Add -moz-win-accentcolor(text)

#31 points 1 and 2

5 files changed, 122 insertions, 5 deletions

diff --git a/widget/LookAndFeel.h b/widget/LookAndFeel.h
index b7a05748ed..8d510f69fe 100644
--- a/widget/LookAndFeel.h
+++ b/widget/LookAndFeel.h
@@ -158,6 +158,10 @@ public:
 
     // vista rebars
 
+    // accent color for title bar
+    eColorID__moz_win_accentcolor,
+    // color from drawing text over the accent color
+    eColorID__moz_win_accentcolortext,
     // media rebar text
     eColorID__moz_win_mediatext,
     // communications rebar text
diff --git a/widget/nsXPLookAndFeel.cpp b/widget/nsXPLookAndFeel.cpp
index 54c6198294..28e1c2c5a7 100644
--- a/widget/nsXPLookAndFeel.cpp
+++ b/widget/nsXPLookAndFeel.cpp
@@ -647,6 +647,11 @@ nsXPLookAndFeel::GetStandinForNativeColor(ColorID aID)
       result = NS_RGB(0x3F, 0x3F, 0x3F); break;
     case eColorID__moz_mac_secondaryhighlight:
       result = NS_RGB(0xD4, 0xD4, 0xD4); break;
+    case eColorID__moz_win_accentcolor:
+      // Seems to be the default color (hardcoded because of bug 1065998)
+      result = NS_RGB(0x9E, 0x9E, 0x9E); break;
+    case eColorID__moz_win_accentcolortext:
+      result = NS_RGB(0x00, 0x00, 0x00); break;
     case eColorID__moz_win_mediatext:
       result = NS_RGB(0xFF, 0xFF, 0xFF); break;
     case eColorID__moz_win_communicationstext:
diff --git a/widget/windows/nsLookAndFeel.cpp b/widget/windows/nsLookAndFeel.cpp
index 60e351323d..63af653067 100644
--- a/widget/windows/nsLookAndFeel.cpp
+++ b/widget/windows/nsLookAndFeel.cpp
@@ -267,6 +267,23 @@ nsLookAndFeel::NativeGetColor(ColorID aID, nscolor &aColor)
     case eColorID__moz_cellhighlight:
       idx = COLOR_3DFACE;
       break;
+    case eColorID__moz_win_accentcolor:
+      res = GetAccentColor(aColor);
+      if (NS_SUCCEEDED(res)) {
+        return res;
+      }
+      NS_WARNING("Using fallback for accent color - UI code failed to use the "
+                 "-moz-windows-accent-color-applies media query properly");
+      // Seems to be the default color (hardcoded because of bug 1065998)
+      aColor = NS_RGB(158, 158, 158);
+      return NS_OK;
+    case eColorID__moz_win_accentcolortext:
+      res = GetAccentColorText(aColor);
+      if (NS_SUCCEEDED(res)) {
+        return res;
+      }
+      aColor = NS_RGB(0, 0, 0);
+      return NS_OK;
     case eColorID__moz_win_mediatext:
       if (IsVistaOrLater() && IsAppThemed()) {
         res = ::GetColorFromTheme(eUXMediaToolbar,
@@ -705,3 +722,68 @@ nsLookAndFeel::SetIntCacheImpl(const nsTArray<LookAndFeelInt>& aLookAndFeelIntCa
   }
 }
 
+/* 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;
+    }
+  }
+
+  rv = mDwmKey->Open(nsIWindowsRegKey::ROOT_KEY_CURRENT_USER,
+                     NS_LITERAL_STRING("SOFTWARE\\Microsoft\\Windows\\DWM"),
+                     nsIWindowsRegKey::ACCESS_QUERY_VALUE);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  // The ColorPrevalence value is set to 1 when the "Show color on title bar"
+  // setting in the Color section of Window's Personalization settings is
+  // turned on.
+  uint32_t accentColor, colorPrevalence;
+  if (NS_SUCCEEDED(mDwmKey->ReadIntValue(NS_LITERAL_STRING("AccentColor"), &accentColor)) &&
+      NS_SUCCEEDED(mDwmKey->ReadIntValue(NS_LITERAL_STRING("ColorPrevalence"), &colorPrevalence)) &&
+      colorPrevalence == 1) {
+    // 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
+  // depending on how light or dark the accent color is.  We do the same
+  // here based on the luminance of the accent color with a threshhold
+  // value and formula that are specified in the UWP guidelines.
+  // See: 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)) / 8;
+
+  aColor = (luminance <= 128) ? NS_RGB(255, 255, 255) : NS_RGB(0, 0, 0);
+
+  return NS_OK;
+}
diff --git a/widget/windows/nsLookAndFeel.h b/widget/windows/nsLookAndFeel.h
index bc2d158b6f..29b6f4b780 100644
--- a/widget/windows/nsLookAndFeel.h
+++ b/widget/windows/nsLookAndFeel.h
@@ -6,6 +6,7 @@
 #ifndef __nsLookAndFeel
 #define __nsLookAndFeel
 #include "nsXPLookAndFeel.h"
+#include "nsIWindowsRegKey.h"
 
 /*
  * Gesture System Metrics
@@ -59,7 +60,25 @@ public:
   virtual void SetIntCacheImpl(const nsTArray<LookAndFeelInt>& aLookAndFeelIntCache);
 
 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);
+
   int32_t mUseAccessibilityTheme;
+  
+  nsCOMPtr<nsIWindowsRegKey> mDwmKey;
 };
 
 #endif
diff --git a/widget/windows/nsWindow.cpp b/widget/windows/nsWindow.cpp
index 2172f2aa0b..dd4f359f73 100644
--- a/widget/windows/nsWindow.cpp
+++ b/widget/windows/nsWindow.cpp
@@ -5084,12 +5084,19 @@ nsWindow::ProcessMessage(UINT msg, WPARAM& wParam, LPARAM& lParam,
 
     case WM_SETTINGCHANGE:
     {
-      if (IsWin10OrLater() && mWindowType == eWindowType_invisible && lParam) {
+      if (lParam) {
         auto lParamString = reinterpret_cast<const wchar_t*>(lParam);
-        if (!wcscmp(lParamString, L"UserInteractionMode")) {
-          nsCOMPtr<nsIWindowsUIUtils> uiUtils(do_GetService("@mozilla.org/windows-ui-utils;1"));
-          if (uiUtils) {
-            uiUtils->UpdateTabletModeState();
+        if (!wcscmp(lParamString, L"ImmersiveColorSet")) {
+          // WM_SYSCOLORCHANGE is not dispatched for accent color changes
+          OnSysColorChanged();
+          break;
+        }
+        if (IsWin10OrLater() && mWindowType == eWindowType_invisible) {
+          if (!wcscmp(lParamString, L"UserInteractionMode")) {
+            nsCOMPtr<nsIWindowsUIUtils> uiUtils(do_GetService("@mozilla.org/windows-ui-utils;1"));
+            if (uiUtils) {
+              uiUtils->UpdateTabletModeState();
+            }
           }
         }
       }