From db70fa6ff9791aacc5d89bcfdaa43c747346f797 Mon Sep 17 00:00:00 2001 From: Sanchayan Maity Date: Thu, 21 Mar 2024 11:35:55 +0530 Subject: [PATCH] Cairo overlay demo Taken from https://gitlab.freedesktop.org/gstreamer/gstreamer/-/blob/main/subprojects/gst-plugins-good/tests/examples/cairo/cairo_overlay.c?ref_type=heads --- .gitignore | 2 + Makefile | 16 +++++ cairo.c | 172 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 190 insertions(+) create mode 100644 .gitignore create mode 100644 Makefile create mode 100644 cairo.c diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..18d4ab7 --- /dev/null +++ b/.gitignore @@ -0,0 +1,2 @@ +cairo +compile_commands.json diff --git a/Makefile b/Makefile new file mode 100644 index 0000000..c590b0c --- /dev/null +++ b/Makefile @@ -0,0 +1,16 @@ +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 diff --git a/cairo.c b/cairo.c new file mode 100644 index 0000000..63e512d --- /dev/null +++ b/cairo.c @@ -0,0 +1,172 @@ +/* GStreamer + * Copyright (C) 2011 Jon Nordby + * + * 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 +#include + +#include +#include + +#include + +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; +}