From e603a2d8d966192e276bf5aeac637424ff3a8442 Mon Sep 17 00:00:00 2001
From: Leonard Hecker <lhecker@microsoft.com>
Date: Thu, 10 Nov 2022 14:39:22 +0100
Subject: [PATCH] wip

---
 src/internal/stubs.cpp | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/src/internal/stubs.cpp b/src/internal/stubs.cpp
index f92f4096969..3ab48a39e3a 100644
--- a/src/internal/stubs.cpp
+++ b/src/internal/stubs.cpp
@@ -5,6 +5,8 @@
 
 #include "../inc/conint.h"
 
+#include <dwmapi.h>
+
 using namespace Microsoft::Console::Internal;
 
 [[nodiscard]] HRESULT ProcessPolicy::CheckAppModelPolicy(const HANDLE /*hToken*/,
@@ -21,7 +23,28 @@ using namespace Microsoft::Console::Internal;
     return S_OK;
 }
 
-[[nodiscard]] HRESULT Theming::TrySetDarkMode(HWND /*hwnd*/) noexcept
+[[nodiscard]] HRESULT Theming::TrySetDarkMode(HWND hwnd) noexcept
 {
+    static const auto ShouldAppsUseDarkMode = []() {
+        static const auto uxtheme = LoadLibraryExW(L"uxtheme.dll", nullptr, LOAD_LIBRARY_SEARCH_SYSTEM32);
+        return uxtheme ? reinterpret_cast<bool(WINAPI*)()>(GetProcAddress(uxtheme, MAKEINTRESOURCEA(132))) : nullptr;
+    }();
+    static const auto IsHighContrastOn = []() {
+        bool highContrast = false;
+        HIGHCONTRAST hc{ sizeof(hc) };
+        if (SystemParametersInfoW(SPI_GETHIGHCONTRAST, sizeof(hc), &hc, 0))
+        {
+            highContrast = (HCF_HIGHCONTRASTON & hc.dwFlags) != 0;
+        }
+        return highContrast;
+    };
+
+    if (ShouldAppsUseDarkMode)
+    {
+        const BOOL useDarkMode = ShouldAppsUseDarkMode() && !IsHighContrastOn();
+        SetWindowTheme(hwnd, useDarkMode ? L"DarkMode_Explorer" : L"", nullptr);
+        DwmSetWindowAttribute(hwnd, DWMWA_USE_IMMERSIVE_DARK_MODE, &useDarkMode, sizeof(useDarkMode));
+    }
+
     return S_FALSE;
 }