62 * XMapRaised (disp, win);
63 *
64 * XSync (disp, FALSE);
65 *
66 * gst_video_overlay_set_window_handle (GST_VIDEO_OVERLAY (GST_MESSAGE_SRC (message)),
67 * win);
68 *
69 * gst_message_unref (message);
70 *
71 * return GST_BUS_DROP;
72 * }
73 * ...
74 * int
75 * main (int argc, char **argv)
76 * {
77 * ...
78 * bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
79 * gst_bus_set_sync_handler (bus, (GstBusSyncHandler) create_window, pipeline,
80 NULL);
81 * ...
82 * }
83 * ]|
84 *
85 * ## Two basic usage scenarios
86 *
87 * There are two basic usage scenarios: in the simplest case, the application
88 * uses #playbin or #playsink or knows exactly what particular element is used
89 * for video output, which is usually the case when the application creates
90 * the videosink to use (e.g. #xvimagesink, #ximagesink, etc.) itself; in this
91 * case, the application can just create the videosink element, create and
92 * realize the window to render the video on and then
93 * call gst_video_overlay_set_window_handle() directly with the XID or native
94 * window handle, before starting up the pipeline.
95 * As #playbin and #playsink implement the video overlay interface and proxy
96 * it transparently to the actual video sink even if it is created later, this
97 * case also applies when using these elements.
98 *
99 * In the other and more common case, the application does not know in advance
100 * what GStreamer video sink element will be used for video output. This is
101 * usually the case when an element such as #autovideosink is used.
102 * In this case, the video sink element itself is created
103 * asynchronously from a GStreamer streaming thread some time after the
104 * pipeline has been started up. When that happens, however, the video sink
105 * will need to know right then whether to render onto an already existing
106 * application window or whether to create its own window. This is when it
107 * posts a prepare-window-handle message, and that is also why this message needs
108 * to be handled in a sync bus handler which will be called from the streaming
109 * thread directly (because the video sink will need an answer right then).
110 *
111 * As response to the prepare-window-handle element message in the bus sync
112 * handler, the application may use gst_video_overlay_set_window_handle() to tell
113 * the video sink to render onto an existing window surface. At this point the
114 * application should already have obtained the window handle / XID, so it
115 * just needs to set it. It is generally not advisable to call any GUI toolkit
116 * functions or window system functions from the streaming thread in which the
117 * prepare-window-handle message is handled, because most GUI toolkits and
118 * windowing systems are not thread-safe at all and a lot of care would be
119 * required to co-ordinate the toolkit and window system calls of the
120 * different threads (Gtk+ users please note: prior to Gtk+ 2.18
121 * `GDK_WINDOW_XID` was just a simple structure access, so generally fine to do
122 * within the bus sync handler; this macro was changed to a function call in
123 * Gtk+ 2.18 and later, which is likely to cause problems when called from a
124 * sync handler; see below for a better approach without `GDK_WINDOW_XID`
125 * used in the callback).
126 *
127 * ## GstVideoOverlay and Gtk+
128 *
129 * |[
130 * #include <gst/video/videooverlay.h>
131 * #include <gtk/gtk.h>
132 * #ifdef GDK_WINDOWING_X11
133 * #include <gdk/gdkx.h> // for GDK_WINDOW_XID
134 * #endif
135 * #ifdef GDK_WINDOWING_WIN32
136 * #include <gdk/gdkwin32.h> // for GDK_WINDOW_HWND
137 * #endif
138 * ...
139 * static guintptr video_window_handle = 0;
140 * ...
141 * static GstBusSyncReply
142 * bus_sync_handler (GstBus * bus, GstMessage * message, gpointer user_data)
143 * {
144 * // ignore anything but 'prepare-window-handle' element messages
145 * if (!gst_is_video_overlay_prepare_window_handle_message (message))
146 * return GST_BUS_PASS;
147 *
148 * if (video_window_handle != 0) {
149 * GstVideoOverlay *overlay;
150 *
151 * // GST_MESSAGE_SRC (message) will be the video sink element
152 * overlay = GST_VIDEO_OVERLAY (GST_MESSAGE_SRC (message));
153 * gst_video_overlay_set_window_handle (overlay, video_window_handle);
154 * } else {
155 * g_warning ("Should have obtained video_window_handle by now!");
156 * }
157 *
158 * gst_message_unref (message);
159 * return GST_BUS_DROP;
160 * }
161 * ...
162 * static void
163 * video_widget_realize_cb (GtkWidget * widget, gpointer data)
164 * {
165 * #if GTK_CHECK_VERSION(2,18,0)
166 * // Tell Gtk+/Gdk to create a native window for this widget instead of
167 * // drawing onto the parent widget.
168 * // This is here just for pedagogical purposes, GDK_WINDOW_XID will call
169 * // it as well in newer Gtk versions
170 * if (!gdk_window_ensure_native (widget->window))
171 * g_error ("Couldn't create native window needed for GstVideoOverlay!");
172 * #endif
173 *
174 * #ifdef GDK_WINDOWING_X11
175 * {
176 * gulong xid = GDK_WINDOW_XID (gtk_widget_get_window (video_window));
177 * video_window_handle = xid;
178 * }
179 * #endif
180 * #ifdef GDK_WINDOWING_WIN32
181 * {
182 * HWND wnd = GDK_WINDOW_HWND (gtk_widget_get_window (video_window));
183 * video_window_handle = (guintptr) wnd;
184 * }
185 * #endif
186 * }
187 * ...
188 * int
189 * main (int argc, char **argv)
190 * {
191 * GtkWidget *video_window;
192 * GtkWidget *app_window;
193 * ...
194 * app_window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
195 * ...
196 * video_window = gtk_drawing_area_new ();
197 * g_signal_connect (video_window, "realize",
198 * G_CALLBACK (video_widget_realize_cb), NULL);
199 * gtk_widget_set_double_buffered (video_window, FALSE);
200 * ...
201 * // usually the video_window will not be directly embedded into the
202 * // application window like this, but there will be many other widgets
203 * // and the video window will be embedded in one of them instead
204 * gtk_container_add (GTK_CONTAINER (ap_window), video_window);
205 * ...
206 * // show the GUI
207 * gtk_widget_show_all (app_window);
208 *
209 * // realize window now so that the video window gets created and we can
210 * // obtain its XID/HWND before the pipeline is started up and the videosink
211 * // asks for the XID/HWND of the window to render onto
212 * gtk_widget_realize (video_window);
213 *
214 * // we should have the XID/HWND now
215 * g_assert (video_window_handle != 0);
216 * ...
217 * // set up sync handler for setting the xid once the pipeline is started
218 * bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
219 * gst_bus_set_sync_handler (bus, (GstBusSyncHandler) bus_sync_handler, NULL,
220 * NULL);
221 * gst_object_unref (bus);
222 * ...
223 * gst_element_set_state (pipeline, GST_STATE_PLAYING);
224 * ...
225 * }
226 * ]|
227 *
228 * ## GstVideoOverlay and Qt
229 *
230 * |[
231 * #include <glib.h>;
232 * #include <gst/gst.h>;
233 * #include <gst/video/videooverlay.h>;
234 *
235 * #include <QApplication>;
236 * #include <QTimer>;
237 * #include <QWidget>;
238 *
239 * int main(int argc, char *argv[])
240 * {
241 * if (!g_thread_supported ())
242 * g_thread_init (NULL);
243 *
244 * gst_init (&argc, &argv);
245 * QApplication app(argc, argv);
246 * app.connect(&app, SIGNAL(lastWindowClosed()), &app, SLOT(quit ()));
247 *
248 * // prepare the pipeline
249 *
250 * GstElement *pipeline = gst_pipeline_new ("xvoverlay");
251 * GstElement *src = gst_element_factory_make ("videotestsrc", NULL);
252 * GstElement *sink = gst_element_factory_make ("xvimagesink", NULL);
253 * gst_bin_add_many (GST_BIN (pipeline), src, sink, NULL);
254 * gst_element_link (src, sink);
255 *
256 * // prepare the ui
257 *
258 * QWidget window;
259 * window.resize(320, 240);
260 * window.show();
261 *
262 * WId xwinid = window.winId();
263 * gst_video_overlay_set_window_handle (GST_VIDEO_OVERLAY (sink), xwinid);
264 *
265 * // run the pipeline
266 *
267 * GstStateChangeReturn sret = gst_element_set_state (pipeline,
268 * GST_STATE_PLAYING);
269 * if (sret == GST_STATE_CHANGE_FAILURE) {
270 * gst_element_set_state (pipeline, GST_STATE_NULL);
271 * gst_object_unref (pipeline);
272 * // Exit application
273 * QTimer::singleShot(0, QApplication::activeWindow(), SLOT(quit()));
274 * }
275 *
276 * int ret = app.exec();
277 *
278 * window.hide();
279 * gst_element_set_state (pipeline, GST_STATE_NULL);
280 * gst_object_unref (pipeline);
281 *
282 * return ret;
283 * }
284 * ]|
285 *
286 */
287
288 #ifdef HAVE_CONFIG_H
289 #include "config.h"
290 #endif
291
292 #include "videooverlay.h"
293
294 enum
295 {
296 PROP_RENDER_RECTANGLE,
297 };
298
299 GST_DEBUG_CATEGORY_STATIC (gst_video_overlay_debug);
300 #define GST_CAT_DEFAULT gst_video_overlay_debug
301
302 GType
gst_video_overlay_get_type(void)303 gst_video_overlay_get_type (void)
304 {
305 static GType gst_video_overlay_type = 0;
306
307 if (!gst_video_overlay_type) {
308 static const GTypeInfo gst_video_overlay_info = {
309 sizeof (GstVideoOverlayInterface),
310 NULL,
311 NULL,
312 NULL,
313 NULL,
314 NULL,
315 0,
316 0,
317 NULL,
318 };
319
320 gst_video_overlay_type = g_type_register_static (G_TYPE_INTERFACE,
321 "GstVideoOverlay", &gst_video_overlay_info, 0);
322
323 GST_DEBUG_CATEGORY_INIT (gst_video_overlay_debug, "videooverlay", 0,
324 "videooverlay interface");
325 }
326
327 return gst_video_overlay_type;
328 }
329
330 /**
331 * gst_video_overlay_set_window_handle:
332 * @overlay: a #GstVideoOverlay to set the window on.
333 * @handle: a handle referencing the window.
334 *
335 * This will call the video overlay's set_window_handle method. You
336 * should use this method to tell to an overlay to display video output to a
337 * specific window (e.g. an XWindow on X11). Passing 0 as the @handle will
338 * tell the overlay to stop using that window and create an internal one.
339 */
340 void
gst_video_overlay_set_window_handle(GstVideoOverlay * overlay,guintptr handle)341 gst_video_overlay_set_window_handle (GstVideoOverlay * overlay, guintptr handle)
342 {
343 GstVideoOverlayInterface *iface;
344
345 g_return_if_fail (overlay != NULL);
346 g_return_if_fail (GST_IS_VIDEO_OVERLAY (overlay));
347
348 iface = GST_VIDEO_OVERLAY_GET_INTERFACE (overlay);
349
350 if (iface->set_window_handle) {
351 iface->set_window_handle (overlay, handle);
352 }
353 }
354
355 /**
356 * gst_video_overlay_got_window_handle:
357 * @overlay: a #GstVideoOverlay which got a window
358 * @handle: a platform-specific handle referencing the window
359 *
360 * This will post a "have-window-handle" element message on the bus.
361 *
362 * This function should only be used by video overlay plugin developers.
363 */
364 void
gst_video_overlay_got_window_handle(GstVideoOverlay * overlay,guintptr handle)365 gst_video_overlay_got_window_handle (GstVideoOverlay * overlay, guintptr handle)
366 {
367 GstStructure *s;
368 GstMessage *msg;
369
370 g_return_if_fail (overlay != NULL);
371 g_return_if_fail (GST_IS_VIDEO_OVERLAY (overlay));
372
373 GST_LOG_OBJECT (GST_OBJECT (overlay), "window_handle = %p", (gpointer)
374 handle);
375 s = gst_structure_new ("have-window-handle",
376 "window-handle", G_TYPE_UINT64, (guint64) handle, NULL);
377 msg = gst_message_new_element (GST_OBJECT (overlay), s);
378 gst_element_post_message (GST_ELEMENT (overlay), msg);
379 }
380
381 /**
382 * gst_video_overlay_prepare_window_handle:
383 * @overlay: a #GstVideoOverlay which does not yet have an Window handle set
384 *
385 * This will post a "prepare-window-handle" element message on the bus
386 * to give applications an opportunity to call
387 * gst_video_overlay_set_window_handle() before a plugin creates its own
388 * window.
389 *
390 * This function should only be used by video overlay plugin developers.
391 */
392 void
gst_video_overlay_prepare_window_handle(GstVideoOverlay * overlay)393 gst_video_overlay_prepare_window_handle (GstVideoOverlay * overlay)
394 {
395 GstStructure *s;
396 GstMessage *msg;
397
398 g_return_if_fail (overlay != NULL);
399 g_return_if_fail (GST_IS_VIDEO_OVERLAY (overlay));
400
401 GST_LOG_OBJECT (GST_OBJECT (overlay), "prepare window handle");
402 s = gst_structure_new_empty ("prepare-window-handle");
403 msg = gst_message_new_element (GST_OBJECT (overlay), s);
404 gst_element_post_message (GST_ELEMENT (overlay), msg);
405 }
406
407 /**
408 * gst_video_overlay_expose:
409 * @overlay: a #GstVideoOverlay to expose.
410 *
411 * Tell an overlay that it has been exposed. This will redraw the current frame
412 * in the drawable even if the pipeline is PAUSED.
413 */
414 void
gst_video_overlay_expose(GstVideoOverlay * overlay)415 gst_video_overlay_expose (GstVideoOverlay * overlay)
416 {
417 GstVideoOverlayInterface *iface;
418
419 g_return_if_fail (overlay != NULL);
420 g_return_if_fail (GST_IS_VIDEO_OVERLAY (overlay));
421
422 iface = GST_VIDEO_OVERLAY_GET_INTERFACE (overlay);
423
424 if (iface->expose) {
425 iface->expose (overlay);
426 }
427 }
428
429 /**
430 * gst_video_overlay_handle_events:
431 * @overlay: a #GstVideoOverlay to expose.
432 * @handle_events: a #gboolean indicating if events should be handled or not.
433 *
434 * Tell an overlay that it should handle events from the window system. These
435 * events are forwarded upstream as navigation events. In some window system,
436 * events are not propagated in the window hierarchy if a client is listening
437 * for them. This method allows you to disable events handling completely
438 * from the #GstVideoOverlay.
439 */
440 void
gst_video_overlay_handle_events(GstVideoOverlay * overlay,gboolean handle_events)441 gst_video_overlay_handle_events (GstVideoOverlay * overlay,
442 gboolean handle_events)
443 {
444 GstVideoOverlayInterface *iface;
445
446 g_return_if_fail (overlay != NULL);
447 g_return_if_fail (GST_IS_VIDEO_OVERLAY (overlay));
448
449 iface = GST_VIDEO_OVERLAY_GET_INTERFACE (overlay);
450
451 if (iface->handle_events) {
452 iface->handle_events (overlay, handle_events);
453 }
454 }
455
456 /**
457 * gst_video_overlay_set_render_rectangle:
458 * @overlay: a #GstVideoOverlay
459 * @x: the horizontal offset of the render area inside the window
460 * @y: the vertical offset of the render area inside the window
461 * @width: the width of the render area inside the window
462 * @height: the height of the render area inside the window
463 *
464 * Configure a subregion as a video target within the window set by
465 * gst_video_overlay_set_window_handle(). If this is not used or not supported
466 * the video will fill the area of the window set as the overlay to 100%.
467 * By specifying the rectangle, the video can be overlayed to a specific region
468 * of that window only. After setting the new rectangle one should call
469 * gst_video_overlay_expose() to force a redraw. To unset the region pass -1 for
470 * the @width and @height parameters.
471 *
472 * This method is needed for non fullscreen video overlay in UI toolkits that
473 * do not support subwindows.
474 *
475 * Returns: %FALSE if not supported by the sink.
476 */
477 gboolean
gst_video_overlay_set_render_rectangle(GstVideoOverlay * overlay,gint x,gint y,gint width,gint height)478 gst_video_overlay_set_render_rectangle (GstVideoOverlay * overlay,
479 gint x, gint y, gint width, gint height)
480 {
481 GstVideoOverlayInterface *iface;
482
483 g_return_val_if_fail (overlay != NULL, FALSE);
484 g_return_val_if_fail (GST_IS_VIDEO_OVERLAY (overlay), FALSE);
485 g_return_val_if_fail ((width == -1 && height == -1) ||
486 (width > 0 && height > 0), FALSE);
487
488 iface = GST_VIDEO_OVERLAY_GET_INTERFACE (overlay);
489
490 if (iface->set_render_rectangle) {
491 iface->set_render_rectangle (overlay, x, y, width, height);
492 return TRUE;
493 }
494 return FALSE;
495 }
496
497 /**
498 * gst_is_video_overlay_prepare_window_handle_message:
499 * @msg: a #GstMessage
500 *
501 * Convenience function to check if the given message is a
502 * "prepare-window-handle" message from a #GstVideoOverlay.
503 *
504 * Returns: whether @msg is a "prepare-window-handle" message
505 */
506 gboolean
gst_is_video_overlay_prepare_window_handle_message(GstMessage * msg)507 gst_is_video_overlay_prepare_window_handle_message (GstMessage * msg)
508 {
509 g_return_val_if_fail (msg != NULL, FALSE);
510
511 if (GST_MESSAGE_TYPE (msg) != GST_MESSAGE_ELEMENT)
512 return FALSE;
513
514 return gst_message_has_name (msg, "prepare-window-handle");
515 }
516
517
518 /**
519 * gst_video_overlay_install_properties:
520 * @oclass: The class on which the properties will be installed
521 * @last_prop_id: The first free property ID to use
522 *
523 * This helper shall be used by classes implementing the #GstVideoOverlay
524 * interface that want the render rectangle to be controllable using
525 * properties. This helper will install "render-rectangle" property into the
526 * class.
527 *
528 * Since: 1.14
529 */
530 void
gst_video_overlay_install_properties(GObjectClass * oclass,gint last_prop_id)531 gst_video_overlay_install_properties (GObjectClass * oclass, gint last_prop_id)
532 {
533 g_object_class_install_property (oclass, last_prop_id + PROP_RENDER_RECTANGLE,
534 gst_param_spec_array ("render-rectangle", "Render Rectangle",
535 "The render rectangle ('<x, y, width, height>')",
536 g_param_spec_int ("rect-value", "Rectangle Value",
537 "One of x, y, width or height value.", G_MININT, G_MAXINT, -1,
538 G_PARAM_WRITABLE | G_PARAM_STATIC_STRINGS),
539 G_PARAM_WRITABLE | G_PARAM_STATIC_STRINGS));
540 }
541
542 /**
543 * gst_video_overlay_set_property:
544 * @object: The instance on which the property is set
545 * @last_prop_id: The highest property ID.
546 * @property_id: The property ID
547 * @value: The #GValue to be set
548 *
549 * This helper shall be used by classes implementing the #GstVideoOverlay
550 * interface that want the render rectangle to be controllable using
551 * properties. This helper will parse and set the render rectangle calling
552 * gst_video_overlay_set_render_rectangle().
553 *
554 * Returns: %TRUE if the @property_id matches the GstVideoOverlay property
555 *
556 * Since: 1.14
557 */
558 gboolean
gst_video_overlay_set_property(GObject * object,gint last_prop_id,guint property_id,const GValue * value)559 gst_video_overlay_set_property (GObject * object, gint last_prop_id,
560 guint property_id, const GValue * value)
561 {
562 gboolean ret = FALSE;
563
564 if (property_id == last_prop_id) {
565 const GValue *v;
566 gint rect[4], i;
567
568 ret = TRUE;
569
570 if (gst_value_array_get_size (value) != 4)
571 goto wrong_format;
572
573 for (i = 0; i < 4; i++) {
574 v = gst_value_array_get_value (value, i);
575 if (!G_VALUE_HOLDS_INT (v))
576 goto wrong_format;
577
578 rect[i] = g_value_get_int (v);
579 }
580
581 gst_video_overlay_set_render_rectangle (GST_VIDEO_OVERLAY (object),
582 rect[0], rect[1], rect[2], rect[3]);
583 }
584
585 return ret;
586
587 wrong_format:
588 {
589 GValue string = G_VALUE_INIT;
590
591 g_value_init (&string, G_TYPE_STRING);
592 g_value_transform (value, &string);
593
594 g_critical ("Badly formatted rectangle, must contains four gint (got '%s')",
595 g_value_get_string (&string));
596
597 g_value_unset (&string);
598 return TRUE;
599 }
600 }
601