/* gst-perspective-example - test program for the GStreamer perspective element
 *
 * Copyright (C) 2013  Antonio Ospite <ospite@studenti.unina.it>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/* FIXME: suppress warnings for deprecated API such as GValueArray
 * with newer GLib versions (>= 2.31.0)
 * 
 * It is just not possible to switch to GArray yet because the python API in
 * 1.2.0 still passes iterable properties as GValueArray */
#define GLIB_DISABLE_DEPRECATION_WARNINGS
#include <gst/gst.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:
		g_error("Got ERROR");
		g_main_loop_quit(loop);
		break;
	case GST_MESSAGE_WARNING:
		g_warning("Got WARNING");
		g_main_loop_quit(loop);
		break;
	case GST_MESSAGE_EOS:
		g_main_loop_quit(loop);
		break;
	default:
		break;
	}

	return TRUE;
}

static void set_matrix(GstElement *element)
{
	GValueArray *va;
	GValue v = { 0, };
	gdouble m[9];
	guint i;

	/* Initialize a 2D perspective matrix, you can use
	 * cvGetPerspectiveTransform() from OpenCV to build it
	 * from a quad-to-quad transformation */
	m[0] = 1.9999999999999982;
	m[1] = 0.8333333333333287;
	m[2] = -399.99999999999926;
	m[3] = 3.9968028886505525e-15;
	m[4] = 1.9999999999999978;
	m[5] = -8.277822871605139e-13;
	m[6] = 2.428612866367518e-18;
	m[7] = 0.0020833333333333294;
	m[8] = 0.9999999999999996;

	va = g_value_array_new(1);

	g_value_init(&v, G_TYPE_DOUBLE);
	for (i = 0; i < 9; i++) {
		g_value_set_double(&v, m[i]);
		g_value_array_append(va, &v);
		g_value_reset(&v);
	}
	g_object_set(G_OBJECT(element), "matrix", va, NULL);
	g_value_array_free(va);
}

int main(void)
{
	GstElement *pipeline, *src, *capsfilter, *perspective, *conv, *sink;
	GstCaps *caps;
	GstBus *bus;
	GMainLoop *loop;
	int ret;

	gst_init(NULL, NULL);

	pipeline = gst_element_factory_make("pipeline", NULL);

	src = gst_element_factory_make("videotestsrc", NULL);

	caps = gst_caps_from_string("video/x-raw,format=AYUV,width=800,height=480");

	capsfilter = gst_element_factory_make("capsfilter", NULL);
	g_object_set(G_OBJECT(capsfilter), "caps", caps, NULL);

	perspective = gst_element_factory_make("perspective", NULL);
	set_matrix(perspective);

	conv = gst_element_factory_make("videoconvert", NULL);

	sink = gst_element_factory_make("autovideosink", NULL);
	g_return_val_if_fail(sink != NULL, -1);

	gst_bin_add_many(GST_BIN(pipeline), src, capsfilter, perspective, conv, sink, NULL);
	ret = gst_element_link_many(src, capsfilter, perspective, conv, sink, NULL);
	if (!ret) {
		g_error("Failed to link elements");
		return -2;
	}

	loop = g_main_loop_new(NULL, FALSE);

	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));

	ret = gst_element_set_state(pipeline, GST_STATE_PLAYING);
	if (ret == GST_STATE_CHANGE_FAILURE) {
		g_error("Failed to go into PLAYING state");
		return -3;
	}

	g_main_loop_run(loop);

	gst_element_set_state(pipeline, GST_STATE_NULL);

	g_main_loop_unref(loop);
	gst_object_unref(pipeline);

	return 0;
}