Embedding game process in editor

doc/classes/DisplayServer.xml

@@ -1883,6 +1883,9 @@
 		<constant name="FEATURE_NATIVE_DIALOG_FILE" value="25" enum="Feature">
 			Display server supports spawning dialogs for selecting files or directories using the operating system's native look-and-feel. 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="25" 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>

editor/editor_run.cpp

@@ -34,6 +34,7 @@
 #include "editor/debugger/editor_debugger_node.h"
 #include "editor/editor_node.h"
 #include "editor/editor_settings.h"
+#include "editor/plugins/game_editor_plugin.h"
 #include "editor/run_instances_dialog.h"
 #include "main/main.h"
 #include "servers/display_server.h"
@@ -175,12 +176,14 @@ Error EditorRun::run(const String &p_scene, const String &p_write_movie) {
 				args.push_back(itos(pos.x) + "," + itos(pos.y));
 			} break;
 			case 3: { // force maximized
+
 				Vector2 pos = screen_rect.position + screen_rect.size / 2;
 				args.push_back("--position");
 				args.push_back(itos(pos.x) + "," + itos(pos.y));
 				args.push_back("--maximized");
 			} break;
 			case 4: { // force fullscreen
+
 				Vector2 pos = screen_rect.position + screen_rect.size / 2;
 				args.push_back("--position");
 				args.push_back(itos(pos.x) + "," + itos(pos.y));
@@ -234,6 +237,9 @@ 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 (GameEditor::get_singleton()) {
+			GameEditor::get_singleton()->get_argument_list_for_instance(i, instance_args);
+		}
 
 		if (OS::get_singleton()->is_stdout_verbose()) {
 			print_line(vformat("Running: %s", exec));
@@ -286,6 +292,13 @@ 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

@@ -32,6 +32,7 @@
 #define EDITOR_RUN_H
 
 #include "core/os/os.h"
+#include "servers/display_server.h"
 
 class EditorRun {
 public:
@@ -58,6 +59,7 @@ 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

@@ -293,6 +293,34 @@ void EditorRunBar::play_custom_scene(const String &p_custom) {
 	current_mode = RunMode::RUN_CUSTOM;
 	_run_scene(p_custom);
 }
+void EditorRunBar::restart() {
+	if (!is_playing()) {
+		return;
+	}
+
+	RunMode last_current_mode = current_mode;
+	String last_run_custom_filename = run_custom_filename;
+	String last_run_current_filename = run_current_filename;
+
+	stop_playing();
+
+	switch (last_current_mode) {
+		case RunMode::RUN_MAIN: {
+			_run_scene();
+		} break;
+		case RunMode::RUN_CUSTOM: {
+			play_custom_scene(last_run_custom_filename);
+		} break;
+		case RunMode::RUN_CURRENT: {
+			_run_scene(last_run_current_filename);
+		} break;
+		case RunMode::STOPPED: {
+			// Nothing to do.
+		} break;
+	}
+
+	current_mode = last_current_mode;
+}
 
 void EditorRunBar::stop_playing() {
 	if (editor_run.get_status() == EditorRun::STATUS_STOP) {
@@ -345,6 +373,10 @@ 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

@@ -96,6 +96,7 @@ class EditorRunBar : public MarginContainer {
 	void play_main_scene(bool p_from_native = false);
 	void play_current_scene(bool p_reload = false);
 	void play_custom_scene(const String &p_custom);
+	void restart();
 
 	void stop_playing();
 	bool is_playing() const;
@@ -105,6 +106,7 @@ 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/plugins/game_editor_plugin.cpp

@@ -30,14 +30,15 @@
 
 #include "game_editor_plugin.h"
 
+#include "core/config/project_settings.h"
 #include "editor/debugger/editor_debugger_node.h"
 #include "editor/editor_main_screen.h"
 #include "editor/editor_node.h"
 #include "editor/editor_settings.h"
+#include "editor/gui/editor_run_bar.h"
 #include "editor/themes/editor_scale.h"
 #include "scene/gui/button.h"
 #include "scene/gui/panel.h"
-#include "scene/gui/separator.h"
 
 void GameEditorDebugger::_session_started(Ref<EditorDebuggerSession> p_session) {
 	p_session->send_message("scene:runtime_node_select_setup", Array());
@@ -118,6 +119,12 @@ void GameEditorDebugger::_bind_methods() {
 
 ///////
 
+GameEditor *GameEditor::singleton = nullptr;
+
+GameEditor *GameEditor::get_singleton() {
+	return singleton;
+}
+
 void GameEditor::_sessions_changed() {
 	// The debugger session's `session_started/stopped` signal can be unreliable, so count it manually.
 	active_sessions = 0;
@@ -131,6 +138,35 @@ void GameEditor::_sessions_changed() {
 	_update_debugger_buttons();
 }
 
+void GameEditor::_play_pressed() {
+	OS::ProcessID current_process_id = EditorRunBar::get_singleton()->get_current_process();
+	if (current_process_id == 0) {
+		return;
+	}
+
+	if (embedded_button->is_pressed()) {
+		embedded_process->embed_process(current_process_id);
+		_update_ui();
+
+		if (auto_focus_button->is_pressed()) {
+			EditorNode::get_singleton()->get_editor_main_screen()->select(EditorMainScreen::EDITOR_GAME);
+		}
+	}
+}
+
+void GameEditor::_stop_pressed() {
+	embedded_process->reset();
+	_update_ui();
+}
+
+void GameEditor::_embedding_completed() {
+	_update_ui();
+}
+
+void GameEditor::_embedding_failed() {
+	state_label->set_text(TTR("Connection impossible to the game process."));
+}
+
 void GameEditor::_update_debugger_buttons() {
 	bool empty = active_sessions == 0;
 	suspend_button->set_disabled(empty);
@@ -167,6 +203,40 @@ void GameEditor::_select_mode_pressed(int p_option) {
 	debugger->set_select_mode(mode);
 }
 
+void GameEditor::_embedded_button_pressed() {
+	EditorSettings::get_singleton()->set_project_metadata("game_editor", "embedded", embedded_button->is_pressed());
+
+	if (EditorRunBar::get_singleton()->is_playing()) {
+		EditorRunBar::get_singleton()->restart();
+	}
+
+	_update_ui();
+}
+
+void GameEditor::_auto_focus_button_pressed() {
+	EditorSettings::get_singleton()->set_project_metadata("game_editor", "auto_focus", auto_focus_button->is_pressed());
+}
+
+void GameEditor::_keep_aspect_button_pressed() {
+	EditorSettings::get_singleton()->set_project_metadata("game_editor", "keep_aspect", keep_aspect_button->is_pressed());
+}
+
+void GameEditor::_update_ui() {
+	if (!DisplayServer::get_singleton()->has_feature(DisplayServer::FEATURE_WINDOW_EMBEDDING)) {
+		state_label->set_text(TTR("Game embedding not available on your OS."));
+	} else if (embedded_process->is_embedding_completed()) {
+		state_label->set_text("");
+	} else if (embedded_process->is_embedding_in_progress()) {
+		state_label->set_text(TTR("Game starting..."));
+	} else if (EditorRunBar::get_singleton()->is_playing()) {
+		state_label->set_text(TTR("Game running not embedded."));
+	} else if (embedded_button->is_pressed()) {
+		state_label->set_text(TTR("Press play to start the game."));
+	} else {
+		state_label->set_text(TTR("Embedding is disabled."));
+	}
+}
+
 void GameEditor::_notification(int p_what) {
 	switch (p_what) {
 		case NOTIFICATION_ENTER_TREE:
@@ -180,12 +250,77 @@ void GameEditor::_notification(int p_what) {
 			select_mode_button[RuntimeNodeSelect::SELECT_MODE_SINGLE]->set_icon(get_editor_theme_icon(SNAME("ToolSelect")));
 			select_mode_button[RuntimeNodeSelect::SELECT_MODE_LIST]->set_icon(get_editor_theme_icon(SNAME("ListSelect")));
 
+			embedded_button->set_icon(get_editor_theme_icon(SNAME("EmbeddedProcess")));
+			auto_focus_button->set_icon(get_editor_theme_icon(SNAME("AutoFocus")));
+			keep_aspect_button->set_icon(get_editor_theme_icon(SNAME("KeepAspect")));
+
 			panel->set_theme_type_variation("GamePanel");
 		} break;
+
+		case NOTIFICATION_READY: {
+			if (DisplayServer::get_singleton()->has_feature(DisplayServer::FEATURE_WINDOW_EMBEDDING)) {
+				// Embedding available.
+				embedded_button->set_pressed(EditorSettings::get_singleton()->get_project_metadata("game_editor", "embedded", true));
+				auto_focus_button->set_pressed(EditorSettings::get_singleton()->get_project_metadata("game_editor", "auto_focus", true));
+				keep_aspect_button->set_pressed(EditorSettings::get_singleton()->get_project_metadata("game_editor", "keep_aspect", true));
+
+				EditorRunBar::get_singleton()->connect("play_pressed", callable_mp(this, &GameEditor::_play_pressed));
+				EditorRunBar::get_singleton()->connect("stop_pressed", callable_mp(this, &GameEditor::_stop_pressed));
+			} else {
+				// Embedding not available.
+				embedding_separator->hide();
+				embedded_button->hide();
+				auto_focus_button->hide();
+				keep_aspect_button->hide();
+				keep_aspect_button->hide();
+			}
+
+			_update_ui();
+		} break;
 	}
 }
 
+void GameEditor::get_argument_list_for_instance(int p_idx, List<String> &r_list) {
+	if (p_idx != 0 || !embedded_button->is_pressed() || !DisplayServer::get_singleton()->has_feature(DisplayServer::FEATURE_WINDOW_EMBEDDING)) {
+		return;
+	}
+
+	// Remove duplicates/unwanted parameters.
+	List<String, DefaultAllocator>::Element *position_item = r_list.find("--position");
+	if (position_item) {
+		r_list.erase(position_item->next());
+		r_list.erase(position_item);
+	}
+	List<String, DefaultAllocator>::Element *resolution_item = r_list.find("--resolution");
+	if (resolution_item) {
+		r_list.erase(resolution_item->next());
+		r_list.erase(resolution_item);
+	}
+	List<String, DefaultAllocator>::Element *screen_item = r_list.find("--screen");
+	if (screen_item) {
+		r_list.erase(screen_item->next());
+		r_list.erase(screen_item);
+	}
+	r_list.erase("-f");
+	r_list.erase("--fullscreen");
+	r_list.erase("-m");
+	r_list.erase("--maximized");
+	r_list.erase("-t");
+	r_list.erase("--always-on-top");
+
+	// Add editor window native id so the started game can directly set it's parent to it.
+	r_list.push_back("--wid");
+	r_list.push_back(itos(DisplayServer::get_singleton()->window_get_native_handle(DisplayServer::WINDOW_HANDLE, get_window()->get_window_id())));
+
+	Rect2i rect = embedded_process->get_screen_rect();
+	r_list.push_back("--position");
+	r_list.push_back(itos(rect.position.x) + "," + itos(rect.position.y));
+	r_list.push_back("--resolution");
+	r_list.push_back(itos(rect.size.x) + "x" + itos(rect.size.y));
+}
+
 GameEditor::GameEditor(Ref<GameEditorDebugger> p_debugger) {
+	singleton = this;
 	debugger = p_debugger;
 
 	// Add some margin to the sides for better aesthetics.
@@ -252,14 +387,55 @@ GameEditor::GameEditor(Ref<GameEditorDebugger> p_debugger) {
 	select_mode_button[RuntimeNodeSelect::SELECT_MODE_LIST]->connect(SceneStringName(pressed), callable_mp(this, &GameEditor::_select_mode_pressed).bind(RuntimeNodeSelect::SELECT_MODE_LIST));
 	select_mode_button[RuntimeNodeSelect::SELECT_MODE_LIST]->set_tooltip_text(TTR("Show list of selectable nodes at position clicked."));
 
+	embedding_separator = memnew(VSeparator);
+	main_menu_hbox->add_child(embedding_separator);
+
+	embedded_button = memnew(Button);
+	main_menu_hbox->add_child(embedded_button);
+	embedded_button->set_toggle_mode(true);
+	embedded_button->set_theme_type_variation("FlatButton");
+	embedded_button->set_tooltip_text(TTR("Activate the game embedding mode."));
+	embedded_button->connect(SceneStringName(pressed), callable_mp(this, &GameEditor::_embedded_button_pressed));
+
+	auto_focus_button = memnew(Button);
+	main_menu_hbox->add_child(auto_focus_button);
+	auto_focus_button->set_toggle_mode(true);
+	auto_focus_button->set_theme_type_variation("FlatButton");
+	auto_focus_button->set_tooltip_text(TTR("Focus the game editor on project run."));
+	auto_focus_button->connect(SceneStringName(pressed), callable_mp(this, &GameEditor::_auto_focus_button_pressed));
+
+	keep_aspect_button = memnew(Button);
+	main_menu_hbox->add_child(keep_aspect_button);
+	keep_aspect_button->set_toggle_mode(true);
+	keep_aspect_button->set_theme_type_variation("FlatButton");
+	keep_aspect_button->set_tooltip_text(TTR("Keep aspect ratio of the embedded game."));
+	keep_aspect_button->connect(SceneStringName(pressed), callable_mp(this, &GameEditor::_keep_aspect_button_pressed));
+
 	panel = memnew(Panel);
 	add_child(panel);
 	panel->set_v_size_flags(SIZE_EXPAND_FILL);
 
+	embedded_process = memnew(EmbeddedProcess);
+	panel->add_child(embedded_process);
+	embedded_process->set_anchors_and_offsets_preset(PRESET_FULL_RECT);
+	embedded_process->connect(SNAME("embedding_failed"), callable_mp(this, &GameEditor::_embedding_failed));
+	embedded_process->connect(SNAME("embedding_completed"), callable_mp(this, &GameEditor::_embedding_completed));
+
+	state_label = memnew(Label());
+	panel->add_child(state_label);
+	state_label->set_horizontal_alignment(HORIZONTAL_ALIGNMENT_CENTER);
+	state_label->set_vertical_alignment(VERTICAL_ALIGNMENT_CENTER);
+	state_label->set_autowrap_mode(TextServer::AUTOWRAP_WORD);
+	state_label->set_anchors_and_offsets_preset(PRESET_FULL_RECT);
+
 	p_debugger->connect("session_started", callable_mp(this, &GameEditor::_sessions_changed));
 	p_debugger->connect("session_stopped", callable_mp(this, &GameEditor::_sessions_changed));
 }
 
+GameEditor::~GameEditor() {
+	singleton = nullptr;
+}
+
 ///////
 
 void GameEditorPlugin::make_visible(bool p_visible) {