Bug 1775310 - Add some accent-color-based dark mode system colors on Windows. r=handyman

This matches UWP apps like Settings on Windows 11, and what we do for other
desktop platforms too.

The system colors match the ones from Win32 otherwise, but using UIUtils we can
access the accent color pallete from UWP apps.

Add a pref just to be safe in any case.

Differential Revision: https://phabricator.services.mozilla.com/D149905

modules/libpref/init/StaticPrefList.yaml

@@ -13758,6 +13758,12 @@
   value: true
   mirror: always
 
+# Whether we allow accessing the UWP system color pallete.
+- name: widget.windows.uwp-system-colors.enabled
+  type: bool
+  value: true
+  mirror: always
+
 - name: widget.windows.window_occlusion_tracking_display_state.enabled
   type: bool
   value: false

widget/windows/WindowsUIUtils.cpp

@@ -382,6 +382,20 @@ static IInspectable* GetUISettings() {
       (void)NS_WARN_IF(FAILED(uiSettings2->add_TextScaleFactorChanged(
           callback.Get(), &unusedToken)));
     }
+
+    ComPtr<IUISettings3> uiSettings3;
+    if (SUCCEEDED(sUiSettingsAsInspectable.As(&uiSettings3))) {
+      EventRegistrationToken unusedToken;
+      auto callback =
+          Callback<ITypedEventHandler<UISettings*, IInspectable*>>([](auto...) {
+            // System color changes change style only.
+            LookAndFeel::NotifyChangedAllWindows(
+                widget::ThemeChangeKind::Style);
+            return S_OK;
+          });
+      (void)NS_WARN_IF(FAILED(
+          uiSettings3->add_ColorValuesChanged(callback.Get(), &unusedToken)));
+    }
   }
 
   return sUiSettingsAsInspectable.Get();
@@ -390,6 +404,89 @@ static IInspectable* GetUISettings() {
 #endif
 }
 
+Maybe<nscolor> WindowsUIUtils::GetAccentColor(int aTone) {
+  MOZ_ASSERT(aTone >= -3);
+  MOZ_ASSERT(aTone <= 3);
+#ifndef __MINGW32__
+  ComPtr<IInspectable> settings = GetUISettings();
+  if (NS_WARN_IF(!settings)) {
+    return Nothing();
+  }
+  ComPtr<IUISettings3> uiSettings3;
+  if (NS_WARN_IF(FAILED(settings.As(&uiSettings3)))) {
+    return Nothing();
+  }
+  Color color;
+  auto colorType = UIColorType(int(UIColorType_Accent) + aTone);
+  if (NS_WARN_IF(FAILED(uiSettings3->GetColorValue(colorType, &color)))) {
+    return Nothing();
+  }
+  return Some(NS_RGBA(color.R, color.G, color.B, color.A));
+#else
+  return Nothing();
+#endif
+}
+
+Maybe<nscolor> WindowsUIUtils::GetSystemColor(ColorScheme aScheme,
+                                              int aSysColor) {
+#ifndef __MINGW32__
+  if (!StaticPrefs::widget_windows_uwp_system_colors_enabled()) {
+    return Nothing();
+  }
+
+  // https://docs.microsoft.com/en-us/windows/apps/design/style/color
+  // Is a useful resource to see which values have decent contrast.
+  if (aSysColor == COLOR_HIGHLIGHT) {
+    int tone = aScheme == ColorScheme::Light ? 0 : -1;
+    if (auto c = GetAccentColor(tone)) {
+      return c;
+    }
+  }
+  if (aSysColor == COLOR_HIGHLIGHTTEXT && GetAccentColor()) {
+    return Some(NS_RGBA(255, 255, 255, 255));
+  }
+  auto knownType = [&]() -> Maybe<UIElementType> {
+#  define MAP(_win32, _uwp) \
+    case COLOR_##_win32:    \
+      return Some(UIElementType_##_uwp)
+    switch (aSysColor) {
+      MAP(HIGHLIGHT, Highlight);
+      MAP(HIGHLIGHTTEXT, HighlightText);
+      MAP(ACTIVECAPTION, ActiveCaption);
+      MAP(BTNFACE, ButtonFace);
+      MAP(BTNTEXT, ButtonText);
+      MAP(CAPTIONTEXT, CaptionText);
+      MAP(GRAYTEXT, GrayText);
+      MAP(HOTLIGHT, Hotlight);
+      MAP(INACTIVECAPTION, InactiveCaption);
+      MAP(INACTIVECAPTIONTEXT, InactiveCaptionText);
+      MAP(WINDOW, Window);
+      MAP(WINDOWTEXT, WindowText);
+      default:
+        return Nothing();
+    }
+#  undef MAP
+  }();
+  if (!knownType) {
+    return Nothing();
+  }
+  ComPtr<IInspectable> settings = GetUISettings();
+  if (NS_WARN_IF(!settings)) {
+    return Nothing();
+  }
+  ComPtr<IUISettings> uiSettings;
+  if (NS_WARN_IF(FAILED(settings.As(&uiSettings)))) {
+    return Nothing();
+  }
+  Color color;
+  if (NS_WARN_IF(FAILED(uiSettings->UIElementColor(*knownType, &color)))) {
+    return Nothing();
+  }
+  return Some(NS_RGBA(color.R, color.G, color.B, color.A));
+#else
+  return Nothing();
+#endif
+}
 bool WindowsUIUtils::ComputeOverlayScrollbars() {
 #ifndef __MINGW32__
   if (!IsWin11OrLater()) {

widget/windows/WindowsUIUtils.h

@@ -8,11 +8,17 @@
 
 #include "nsIWindowsUIUtils.h"
 #include "nsString.h"
+#include "nsColor.h"
+#include "mozilla/Maybe.h"
 #include "mozilla/MozPromise.h"
 
 using SharePromise =
     mozilla::MozPromise<bool, nsresult, /* IsExclusive */ true>;
 
+namespace mozilla {
+enum class ColorScheme : uint8_t;
+}
+
 class WindowsUIUtils final : public nsIWindowsUIUtils {
  public:
   NS_DECL_ISUPPORTS
@@ -26,6 +32,12 @@ class WindowsUIUtils final : public nsIWindowsUIUtils {
   static void UpdateInTabletMode();
   static bool GetInTabletMode();
 
+  // Gets the system accent color, or one of the darker / lighter variants
+  // (darker = -1/2/3, lighter=+1/2/3, values outside of that range are
+  // disallowed).
+  static mozilla::Maybe<nscolor> GetAccentColor(int aTone = 0);
+  static mozilla::Maybe<nscolor> GetSystemColor(mozilla::ColorScheme, int);
+
   // Use LookAndFeel for a cached getter.
   static bool ComputeOverlayScrollbars();
   static double ComputeTextScaleFactor();

widget/windows/nsLookAndFeel.cpp

@@ -22,17 +22,15 @@
 using namespace mozilla;
 using namespace mozilla::widget;
 
-static nsresult GetColorFromTheme(nsUXThemeClass cls, int32_t aPart,
-                                  int32_t aState, int32_t aPropId,
-                                  nscolor& aColor) {
+static Maybe<nscolor> GetColorFromTheme(nsUXThemeClass cls, int32_t aPart,
+                                        int32_t aState, int32_t aPropId) {
   COLORREF color;
   HRESULT hr = GetThemeColor(nsUXThemeData::GetTheme(cls), aPart, aState,
                              aPropId, &color);
   if (hr == S_OK) {
-    aColor = COLOREF_2_NSRGB(color);
-    return NS_OK;
+    return Some(COLOREF_2_NSRGB(color));
   }
-  return NS_ERROR_FAILURE;
+  return Nothing();
 }
 
 static int32_t GetSystemParam(long flag, int32_t def) {
@@ -72,19 +70,12 @@ static nsresult SystemWantsDarkTheme(int32_t& darkThemeEnabled) {
   return rv;
 }
 
-nsLookAndFeel::nsLookAndFeel()
-    : nsXPLookAndFeel(),
-      mHasColorMenuHoverText(false),
-      mHasColorAccent(false),
-      mHasColorAccentText(false),
-      mHasColorMediaText(false),
-      mHasColorCommunicationsText(false),
-      mInitialized(false) {
+nsLookAndFeel::nsLookAndFeel() {
   mozilla::Telemetry::Accumulate(mozilla::Telemetry::TOUCH_ENABLED_DEVICE,
                                  WinUtils::IsTouchDeviceSupportPresent());
 }
 
-nsLookAndFeel::~nsLookAndFeel() {}
+nsLookAndFeel::~nsLookAndFeel() = default;
 
 void nsLookAndFeel::NativeInit() { EnsureInit(); }
 
@@ -94,11 +85,47 @@ void nsLookAndFeel::RefreshImpl() {
   nsXPLookAndFeel::RefreshImpl();
 }
 
+static bool IsHighlightColor(StyleSystemColor aColor) {
+  switch (aColor) {
+    case StyleSystemColor::Highlight:
+    case StyleSystemColor::Selecteditem:
+    case StyleSystemColor::MozMenuhover:
+    case StyleSystemColor::IMESelectedRawTextBackground:
+    case StyleSystemColor::IMESelectedConvertedTextBackground:
+      return true;
+    default:
+      return false;
+  }
+}
+
+static bool IsHighlightTextColor(StyleSystemColor aColor) {
+  switch (aColor) {
+    case StyleSystemColor::Highlighttext:
+    case StyleSystemColor::Selecteditemtext:
+    case StyleSystemColor::MozMenuhovertext:
+    case StyleSystemColor::MozMenubarhovertext:
+    case StyleSystemColor::IMESelectedRawTextForeground:
+    case StyleSystemColor::IMESelectedConvertedTextForeground:
+    case StyleSystemColor::MozDragtargetzone:
+      return true;
+    default:
+      return false;
+  }
+}
+
 nsresult nsLookAndFeel::NativeGetColor(ColorID aID, ColorScheme aScheme,
                                        nscolor& aColor) {
   EnsureInit();
 
   if (aScheme == ColorScheme::Dark) {
+    if (IsHighlightColor(aID) && mDarkHighlight) {
+      aColor = *mDarkHighlight;
+      return NS_OK;
+    }
+    if (IsHighlightTextColor(aID) && mDarkHighlightText) {
+      aColor = *mDarkHighlightText;
+      return NS_OK;
+    }
     if (auto color = GenericDarkColor(aID)) {
       aColor = *color;
       return NS_OK;
@@ -171,13 +198,6 @@ nsresult nsLookAndFeel::NativeGetColor(ColorID aID, ColorScheme aScheme,
     case ColorID::Graytext:
       idx = COLOR_GRAYTEXT;
       break;
-    case ColorID::Highlight:
-    case ColorID::Selecteditem:
-    case ColorID::MozMenuhover:
-    case ColorID::IMESelectedRawTextBackground:
-    case ColorID::IMESelectedConvertedTextBackground:
-      idx = COLOR_HIGHLIGHT;
-      break;
     case ColorID::MozMenubarhovertext:
       if (!nsUXThemeData::IsAppThemed()) {
         idx = nsUXThemeData::AreFlatMenusEnabled() ? COLOR_HIGHLIGHTTEXT
@@ -186,15 +206,10 @@ nsresult nsLookAndFeel::NativeGetColor(ColorID aID, ColorScheme aScheme,
       }
       [[fallthrough]];
     case ColorID::MozMenuhovertext:
-      if (mHasColorMenuHoverText) {
-        aColor = mColorMenuHoverText;
+      if (mColorMenuHoverText) {
+        aColor = *mColorMenuHoverText;
         return NS_OK;
       }
-      [[fallthrough]];
-    case ColorID::Highlighttext:
-    case ColorID::Selecteditemtext:
-    case ColorID::IMESelectedRawTextForeground:
-    case ColorID::IMESelectedConvertedTextForeground:
       idx = COLOR_HIGHLIGHTTEXT;
       break;
     case ColorID::Inactiveborder:
@@ -261,31 +276,31 @@ nsresult nsLookAndFeel::NativeGetColor(ColorID aID, ColorScheme aScheme,
       idx = COLOR_3DFACE;
       break;
     case ColorID::Accentcolor:
-      if (mHasColorAccent) {
-        aColor = mColorAccent;
+      if (mColorAccent) {
+        aColor = *mColorAccent;
       } else {
         // Seems to be the default color (hardcoded because of bug 1065998)
         aColor = NS_RGB(0, 120, 215);
       }
       return NS_OK;
     case ColorID::Accentcolortext:
-      if (mHasColorAccentText) {
-        aColor = mColorAccentText;
+      if (mColorAccentText) {
+        aColor = *mColorAccentText;
       } else {
         aColor = NS_RGB(255, 255, 255);
       }
       return NS_OK;
     case ColorID::MozWinMediatext:
-      if (mHasColorMediaText) {
-        aColor = mColorMediaText;
+      if (mColorMediaText) {
+        aColor = *mColorMediaText;
         return NS_OK;
       }
       // if we've gotten here just return -moz-dialogtext instead
       idx = COLOR_WINDOWTEXT;
       break;
     case ColorID::MozWinCommunicationstext:
-      if (mHasColorCommunicationsText) {
-        aColor = mColorCommunicationsText;
+      if (mColorCommunicationsText) {
+        aColor = *mColorCommunicationsText;
         return NS_OK;
       }
       // if we've gotten here just return -moz-dialogtext instead
@@ -296,9 +311,6 @@ nsresult nsLookAndFeel::NativeGetColor(ColorID aID, ColorScheme aScheme,
     case ColorID::MozColheaderhovertext:
       idx = COLOR_WINDOWTEXT;
       break;
-    case ColorID::MozDragtargetzone:
-      idx = COLOR_HIGHLIGHTTEXT;
-      break;
     case ColorID::MozButtondefault:
       idx = COLOR_3DDKSHADOW;
       break;
@@ -306,8 +318,14 @@ nsresult nsLookAndFeel::NativeGetColor(ColorID aID, ColorScheme aScheme,
       idx = COLOR_HOTLIGHT;
       break;
     default:
-      idx = COLOR_WINDOW;
-      res = NS_ERROR_FAILURE;
+      if (IsHighlightColor(aID)) {
+        idx = COLOR_HIGHLIGHT;
+      } else if (IsHighlightTextColor(aID)) {
+        idx = COLOR_HIGHLIGHTTEXT;
+      } else {
+        idx = COLOR_WINDOW;
+        res = NS_ERROR_FAILURE;
+      }
       break;
   }
 
@@ -317,6 +335,7 @@ nsresult nsLookAndFeel::NativeGetColor(ColorID aID, ColorScheme aScheme,
 }
 
 nsresult nsLookAndFeel::NativeGetInt(IntID aID, int32_t& aResult) {
+  EnsureInit();
   nsresult res = NS_OK;
 
   switch (aID) {
@@ -409,12 +428,17 @@ nsresult nsLookAndFeel::NativeGetInt(IntID aID, int32_t& aResult) {
       aResult = gfxWindowsPlatform::GetPlatform()->DwmCompositionEnabled();
       break;
     case IntID::WindowsAccentColorInTitlebar: {
-      nscolor unused;
-      if (NS_WARN_IF(NS_FAILED(GetAccentColor(unused)))) {
-        aResult = 0;
+      aResult = 0;
+      if (NS_WARN_IF(!mColorAccent)) {
         break;
       }
 
+      if (!mDwmKey) {
+        mDwmKey = do_CreateInstance("@mozilla.org/windows-registry-key;1");
+        if (!mDwmKey) {
+          break;
+        }
+      }
       uint32_t colorPrevalence;
       nsresult rv = mDwmKey->Open(nsIWindowsRegKey::ROOT_KEY_CURRENT_USER,
                                   u"SOFTWARE\\Microsoft\\Windows\\DWM"_ns,
@@ -699,48 +723,10 @@ char16_t nsLookAndFeel::GetPasswordCharacterImpl() {
   return UNICODE_BLACK_CIRCLE_CHAR;
 }
 
-/* static */
-nsresult nsLookAndFeel::GetAccentColor(nscolor& aColor) {
-  nsresult rv;
-
-  if (!mDwmKey) {
-    mDwmKey = do_CreateInstance("@mozilla.org/windows-registry-key;1", &rv);
-    if (NS_WARN_IF(NS_FAILED(rv))) {
-      return rv;
-    }
+static Maybe<nscolor> GetAccentColorText(const Maybe<nscolor>& aAccentColor) {
+  if (!aAccentColor) {
+    return Nothing();
   }
-
-  rv = mDwmKey->Open(nsIWindowsRegKey::ROOT_KEY_CURRENT_USER,
-                     u"SOFTWARE\\Microsoft\\Windows\\DWM"_ns,
-                     nsIWindowsRegKey::ACCESS_QUERY_VALUE);
-  if (NS_WARN_IF(NS_FAILED(rv))) {
-    return rv;
-  }
-
-  uint32_t accentColor;
-  if (NS_SUCCEEDED(mDwmKey->ReadIntValue(u"AccentColor"_ns, &accentColor))) {
-    // The order of the color components in the DWORD stored in the registry
-    // happens to be the same order as we store the components in nscolor
-    // so we can just assign directly here.
-    aColor = accentColor;
-    rv = NS_OK;
-  } else {
-    rv = NS_ERROR_NOT_AVAILABLE;
-  }
-
-  mDwmKey->Close();
-
-  return rv;
-}
-
-/* static */
-nsresult nsLookAndFeel::GetAccentColorText(nscolor& aColor) {
-  nscolor accentColor;
-  nsresult rv = GetAccentColor(accentColor);
-  if (NS_WARN_IF(NS_FAILED(rv))) {
-    return rv;
-  }
-
   // We want the color that we return for text that will be drawn over
   // a background that has the accent color to have good contrast with
   // the accent color.  Windows itself uses either white or black text
@@ -749,14 +735,11 @@ nsresult nsLookAndFeel::GetAccentColorText(nscolor& aColor) {
   // value.  This algorithm should match what Windows does.  It comes from:
   //
   // https://docs.microsoft.com/en-us/windows/uwp/style/color
-
-  float luminance = (NS_GET_R(accentColor) * 2 + NS_GET_G(accentColor) * 5 +
-                     NS_GET_B(accentColor)) /
+  float luminance = (NS_GET_R(*aAccentColor) * 2 + NS_GET_G(*aAccentColor) * 5 +
+                     NS_GET_B(*aAccentColor)) /
                     8;
 
-  aColor = (luminance <= 128) ? NS_RGB(255, 255, 255) : NS_RGB(0, 0, 0);
-
-  return NS_OK;
+  return Some(luminance <= 128 ? NS_RGB(255, 255, 255) : NS_RGB(0, 0, 0));
 }
 
 nscolor nsLookAndFeel::GetColorForSysColorIndex(int index) {
@@ -770,33 +753,33 @@ void nsLookAndFeel::EnsureInit() {
   }
   mInitialized = true;
 
-  nsresult res;
-
-  res = GetAccentColor(mColorAccent);
-  mHasColorAccent = NS_SUCCEEDED(res);
-
-  res = GetAccentColorText(mColorAccentText);
-  mHasColorAccentText = NS_SUCCEEDED(res);
+  mColorAccent = WindowsUIUtils::GetAccentColor();
+  mColorAccentText = GetAccentColorText(mColorAccent);
 
   if (nsUXThemeData::IsAppThemed()) {
-    res = ::GetColorFromTheme(eUXMenu, MENU_POPUPITEM, MPI_HOT, TMT_TEXTCOLOR,
-                              mColorMenuHoverText);
-    mHasColorMenuHoverText = NS_SUCCEEDED(res);
-
-    res = ::GetColorFromTheme(eUXMediaToolbar, TP_BUTTON, TS_NORMAL,
-                              TMT_TEXTCOLOR, mColorMediaText);
-    mHasColorMediaText = NS_SUCCEEDED(res);
-
-    res = ::GetColorFromTheme(eUXCommunicationsToolbar, TP_BUTTON, TS_NORMAL,
-                              TMT_TEXTCOLOR, mColorCommunicationsText);
-    mHasColorCommunicationsText = NS_SUCCEEDED(res);
+    mColorMenuHoverText =
+        ::GetColorFromTheme(eUXMenu, MENU_POPUPITEM, MPI_HOT, TMT_TEXTCOLOR);
+    mColorMediaText = ::GetColorFromTheme(eUXMediaToolbar, TP_BUTTON, TS_NORMAL,
+                                          TMT_TEXTCOLOR);
+    mColorCommunicationsText = ::GetColorFromTheme(
+        eUXCommunicationsToolbar, TP_BUTTON, TS_NORMAL, TMT_TEXTCOLOR);
   }
 
   // Fill out the sys color table.
   for (int i = SYS_COLOR_MIN; i <= SYS_COLOR_MAX; ++i) {
-    DWORD color = ::GetSysColor(i);
-    mSysColorTable[i - SYS_COLOR_MIN] = COLOREF_2_NSRGB(color);
+    mSysColorTable[i - SYS_COLOR_MIN] = [&] {
+      if (auto c = WindowsUIUtils::GetSystemColor(ColorScheme::Light, i)) {
+        return *c;
+      }
+      DWORD color = ::GetSysColor(i);
+      return COLOREF_2_NSRGB(color);
+    }();
   }
 
+  mDarkHighlight =
+      WindowsUIUtils::GetSystemColor(ColorScheme::Dark, COLOR_HIGHLIGHT);
+  mDarkHighlightText =
+      WindowsUIUtils::GetSystemColor(ColorScheme::Dark, COLOR_HIGHLIGHTTEXT);
+
   RecordTelemetry();
 }

widget/windows/nsLookAndFeel.h

@@ -58,22 +58,6 @@ class nsLookAndFeel final : public nsXPLookAndFeel {
   char16_t GetPasswordCharacterImpl() override;
 
  private:
-  /**
-   * Fetches the Windows accent color from the Windows settings if
-   * the accent color is set to apply to the title bar, otherwise
-   * returns an error code.
-   */
-  nsresult GetAccentColor(nscolor& aColor);
-
-  /**
-   * If the Windows accent color from the Windows settings is set
-   * to apply to the title bar, this computes the color that should
-   * be used for text that is to be written over a background that has
-   * the accent color.  Otherwise, (if the accent color should not
-   * apply to the title bar) this returns an error code.
-   */
-  nsresult GetAccentColorText(nscolor& aColor);
-
   nscolor GetColorForSysColorIndex(int index);
 
   LookAndFeelFont GetLookAndFeelFontInternal(const LOGFONTW& aLogFont,
@@ -82,20 +66,18 @@ class nsLookAndFeel final : public nsXPLookAndFeel {
   LookAndFeelFont GetLookAndFeelFont(LookAndFeel::FontID anID);
 
   // Cached colors and flags indicating success in their retrieval.
-  nscolor mColorMenuHoverText;
-  bool mHasColorMenuHoverText;
-  nscolor mColorAccent;
-  bool mHasColorAccent;
-  nscolor mColorAccentText;
-  bool mHasColorAccentText;
-  nscolor mColorMediaText;
-  bool mHasColorMediaText;
-  nscolor mColorCommunicationsText;
-  bool mHasColorCommunicationsText;
+  mozilla::Maybe<nscolor> mColorMenuHoverText;
+  mozilla::Maybe<nscolor> mColorAccent;
+  mozilla::Maybe<nscolor> mColorAccentText;
+  mozilla::Maybe<nscolor> mColorMediaText;
+  mozilla::Maybe<nscolor> mColorCommunicationsText;
+
+  mozilla::Maybe<nscolor> mDarkHighlight;
+  mozilla::Maybe<nscolor> mDarkHighlightText;
 
   nscolor mSysColorTable[SYS_COLOR_COUNT];
 
-  bool mInitialized;
+  bool mInitialized = false;
 
   void EnsureInit();