/* GStreamer X-based Overlay * Copyright (C) 2003 Ronald Bultje * * x-overlay.c: X-based overlay interface design * * 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. */ /** * SECTION:gstxoverlay * @short_description: Interface for setting/getting a Window on elements * supporting it * * * * The XOverlay interface is used for 2 main purposes : * * * * To get a grab on the Window where the video sink element is going to render. * This is achieved by either being informed about the Window identifier that * the video sink element generated, or by forcing the video sink element to use * a specific Window identifier for rendering. * * * * * To force a redrawing of the latest video frame the video sink element * displayed on the Window. Indeed if the #GstPipeline is in #GST_STATE_PAUSED * state, moving the Window around will damage its content. Application * developers will want to handle the Expose events themselves and force the * video sink element to refresh the Window's content. * * * * * * Using the Window created by the video sink is probably the simplest scenario, * in some cases, though, it might not be flexible enough for application * developers if they need to catch events such as mouse moves and button * clicks. * * * Setting a specific Window identifier on the video sink element is the most * flexible solution but it has some issues. Indeed the application needs to set * its Window identifier at the right time to avoid internal Window creation * from the video sink element. To solve this issue a #GstMessage is posted on * the bus to inform the application that it should set the Window identifier * immediately. Here is an example on how to do that correctly: * |[ * static GstBusSyncReply * create_window (GstBus * bus, GstMessage * message, GstPipeline * pipeline) * { * // ignore anything but 'prepare-xwindow-id' element messages * if (GST_MESSAGE_TYPE (message) != GST_MESSAGE_ELEMENT) * return GST_BUS_PASS; * * if (!gst_structure_has_name (message->structure, "prepare-xwindow-id")) * return GST_BUS_PASS; * * win = XCreateSimpleWindow (disp, root, 0, 0, 320, 240, 0, 0, 0); * * XSetWindowBackgroundPixmap (disp, win, None); * * XMapRaised (disp, win); * * XSync (disp, FALSE); * * gst_x_overlay_set_xwindow_id (GST_X_OVERLAY (GST_MESSAGE_SRC (message)), * win); * * gst_message_unref (message); * * return GST_BUS_DROP; * } * ... * int * main (int argc, char **argv) * { * ... * bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline)); * gst_bus_set_sync_handler (bus, (GstBusSyncHandler) create_window, pipeline); * ... * } * ]| * * * * Two basic usage scenarios * * There are two basic usage scenarios: in the simplest case, the application * knows exactly what particular element is used for video output, which is * usually the case when the application creates the videosink to use * (e.g. #xvimagesink, #ximagesink, etc.) itself; in this case, the application * can just create the videosink element, create and realize the window to * render the video on and then call gst_x_overlay_set_xwindow_id() directly * with the XID or native window handle, before starting up the pipeline. * * * In the other and more common case, the application does not know in advance * what GStreamer video sink element will be used for video output. This is * usually the case when an element such as #autovideosink or #gconfvideosink * is used. In this case, the video sink element itself is created * asynchronously from a GStreamer streaming thread some time after the * pipeline has been started up. When that happens, however, the video sink * will need to know right then whether to render onto an already existing * application window or whether to create its own window. This is when it * posts a prepare-xwindow-id message, and that is also why this message needs * to be handled in a sync bus handler which will be called from the streaming * thread directly (because the video sink will need an answer right then). * * * As response to the prepare-xwindow-id element message in the bus sync * handler, the application may use gst_x_overlay_set_xwindow_id() to tell * the video sink to render onto an existing window surface. At this point the * application should already have obtained the window handle / XID, so it * just needs to set it. It is generally not advisable to call any GUI toolkit * functions or window system functions from the streaming thread in which the * prepare-xwindow-id message is handled, because most GUI toolkits and * windowing systems are not thread-safe at all and a lot of care would be * required to co-ordinate the toolkit and window system calls of the * different threads (Gtk+ users please note: prior to Gtk+ 2.18 * GDK_WINDOW_XID() was just a simple structure access, so generally fine to do * within the bus sync handler; this macro was changed to a function call in * Gtk+ 2.18 and later, which is likely to cause problems when called from a * sync handler; see below for a better approach without GDK_WINDOW_XID() * used in the callback). * * * * GstXOverlay and Gtk+ * * |[ * #include <gtk/gtk.h> * #ifdef GDK_WINDOWING_X11 * #include <gdk/gdkx.h> // for GDK_WINDOW_XID * #endif * ... * static gulong video_window_xid = 0; * ... * static GstBusSyncReply * bus_sync_handler (GstBus * bus, GstMessage * message, gpointer user_data) * { * // ignore anything but 'prepare-xwindow-id' element messages * if (GST_MESSAGE_TYPE (message) != GST_MESSAGE_ELEMENT) * return GST_BUS_PASS; * if (!gst_structure_has_name (message->structure, "prepare-xwindow-id")) * return GST_BUS_PASS; * * if (video_window_xid != 0) { * GstXOverlay *xoverlay; * * // GST_MESSAGE_SRC (message) will be the video sink element * xoverlay = GST_X_OVERLAY (GST_MESSAGE_SRC (message)); * gst_x_overlay_set_xwindow_id (xoverlay, video_window_xid); * } else { * g_warning ("Should have obtained video_window_xid by now!"); * } * * gst_message_unref (message); * return GST_BUS_DROP; * } * ... * static void * video_widget_realize_cb (GtkWidget * widget, gpointer data) * { * #if GTK_CHECK_VERSION(2,18,0) * // This is here just for pedagogical purposes, GDK_WINDOW_XID will call * // it as well in newer Gtk versions * if (!gdk_window_ensure_native (widget->window)) * g_error ("Couldn't create native window needed for GstXOverlay!"); * #endif * * #ifdef GDK_WINDOWING_X11 * video_window_xid = GDK_WINDOW_XID (video_window->window); * #endif * } * ... * int * main (int argc, char **argv) * { * GtkWidget *video_window; * GtkWidget *app_window; * ... * app_window = gtk_window_new (GTK_WINDOW_TOPLEVEL); * ... * video_window = gtk_drawing_area_new (); * g_signal_connect (video_window, "realize", * G_CALLBACK (video_widget_realize_cb), NULL); * gtk_widget_set_double_buffered (video_window, FALSE); * ... * // usually the video_window will not be directly embedded into the * // application window like this, but there will be many other widgets * // and the video window will be embedded in one of them instead * gtk_container_add (GTK_CONTAINER (ap_window), video_window); * ... * // show the GUI * gtk_widget_show_all (app_window); * * // realize window now so that the video window gets created and we can * // obtain its XID before the pipeline is started up and the videosink * // asks for the XID of the window to render onto * gtk_widget_realize (window); * * // we should have the XID now * g_assert (video_window_xid != 0); * ... * // set up sync handler for setting the xid once the pipeline is started * bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline)); * gst_bus_set_sync_handler (bus, (GstBusSyncHandler) bus_sync_handler, NULL); * gst_object_unref (bus); * ... * gst_element_set_state (pipeline, GST_STATE_PLAYING); * ... * } * ]| * * * * GstXOverlay and Qt * * |[ * #include <glib.h> * #include <gst/gst.h> * #include <gst/interfaces/xoverlay.h> * * #include <QApplication> * #include <QTimer> * #include <QWidget> * * int main(int argc, char *argv[]) * { * if (!g_thread_supported ()) * g_thread_init (NULL); * * gst_init (&argc, &argv); * QApplication app(argc, argv); * app.connect(&app, SIGNAL(lastWindowClosed()), &app, SLOT(quit ())); * * // prepare the pipeline * * GstElement *pipeline = gst_pipeline_new ("xvoverlay"); * GstElement *src = gst_element_factory_make ("videotestsrc", NULL); * GstElement *sink = gst_element_factory_make ("xvimagesink", NULL); * gst_bin_add_many (GST_BIN (pipeline), src, sink, NULL); * gst_element_link (src, sink); * * // prepare the ui * * QWidget window; * window.resize(320, 240); * window.show(); * * WId xwinid = window.winId(); * gst_x_overlay_set_xwindow_id (GST_X_OVERLAY (sink), xwinid); * * // run the pipeline * * GstStateChangeReturn sret = gst_element_set_state (pipeline, * GST_STATE_PLAYING); * if (sret == GST_STATE_CHANGE_FAILURE) { * gst_element_set_state (pipeline, GST_STATE_NULL); * gst_object_unref (pipeline); * // Exit application * QTimer::singleShot(0, QApplication::activeWindow(), SLOT(quit())); * } * * int ret = app.exec(); * * window.hide(); * gst_element_set_state (pipeline, GST_STATE_NULL); * gst_object_unref (pipeline); * * return ret; * } * ]| * * */ #ifdef HAVE_CONFIG_H #include "config.h" #endif #include "xoverlay.h" static void gst_x_overlay_base_init (gpointer g_class); GType gst_x_overlay_get_type (void) { static GType gst_x_overlay_type = 0; if (!gst_x_overlay_type) { static const GTypeInfo gst_x_overlay_info = { sizeof (GstXOverlayClass), gst_x_overlay_base_init, NULL, NULL, NULL, NULL, 0, 0, NULL, }; gst_x_overlay_type = g_type_register_static (G_TYPE_INTERFACE, "GstXOverlay", &gst_x_overlay_info, 0); g_type_interface_add_prerequisite (gst_x_overlay_type, GST_TYPE_IMPLEMENTS_INTERFACE); } return gst_x_overlay_type; } static void gst_x_overlay_base_init (gpointer g_class) { GstXOverlayClass *overlay_class = (GstXOverlayClass *) g_class; overlay_class->set_xwindow_id = NULL; } /** * gst_x_overlay_set_xwindow_id: * @overlay: a #GstXOverlay to set the XWindow on. * @xwindow_id: a #XID referencing the XWindow. * * This will call the video overlay's set_xwindow_id method. You should * use this method to tell to a XOverlay to display video output to a * specific XWindow. Passing 0 as the xwindow_id will tell the overlay to * stop using that window and create an internal one. */ void gst_x_overlay_set_xwindow_id (GstXOverlay * overlay, gulong xwindow_id) { GstXOverlayClass *klass; g_return_if_fail (overlay != NULL); g_return_if_fail (GST_IS_X_OVERLAY (overlay)); klass = GST_X_OVERLAY_GET_CLASS (overlay); if (klass->set_xwindow_id) { klass->set_xwindow_id (overlay, xwindow_id); } } /** * gst_x_overlay_got_xwindow_id: * @overlay: a #GstXOverlay which got a XWindow. * @xwindow_id: a #XID referencing the XWindow. * * This will post a "have-xwindow-id" element message on the bus. * * This function should only be used by video overlay plugin developers. */ void gst_x_overlay_got_xwindow_id (GstXOverlay * overlay, gulong xwindow_id) { GstStructure *s; GstMessage *msg; g_return_if_fail (overlay != NULL); g_return_if_fail (GST_IS_X_OVERLAY (overlay)); GST_LOG_OBJECT (GST_OBJECT (overlay), "xwindow_id = %lu", xwindow_id); s = gst_structure_new ("have-xwindow-id", "xwindow-id", G_TYPE_ULONG, xwindow_id, NULL); msg = gst_message_new_element (GST_OBJECT (overlay), s); gst_element_post_message (GST_ELEMENT (overlay), msg); } /** * gst_x_overlay_prepare_xwindow_id: * @overlay: a #GstXOverlay which does not yet have an XWindow. * * This will post a "prepare-xwindow-id" element message on the bus * to give applications an opportunity to call * gst_x_overlay_set_xwindow_id() before a plugin creates its own * window. * * This function should only be used by video overlay plugin developers. */ void gst_x_overlay_prepare_xwindow_id (GstXOverlay * overlay) { GstStructure *s; GstMessage *msg; g_return_if_fail (overlay != NULL); g_return_if_fail (GST_IS_X_OVERLAY (overlay)); GST_LOG_OBJECT (GST_OBJECT (overlay), "prepare xwindow_id"); s = gst_structure_new ("prepare-xwindow-id", NULL); msg = gst_message_new_element (GST_OBJECT (overlay), s); gst_element_post_message (GST_ELEMENT (overlay), msg); } /** * gst_x_overlay_expose: * @overlay: a #GstXOverlay to expose. * * Tell an overlay that it has been exposed. This will redraw the current frame * in the drawable even if the pipeline is PAUSED. */ void gst_x_overlay_expose (GstXOverlay * overlay) { GstXOverlayClass *klass; g_return_if_fail (overlay != NULL); g_return_if_fail (GST_IS_X_OVERLAY (overlay)); klass = GST_X_OVERLAY_GET_CLASS (overlay); if (klass->expose) { klass->expose (overlay); } } /** * gst_x_overlay_handle_events: * @overlay: a #GstXOverlay to expose. * @handle_events: a #gboolean indicating if events should be handled or not. * * Tell an overlay that it should handle events from the window system. These * events are forwared upstream as navigation events. In some window system, * events are not propagated in the window hierarchy if a client is listening * for them. This method allows you to disable events handling completely * from the XOverlay. */ void gst_x_overlay_handle_events (GstXOverlay * overlay, gboolean handle_events) { GstXOverlayClass *klass; g_return_if_fail (overlay != NULL); g_return_if_fail (GST_IS_X_OVERLAY (overlay)); klass = GST_X_OVERLAY_GET_CLASS (overlay); if (klass->handle_events) { klass->handle_events (overlay, handle_events); } }