Add linux camera support

modules/camera/camera_linux.cpp

@@ -0,0 +1,169 @@
+/**************************************************************************/
+/*  camera_linux.cpp                                                      */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* Permission is hereby granted, free of charge, to any person obtaining  */
+/* a copy of this software and associated documentation files (the        */
+/* "Software"), to deal in the Software without restriction, including    */
+/* without limitation the rights to use, copy, modify, merge, publish,    */
+/* distribute, sublicense, and/or sell copies of the Software, and to     */
+/* permit persons to whom the Software is furnished to do so, subject to  */
+/* the following conditions:                                              */
+/*                                                                        */
+/* The above copyright notice and this permission notice shall be         */
+/* included in all copies or substantial portions of the Software.        */
+/*                                                                        */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,        */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF     */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY   */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,   */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE      */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
+/**************************************************************************/
+
+#include "camera_linux.h"
+
+#include "camera_feed_linux.h"
+
+#include <dirent.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+void CameraLinux::camera_thread_func(void *p_camera_linux) {
+	if (p_camera_linux) {
+		CameraLinux *camera_linux = (CameraLinux *)p_camera_linux;
+		camera_linux->_update_devices();
+	}
+}
+
+void CameraLinux::_update_devices() {
+	while (!exit_flag.is_set()) {
+		{
+			MutexLock lock(camera_mutex);
+
+			for (int i = feeds.size() - 1; i >= 0; i--) {
+				Ref<CameraFeedLinux> feed = (Ref<CameraFeedLinux>)feeds[i];
+				String device_name = feed->get_device_name();
+				if (!_is_active(device_name)) {
+					remove_feed(feed);
+				}
+			}
+
+			DIR *devices = opendir("/dev");
+
+			if (devices) {
+				struct dirent *device;
+
+				while ((device = readdir(devices)) != nullptr) {
+					if (strncmp(device->d_name, "video", 5) != 0) {
+						continue;
+					}
+					String device_name = String("/dev/") + String(device->d_name);
+					if (!_has_device(device_name)) {
+						_add_device(device_name);
+					}
+				}
+			}
+
+			closedir(devices);
+		}
+
+		usleep(1000000);
+	}
+}
+
+bool CameraLinux::_has_device(const String &p_device_name) {
+	for (int i = 0; i < feeds.size(); i++) {
+		Ref<CameraFeedLinux> feed = (Ref<CameraFeedLinux>)feeds[i];
+		if (feed->get_device_name() == p_device_name) {
+			return true;
+		}
+	}
+	return false;
+}
+
+void CameraLinux::_add_device(const String &p_device_name) {
+	int file_descriptor = _open_device(p_device_name);
+
+	if (file_descriptor != -1) {
+		if (_is_video_capture_device(file_descriptor)) {
+			Ref<CameraFeedLinux> feed = memnew(CameraFeedLinux(p_device_name));
+			add_feed(feed);
+		}
+	}
+
+	close(file_descriptor);
+}
+
+int CameraLinux::_open_device(const String &p_device_name) {
+	struct stat s;
+
+	if (stat(p_device_name.ascii(), &s) == -1) {
+		return -1;
+	}
+
+	if (!S_ISCHR(s.st_mode)) {
+		return -1;
+	}
+
+	return open(p_device_name.ascii(), O_RDWR | O_NONBLOCK, 0);
+}
+
+// TODO any cheaper/cleaner way to check if file descriptor is invalid?
+bool CameraLinux::_is_active(const String &p_device_name) {
+	struct v4l2_capability capability;
+	bool result = false;
+	int file_descriptor = _open_device(p_device_name);
+	if (file_descriptor != -1 && ioctl(file_descriptor, VIDIOC_QUERYCAP, &capability) != -1) {
+		result = true;
+	}
+	close(file_descriptor);
+	return result;
+}
+
+bool CameraLinux::_is_video_capture_device(int p_file_descriptor) {
+	struct v4l2_capability capability;
+
+	if (ioctl(p_file_descriptor, VIDIOC_QUERYCAP, &capability) == -1) {
+		print_verbose("Cannot query device");
+		return false;
+	}
+
+	if (!(capability.capabilities & V4L2_CAP_VIDEO_CAPTURE)) {
+		print_verbose(vformat("%s is no video capture device\n", String((char *)capability.card)));
+		return false;
+	}
+
+	if (!(capability.capabilities & V4L2_CAP_STREAMING)) {
+		print_verbose(vformat("%s does not support streaming", String((char *)capability.card)));
+		return false;
+	}
+
+	return _can_query_format(p_file_descriptor, V4L2_BUF_TYPE_VIDEO_CAPTURE);
+}
+
+bool CameraLinux::_can_query_format(int p_file_descriptor, int p_type) {
+	struct v4l2_format format;
+	memset(&format, 0, sizeof(format));
+	format.type = p_type;
+
+	return ioctl(p_file_descriptor, VIDIOC_G_FMT, &format) != -1;
+}
+
+CameraLinux::CameraLinux() {
+	camera_thread.start(CameraLinux::camera_thread_func, this);
+};
+
+CameraLinux::~CameraLinux() {
+	exit_flag.set();
+	camera_thread.wait_to_finish();
+}