SDL2: Support highdpi (#14703)

and handle DPI changes at runtime

builtin/settingtypes.txt

@@ -2187,9 +2187,6 @@ curl_file_download_timeout (cURL file download timeout) int 300000 5000 21474836
 
 [**Miscellaneous]
 
-#    Adjust dpi configuration to your screen (non X11/Android only) e.g. for 4k screens.
-screen_dpi (DPI) int 72 1
-
 #    Adjust the detected display density, used for scaling UI elements.
 display_density_factor (Display Density Scaling Factor) float 1 0.5 5.0
 

irr/include/IEventReceiver.h

@@ -205,6 +205,9 @@ enum EAPPLICATION_EVENT_TYPE
 	//! The application received a memory warning.
 	EAET_MEMORY_WARNING,
 
+	//! The display density changed (only works on SDL).
+	EAET_DPI_CHANGED,
+
 	//! No real event, but to get number of event types.
 	EAET_COUNT
 };

irr/src/CIrrDeviceSDL.cpp

@@ -285,6 +285,11 @@ CIrrDeviceSDL::CIrrDeviceSDL(const SIrrlichtCreationParameters &param) :
 		SDL_SetHint(SDL_HINT_TV_REMOTE_AS_JOYSTICK, "0");
 #endif
 
+#if SDL_VERSION_ATLEAST(2, 24, 0)
+		// highdpi support on Windows
+		SDL_SetHint(SDL_HINT_WINDOWS_DPI_SCALING, "1");
+#endif
+
 		// Minetest has its own code to synthesize mouse events from touch events,
 		// so we prevent SDL from doing it.
 		SDL_SetHint(SDL_HINT_TOUCH_MOUSE_EVENTS, "0");
@@ -475,6 +480,7 @@ bool CIrrDeviceSDL::createWindow()
 bool CIrrDeviceSDL::createWindowWithContext()
 {
 	u32 SDL_Flags = 0;
+	SDL_Flags |= SDL_WINDOW_ALLOW_HIGHDPI;
 
 	SDL_Flags |= getFullscreenFlag(CreationParams.Fullscreen);
 	if (Resizable)
@@ -589,13 +595,16 @@ bool CIrrDeviceSDL::createWindowWithContext()
 		return false;
 	}
 
-	// Update Width and Height to match the actual window size.
-	// In fullscreen mode, the window size specified in SIrrlichtCreationParameters
-	// is ignored, so we cannot rely on it.
-	int w = 0, h = 0;
-	SDL_GetWindowSize(Window, &w, &h);
-	Width = w;
-	Height = h;
+	updateSizeAndScale();
+	if (ScaleX != 1.0f || ScaleY != 1.0f) {
+		// The given window size is in pixels, not in screen coordinates.
+		// We can only do the conversion now since we didn't know the scale before.
+		SDL_SetWindowSize(Window, CreationParams.WindowSize.Width / ScaleX,
+				CreationParams.WindowSize.Height / ScaleY);
+		// Re-center, otherwise large, non-maximized windows go offscreen.
+		SDL_SetWindowPosition(Window, SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED);
+		updateSizeAndScale();
+	}
 
 	return true;
 #endif // !_IRR_EMSCRIPTEN_PLATFORM_
@@ -659,10 +668,10 @@ bool CIrrDeviceSDL::run()
 
 			irrevent.EventType = irr::EET_MOUSE_INPUT_EVENT;
 			irrevent.MouseInput.Event = irr::EMIE_MOUSE_MOVED;
-			MouseX = irrevent.MouseInput.X = SDL_event.motion.x;
-			MouseY = irrevent.MouseInput.Y = SDL_event.motion.y;
-			MouseXRel = SDL_event.motion.xrel;
-			MouseYRel = SDL_event.motion.yrel;
+			MouseX = irrevent.MouseInput.X = SDL_event.motion.x * ScaleX;
+			MouseY = irrevent.MouseInput.Y = SDL_event.motion.y * ScaleY;
+			MouseXRel = SDL_event.motion.xrel * ScaleX;
+			MouseYRel = SDL_event.motion.yrel * ScaleY;
 			irrevent.MouseInput.ButtonStates = MouseButtonStates;
 			irrevent.MouseInput.Shift = (keymod & KMOD_SHIFT) != 0;
 			irrevent.MouseInput.Control = (keymod & KMOD_CTRL) != 0;
@@ -694,8 +703,8 @@ bool CIrrDeviceSDL::run()
 			SDL_Keymod keymod = SDL_GetModState();
 
 			irrevent.EventType = irr::EET_MOUSE_INPUT_EVENT;
-			irrevent.MouseInput.X = SDL_event.button.x;
-			irrevent.MouseInput.Y = SDL_event.button.y;
+			irrevent.MouseInput.X = SDL_event.button.x * ScaleX;
+			irrevent.MouseInput.Y = SDL_event.button.y * ScaleY;
 			irrevent.MouseInput.Shift = (keymod & KMOD_SHIFT) != 0;
 			irrevent.MouseInput.Control = (keymod & KMOD_CTRL) != 0;
 
@@ -827,14 +836,25 @@ bool CIrrDeviceSDL::run()
 		case SDL_WINDOWEVENT:
 			switch (SDL_event.window.event) {
 			case SDL_WINDOWEVENT_RESIZED:
-				if ((SDL_event.window.data1 != (int)Width) || (SDL_event.window.data2 != (int)Height)) {
-					Width = SDL_event.window.data1;
-					Height = SDL_event.window.data2;
+			case SDL_WINDOWEVENT_SIZE_CHANGED:
+#if SDL_VERSION_ATLEAST(2, 0, 18)
+			case SDL_WINDOWEVENT_DISPLAY_CHANGED:
+#endif
+				u32 old_w = Width, old_h = Height;
+				f32 old_scale_x = ScaleX, old_scale_y = ScaleY;
+				updateSizeAndScale();
+				if (old_w != Width || old_h != Height) {
 					if (VideoDriver)
 						VideoDriver->OnResize(core::dimension2d<u32>(Width, Height));
 				}
+				if (old_scale_x != ScaleX || old_scale_y != ScaleY) {
+					irrevent.EventType = EET_APPLICATION_EVENT;
+					irrevent.ApplicationEvent.EventType = EAET_DPI_CHANGED;
+					postEventFromUser(irrevent);
+				}
 				break;
 			}
+			break;
 
 		case SDL_USEREVENT:
 			irrevent.EventType = irr::EET_USER_EVENT;
@@ -1030,25 +1050,26 @@ bool CIrrDeviceSDL::activateJoysticks(core::array<SJoystickInfo> &joystickInfo)
 	return false;
 }
 
+void CIrrDeviceSDL::updateSizeAndScale()
+{
+	int window_w, window_h;
+	SDL_GetWindowSize(Window, &window_w, &window_h);
+
+	int drawable_w, drawable_h;
+	SDL_GL_GetDrawableSize(Window, &drawable_w, &drawable_h);
+
+	ScaleX = (float)drawable_w / (float)window_w;
+	ScaleY = (float)drawable_h / (float)window_h;
+
+	Width = drawable_w;
+	Height = drawable_h;
+}
+
 //! Get the display density in dots per inch.
 float CIrrDeviceSDL::getDisplayDensity() const
 {
-	if (!Window)
-		return 0.0f;
-
-	int window_w;
-	int window_h;
-	SDL_GetWindowSize(Window, &window_w, &window_h);
-
-	int drawable_w;
-	int drawable_h;
-	SDL_GL_GetDrawableSize(Window, &drawable_w, &drawable_h);
-
 	// assume 96 dpi
-	float dpi_w = (float)drawable_w / (float)window_w * 96.0f;
-	float dpi_h = (float)drawable_h / (float)window_h * 96.0f;
-
-	return std::max(dpi_w, dpi_h);
+	return std::max(ScaleX * 96.0f, ScaleY * 96.0f);
 }
 
 void CIrrDeviceSDL::SwapWindow()

irr/src/CIrrDeviceSDL.h

@@ -158,7 +158,8 @@ public:
 		//! Sets the new position of the cursor.
 		void setPosition(s32 x, s32 y) override
 		{
-			SDL_WarpMouseInWindow(Device->Window, x, y);
+			SDL_WarpMouseInWindow(Device->Window,
+					x / Device->ScaleX, y / Device->ScaleY);
 
 			if (SDL_GetRelativeMouseMode()) {
 				// There won't be an event for this warp (details on libsdl-org/SDL/issues/6034)
@@ -300,6 +301,8 @@ private:
 	u32 MouseButtonStates;
 
 	u32 Width, Height;
+	f32 ScaleX = 1.0f, ScaleY = 1.0f;
+	void updateSizeAndScale();
 
 	bool Resizable;
 

irr/src/CMakeLists.txt

@@ -1,3 +1,5 @@
+# When enabling SDL2 by default on macOS, don't forget to change
+# "NSHighResolutionCapable" to true in "Info.plist".
 if(NOT APPLE)
 	set(DEFAULT_SDL2 ON)
 endif()

misc/minetest.exe.manifest

@@ -10,7 +10,9 @@
     </trustInfo>
     <application xmlns="urn:schemas-microsoft-com:asm.v3">
         <windowsSettings>
+            <!-- https://learn.microsoft.com/en-us/windows/win32/hidpi/setting-the-default-dpi-awareness-for-a-process#setting-default-awareness-with-the-application-manifest -->
             <dpiAware xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">true</dpiAware>
+            <dpiAwareness xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">PerMonitorV2</dpiAwareness>
             <activeCodePage xmlns="http://schemas.microsoft.com/SMI/2019/WindowsSettings">UTF-8</activeCodePage>
             <heapType xmlns="http://schemas.microsoft.com/SMI/2020/WindowsSettings">SegmentHeap</heapType>
         </windowsSettings>

src/client/clientlauncher.cpp

@@ -69,6 +69,7 @@ static void dump_start_data(const GameStartData &data)
 ClientLauncher::~ClientLauncher()
 {
 	delete input;
+	g_settings->deregisterChangedCallback("dpi_change_notifier", setting_changed_callback, this);
 	g_settings->deregisterChangedCallback("gui_scaling", setting_changed_callback, this);
 
 	delete g_fontengine;
@@ -129,6 +130,7 @@ bool ClientLauncher::run(GameStartData &start_data, const Settings &cmd_args)
 
 	guienv = m_rendering_engine->get_gui_env();
 	config_guienv();
+	g_settings->registerChangedCallback("dpi_change_notifier", setting_changed_callback, this);
 	g_settings->registerChangedCallback("gui_scaling", setting_changed_callback, this);
 
 	g_fontengine = new FontEngine(guienv);

src/client/fontengine.cpp

@@ -59,7 +59,7 @@ FontEngine::FontEngine(gui::IGUIEnvironment* env) :
 		"mono_font_path", "mono_font_path_bold", "mono_font_path_italic",
 		"mono_font_path_bold_italic",
 		"fallback_font_path",
-		"screen_dpi", "gui_scaling",
+		"dpi_change_notifier", "gui_scaling",
 	};
 
 	for (auto name : settings)

src/client/hud.cpp

@@ -60,6 +60,7 @@ Hud::Hud(Client *client, LocalPlayer *player,
 	this->inventory   = inventory;
 
 	readScalingSetting();
+	g_settings->registerChangedCallback("dpi_change_notifier", setting_changed_callback, this);
 	g_settings->registerChangedCallback("hud_scaling", setting_changed_callback, this);
 
 	for (auto &hbar_color : hbar_colors)
@@ -153,6 +154,7 @@ void Hud::readScalingSetting()
 
 Hud::~Hud()
 {
+	g_settings->deregisterChangedCallback("dpi_change_notifier", setting_changed_callback, this);
 	g_settings->deregisterChangedCallback("hud_scaling", setting_changed_callback, this);
 
 	if (m_selection_mesh)

src/client/inputhandler.cpp

@@ -113,6 +113,15 @@ bool MyEventReceiver::OnEvent(const SEvent &event)
 		return true;
 	}
 
+	if (event.EventType == EET_APPLICATION_EVENT &&
+			event.ApplicationEvent.EventType == EAET_DPI_CHANGED) {
+		// This is a fake setting so that we can use (de)registerChangedCallback
+		// not only to listen for gui/hud_scaling changes, but also for DPI changes.
+		g_settings->setU16("dpi_change_notifier",
+				g_settings->getU16("dpi_change_notifier") + 1);
+		return true;
+	}
+
 	// This is separate from other keyboard handling so that it also works in menus.
 	if (event.EventType == EET_KEY_INPUT_EVENT) {
 		const KeyPress keyCode(event.KeyInput);

src/client/renderingengine.cpp

@@ -462,18 +462,14 @@ const VideoDriverInfo &RenderingEngine::getVideoDriverInfo(irr::video::E_DRIVER_
 
 float RenderingEngine::getDisplayDensity()
 {
+	float user_factor = g_settings->getFloat("display_density_factor", 0.5f, 5.0f);
 #ifndef __ANDROID__
-	static float cached_display_density = [&] {
-		float dpi = get_raw_device()->getDisplayDensity();
-		// fall back to manually specified dpi
-		if (dpi == 0.0f)
-			dpi = g_settings->getFloat("screen_dpi");
-		return dpi / 96.0f;
-	}();
-	return std::max(cached_display_density * g_settings->getFloat("display_density_factor"), 0.5f);
-
+	float dpi = get_raw_device()->getDisplayDensity();
+	if (dpi == 0.0f)
+		dpi = 96.0f;
+	return std::max(dpi / 96.0f * user_factor, 0.5f);
 #else // __ANDROID__
-	return porting::getDisplayDensity();
+	return porting::getDisplayDensity() * user_factor;
 #endif // __ANDROID__
 }
 

src/defaultsettings.cpp

@@ -536,8 +536,8 @@ void set_default_settings()
 	settings->setDefault("server_description", "");
 
 	settings->setDefault("enable_console", "false");
-	settings->setDefault("screen_dpi", "72");
 	settings->setDefault("display_density_factor", "1");
+	settings->setDefault("dpi_change_notifier", "0");
 
 	// Altered settings for macOS
 #if defined(__MACH__) && defined(__APPLE__)