[macOS] Implement seamless display scaling.

doc/classes/DisplayServer.xml

@@ -523,6 +523,15 @@
 			<description>
 			</description>
 		</method>
+		<method name="screen_get_max_scale" qualifiers="const">
+			<return type="float">
+			</return>
+			<description>
+				Return the greatest scale factor of all screens.
+				[b]Note:[/b] On macOS returned value is [code]2.0[/code] if there is at least one hiDPI (Retina) screen in the system, and [code]1.0[/code] in all other cases.
+				[b]Note:[/b] This method is implemented on macOS.
+			</description>
+		</method>
 		<method name="screen_get_orientation" qualifiers="const">
 			<return type="int" enum="DisplayServer.ScreenOrientation">
 			</return>
@@ -545,6 +554,9 @@
 			<argument index="0" name="screen" type="int" default="-1">
 			</argument>
 			<description>
+				Return the scale factor of the specified screen by index.
+				[b]Note:[/b] On macOS returned value is [code]2.0[/code] for hiDPI (Retina) screen, and [code]1.0[/code] for all other cases.
+				[b]Note:[/b] This method is implemented on macOS.
 			</description>
 		</method>
 		<method name="screen_get_size" qualifiers="const">

editor/editor_node.cpp

@@ -5520,10 +5520,10 @@ EditorNode::EditorNode() {
 		switch (display_scale) {
 			case 0: {
 				// Try applying a suitable display scale automatically
-				const int screen = DisplayServer::get_singleton()->window_get_current_screen();
 #ifdef OSX_ENABLED
-				editor_set_scale(DisplayServer::get_singleton()->screen_get_scale(screen));
+				editor_set_scale(DisplayServer::get_singleton()->screen_get_max_scale());
 #else
+				const int screen = DisplayServer::get_singleton()->window_get_current_screen();
 				editor_set_scale(DisplayServer::get_singleton()->screen_get_dpi(screen) >= 192 && DisplayServer::get_singleton()->screen_get_size(screen).x > 2000 ? 2.0 : 1.0);
 #endif
 			} break;

editor/editor_run.cpp

@@ -108,24 +108,33 @@ Error EditorRun::run(const String &p_scene, const String &p_custom_args, const L
 	}
 
 	int window_placement = EditorSettings::get_singleton()->get("run/window_placement/rect");
+	bool hidpi_proj = ProjectSettings::get_singleton()->get("display/window/dpi/allow_hidpi");
+	int display_scale = 1;
+	if (DisplayServer::get_singleton()->has_feature(DisplayServer::FEATURE_HIDPI)) {
+		if (OS::get_singleton()->is_hidpi_allowed()) {
+			if (hidpi_proj) {
+				display_scale = 1; // Both editor and project runs in hiDPI mode, do not scale.
+			} else {
+				display_scale = DisplayServer::get_singleton()->screen_get_max_scale(); // Editor is in hiDPI mode, project is not, scale down.
+			}
+		} else {
+			if (hidpi_proj) {
+				display_scale = (1.f / DisplayServer::get_singleton()->screen_get_max_scale()); // Editor is not in hiDPI mode, project is, scale up.
+			} else {
+				display_scale = 1; // Both editor and project runs in lowDPI mode, do not scale.
+			}
+		}
+		screen_rect.position /= display_scale;
+		screen_rect.size /= display_scale;
+	}
 
 	switch (window_placement) {
 		case 0: { // top left
-
 			args.push_back("--position");
 			args.push_back(itos(screen_rect.position.x) + "," + itos(screen_rect.position.y));
 		} break;
 		case 1: { // centered
-			int display_scale = 1;
-#ifdef OSX_ENABLED
-			display_scale = DisplayServer::get_singleton()->screen_get_scale(screen);
-#else
-			if (DisplayServer::get_singleton()->screen_get_dpi(screen) >= 192 && DisplayServer::get_singleton()->screen_get_size(screen).x > 2000) {
-				display_scale = 2;
-			}
-#endif
-
-			Vector2 pos = screen_rect.position + ((screen_rect.size / display_scale - desired_size) / 2).floor();
+			Vector2 pos = (screen_rect.position) + ((screen_rect.size - desired_size) / 2).floor();
 			args.push_back("--position");
 			args.push_back(itos(pos.x) + "," + itos(pos.y));
 		} break;
@@ -140,10 +149,8 @@ Error EditorRun::run(const String &p_scene, const String &p_custom_args, const L
 			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;
 			args.push_back("--position");
 			args.push_back(itos(pos.x) + "," + itos(pos.y));

editor/project_manager.cpp

@@ -2336,10 +2336,10 @@ ProjectManager::ProjectManager() {
 		switch (display_scale) {
 			case 0: {
 				// Try applying a suitable display scale automatically
-				const int screen = DisplayServer::get_singleton()->window_get_current_screen();
 #ifdef OSX_ENABLED
-				editor_set_scale(DisplayServer::get_singleton()->screen_get_scale(screen));
+				editor_set_scale(DisplayServer::get_singleton()->screen_get_max_scale());
 #else
+				const int screen = DisplayServer::get_singleton()->window_get_current_screen();
 				editor_set_scale(DisplayServer::get_singleton()->screen_get_dpi(screen) >= 192 && DisplayServer::get_singleton()->screen_get_size(screen).x > 2000 ? 2.0 : 1.0);
 #endif
 			} break;
@@ -2371,11 +2371,8 @@ ProjectManager::ProjectManager() {
 		// Define a minimum window size to prevent UI elements from overlapping or being cut off
 		DisplayServer::get_singleton()->window_set_min_size(Size2(750, 420) * EDSCALE);
 
-#ifndef OSX_ENABLED
-		// The macOS platform implementation uses its own hiDPI window resizing code
 		// TODO: Resize windows on hiDPI displays on Windows and Linux and remove the line below
 		DisplayServer::get_singleton()->window_set_size(DisplayServer::get_singleton()->window_get_size() * MAX(1, EDSCALE));
-#endif
 	}
 
 	FileDialog::set_default_show_hidden_files(EditorSettings::get_singleton()->get("filesystem/file_dialog/show_hidden_files"));

platform/osx/display_server_osx.h

@@ -132,6 +132,7 @@ public:
 		bool on_top = false;
 		bool borderless = false;
 		bool resize_disabled = false;
+		bool no_focus = false;
 	};
 
 	Point2i im_selection;
@@ -150,7 +151,6 @@ public:
 
 	void _set_window_per_pixel_transparency_enabled(bool p_enabled, WindowID p_window);
 
-	float _display_scale(id screen) const;
 	Point2i _get_screens_origin() const;
 	Point2i _get_native_screen_position(int p_screen) const;
 
@@ -224,6 +224,7 @@ public:
 	virtual Size2i screen_get_size(int p_screen = SCREEN_OF_MAIN_WINDOW) const;
 	virtual int screen_get_dpi(int p_screen = SCREEN_OF_MAIN_WINDOW) const;
 	virtual float screen_get_scale(int p_screen = SCREEN_OF_MAIN_WINDOW) const;
+	virtual float screen_get_max_scale() const;
 	virtual Rect2i screen_get_usable_rect(int p_screen = SCREEN_OF_MAIN_WINDOW) const;
 
 	virtual Vector<int> get_window_list() const;

scene/main/window.cpp

@@ -338,6 +338,7 @@ void Window::_event_callback(DisplayServer::WindowEvent p_event) {
 			emit_signal("go_back_requested");
 		} break;
 		case DisplayServer::WINDOW_EVENT_DPI_CHANGE: {
+			_update_viewport_size();
 			_propagate_window_notification(this, NOTIFICATION_WM_DPI_CHANGE);
 			emit_signal("dpi_changed");
 		} break;

servers/display_server.cpp

@@ -392,6 +392,7 @@ void DisplayServer::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("screen_get_dpi", "screen"), &DisplayServer::screen_get_dpi, DEFVAL(SCREEN_OF_MAIN_WINDOW));
 	ClassDB::bind_method(D_METHOD("screen_get_scale", "screen"), &DisplayServer::screen_get_scale, DEFVAL(SCREEN_OF_MAIN_WINDOW));
 	ClassDB::bind_method(D_METHOD("screen_is_touchscreen", "screen"), &DisplayServer::screen_is_touchscreen, DEFVAL(SCREEN_OF_MAIN_WINDOW));
+	ClassDB::bind_method(D_METHOD("screen_get_max_scale"), &DisplayServer::screen_get_max_scale);
 
 	ClassDB::bind_method(D_METHOD("screen_set_orientation", "orientation", "screen"), &DisplayServer::screen_set_orientation, DEFVAL(SCREEN_OF_MAIN_WINDOW));
 	ClassDB::bind_method(D_METHOD("screen_get_orientation", "screen"), &DisplayServer::screen_get_orientation, DEFVAL(SCREEN_OF_MAIN_WINDOW));

servers/display_server.h

@@ -167,6 +167,14 @@ public:
 	virtual Rect2i screen_get_usable_rect(int p_screen = SCREEN_OF_MAIN_WINDOW) const = 0;
 	virtual int screen_get_dpi(int p_screen = SCREEN_OF_MAIN_WINDOW) const = 0;
 	virtual float screen_get_scale(int p_screen = SCREEN_OF_MAIN_WINDOW) const;
+	virtual float screen_get_max_scale() const {
+		float scale = 1.f;
+		int screen_count = get_screen_count();
+		for (int i = 0; i < screen_count; i++) {
+			scale = fmax(scale, screen_get_scale(i));
+		}
+		return scale;
+	}
 	virtual bool screen_is_touchscreen(int p_screen = SCREEN_OF_MAIN_WINDOW) const;
 	enum ScreenOrientation {