linux-v4l2: Always display currently selected device.

This adds some code to the device enumeration that checks if the
currently selected device is present. In case it is not it will
add the device but disable it.

plugins/linux-v4l2/v4l2-input.c

@@ -224,16 +224,20 @@ static void v4l2_defaults(obs_data_t *settings)
  */
 static void v4l2_device_list(obs_property_t *prop, obs_data_t *settings)
 {
-	UNUSED_PARAMETER(settings);
-
 	DIR *dirp;
 	struct dirent *dp;
 	struct dstr device;
+	bool cur_device_found;
+	size_t cur_device_index;
+	const char *cur_device_name;
 
 	dirp = opendir("/sys/class/video4linux");
 	if (!dirp)
 		return;
 
+	cur_device_found = false;
+	cur_device_name  = obs_data_get_string(settings, "device_id");
+
 	obs_property_list_clear(prop);
 
 	dstr_init_copy(&device, "/dev/");
@@ -277,9 +281,20 @@ static void v4l2_device_list(obs_property_t *prop, obs_data_t *settings)
 		blog(LOG_INFO, "Found device '%s' at %s", video_cap.card,
 				device.array);
 
+		/* check if this is the currently used device */
+		if (cur_device_name && !strcmp(cur_device_name, device.array))
+			cur_device_found = true;
+
 		v4l2_close(fd);
 	}
 
+	/* add currently selected device if not present, but disable it ... */
+	if (!cur_device_found && cur_device_name && strlen(cur_device_name)) {
+		cur_device_index = obs_property_list_add_string(prop,
+				cur_device_name, cur_device_name);
+		obs_property_list_item_disable(prop, cur_device_index, true);
+	}
+
 	closedir(dirp);
 	dstr_free(&device);
 }
@@ -566,9 +581,9 @@ static void device_removed(const char *dev, void *vptr)
 
 #endif
 
-static obs_properties_t *v4l2_properties(void *unused)
+static obs_properties_t *v4l2_properties(void *vptr)
 {
-	UNUSED_PARAMETER(unused);
+	V4L2_DATA(vptr);
 
 	obs_properties_t *props = obs_properties_create();
 
@@ -595,12 +610,16 @@ static obs_properties_t *v4l2_properties(void *unused)
 	obs_properties_add_bool(props,
 			"system_timing", obs_module_text("UseSystemTiming"));
 
-	v4l2_device_list(device_list, NULL);
+	obs_data_t *settings = obs_source_get_settings(data->source);
+	v4l2_device_list(device_list, settings);
+	obs_data_release(settings);
+
 	obs_property_set_modified_callback(device_list, device_selected);
 	obs_property_set_modified_callback(input_list, input_selected);
 	obs_property_set_modified_callback(format_list, format_selected);
 	obs_property_set_modified_callback(resolution_list,
 			resolution_selected);
+
 	return props;
 }