gstreamer/gst-libs/gst/interfaces/xoverlay.c
2010-03-11 10:55:21 +02:00

496 lines
16 KiB
C

/* GStreamer X-based Overlay
* Copyright (C) 2003 Ronald Bultje <rbultje@ronald.bitfreak.net>
*
* 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
*
* <refsect2>
* <para>
* The XOverlay interface is used for 2 main purposes :
* <itemizedlist>
* <listitem>
* <para>
* 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.
* </para>
* </listitem>
* <listitem>
* <para>
* 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.
* </para>
* </listitem>
* </itemizedlist>
* </para>
* <para>
* 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.
* </para>
* <para>
* 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-&gt;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);
* ...
* }
* ]|
* </para>
* </refsect2>
* <refsect2>
* <title>Two basic usage scenarios</title>
* <para>
* 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.
* </para>
* <para>
* 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).
* </para>
* <para>
* 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).
* </para>
* </refsect2>
* <refsect2>
* <title>GstXOverlay and Gtk+</title>
* <para>
* |[
* #include &lt;gtk/gtk.h&gt;
* #ifdef GDK_WINDOWING_X11
* #include &lt;gdk/gdkx.h&gt; // 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-&gt;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);
* ...
* }
* ]|
* </para>
* </refsect2>
* <refsect2>
* <title>GstXOverlay and Qt</title>
* <para>
* |[
* #include &lt;glib.h&gt;
* #include &lt;gst/gst.h&gt;
* #include &lt;gst/interfaces/xoverlay.h&gt;
*
* #include &lt;QApplication&gt;
* #include &lt;QTimer&gt;
* #include &lt;QWidget&gt;
*
* 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;
* }
* ]|
* </para>
* </refsect2>
*/
#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);
}
}
/**
* gst_x_overlay_set_render_rectangle:
* @overlay: a #GstXOverlay
* @rect: the target area inside the window
*
* Configure a subregion as a video target within the window set by
* gst_x_overlay_set_xwindow_id(). If this is not used or not supported
* the video will fill the area of the window set as the overlay to 100%.
* By specifying the rectangle, the video can be overlayed to a specific region
* of that window only. After setting the new rectangle one should call
* gst_x_overlay_expose() to force a redraw. To unset the region pass %NULL for
* the @rect parameter.
*
* This method is needed for non fullscreen video overlay in UI toolkits that do
* not support subwindows.
*
* Return: %FALSE if not supported by the sink.
*
* Since: 0.10.29
*/
gboolean
gst_x_overlay_set_render_rectangle (GstXOverlay * overlay,
GstVideoRectangle * rect)
{
GstXOverlayClass *klass;
g_return_val_if_fail (overlay != NULL, FALSE);
g_return_val_if_fail (GST_IS_X_OVERLAY (overlay), FALSE);
klass = GST_X_OVERLAY_GET_CLASS (overlay);
if (klass->set_render_rectangle) {
klass->set_render_rectangle (overlay, rect);
return TRUE;
}
return FALSE;
}