From cd14cb3f5bbf87a9660091207bdf1e714bdc34cf Mon Sep 17 00:00:00 2001
From: trustable-code <krauter.simon@arcor.de>
Date: Sat, 17 Aug 2019 13:31:52 +0200
Subject: Fix #46 Apps don't run on Windows 7 any more

---
 src/nigui/private/windows/platform_impl.nim | 21 ++++++++++++++++-----
 src/nigui/private/windows/windows.nim       |  9 ++++-----
 2 files changed, 20 insertions(+), 10 deletions(-)

(limited to 'src')

diff --git a/src/nigui/private/windows/platform_impl.nim b/src/nigui/private/windows/platform_impl.nim
index 6a04c46..fba9f65 100755
--- a/src/nigui/private/windows/platform_impl.nim
+++ b/src/nigui/private/windows/platform_impl.nim
@@ -8,6 +8,7 @@
 # math, os, strutils, times are imported by nigui.nim
 import windows
 import tables
+import dynlib
 
 
 # ----------------------------------------------------------------------------------------
@@ -36,7 +37,7 @@ proc pCheckGdiplusStatus(status: int32, showAlert = true) =
       pRaiseLastOSError(showAlert)
     else:
       raiseError("A GDI+ error occured. (Status: " & $status & ")", showAlert)
-  
+
 proc pColorToRGB32(color: Color): RGB32 =
   result.red = color.red
   result.green = color.green
@@ -367,6 +368,19 @@ proc pGetTextSize(hDC, font: pointer, text: string): Size =
 #                                    App Procedures
 # ----------------------------------------------------------------------------------------
 
+proc pEnableHighDpiSupport() =
+  let shcoreLib = loadLib("Shcore.dll")
+  if shcoreLib == nil:
+    return
+  let SetProcessDpiAwareness = cast[SetProcessDpiAwarenessType](shcoreLib.symAddr("SetProcessDpiAwareness"))
+  discard SetProcessDpiAwareness(PROCESS_SYSTEM_DPI_AWARE)
+  let user32Lib = loadLib("User32.dll")
+  if user32Lib == nil:
+    return
+  let GetDpiForWindow = cast[GetDpiForWindowType](user32Lib.symAddr("GetDpiForWindow"))
+  fSystemDpi = GetDpiForWindow(pDefaultParentWindow)
+  fDefaultFontSize = defaultFontSizeForDefaultDpi.scaleToDpi
+
 proc init(app: App) =
   pInitGdiplus()
   pEnableVisualStyles()
@@ -378,10 +392,7 @@ proc init(app: App) =
   app.defaultBackgroundColor = GetSysColor(COLOR_BTNFACE).pRgb32ToColor()
   app.defaultFontFamily = "Arial"
   fScrollbarSize = GetSystemMetrics(SM_CXVSCROLL)
-  # High DPI support:
-  discard SetProcessDpiAwareness(PROCESS_SYSTEM_DPI_AWARE)
-  fSystemDpi = GetDpiForWindow(pDefaultParentWindow)
-  fDefaultFontSize = defaultFontSizeForDefaultDpi.scaleToDpi
+  pEnableHighDpiSupport()
 
 proc runMainLoop() =
   var msg: Msg
diff --git a/src/nigui/private/windows/windows.nim b/src/nigui/private/windows/windows.nim
index e43bc56..638c701 100755
--- a/src/nigui/private/windows/windows.nim
+++ b/src/nigui/private/windows/windows.nim
@@ -24,7 +24,6 @@
 {.pragma: libShell32, stdcall, dynlib: "Shell32.dll".}
 {.pragma: libGdiplus, stdcall, dynlib: "Gdiplus.dll".}
 {.pragma: libComdlg32, stdcall, dynlib: "Comdlg32.dll".}
-{.pragma: libShcore, stdcall, dynlib: "Shcore.dll".}
 
 
 # ----------------------------------------------------------------------------------------
@@ -431,7 +430,8 @@ proc GetClipboardData*(uFormat: int32): pointer {.importc: "GetClipboardData", l
 proc SetClipboardData*(uFormat: int32, hMem: pointer): pointer {.importc: "SetClipboardData", libUser32.}
 proc EmptyClipboard*(): bool {.importc: "EmptyClipboard", libUser32.}
 proc MapVirtualKeyW*(uCode, uMapType: int32): int32 {.importc: "MapVirtualKeyW", libUser32.}
-proc GetDpiForWindow*(hWnd: pointer): int32 {.importc: "GetDpiForWindow", libUser32.}
+
+type GetDpiForWindowType* = proc(hWnd: pointer): int32 {.gcsafe, stdcall.} # not available on Windows 7
 
 when defined(cpu64):
   # Only available on 64-bit Windows:
@@ -529,8 +529,7 @@ proc GetSaveFileNameW*(lpofn: var OpenFileName): bool {.importc: "GetSaveFileNam
 
 
 # ----------------------------------------------------------------------------------------
-#                                       Comdlg32 Procs
+#                                       Shcore Procs
 # ----------------------------------------------------------------------------------------
 
-proc SetProcessDpiAwareness*(value: int32): int32 {.importc: "SetProcessDpiAwareness", libShcore.}
-
+type SetProcessDpiAwarenessType* = proc(value: int32): int32 {.gcsafe, stdcall.} # not available on Windows 7
-- 
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