Add partial support for Windows 8.1 per-monitor DPI

Related to #235.

README.md

@@ -70,6 +70,7 @@ used by the tests and examples and are not required to build the library.
  - Added `GLFW_CONTEXT_NO_ERROR` context hint for `GL_KHR_no_error` support
  - Added `GLFW_TRUE` and `GLFW_FALSE` as client API independent boolean values
  - Removed dependency on external OpenGL or OpenGL ES headers
+ - [Win32] Added support for Windows 8.1 per-monitor DPI
  - [Cocoa] Removed support for OS X 10.6
  - [X11] Bugfix: Monitor connection and disconnection events were not reported
  - [X11] Bugfix: Decoding of UTF-8 text from XIM could continue past the end

src/win32_init.c

@@ -99,6 +99,13 @@ static GLFWbool initLibraries(void)
             GetProcAddress(_glfw.win32.dwmapi.instance, "DwmFlush");
     }
 
+    _glfw.win32.shcore.instance = LoadLibraryW(L"shcore.dll");
+    if (_glfw.win32.shcore.instance)
+    {
+        _glfw.win32.shcore.SetProcessDPIAwareness = (SETPROCESSDPIAWARENESS_T)
+            GetProcAddress(_glfw.win32.shcore.instance, "SetProcessDPIAwareness");
+    }
+
     return GLFW_TRUE;
 }
 
@@ -114,6 +121,9 @@ static void terminateLibraries(void)
 
     if (_glfw.win32.dwmapi.instance)
         FreeLibrary(_glfw.win32.dwmapi.instance);
+
+    if (_glfw.win32.shcore.instance)
+        FreeLibrary(_glfw.win32.shcore.instance);
 }
 
 // Create key code translation tables
@@ -328,7 +338,9 @@ int _glfwPlatformInit(void)
 
     createKeyTables();
 
-    if (_glfw_SetProcessDPIAware)
+    if (_glfw_SetProcessDPIAwareness)
+        _glfw_SetProcessDPIAwareness(PROCESS_PER_MONITOR_DPI_AWARE);
+    else if (_glfw_SetProcessDPIAware)
         _glfw_SetProcessDPIAware();
 
     if (!_glfwRegisterWindowClass())

src/win32_platform.h

@@ -86,6 +86,9 @@
 #ifndef UNICODE_NOCHAR
  #define UNICODE_NOCHAR 0xFFFF
 #endif
+#ifndef WM_DPICHANGED
+ #define WM_DPICHANGED 0x02E0
+#endif
 
 #if WINVER < 0x0601
 typedef struct tagCHANGEFILTERSTRUCT
@@ -99,6 +102,15 @@ typedef struct tagCHANGEFILTERSTRUCT
 #endif
 #endif /*Windows 7*/
 
+#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;
+#endif /*DPI_ENUMS_DECLARED*/
+
 // winmm.dll function pointer typedefs
 typedef MMRESULT (WINAPI * JOYGETDEVCAPS_T)(UINT,LPJOYCAPS,UINT);
 typedef MMRESULT (WINAPI * JOYGETPOS_T)(UINT,LPJOYINFO);
@@ -121,6 +133,10 @@ typedef HRESULT (WINAPI * DWMFLUSH_T)(VOID);
 #define _glfw_DwmIsCompositionEnabled _glfw.win32.dwmapi.DwmIsCompositionEnabled
 #define _glfw_DwmFlush _glfw.win32.dwmapi.DwmFlush
 
+// shcore.dll function pointer typedefs
+typedef HRESULT (WINAPI * SETPROCESSDPIAWARENESS_T)(PROCESS_DPI_AWARENESS);
+#define _glfw_SetProcessDPIAwareness _glfw.win32.shcore.SetProcessDPIAwareness
+
 #include "win32_tls.h"
 #include "winmm_joystick.h"
 
@@ -191,6 +207,12 @@ typedef struct _GLFWlibraryWin32
         DWMFLUSH_T      DwmFlush;
     } dwmapi;
 
+    // shcore.dll
+    struct {
+        HINSTANCE       instance;
+        SETPROCESSDPIAWARENESS_T SetProcessDPIAwareness;
+    } shcore;
+
 } _GLFWlibraryWin32;
 
 

src/win32_window.c

@@ -584,6 +584,19 @@ static LRESULT CALLBACK windowProc(HWND hWnd, UINT uMsg,
             break;
         }
 
+        case WM_DPICHANGED:
+        {
+            RECT* rect = (RECT*) lParam;
+            SetWindowPos(window->win32.handle,
+                         HWND_TOP,
+                         rect->left,
+                         rect->top,
+                         rect->right - rect->left,
+                         rect->bottom - rect->top,
+                         SWP_NOACTIVATE | SWP_NOZORDER);
+            break;
+        }
+
         case WM_DEVICECHANGE:
         {
             if (DBT_DEVNODES_CHANGED == wParam)