Embed game process in editor

core/config/engine.cpp

@@ -412,6 +412,14 @@ void Engine::set_freeze_time_scale(bool p_frozen) {
 	freeze_time_scale = p_frozen;
 }
 
+void Engine::set_embedded_in_editor(bool p_enabled) {
+	embedded_in_editor = p_enabled;
+}
+
+bool Engine::is_embedded_in_editor() const {
+	return embedded_in_editor;
+}
+
 Engine::Engine() {
 	singleton = this;
 }

core/config/engine.h

@@ -87,6 +87,7 @@ class Engine {
 	bool editor_hint = false;
 	bool project_manager_hint = false;
 	bool extension_reloading = false;
+	bool embedded_in_editor = false;
 
 	bool _print_header = true;
 
@@ -201,6 +202,8 @@ class Engine {
 	bool notify_frame_server_synced();
 
 	void set_freeze_time_scale(bool p_frozen);
+	void set_embedded_in_editor(bool p_enabled);
+	bool is_embedded_in_editor() const;
 
 	Engine();
 	virtual ~Engine();

core/core_bind.cpp

@@ -1897,6 +1897,10 @@ bool Engine::is_editor_hint() const {
 	return ::Engine::get_singleton()->is_editor_hint();
 }
 
+bool Engine::is_embedded_in_editor() const {
+	return ::Engine::get_singleton()->is_embedded_in_editor();
+}
+
 String Engine::get_write_movie_path() const {
 	return ::Engine::get_singleton()->get_write_movie_path();
 }
@@ -1974,6 +1978,7 @@ void Engine::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("get_script_language", "index"), &Engine::get_script_language);
 
 	ClassDB::bind_method(D_METHOD("is_editor_hint"), &Engine::is_editor_hint);
+	ClassDB::bind_method(D_METHOD("is_embedded_in_editor"), &Engine::is_embedded_in_editor);
 
 	ClassDB::bind_method(D_METHOD("get_write_movie_path"), &Engine::get_write_movie_path);
 

core/core_bind.h

@@ -584,6 +584,8 @@ class Engine : public Object {
 	void set_editor_hint(bool p_enabled);
 	bool is_editor_hint() const;
 
+	bool is_embedded_in_editor() const;
+
 	// `set_write_movie_path()` is not exposed to the scripting API as changing it at run-time has no effect.
 	String get_write_movie_path() const;
 

core/os/os.cpp

@@ -405,6 +405,8 @@ bool OS::has_feature(const String &p_feature) {
 		return _in_editor;
 	} else if (p_feature == "editor_runtime") {
 		return !_in_editor;
+	} else if (p_feature == "embedded_in_editor") {
+		return _embedded_in_editor;
 	}
 #else
 	if (p_feature == "template") {

core/os/os.h

@@ -63,6 +63,7 @@ class OS {
 	bool _stderr_enabled = true;
 	bool _writing_movie = false;
 	bool _in_editor = false;
+	bool _embedded_in_editor = false;
 
 	CompositeLogger *_logger = nullptr;
 

doc/classes/DisplayServer.xml

@@ -1895,6 +1895,9 @@
 		<constant name="FEATURE_NATIVE_DIALOG_FILE_EXTRA" value="26" enum="Feature">
 			The display server supports all features of [constant FEATURE_NATIVE_DIALOG_FILE], with the added functionality of Options and native dialog file access to [code]res://[/code] and [code]user://[/code] paths. See [method file_dialog_show] and [method file_dialog_with_options_show]. [b]Windows, macOS, Linux (X11/Wayland)[/b]
 		</constant>
+		<constant name="FEATURE_WINDOW_EMBEDDING" value="27" enum="Feature">
+			Display server supports embedding a window from another process. [b]Windows, Linux (X11)[/b]
+		</constant>
 		<constant name="MOUSE_MODE_VISIBLE" value="0" enum="MouseMode">
 			Makes the mouse cursor visible if it is hidden.
 		</constant>

doc/classes/Engine.xml

@@ -254,6 +254,12 @@
 				[b]Note:[/b] To detect whether the script is running on an editor [i]build[/i] (such as when pressing [kbd]F5[/kbd]), use [method OS.has_feature] with the [code]"editor"[/code] argument instead. [code]OS.has_feature("editor")[/code] evaluate to [code]true[/code] both when the script is running in the editor and when running the project from the editor, but returns [code]false[/code] when run from an exported project.
 			</description>
 		</method>
+		<method name="is_embedded_in_editor" qualifiers="const">
+			<return type="bool" />
+			<description>
+				Returns [code]true[/code] if the engine is running embedded in the editor. This is useful to prevent attempting to update window mode or window flags that are not supported when running the project embedded in the editor.
+			</description>
+		</method>
 		<method name="is_in_physics_frame" qualifiers="const">
 			<return type="bool" />
 			<description>

editor/editor_node.cpp

@@ -755,7 +755,9 @@ void EditorNode::_notification(int p_what) {
 			}
 
 			// Set a low FPS cap to decrease CPU/GPU usage while the editor is unfocused.
-			OS::get_singleton()->set_low_processor_usage_mode_sleep_usec(int(EDITOR_GET("interface/editor/unfocused_low_processor_mode_sleep_usec")));
+			if (unfocused_low_processor_usage_mode_enabled) {
+				OS::get_singleton()->set_low_processor_usage_mode_sleep_usec(int(EDITOR_GET("interface/editor/unfocused_low_processor_mode_sleep_usec")));
+			}
 		} break;
 
 		case NOTIFICATION_WM_ABOUT: {
@@ -6713,6 +6715,10 @@ int EditorNode::execute_and_show_output(const String &p_title, const String &p_p
 	return eta.exitcode;
 }
 
+void EditorNode::set_unfocused_low_processor_usage_mode_enabled(bool p_enabled) {
+	unfocused_low_processor_usage_mode_enabled = p_enabled;
+}
+
 EditorNode::EditorNode() {
 	DEV_ASSERT(!singleton);
 	singleton = this;

editor/editor_node.h

@@ -474,6 +474,8 @@ class EditorNode : public Node {
 
 	bool was_window_windowed_last = false;
 
+	bool unfocused_low_processor_usage_mode_enabled = true;
+
 	static EditorBuildCallback build_callbacks[MAX_BUILD_CALLBACKS];
 	static EditorPluginInitializeCallback plugin_init_callbacks[MAX_INIT_CALLBACKS];
 	static int build_callback_count;
@@ -788,6 +790,8 @@ class EditorNode : public Node {
 	HashMap<StringName, Variant> get_modified_properties_for_node(Node *p_node, bool p_node_references_only);
 	HashMap<StringName, Variant> get_modified_properties_reference_to_nodes(Node *p_node, List<Node *> &p_nodes_referenced_by);
 
+	void set_unfocused_low_processor_usage_mode_enabled(bool p_enabled);
+
 	struct AdditiveNodeEntry {
 		Node *node = nullptr;
 		NodePath parent;

editor/editor_run.cpp

@@ -229,6 +229,9 @@ Error EditorRun::run(const String &p_scene, const String &p_write_movie) {
 		List<String> instance_args(args);
 		RunInstancesDialog::get_singleton()->get_argument_list_for_instance(i, instance_args);
 		RunInstancesDialog::get_singleton()->apply_custom_features(i);
+		if (instance_starting_callback) {
+			instance_starting_callback(i, instance_args);
+		}
 
 		if (OS::get_singleton()->is_stdout_verbose()) {
 			print_line(vformat("Running: %s", exec));
@@ -281,6 +284,13 @@ void EditorRun::stop() {
 	running_scene = "";
 }
 
+OS::ProcessID EditorRun::get_current_process() const {
+	if (pids.is_empty()) {
+		return 0;
+	}
+	return pids.get(0);
+}
+
 EditorRun::EditorRun() {
 	status = STATUS_STOP;
 	running_scene = "";

editor/editor_run.h

@@ -33,6 +33,8 @@
 
 #include "core/os/os.h"
 
+typedef void (*EditorRunInstanceStarting)(int p_index, List<String> &r_arguments);
+
 class EditorRun {
 public:
 	enum Status {
@@ -48,6 +50,8 @@ class EditorRun {
 	String running_scene;
 
 public:
+	inline static EditorRunInstanceStarting instance_starting_callback = nullptr;
+
 	Status get_status() const;
 	String get_running_scene() const;
 
@@ -58,6 +62,7 @@ class EditorRun {
 	void stop_child_process(OS::ProcessID p_pid);
 	bool has_child_process(OS::ProcessID p_pid) const;
 	int get_child_process_count() const { return pids.size(); }
+	OS::ProcessID get_current_process() const;
 
 	EditorRun();
 };

editor/gui/editor_run_bar.cpp

@@ -344,6 +344,10 @@ void EditorRunBar::stop_child_process(OS::ProcessID p_pid) {
 	}
 }
 
+OS::ProcessID EditorRunBar::get_current_process() const {
+	return editor_run.get_current_process();
+}
+
 void EditorRunBar::set_movie_maker_enabled(bool p_enabled) {
 	write_movie_button->set_pressed(p_enabled);
 }

editor/gui/editor_run_bar.h

@@ -102,6 +102,7 @@ class EditorRunBar : public MarginContainer {
 
 	OS::ProcessID has_child_process(OS::ProcessID p_pid) const;
 	void stop_child_process(OS::ProcessID p_pid);
+	OS::ProcessID get_current_process() const;
 
 	void set_movie_maker_enabled(bool p_enabled);
 	bool is_movie_maker_enabled() const;

editor/gui/editor_scene_tabs.cpp

@@ -30,11 +30,13 @@
 
 #include "editor_scene_tabs.h"
 
+#include "editor/editor_main_screen.h"
 #include "editor/editor_node.h"
 #include "editor/editor_resource_preview.h"
 #include "editor/editor_settings.h"
 #include "editor/editor_string_names.h"
 #include "editor/editor_undo_redo_manager.h"
+#include "editor/gui/editor_run_bar.h"
 #include "editor/inspector_dock.h"
 #include "editor/themes/editor_scale.h"
 #include "scene/gui/box_container.h"
@@ -90,6 +92,14 @@ void EditorSceneTabs::_scene_tab_hovered(int p_tab) {
 	if (!bool(EDITOR_GET("interface/scene_tabs/show_thumbnail_on_hover"))) {
 		return;
 	}
+
+	// Currently the tab previews are displayed under the running game process when embed.
+	// Right now, the easiest technique to fix that is to prevent displaying the tab preview
+	// when the user is in the Game View.
+	if (EditorNode::get_singleton()->get_editor_main_screen()->get_selected_index() == EditorMainScreen::EDITOR_GAME && EditorRunBar::get_singleton()->is_playing()) {
+		return;
+	}
+
 	int current_tab = scene_tabs->get_current_tab();
 
 	if (p_tab == current_tab || p_tab < 0) {