From db6974eda1dc1fada95af97ea53c369db58fda41 Mon Sep 17 00:00:00 2001
From: Jonas Kümmerlin <jonas@kuemmerlin.eu>
Date: Mon, 1 Jun 2020 12:03:57 +0200
Subject: replace windows version checks with compat bits

this saves us from calling GetVersion() and massaging the result
in hot code paths
---
 alf/alfcompat.cpp | 40 ++++++++++++++++++++++++++++++++--------
 1 file changed, 32 insertions(+), 8 deletions(-)

(limited to 'alf/alfcompat.cpp')

diff --git a/alf/alfcompat.cpp b/alf/alfcompat.cpp
index 12a79f4..b986ee8 100644
--- a/alf/alfcompat.cpp
+++ b/alf/alfcompat.cpp
@@ -2,6 +2,8 @@
 
 #include <shlwapi.h>
 
+DWORD _alf_compatBits = 0;
+
 static
 DWORD ALF_DllGetVersion(const char *dll)
 {
@@ -32,7 +34,7 @@ static int WINAPI
 ALF_Compat_fallbackGetSystemMetricsForDpi(int nIndex, UINT dpi)
 {
     (void)dpi;
-    if (!ALF_Compat_IsMinWindowsVersion(4, 0)) {
+    if (!ALF_Compat_Is40()) {
         // old NT does not support several properties, so we fake them
         switch (nIndex) {
             case SM_CXEDGE:
@@ -84,7 +86,7 @@ ALF_Compat_fallbackSystemParametersInfoForDpi(UINT uiAction, UINT uiParam, PVOID
         // we need to provide a fallback even on ANSI systems
 #ifdef UNICODE
         SIZE_T s = sizeof(*ncmw);
-        if (!ALF_Compat_IsMinWindowsVersion(6, 0)) {
+        if (!ALF_Compat_IsVista()) {
             // pre-vista OS doesn't contain last member
             s -= sizeof(ncmw->iPaddedBorderWidth);
             ncmw->iPaddedBorderWidth = 0;
@@ -97,7 +99,7 @@ ALF_Compat_fallbackSystemParametersInfoForDpi(UINT uiAction, UINT uiParam, PVOID
         ZeroMemory(&ncma, sizeof(ncma));
 
         SIZE_T s = sizeof(ncma);
-        if (!ALF_Compat_IsMinWindowsVersion(6, 0)) {
+        if (!ALF_Compat_IsVista()) {
             // pre-vista OS doesn't contain last member
             s -= sizeof(ncma.iPaddedBorderWidth);
             ncma.iPaddedBorderWidth = 0;
@@ -428,17 +430,39 @@ static HMODULE _alf_dll_comctl32 = NULL;
 
 void ALF_LoadCompatFunctions(void)
 {
-    if (ALF_Compat_IsWinNT()) // don't attempt to load uxtheme.dll on non-NT platforms (ugly error on Win32s)
+    // setup compat bits
+    DWORD v = GetVersion();
+    DWORD vMajor = LOBYTE(LOWORD(v));
+    DWORD vMinor = HIBYTE(LOWORD(v));
+
+    if (v < 0x80000000)
+        _alf_compatBits |= ALF_COMPAT_ISNT;
+
+    if (vMajor >= 4)
+        _alf_compatBits |= ALF_COMPAT_IS40;
+
+    if (vMajor >= 5)
+        _alf_compatBits |= ALF_COMPAT_ISW2K;
+
+    if (vMajor > 5 || (vMajor == 5 && vMinor >= 1))
+        _alf_compatBits |= ALF_COMPAT_ISXP;
+
+    if (vMajor >= 6)
+        _alf_compatBits |= ALF_COMPAT_ISVISTA;
+
+    // load compat functions
+    if (ALF_Compat_IsXP()) // don't even attempt to load uxtheme.dll on non-XP
         _alf_dll_uxtheme  = LoadLibraryA("uxtheme.dll");
 
     _alf_dll_user32   = LoadLibraryA("user32.dll");
     _alf_dll_comctl32 = LoadLibraryA("comctl32.dll");
 
-
-    if (ALF_DllGetVersion("comctl32.dll") >= 0x60000)
+    if (ALF_DllGetVersion("comctl32.dll") >= 0x60000) {
+        _alf_compatBits |= ALF_COMPAT_ISCOMCTLV6;
         LOAD_FUNC(uxtheme, IsAppThemed);
-    else
+    } else {
         ALF_Compat_IsAppThemed = ALF_Compat_fallbackIsAppThemed;
+    }
 
     LOAD_FUNC(user32, GetDpiForWindow);
     LOAD_FUNC(user32, AdjustWindowRectExForDpi);
@@ -467,7 +491,7 @@ void ALF_LoadCompatFunctions(void)
     LOAD_FUNC(uxtheme, GetThemeColor);
 
     // initialize helper function for disabled text
-    if (ALF_Compat_IsMinWindowsVersion(4, 0)) {
+    if (ALF_Compat_Is40()) {
         if (GetSystemMetrics(SM_SLOWMACHINE)) {
             ALF_Compat_DrawDisabledText = ALF_Compat_DrawDisabledTextSolid;
         } else {
-- 
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