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1 /* GStreamer
2  * Copyright (C) 2011 Jon Nordby <jononor@gmail.com>
3  *
4  * This library is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU Library General Public
6  * License as published by the Free Software Foundation; either
7  * version 2 of the License, or (at your option) any later version.
8  *
9  * This library is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12  * Library General Public License for more details.
13  *
14  * You should have received a copy of the GNU Library General Public
15  * License along with this library; if not, write to the
16  * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
17  * Boston, MA 02110-1301, USA.
18  */
19 
20 /*
21  * Example showing usage of the cairooverlay element
22  */
23 
24 #include <gst/gst.h>
25 #include <gst/video/video.h>
26 
27 #include <cairo.h>
28 #include <cairo-gobject.h>
29 
30 #include <glib.h>
31 
32 
33 static gboolean
on_message(GstBus * bus,GstMessage * message,gpointer user_data)34 on_message (GstBus * bus, GstMessage * message, gpointer user_data)
35 {
36   GMainLoop *loop = (GMainLoop *) user_data;
37 
38   switch (GST_MESSAGE_TYPE (message)) {
39     case GST_MESSAGE_ERROR:{
40       GError *err = NULL;
41       gchar *debug;
42 
43       gst_message_parse_error (message, &err, &debug);
44       g_critical ("Got ERROR: %s (%s)", err->message, GST_STR_NULL (debug));
45       g_main_loop_quit (loop);
46       break;
47     }
48     case GST_MESSAGE_WARNING:{
49       GError *err = NULL;
50       gchar *debug;
51 
52       gst_message_parse_warning (message, &err, &debug);
53       g_warning ("Got WARNING: %s (%s)", err->message, GST_STR_NULL (debug));
54       g_main_loop_quit (loop);
55       break;
56     }
57     case GST_MESSAGE_EOS:
58       g_main_loop_quit (loop);
59       break;
60     default:
61       break;
62   }
63 
64   return TRUE;
65 }
66 
67 /* Datastructure to share the state we are interested in between
68  * prepare and render function. */
69 typedef struct
70 {
71   gboolean valid;
72   GstVideoInfo vinfo;
73 } CairoOverlayState;
74 
75 /* Store the information from the caps that we are interested in. */
76 static void
prepare_overlay(GstElement * overlay,GstCaps * caps,gpointer user_data)77 prepare_overlay (GstElement * overlay, GstCaps * caps, gpointer user_data)
78 {
79   CairoOverlayState *state = (CairoOverlayState *) user_data;
80 
81   state->valid = gst_video_info_from_caps (&state->vinfo, caps);
82 }
83 
84 /* Draw the overlay.
85  * This function draws a cute "beating" heart. */
86 static void
draw_overlay(GstElement * overlay,cairo_t * cr,guint64 timestamp,guint64 duration,gpointer user_data)87 draw_overlay (GstElement * overlay, cairo_t * cr, guint64 timestamp,
88     guint64 duration, gpointer user_data)
89 {
90   CairoOverlayState *s = (CairoOverlayState *) user_data;
91   double scale;
92   int width, height;
93 
94   if (!s->valid)
95     return;
96 
97   width = GST_VIDEO_INFO_WIDTH (&s->vinfo);
98   height = GST_VIDEO_INFO_HEIGHT (&s->vinfo);
99 
100   scale = 2 * (((timestamp / (int) 1e7) % 70) + 30) / 100.0;
101   cairo_translate (cr, width / 2, (height / 2) - 30);
102 
103   /* FIXME: this assumes a pixel-aspect-ratio of 1/1 */
104   cairo_scale (cr, scale, scale);
105 
106   cairo_move_to (cr, 0, 0);
107   cairo_curve_to (cr, 0, -30, -50, -30, -50, 0);
108   cairo_curve_to (cr, -50, 30, 0, 35, 0, 60);
109   cairo_curve_to (cr, 0, 35, 50, 30, 50, 0);
110   cairo_curve_to (cr, 50, -30, 0, -30, 0, 0);
111   cairo_set_source_rgba (cr, 0.9, 0.0, 0.1, 0.7);
112   cairo_fill (cr);
113 }
114 
115 static GstElement *
setup_gst_pipeline(CairoOverlayState * overlay_state)116 setup_gst_pipeline (CairoOverlayState * overlay_state)
117 {
118   GstElement *pipeline;
119   GstElement *cairo_overlay;
120   GstElement *source, *adaptor1, *adaptor2, *sink;
121 
122   pipeline = gst_pipeline_new ("cairo-overlay-example");
123 
124   /* Adaptors needed because cairooverlay only supports ARGB data */
125   source = gst_element_factory_make ("videotestsrc", "source");
126   adaptor1 = gst_element_factory_make ("videoconvert", "adaptor1");
127   cairo_overlay = gst_element_factory_make ("cairooverlay", "overlay");
128   adaptor2 = gst_element_factory_make ("videoconvert", "adaptor2");
129   sink = gst_element_factory_make ("ximagesink", "sink");
130   if (sink == NULL)
131     sink = gst_element_factory_make ("autovideosink", "sink");
132 
133   /* If failing, the element could not be created */
134   g_assert (cairo_overlay);
135 
136   /* Hook up the necessary signals for cairooverlay */
137   g_signal_connect (cairo_overlay, "draw",
138       G_CALLBACK (draw_overlay), overlay_state);
139   g_signal_connect (cairo_overlay, "caps-changed",
140       G_CALLBACK (prepare_overlay), overlay_state);
141 
142   gst_bin_add_many (GST_BIN (pipeline), source, adaptor1,
143       cairo_overlay, adaptor2, sink, NULL);
144 
145   if (!gst_element_link_many (source, adaptor1,
146           cairo_overlay, adaptor2, sink, NULL)) {
147     g_warning ("Failed to link elements!");
148   }
149 
150   return pipeline;
151 }
152 
153 int
main(int argc,char ** argv)154 main (int argc, char **argv)
155 {
156   GMainLoop *loop;
157   GstElement *pipeline;
158   GstBus *bus;
159   CairoOverlayState *overlay_state;
160 
161   gst_init (&argc, &argv);
162   loop = g_main_loop_new (NULL, FALSE);
163 
164   /* allocate on heap for pedagogical reasons, makes code easier to transfer */
165   overlay_state = g_new0 (CairoOverlayState, 1);
166 
167   pipeline = setup_gst_pipeline (overlay_state);
168 
169   bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
170   gst_bus_add_signal_watch (bus);
171   g_signal_connect (G_OBJECT (bus), "message", G_CALLBACK (on_message), loop);
172   gst_object_unref (GST_OBJECT (bus));
173 
174   gst_element_set_state (pipeline, GST_STATE_PLAYING);
175   g_main_loop_run (loop);
176 
177   gst_element_set_state (pipeline, GST_STATE_NULL);
178   gst_object_unref (pipeline);
179 
180   g_free (overlay_state);
181   return 0;
182 }
183