From 416fe35c67352dd23ad698d8f732545caee3d82d Mon Sep 17 00:00:00 2001
From: Jonas Kümmerlin <jonas@kuemmerlin.eu>
Date: Fri, 28 Dec 2018 21:40:36 +0100
Subject: add per-monitor dpi support

---
 alf/alfcompat.cpp | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

(limited to 'alf/alfcompat.cpp')

diff --git a/alf/alfcompat.cpp b/alf/alfcompat.cpp
index 3ffc9f9..e6a9851 100644
--- a/alf/alfcompat.cpp
+++ b/alf/alfcompat.cpp
@@ -41,6 +41,42 @@ fallbackIsAppThemed(void)
     return FALSE;
 }
 
+static UINT WINAPI
+fallbackGetDpiForWindow(HWND win)
+{
+    (void)win;
+
+    UINT dpi = 0;
+
+    HDC hdcScreen = GetDC(NULL);
+    if (hdcScreen) {
+        dpi = GetDeviceCaps(hdcScreen, LOGPIXELSY);
+        ReleaseDC(NULL, hdcScreen);
+    }
+
+    if (!dpi) {
+        dpi = 96; // FIXME! fallback to default DPI
+    }
+
+    return dpi;
+}
+
+static BOOL WINAPI
+fallbackSystemParametersInfoForDpi(UINT uiAction, UINT uiParam, PVOID pvParam, UINT fWinIni, UINT dpi)
+{
+    (void)dpi;
+
+    return SystemParametersInfo(uiAction, uiParam, pvParam, fWinIni);
+}
+
+static BOOL WINAPI
+fallbackAdjustWindowRectExForDpi(LPRECT lpRect, DWORD dwStyle, BOOL bMenu, DWORD dwExStyle, UINT dpi)
+{
+    (void)dpi;
+
+    return AdjustWindowRectEx(lpRect, dwStyle, bMenu, dwExStyle);
+}
+
 ALFCompatFunctions *
 ALF_CreateCompatFuncTable(void)
 {
@@ -61,6 +97,19 @@ ALF_CreateCompatFuncTable(void)
     COMPAT(comctl32.dll, DefSubclassProc, 413, NULL);
     COMPAT(comctl32.dll, RemoveWindowSubclass, 412, NULL);
     COMPAT(user32.dll, GetSystemMetricsForDpi, 0, fallbackGetSystemMetricsForDpi);
+    COMPAT(user32.dll, GetDpiForWindow, 0, fallbackGetDpiForWindow);
+
+    // FIXME: SystemParametersInfoForDpi is Unicode-Only.
+    // Writing a wrapper function would have been The Right Way, but such a function
+    // is yet to be written. So the current practical recommendation is to make
+    // ANSI builds System DPI aware only.
+#ifdef UNICODE
+    COMPAT(user32.dll, SystemParametersInfoForDpi, 0, fallbackSystemParametersInfoForDpi);
+#else
+    compatfn->SystemParametersInfoForDpi = fallbackSystemParametersInfoForDpi;
+#endif
+
+    COMPAT(user32.dll, AdjustWindowRectExForDpi, 0, fallbackAdjustWindowRectExForDpi);
 
     // IsAppThemed would return TRUE even when we're linked against comctl32 v5
     if (ALF_DllGetVersion("comctl32.dll") >= 0x60000) {
-- 
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