From 9f7ebaea5c43b3c5c860de782ed1d0f544124062 Mon Sep 17 00:00:00 2001
From: Haoyu Qiu <timothyqiu32@gmail.com>
Date: Mon, 6 Oct 2025 22:48:31 +0800
Subject: [PATCH] Fix editor auto scale on Windows

---
 editor/settings/editor_settings.cpp         |  7 ++++++-
 platform/windows/display_server_windows.cpp | 22 +++++++++++----------
 2 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/editor/settings/editor_settings.cpp b/editor/settings/editor_settings.cpp
index 4ab88e4abdc..2255827e92e 100644
--- a/editor/settings/editor_settings.cpp
+++ b/editor/settings/editor_settings.cpp
@@ -1823,6 +1823,9 @@ float EditorSettings::get_auto_display_scale() {
 		return 1.0;
 	}
 
+#if defined(WINDOWS_ENABLED)
+	return DisplayServer::get_singleton()->screen_get_dpi(screen) / 96.0;
+#else
 	// Use the smallest dimension to use a correct display scale on portrait 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) {
@@ -1838,7 +1841,9 @@ float EditorSettings::get_auto_display_scale() {
 		return 0.75;
 	}
 	return 1.0;
-#endif
+#endif // defined(WINDOWS_ENABLED)
+
+#endif // defined(MACOS_ENABLED) || defined(ANDROID_ENABLED)
 }
 
 // Shortcuts
diff --git a/platform/windows/display_server_windows.cpp b/platform/windows/display_server_windows.cpp
index 1cce42d57f2..cd6633f6669 100644
--- a/platform/windows/display_server_windows.cpp
+++ b/platform/windows/display_server_windows.cpp
@@ -1331,17 +1331,17 @@ Rect2i DisplayServerWindows::screen_get_usable_rect(int p_screen) const {
 }
 
 typedef struct {
-	int count;
+	int current_index;
 	int screen;
 	int dpi;
 } EnumDpiData;
 
-static int QueryDpiForMonitor(HMONITOR hmon, MONITOR_DPI_TYPE dpiType = MDT_DEFAULT) {
+static int QueryDpiForMonitor(HMONITOR hmon) {
 	int dpiX = 96, dpiY = 96;
 
 	UINT x = 0, y = 0;
 	if (hmon) {
-		HRESULT hr = GetDpiForMonitor(hmon, dpiType, &x, &y);
+		HRESULT hr = GetDpiForMonitor(hmon, MDT_DEFAULT, &x, &y);
 		if (SUCCEEDED(hr) && (x > 0) && (y > 0)) {
 			dpiX = (int)x;
 			dpiY = (int)y;
@@ -1367,11 +1367,13 @@ static int QueryDpiForMonitor(HMONITOR hmon, MONITOR_DPI_TYPE dpiType = MDT_DEFA
 
 static BOOL CALLBACK _MonitorEnumProcDpi(HMONITOR hMonitor, HDC hdcMonitor, LPRECT lprcMonitor, LPARAM dwData) {
 	EnumDpiData *data = (EnumDpiData *)dwData;
-	if (data->count == data->screen) {
-		data->dpi = QueryDpiForMonitor(hMonitor);
-	}
 
-	data->count++;
+	data->current_index++;
+
+	if (data->current_index == data->screen) {
+		data->dpi = QueryDpiForMonitor(hMonitor);
+		return FALSE;
+	}
 	return TRUE;
 }
 
@@ -1379,11 +1381,11 @@ int DisplayServerWindows::screen_get_dpi(int p_screen) const {
 	_THREAD_SAFE_METHOD_
 
 	p_screen = _get_screen_index(p_screen);
-	int screen_count = get_screen_count();
-	ERR_FAIL_INDEX_V(p_screen, screen_count, 72);
 
-	EnumDpiData data = { 0, p_screen, 72 };
+	EnumDpiData data = { -1, p_screen, 96 };
 	EnumDisplayMonitors(nullptr, nullptr, _MonitorEnumProcDpi, (LPARAM)&data);
+
+	ERR_FAIL_COND_V_MSG(data.current_index < p_screen, 96, vformat("Screen index %d out of range [0, %d].", p_screen, data.current_index));
 	return data.dpi;
 }