From 40df3931d882daaeee42c8de69882b9f9df5c312 Mon Sep 17 00:00:00 2001
From: sfan5 <sfan5@live.de>
Date: Sat, 11 Apr 2020 20:03:59 +0200
Subject: Implement DPI scaling for Windows (#9586)

---
 src/client/renderingengine.cpp | 77 ++++++++++++++++++++++++++++++++----------
 1 file changed, 60 insertions(+), 17 deletions(-)

(limited to 'src/client/renderingengine.cpp')

diff --git a/src/client/renderingengine.cpp b/src/client/renderingengine.cpp
index 8b7bbf328..eae6ca7d3 100644
--- a/src/client/renderingengine.cpp
+++ b/src/client/renderingengine.cpp
@@ -45,7 +45,11 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
 #include <X11/Xatom.h>
+#endif
 
+#ifdef _WIN32
+#include <windows.h>
+#include <winuser.h>
 #endif
 
 #if ENABLE_GLES
@@ -318,6 +322,28 @@ void RenderingEngine::setupTopLevelXorgWindow(const std::string &name)
 #endif
 }
 
+#ifdef _WIN32
+static bool getWindowHandle(irr::video::IVideoDriver *driver, HWND &hWnd)
+{
+	const video::SExposedVideoData exposedData = driver->getExposedVideoData();
+
+	switch (driver->getDriverType()) {
+	case video::EDT_DIRECT3D8:
+		hWnd = reinterpret_cast<HWND>(exposedData.D3D8.HWnd);
+		break;
+	case video::EDT_DIRECT3D9:
+		hWnd = reinterpret_cast<HWND>(exposedData.D3D9.HWnd);
+		break;
+	case video::EDT_OPENGL:
+		hWnd = reinterpret_cast<HWND>(exposedData.OpenGLWin32.HWnd);
+		break;
+	default:
+		return false;
+	}
+
+	return true;
+}
+#endif
 
 bool RenderingEngine::setWindowIcon()
 {
@@ -335,22 +361,9 @@ bool RenderingEngine::setWindowIcon()
 							       "-xorg-icon-128.png");
 #endif
 #elif defined(_WIN32)
-	const video::SExposedVideoData exposedData = driver->getExposedVideoData();
 	HWND hWnd; // Window handle
-
-	switch (driver->getDriverType()) {
-	case video::EDT_DIRECT3D8:
-		hWnd = reinterpret_cast<HWND>(exposedData.D3D8.HWnd);
-		break;
-	case video::EDT_DIRECT3D9:
-		hWnd = reinterpret_cast<HWND>(exposedData.D3D9.HWnd);
-		break;
-	case video::EDT_OPENGL:
-		hWnd = reinterpret_cast<HWND>(exposedData.OpenGLWin32.HWnd);
-		break;
-	default:
+	if (!getWindowHandle(driver, hWnd))
 		return false;
-	}
 
 	// Load the ICON from resource file
 	const HICON hicon = LoadIcon(GetModuleHandle(NULL),
@@ -632,7 +645,7 @@ const char *RenderingEngine::getVideoDriverFriendlyName(irr::video::E_DRIVER_TYP
 }
 
 #ifndef __ANDROID__
-#ifdef XORG_USED
+#if defined(XORG_USED)
 
 static float calcDisplayDensity()
 {
@@ -667,12 +680,42 @@ float RenderingEngine::getDisplayDensity()
 	return cached_display_density;
 }
 
-#else  // XORG_USED
+#elif defined(_WIN32)
+
+
+static float calcDisplayDensity(irr::video::IVideoDriver *driver)
+{
+	HWND hWnd;
+	if (getWindowHandle(driver, hWnd)) {
+		HDC hdc = GetDC(hWnd);
+		float dpi = GetDeviceCaps(hdc, LOGPIXELSX);
+		ReleaseDC(hWnd, hdc);
+		return dpi / 96.0f;
+	}
+
+	/* return manually specified dpi */
+	return g_settings->getFloat("screen_dpi") / 96.0f;
+}
+
+float RenderingEngine::getDisplayDensity()
+{
+	static bool cached = false;
+	static float display_density;
+	if (!cached) {
+		display_density = calcDisplayDensity(get_video_driver());
+		cached = true;
+	}
+	return display_density;
+}
+
+#else
+
 float RenderingEngine::getDisplayDensity()
 {
 	return g_settings->getFloat("screen_dpi") / 96.0;
 }
-#endif // XORG_USED
+
+#endif
 
 v2u32 RenderingEngine::getDisplaySize()
 {
-- 
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