Sanchayan Maity 2024-03-21 11:35:55 +05:30
commit db70fa6ff9
3 changed files with 190 additions and 0 deletions

2
.gitignore vendored Normal file
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cairo
compile_commands.json

16
Makefile Normal file
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CC = gcc
CFLAGS = -g -Wall -Wshadow `pkg-config --cflags gstreamer-1.0 gstreamer-video-1.0 cairo`
LDFLAGS = `(pkg-config --libs gstreamer-1.0 gstreamer-video-1.0 cairo)`
SRCS = $(wildcard *.c)
all:
make clean
make build
./cairo
build:
$(CC) $(CFLAGS) $(LDFLAGS) $(SRCS) -o cairo
clean:
$(RM) cairo

172
cairo.c Normal file
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/* GStreamer
* Copyright (C) 2011 Jon Nordby <jononor@gmail.com>
*
* 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., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
/*
* Example showing usage of the cairooverlay element
*/
#include <gst/gst.h>
#include <gst/video/video.h>
#include <cairo-gobject.h>
#include <cairo.h>
#include <glib.h>
static gboolean on_message(GstBus *bus, GstMessage *message,
gpointer user_data) {
GMainLoop *loop = (GMainLoop *)user_data;
switch (GST_MESSAGE_TYPE(message)) {
case GST_MESSAGE_ERROR: {
GError *err = NULL;
gchar *debug;
gst_message_parse_error(message, &err, &debug);
g_critical("Got ERROR: %s (%s)", err->message, GST_STR_NULL(debug));
g_main_loop_quit(loop);
break;
}
case GST_MESSAGE_WARNING: {
GError *err = NULL;
gchar *debug;
gst_message_parse_warning(message, &err, &debug);
g_warning("Got WARNING: %s (%s)", err->message, GST_STR_NULL(debug));
g_main_loop_quit(loop);
break;
}
case GST_MESSAGE_EOS:
g_main_loop_quit(loop);
break;
default:
break;
}
return TRUE;
}
/* Datastructure to share the state we are interested in between
* prepare and render function. */
typedef struct {
gboolean valid;
GstVideoInfo vinfo;
} CairoOverlayState;
/* Store the information from the caps that we are interested in. */
static void prepare_overlay(GstElement *overlay, GstCaps *caps,
gpointer user_data) {
CairoOverlayState *state = (CairoOverlayState *)user_data;
state->valid = gst_video_info_from_caps(&state->vinfo, caps);
}
/* Draw the overlay.
* This function draws a cute "beating" heart. */
static void draw_overlay(GstElement *overlay, cairo_t *cr, guint64 timestamp,
guint64 duration, gpointer user_data) {
CairoOverlayState *s = (CairoOverlayState *)user_data;
double scale;
int width, height;
if (!s->valid)
return;
width = GST_VIDEO_INFO_WIDTH(&s->vinfo);
height = GST_VIDEO_INFO_HEIGHT(&s->vinfo);
scale = 2 * (((timestamp / (int)1e7) % 70) + 30) / 100.0;
cairo_translate(cr, width / 2, (height / 2) - 30);
/* FIXME: this assumes a pixel-aspect-ratio of 1/1 */
cairo_scale(cr, scale, scale);
cairo_move_to(cr, 0, 0);
cairo_curve_to(cr, 0, -30, -50, -30, -50, 0);
cairo_curve_to(cr, -50, 30, 0, 35, 0, 60);
cairo_curve_to(cr, 0, 35, 50, 30, 50, 0);
cairo_curve_to(cr, 50, -30, 0, -30, 0, 0);
cairo_set_source_rgba(cr, 0.9, 0.0, 0.1, 0.7);
cairo_fill(cr);
}
static GstElement *setup_gst_pipeline(CairoOverlayState *overlay_state) {
GstElement *pipeline;
GstElement *cairo_overlay;
GstElement *source, *adaptor1, *adaptor2, *sink;
pipeline = gst_pipeline_new("cairo-overlay-example");
/* Adaptors needed because cairooverlay only supports ARGB data */
source = gst_element_factory_make("videotestsrc", "source");
adaptor1 = gst_element_factory_make("videoconvert", "adaptor1");
cairo_overlay = gst_element_factory_make("cairooverlay", "overlay");
adaptor2 = gst_element_factory_make("videoconvert", "adaptor2");
sink = gst_element_factory_make("ximagesink", "sink");
if (sink == NULL)
sink = gst_element_factory_make("autovideosink", "sink");
/* If failing, the element could not be created */
g_assert(cairo_overlay);
/* Hook up the necessary signals for cairooverlay */
g_signal_connect(cairo_overlay, "draw", G_CALLBACK(draw_overlay),
overlay_state);
g_signal_connect(cairo_overlay, "caps-changed", G_CALLBACK(prepare_overlay),
overlay_state);
gst_bin_add_many(GST_BIN(pipeline), source, adaptor1, cairo_overlay, adaptor2,
sink, NULL);
if (!gst_element_link_many(source, adaptor1, cairo_overlay, adaptor2, sink,
NULL)) {
g_warning("Failed to link elements!");
}
return pipeline;
}
int main(int argc, char **argv) {
GMainLoop *loop;
GstElement *pipeline;
GstBus *bus;
CairoOverlayState *overlay_state;
gst_init(&argc, &argv);
loop = g_main_loop_new(NULL, FALSE);
/* allocate on heap for pedagogical reasons, makes code easier to transfer */
overlay_state = g_new0(CairoOverlayState, 1);
pipeline = setup_gst_pipeline(overlay_state);
bus = gst_pipeline_get_bus(GST_PIPELINE(pipeline));
gst_bus_add_signal_watch(bus);
g_signal_connect(G_OBJECT(bus), "message", G_CALLBACK(on_message), loop);
gst_object_unref(GST_OBJECT(bus));
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_main_loop_run(loop);
gst_element_set_state(pipeline, GST_STATE_NULL);
gst_object_unref(pipeline);
g_free(overlay_state);
return 0;
}