9 files changed, 187 insertions, 0 deletions
diff --git a/intern/ghost/intern/GHOST_C-api.cpp b/intern/ghost/intern/GHOST_C-api.cpp
index 41bc735e1e2..ce653188760 100644
--- a/intern/ghost/intern/GHOST_C-api.cpp
+++ b/intern/ghost/intern/GHOST_C-api.cpp
@@ -914,6 +914,12 @@ float GHOST_GetNativePixelSize(GHOST_WindowHandle windowhandle)
 	return 1.0f;
 }
 
+GHOST_TUns16 GHOST_GetDPIHint(GHOST_WindowHandle windowhandle)
+{
+	GHOST_IWindow *window = (GHOST_IWindow *)windowhandle;
+	return window->getDPIHint();
+}
+
 #ifdef WITH_INPUT_IME
 
 void GHOST_BeginIME(GHOST_WindowHandle windowhandle,
diff --git a/intern/ghost/intern/GHOST_SystemWin32.cpp b/intern/ghost/intern/GHOST_SystemWin32.cpp
index 7d55a973f91..240d7ccd2fe 100644
--- a/intern/ghost/intern/GHOST_SystemWin32.cpp
+++ b/intern/ghost/intern/GHOST_SystemWin32.cpp
@@ -111,6 +111,11 @@
 #define VK_MEDIA_PLAY_PAUSE 0xB3
 #endif // VK_MEDIA_PLAY_PAUSE
 
+// Window message newer than Windows 7
+#ifndef WM_DPICHANGED
+#define WM_DPICHANGED 0x02E0
+#endif // WM_DPICHANGED
+
 /* Workaround for some laptop touchpads, some of which seems to
  * have driver issues which makes it so window function receives
  * the message, but PeekMessage doesn't pick those messages for
@@ -152,6 +157,27 @@ static void initRawInput()
 #undef DEVICE_COUNT
 }
 
+#ifndef DPI_ENUMS_DECLARED
+typedef enum PROCESS_DPI_AWARENESS {
+	PROCESS_DPI_UNAWARE = 0,
+	PROCESS_SYSTEM_DPI_AWARE = 1,
+	PROCESS_PER_MONITOR_DPI_AWARE = 2
+} PROCESS_DPI_AWARENESS;
+
+typedef enum MONITOR_DPI_TYPE {
+	MDT_EFFECTIVE_DPI = 0,
+	MDT_ANGULAR_DPI = 1,
+	MDT_RAW_DPI = 2,
+	MDT_DEFAULT = MDT_EFFECTIVE_DPI
+} MONITOR_DPI_TYPE;
+
+#define USER_DEFAULT_SCREEN_DPI 96
+
+#define DPI_ENUMS_DECLARED
+#endif
+typedef HRESULT(API * GHOST_WIN32_SetProcessDpiAwareness)(PROCESS_DPI_AWARENESS);
+typedef BOOL(API * GHOST_WIN32_EnableNonClientDpiScaling)(HWND);
+
 GHOST_SystemWin32::GHOST_SystemWin32()
 	: m_hasPerformanceCounter(false), m_freq(0), m_start(0)
 {
@@ -161,6 +187,18 @@ GHOST_SystemWin32::GHOST_SystemWin32()
 
 	m_consoleStatus = 1;
 
+	// Tell Windows we are per monitor DPI aware. This disables the default
+	// blurry scaling and enables WM_DPICHANGED to allow us to draw at proper DPI.
+	HMODULE m_shcore = ::LoadLibrary("Shcore.dll");
+	if (m_shcore) {
+		GHOST_WIN32_SetProcessDpiAwareness fpSetProcessDpiAwareness =
+			(GHOST_WIN32_SetProcessDpiAwareness) ::GetProcAddress(m_shcore, "SetProcessDpiAwareness");
+
+		if (fpSetProcessDpiAwareness) {
+			fpSetProcessDpiAwareness(PROCESS_PER_MONITOR_DPI_AWARE);
+		}
+	}
+
 	// Check if current keyboard layout uses AltGr and save keylayout ID for
 	// specialized handling if keys like VK_OEM_*. I.e. french keylayout
 	// generates VK_OEM_8 for their exclamation key (key left of right shift)
@@ -922,6 +960,20 @@ LRESULT WINAPI GHOST_SystemWin32::s_wndProc(HWND hwnd, UINT msg, WPARAM wParam,
 	GHOST_ASSERT(system, "GHOST_SystemWin32::s_wndProc(): system not initialized");
 
 	if (hwnd) {
+		if(msg == WM_NCCREATE) {
+			// Tell Windows to automatically handle scaling of non-client areas
+			// such as the caption bar. EnableNonClientDpiScaling was introduced in Windows 10
+			HMODULE m_user32 = ::LoadLibrary("User32.dll");
+			if (m_user32) {
+				GHOST_WIN32_EnableNonClientDpiScaling fpEnableNonClientDpiScaling =
+					(GHOST_WIN32_EnableNonClientDpiScaling) ::GetProcAddress(m_user32, "EnableNonClientDpiScaling");
+
+				if (fpEnableNonClientDpiScaling) {
+					fpEnableNonClientDpiScaling(hwnd);
+				}
+			}
+		}
+
 		GHOST_WindowWin32 *window = (GHOST_WindowWin32 *)::GetWindowLongPtr(hwnd, GWLP_USERDATA);
 		if (window) {
 			switch (msg) {
@@ -1294,6 +1346,32 @@ LRESULT WINAPI GHOST_SystemWin32::s_wndProc(HWND hwnd, UINT msg, WPARAM wParam,
 					}
 
 					break;
+				case WM_DPICHANGED:
+					/* The WM_DPICHANGED message is sent when the effective dots per inch (dpi) for a window has changed.
+					* The DPI is the scale factor for a window. There are multiple events that can cause the DPI to
+					* change such as when the window is moved to a monitor with a different DPI.
+					*/
+					{
+						WORD newYAxisDPI = HIWORD(wParam);
+						WORD newXAxisDPI = LOWORD(wParam);
+						// The suggested new size and position of the window.
+						RECT* const suggestedWindowRect = (RECT*)lParam;
+
+						// Push DPI change event first
+						system->pushEvent(processWindowEvent(GHOST_kEventWindowDPIHintChanged, window));
+						system->dispatchEvents();
+						eventHandled = true;
+
+						// Then move and resize window
+						SetWindowPos(hwnd,
+							NULL,
+							suggestedWindowRect->left,
+							suggestedWindowRect->top,
+							suggestedWindowRect->right - suggestedWindowRect->left,
+							suggestedWindowRect->bottom - suggestedWindowRect->top,
+							SWP_NOZORDER | SWP_NOACTIVATE);
+					}
+					break;
 				////////////////////////////////////////////////////////////////////////
 				// Window events, ignored
 				////////////////////////////////////////////////////////////////////////
diff --git a/intern/ghost/intern/GHOST_Window.h b/intern/ghost/intern/GHOST_Window.h
index d778628ea37..2798bdf72f3 100644
--- a/intern/ghost/intern/GHOST_Window.h
+++ b/intern/ghost/intern/GHOST_Window.h
@@ -295,6 +295,15 @@ public:
 		return 1.0f;
 	}
 
+	/**
+	* Returns the recommended DPI for this window.
+	* \return The recommended DPI for this window.
+	*/
+	virtual inline GHOST_TUns16 getDPIHint()
+	{
+		return 96;
+	}
+
 #ifdef WITH_INPUT_IME
 	virtual void beginIME(GHOST_TInt32 x,
 	                      GHOST_TInt32 y,
diff --git a/intern/ghost/intern/GHOST_WindowSDL.cpp b/intern/ghost/intern/GHOST_WindowSDL.cpp
index 1335c38d977..aeb6188daef 100644
--- a/intern/ghost/intern/GHOST_WindowSDL.cpp
+++ b/intern/ghost/intern/GHOST_WindowSDL.cpp
@@ -563,3 +563,19 @@ GHOST_WindowSDL::setWindowCursorVisibility(bool visible)
 	SDL_ShowCursor(visible);
 	return GHOST_kSuccess;
 }
+
+GHOST_TUns16
+GHOST_WindowSDL::getDPIHint()
+{
+	int displayIndex = SDL_GetWindowDisplayIndex(m_sdl_win);
+	if (displayIndex < 0) {
+		return 96;
+	}
+
+	float ddpi;
+	if (SDL_GetDisplayDPI(displayIndex, &ddpi, NULL, NULL) != 0) {
+		return 96;
+	}
+
+	return (int)ddpi;
+}
diff --git a/intern/ghost/intern/GHOST_WindowSDL.h b/intern/ghost/intern/GHOST_WindowSDL.h
index 5f658e8ad01..96104ec28b4 100644
--- a/intern/ghost/intern/GHOST_WindowSDL.h
+++ b/intern/ghost/intern/GHOST_WindowSDL.h
@@ -168,6 +168,8 @@ protected:
 	GHOST_TSuccess beginFullScreen() const { return GHOST_kFailure; }
 
 	GHOST_TSuccess endFullScreen() const { return GHOST_kFailure; }
+
+	GHOST_TUns16 getDPIHint();
 };
 
 
diff --git a/intern/ghost/intern/GHOST_WindowWin32.cpp b/intern/ghost/intern/GHOST_WindowWin32.cpp
index 7d80aa43a40..fc46164c135 100644
--- a/intern/ghost/intern/GHOST_WindowWin32.cpp
+++ b/intern/ghost/intern/GHOST_WindowWin32.cpp
@@ -92,6 +92,7 @@ GHOST_WindowWin32::GHOST_WindowWin32(GHOST_SystemWin32 *system,
       m_tablet(0),
       m_maxPressure(0),
       m_normal_state(GHOST_kWindowStateNormal),
+	  m_user32(NULL),
       m_parentWindowHwnd(parentwindowhwnd),
       m_debug_context(is_debug)
 {
@@ -965,6 +966,23 @@ void GHOST_WindowWin32::bringTabletContextToFront()
 	}
 }
 
+GHOST_TUns16 GHOST_WindowWin32::getDPIHint()
+{
+	if (!m_user32) {
+		m_user32 = ::LoadLibrary("user32.dll");
+	}
+
+	if (m_user32) {
+		GHOST_WIN32_GetDpiForWindow fpGetDpiForWindow = (GHOST_WIN32_GetDpiForWindow) ::GetProcAddress(m_user32, "GetDpiForWindow");
+
+		if (fpGetDpiForWindow) {
+			return fpGetDpiForWindow(this->m_hWnd);
+		}
+	}
+
+	return USER_DEFAULT_SCREEN_DPI;
+}
+
 /** Reverse the bits in a GHOST_TUns8 */
 static GHOST_TUns8 uns8ReverseBits(GHOST_TUns8 ch)
 {
diff --git a/intern/ghost/intern/GHOST_WindowWin32.h b/intern/ghost/intern/GHOST_WindowWin32.h
index a1cf58c9ceb..75a33951ff4 100644
--- a/intern/ghost/intern/GHOST_WindowWin32.h
+++ b/intern/ghost/intern/GHOST_WindowWin32.h
@@ -58,6 +58,12 @@ typedef BOOL (API * GHOST_WIN32_WTClose)(HCTX);
 typedef BOOL (API * GHOST_WIN32_WTPacket)(HCTX, UINT, LPVOID);
 typedef BOOL (API * GHOST_WIN32_WTOverlap)(HCTX, BOOL);
 
+// typedefs for user32 functions to allow dynamic loading of Windows 10 DPI scaling functions
+typedef UINT(API * GHOST_WIN32_GetDpiForWindow)(HWND);
+#ifndef USER_DEFAULT_SCREEN_DPI
+#define USER_DEFAULT_SCREEN_DPI 96
+#endif // USER_DEFAULT_SCREEN_DPI
+
 /**
  * GHOST window on M$ Windows OSs.
  * \author	Maarten Gribnau
@@ -251,6 +257,8 @@ public:
 
 	GHOST_TSuccess endFullScreen() const {return GHOST_kFailure;}
 
+	GHOST_TUns16 getDPIHint() override;
+
 	/** if the window currently resizing */
 	bool m_inLiveResize;
 
@@ -351,6 +359,9 @@ private:
 
 	GHOST_TWindowState m_normal_state;
 
+	/** user32 dll handle*/
+	HMODULE m_user32;
+
 	/** Hwnd to parent window */
 	GHOST_TEmbedderWindowID m_parentWindowHwnd;
 
diff --git a/intern/ghost/intern/GHOST_WindowX11.cpp b/intern/ghost/intern/GHOST_WindowX11.cpp
index 47fbe1256b1..2019f58251f 100644
--- a/intern/ghost/intern/GHOST_WindowX11.cpp
+++ b/intern/ghost/intern/GHOST_WindowX11.cpp
@@ -56,6 +56,9 @@
 #  include <X11/extensions/XInput2.h>
 #endif
 
+//For DPI value
+#include <X11/Xresource.h>
+
 #if defined(__sun__) || defined(__sun) || defined(__sparc) || defined(__sparc__) || defined(_AIX)
 #  include <strings.h>
 #endif
@@ -68,6 +71,7 @@
 
 #include <algorithm>
 #include <string>
+#include <math.h>
 
 /* For obscure full screen mode stuff
  * lifted verbatim from blut. */
@@ -1672,3 +1676,44 @@ endFullScreen() const
 
 	return GHOST_kSuccess;
 }
+
+GHOST_TUns16
+GHOST_WindowX11::
+getDPIHint()
+{
+	/* Try to read DPI setting set using xrdb */
+	char* resMan = XResourceManagerString(m_display);
+	if (resMan) {
+		XrmDatabase xrdb = XrmGetStringDatabase(resMan);
+		if (xrdb) {
+			char* type = NULL;
+			XrmValue val;
+
+			int success = XrmGetResource(xrdb, "Xft.dpi", "Xft.Dpi", &type, &val);
+			if (success && type) {
+				if (strcmp(type, "String") == 0) {
+					return atoi((char*)val.addr);
+				}
+			}
+		}
+	}
+
+	/* Fallback to calculating DPI using X reported DPI, set using xrandr --dpi */
+	XWindowAttributes attr;
+	if (!XGetWindowAttributes(m_display, m_window, &attr)) {
+		/* Failed to get window attributes, return X11 default DPI */
+		return 96;
+	}
+
+	Screen* screen = attr.screen;
+	int pixelWidth = WidthOfScreen(screen);
+	int pixelHeight = HeightOfScreen(screen);
+	int mmWidth = WidthMMOfScreen(screen);
+	int mmHeight = HeightMMOfScreen(screen);
+
+	double pixelDiagonal = sqrt((pixelWidth * pixelWidth) + (pixelHeight * pixelHeight));
+	double mmDiagonal = sqrt((mmWidth * mmWidth) + (mmHeight * mmHeight));
+	float inchDiagonal = mmDiagonal * 0.039f;
+	int dpi = pixelDiagonal / inchDiagonal;
+	return dpi;
+}
diff --git a/intern/ghost/intern/GHOST_WindowX11.h b/intern/ghost/intern/GHOST_WindowX11.h
index 9380aa9d631..5c54c1e8162 100644
--- a/intern/ghost/intern/GHOST_WindowX11.h
+++ b/intern/ghost/intern/GHOST_WindowX11.h
@@ -235,6 +235,8 @@ public:
 
 	GHOST_TSuccess endFullScreen() const;
 
+	GHOST_TUns16 getDPIHint();
+
 protected:
 	/**
 	 * \param type	The type of rendering context create.