gamescope: Add Gamescope capture backend

Add a Gamescope capture backend.

A few options were considered here, such as implementing a screenshare
portal inside Gamescope, etc, but I decided to persue a Gamescope
capture backend directly for a few reasons:

1) Steam Deck support for OBS. Users will be able to share, stream and
record their gameplay.

2) Many compositors do not support screensharing a single window, only
the entire desktop. This allows a user to launch a game in Gamescope
and immediately be able to share it.

3) This allows Gamescope to perform eg. color management, effects, have
a Steam/performance overlay up for the user, but stream only the raw
base-plane of the game. We can add a bunch of options to control what
gets streamed on the Gamescope side. (Potentially also controlling that
in OBS down the line with some custom metadata)

4) Doing a desktop portal for nested Gamescope (ie. run inside another
compositor) would not be feasible.

Signed-off-by: Joshua Ashton <joshua@froggi.es>

plugins/linux-pipewire/CMakeLists.txt

@@ -23,7 +23,9 @@ add_library(OBS::pipewire ALIAS linux-pipewire)
 
 target_sources(
   linux-pipewire
-  PRIVATE linux-pipewire.c
+  PRIVATE gamescope.c
+          gamescope.h
+          linux-pipewire.c
           pipewire.c
           pipewire.h
           portal.c

plugins/linux-pipewire/data/locale/en-US.ini

@@ -2,4 +2,5 @@ PipeWireDesktopCapture="Screen Capture (PipeWire)"
 PipeWireSelectMonitor="Select Monitor"
 PipeWireSelectWindow="Select Window"
 PipeWireWindowCapture="Window Capture (PipeWire)"
+PipeWireGamescopeCapture="Gamescope Capture (PipeWire)"
 ShowCursor="Show Cursor"

plugins/linux-pipewire/gamescope.c

@@ -0,0 +1,220 @@
+/* gamescope.c
+ *
+ * Copyright 2023 Joshua Ashton for Valve Software
+ *
+ * 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/>.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "pipewire.h"
+
+#include <pipewire/pipewire.h>
+#include <gio/gio.h>
+
+struct gamescope_capture {
+    uint32_t pipewire_node;
+
+    obs_source_t *source;
+
+	obs_pipewire *obs_pw;
+	obs_pipewire_stream *obs_pw_stream;
+};
+
+static void registry_event_global(void *user_data, uint32_t id,
+                                  uint32_t permissions, const char *type, uint32_t version,
+                                  const struct spa_dict *props)
+{
+	obs_pipewire *obs_pw = user_data;
+	struct gamescope_capture *capture = obs_pipewire_get_userdata(obs_pw);
+    UNUSED_PARAMETER(permissions);
+    UNUSED_PARAMETER(version);
+
+	if (spa_streq(type, PW_TYPE_INTERFACE_Node)) {
+		const char *node_name = spa_dict_lookup(props, PW_KEY_NODE_NAME);
+        if (spa_streq(node_name, "gamescope")) {
+			blog(LOG_INFO, "[gamescope-obs] Found gamescope node: %u", id);
+            capture->pipewire_node = id;
+
+			capture->obs_pw_stream = obs_pipewire_connect_stream(
+				obs_pw, capture->source, capture->pipewire_node,
+				"OBS Studio",
+				pw_properties_new(PW_KEY_MEDIA_TYPE, "Video",
+						PW_KEY_MEDIA_CATEGORY, "Capture",
+						PW_KEY_MEDIA_ROLE, "Screen", NULL));
+		}
+	}
+}
+
+static void registry_event_global_remove(void *user_data, uint32_t id)
+{
+	obs_pipewire *obs_pw = user_data;
+	struct gamescope_capture *capture = obs_pipewire_get_userdata(obs_pw);
+
+    if (!capture)
+        return;
+
+	if (capture->pipewire_node == id) {
+		blog(LOG_INFO, "[gamescope-obs] Removing current node: %u", id);
+		capture->pipewire_node = SPA_ID_INVALID;
+        g_clear_pointer(&capture->obs_pw_stream, obs_pipewire_stream_destroy);
+    }
+}
+
+static const struct pw_registry_events registry_events = {
+	PW_VERSION_REGISTRY_EVENTS,
+	.global = registry_event_global,
+	.global_remove = registry_event_global_remove,
+};
+
+static const char *gamescope_capture_get_name(void *data)
+{
+	UNUSED_PARAMETER(data);
+	return obs_module_text("PipeWireGamescopeCapture");
+}
+
+static void gamescope_capture_destroy(void *data)
+{
+	struct gamescope_capture *capture = data;
+
+	if (!capture)
+		return;
+
+    capture->pipewire_node = SPA_ID_INVALID;
+	g_clear_pointer(&capture->obs_pw_stream, obs_pipewire_stream_destroy);
+	obs_pipewire_destroy(capture->obs_pw);
+	bfree(capture);
+}
+
+static void *gamescope_capture_create(obs_data_t *settings,
+					    obs_source_t *source)
+{
+    struct gamescope_capture *capture;
+    UNUSED_PARAMETER(settings);
+
+    capture = bzalloc(sizeof(struct gamescope_capture));
+    capture->pipewire_node = SPA_ID_INVALID;
+    capture->source = source;
+    capture->obs_pw = obs_pipewire_create(-1, &registry_events, capture);
+
+	if (!capture->obs_pw) {
+		gamescope_capture_destroy(capture);
+		return NULL;
+	}
+
+	return capture;
+}
+
+static void gamescope_capture_save(void *data, obs_data_t *settings)
+{
+	struct gamescope_capture *capture = data;
+    UNUSED_PARAMETER(capture);
+    UNUSED_PARAMETER(settings);
+}
+
+static void gamescope_capture_get_defaults(obs_data_t *settings)
+{
+    UNUSED_PARAMETER(settings);
+}
+
+static obs_properties_t *gamescope_capture_get_properties(void *data)
+{
+	struct gamescope_capture *capture = data;
+	obs_properties_t *properties;
+
+	properties = obs_properties_create();
+
+	return properties;
+}
+
+static void gamescope_capture_update(void *data, obs_data_t *settings)
+{
+	struct gamescope_capture *capture = data;
+    UNUSED_PARAMETER(capture);
+    UNUSED_PARAMETER(settings);
+}
+
+static void gamescope_capture_show(void *data)
+{
+	struct gamescope_capture *capture = data;
+
+	if (capture->obs_pw_stream)
+		obs_pipewire_stream_show(capture->obs_pw_stream);
+}
+
+static void gamescope_capture_hide(void *data)
+{
+	struct gamescope_capture *capture = data;
+
+	if (capture->obs_pw_stream)
+		obs_pipewire_stream_hide(capture->obs_pw_stream);
+}
+
+static uint32_t gamescope_capture_get_width(void *data)
+{
+	struct gamescope_capture *capture = data;
+
+	if (capture->obs_pw_stream)
+		return obs_pipewire_stream_get_width(capture->obs_pw_stream);
+	else
+		return 0;
+}
+
+static uint32_t gamescope_capture_get_height(void *data)
+{
+	struct gamescope_capture *capture = data;
+
+	if (capture->obs_pw_stream)
+		return obs_pipewire_stream_get_height(capture->obs_pw_stream);
+	else
+		return 0;
+}
+
+static void gamescope_capture_video_render(void *data,
+						   gs_effect_t *effect)
+{
+	struct gamescope_capture *capture = data;
+
+	if (capture->obs_pw_stream)
+		obs_pipewire_stream_video_render(capture->obs_pw_stream,
+						 effect);
+}
+
+void gamescope_load(void)
+{
+	const struct obs_source_info gamescope_capture_info = {
+		.id = "pipewire-gamescope-capture-source",
+		.type = OBS_SOURCE_TYPE_INPUT,
+		.output_flags = OBS_SOURCE_VIDEO,
+		.get_name = gamescope_capture_get_name,
+		.create = gamescope_capture_create,
+		.destroy = gamescope_capture_destroy,
+		.save = gamescope_capture_save,
+		.get_defaults = gamescope_capture_get_defaults,
+		.get_properties = gamescope_capture_get_properties,
+		.update = gamescope_capture_update,
+		.show = gamescope_capture_show,
+		.hide = gamescope_capture_hide,
+		.get_width = gamescope_capture_get_width,
+		.get_height = gamescope_capture_get_height,
+		.video_render = gamescope_capture_video_render,
+		.icon_type = OBS_ICON_TYPE_GAME_CAPTURE,
+	};
+
+    obs_register_source(&gamescope_capture_info);
+}
+
+void gamescope_unload(void)
+{
+}

plugins/linux-pipewire/gamescope.h

@@ -0,0 +1,24 @@
+/* gamescope.h
+ *
+ * Copyright 2023 Joshua Ashton for Valve Software
+ *
+ * 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/>.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#pragma once
+
+void gamescope_load(void);
+void gamescope_unload(void);

plugins/linux-pipewire/linux-pipewire.c

@@ -24,6 +24,7 @@
 
 #include <pipewire/pipewire.h>
 #include "screencast-portal.h"
+#include "gamescope.h"
 
 OBS_DECLARE_MODULE()
 OBS_MODULE_USE_DEFAULT_LOCALE("linux-pipewire", "en-US")
@@ -37,13 +38,15 @@ bool obs_module_load(void)
 	pw_init(NULL, NULL);
 
 	screencast_portal_load();
+	gamescope_load();
 
 	return true;
 }
 
 void obs_module_unload(void)
 {
 	screencast_portal_unload();
+	gamescope_unload();
 
 #if PW_CHECK_VERSION(0, 3, 49)
 	pw_deinit();