EditorSettings: Factor code to compute auto display scale

Also fixes typo introduced in https://github.com/godotengine/godot/pull/48597/files#r652636544.

editor/editor_node.cpp

@@ -5689,36 +5689,10 @@ EditorNode::EditorNode() {
 		int display_scale = EditorSettings::get_singleton()->get("interface/editor/display_scale");
 
 		switch (display_scale) {
-			case 0: {
+			case 0:
 				// Try applying a suitable display scale automatically.
-				// The code below is adapted in `editor/editor_settings.cpp` and `editor/project_manager.cpp`.
-				// Make sure to update those when modifying the code below.
-#ifdef OSX_ENABLED
-				editor_set_scale(DisplayServer::get_singleton()->screen_get_max_scale());
-#else
-				const int screen = DisplayServer::get_singleton()->window_get_current_screen();
-				// Use the smallest dimension to use a correct display scale on portait displays.
-				const int smallest_dimension = MIN(DisplayServer::get_singleton()->screen_get_size(screen).x, DisplayServer::get_singleton()->screen_get_size(screen).y);
-				float scale;
-				if (DisplayServer::get_singleton()->screen_get_dpi(screen) >= 192 && smallest_dimension >= 1400) {
-					// hiDPI display.
-					scale = 2.0;
-				} else if (smallest_dimension >= 1700) {
-					// Likely a hiDPI display, but we aren't certain due to the returned DPI.
-					// Use an intermediate scale to handle this situation.
-					scale = 1.5;
-				} else if (smallest_dimension <= 800) {
-					// Small loDPI display. Use a smaller display scale so that editor elements fit more easily.
-					// Icons won't look great, but this is better than having editor elements overflow from its window.
-					scale = 0.75;
-				} else {
-					scale = 1.0;
-				}
-
-				editor_set_scale(scale);
-#endif
-			} break;
-
+				editor_set_scale(EditorSettings::get_singleton()->get_auto_display_scale());
+				break;
 			case 1:
 				editor_set_scale(0.75);
 				break;

editor/editor_settings.cpp

@@ -373,30 +373,7 @@ void EditorSettings::_load_defaults(Ref<ConfigFile> p_extra_config) {
 	// Editor
 	_initial_set("interface/editor/display_scale", 0);
 	// Display what the Auto display scale setting effectively corresponds to.
-	// The code below is adapted in `editor/editor_node.cpp` and `editor/project_manager.cpp`.
-	// Make sure to update those when modifying the code below.
-#ifdef OSX_ENABLED
-	float scale = DisplayServer::get_singleton()->screen_get_max_scale();
-#else
-	const int screen = DisplayServer::get_singleton()->window_get_current_screen();
-	// Use the smallest dimension to use a correct display scale on portait displays.
-	const int smallest_dimension = MIN(DisplayServer::get_singleton()->screen_get_size(screen).x, DisplayServer::get_singleton()->screen_get_size(screen).y);
-	float scale;
-	if (DisplayServer::get_singleton()->screen_get_dpi(screen) >= 192 && smallest_dimension >= 1400) {
-		// hiDPI display.
-		scale = 2.0;
-	} else if (smallest_dimension <= 1700) {
-		// Likely a hiDPI display, but we aren't certain due to the returned DPI.
-		// Use an intermediate scale to handle this situation.
-		scale = 1.5;
-	} else if (smallest_dimension <= 800) {
-		// Small loDPI display. Use a smaller display scale so that editor elements fit more easily.
-		// Icons won't look great, but this is better than having editor elements overflow from its window.
-		scale = 0.75;
-	} else {
-		scale = 1.0;
-	}
-#endif
+	float scale = get_auto_display_scale();
 	hints["interface/editor/display_scale"] = PropertyInfo(Variant::INT, "interface/editor/display_scale", PROPERTY_HINT_ENUM, vformat("Auto (%d%%),75%%,100%%,125%%,150%%,175%%,200%%,Custom", Math::round(scale * 100)), PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_RESTART_IF_CHANGED);
 	_initial_set("interface/editor/custom_display_scale", 1.0f);
 	hints["interface/editor/custom_display_scale"] = PropertyInfo(Variant::FLOAT, "interface/editor/custom_display_scale", PROPERTY_HINT_RANGE, "0.5,3,0.01", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_RESTART_IF_CHANGED);
@@ -1447,6 +1424,29 @@ String EditorSettings::get_editor_layouts_config() const {
 	return EditorPaths::get_singleton()->get_config_dir().plus_file("editor_layouts.cfg");
 }
 
+float EditorSettings::get_auto_display_scale() const {
+#ifdef OSX_ENABLED
+	return DisplayServer::get_singleton()->screen_get_max_scale();
+#else
+	const int screen = DisplayServer::get_singleton()->window_get_current_screen();
+	// Use the smallest dimension to use a correct display scale on portait displays.
+	const int smallest_dimension = MIN(DisplayServer::get_singleton()->screen_get_size(screen).x, DisplayServer::get_singleton()->screen_get_size(screen).y);
+	if (DisplayServer::get_singleton()->screen_get_dpi(screen) >= 192 && smallest_dimension >= 1400) {
+		// hiDPI display.
+		return 2.0;
+	} else if (smallest_dimension >= 1700) {
+		// Likely a hiDPI display, but we aren't certain due to the returned DPI.
+		// Use an intermediate scale to handle this situation.
+		return 1.5;
+	} else if (smallest_dimension <= 800) {
+		// Small loDPI display. Use a smaller display scale so that editor elements fit more easily.
+		// Icons won't look great, but this is better than having editor elements overflow from its window.
+		return 0.75;
+	}
+	return 1.0;
+#endif
+}
+
 // Shortcuts
 
 void EditorSettings::add_shortcut(const String &p_name, Ref<Shortcut> &p_shortcut) {

editor/editor_settings.h

@@ -174,6 +174,7 @@ public:
 
 	Vector<String> get_script_templates(const String &p_extension, const String &p_custom_path = String());
 	String get_editor_layouts_config() const;
+	float get_auto_display_scale() const;
 
 	void add_shortcut(const String &p_name, Ref<Shortcut> &p_shortcut);
 	bool is_shortcut(const String &p_name, const Ref<InputEvent> &p_event) const;

editor/project_manager.cpp

@@ -2400,36 +2400,10 @@ ProjectManager::ProjectManager() {
 		int display_scale = EditorSettings::get_singleton()->get("interface/editor/display_scale");
 
 		switch (display_scale) {
-			case 0: {
+			case 0:
 				// Try applying a suitable display scale automatically.
-				// The code below is adapted in `editor/editor_settings.cpp` and `editor/editor_node.cpp`.
-				// Make sure to update those when modifying the code below.
-#ifdef OSX_ENABLED
-				editor_set_scale(DisplayServer::get_singleton()->screen_get_max_scale());
-#else
-				const int screen = DisplayServer::get_singleton()->window_get_current_screen();
-				// Use the smallest dimension to use a correct display scale on portait displays.
-				const int smallest_dimension = MIN(DisplayServer::get_singleton()->screen_get_size(screen).x, DisplayServer::get_singleton()->screen_get_size(screen).y);
-				float scale;
-				if (DisplayServer::get_singleton()->screen_get_dpi(screen) >= 192 && smallest_dimension >= 1400) {
-					// hiDPI display.
-					scale = 2.0;
-				} else if (smallest_dimension >= 1700) {
-					// Likely a hiDPI display, but we aren't certain due to the returned DPI.
-					// Use an intermediate scale to handle this situation.
-					scale = 1.5;
-				} else if (smallest_dimension <= 800) {
-					// Small loDPI display. Use a smaller display scale so that editor elements fit more easily.
-					// Icons won't look great, but this is better than having editor elements overflow from its window.
-					scale = 0.75;
-				} else {
-					scale = 1.0;
-				}
-
-				editor_set_scale(scale);
-#endif
-			} break;
-
+				editor_set_scale(EditorSettings::get_singleton()->get_auto_display_scale());
+				break;
 			case 1:
 				editor_set_scale(0.75);
 				break;