Bug 1344910, part 2 - Add a '-moz-win-accentcolortext' color keyword …

…to color text that will be drawn over an accent color background. r=jimm

on a CLOSED TREE, because it failed to autoland before bug 1344917 landed.

MozReview-Commit-ID: 9l2NsQlewIJ

layout/style/nsCSSKeywordList.h

@@ -748,6 +748,7 @@ CSS_KEY(-moz-win-media-toolbox, _moz_win_media_toolbox)
 CSS_KEY(-moz-win-communications-toolbox, _moz_win_communications_toolbox)
 CSS_KEY(-moz-win-browsertabbar-toolbox, _moz_win_browsertabbar_toolbox)
 CSS_KEY(-moz-win-accentcolor, _moz_win_accentcolor)
+CSS_KEY(-moz-win-accentcolortext, _moz_win_accentcolortext)
 CSS_KEY(-moz-win-mediatext, _moz_win_mediatext)
 CSS_KEY(-moz-win-communicationstext, _moz_win_communicationstext)
 CSS_KEY(-moz-win-glass, _moz_win_glass)

layout/style/nsCSSProps.cpp

@@ -1138,6 +1138,7 @@ const KTableEntry nsCSSProps::kColorKTable[] = {
   { eCSSKeyword__moz_visitedhyperlinktext, NS_COLOR_MOZ_VISITEDHYPERLINKTEXT },
   { eCSSKeyword_currentcolor, NS_COLOR_CURRENTCOLOR },
   { eCSSKeyword__moz_win_accentcolor, LookAndFeel::eColorID__moz_win_accentcolor },
+  { eCSSKeyword__moz_win_accentcolortext, LookAndFeel::eColorID__moz_win_accentcolortext },
   { eCSSKeyword__moz_win_mediatext, LookAndFeel::eColorID__moz_win_mediatext },
   { eCSSKeyword__moz_win_communicationstext, LookAndFeel::eColorID__moz_win_communicationstext },
   { eCSSKeyword__moz_nativehyperlinktext, LookAndFeel::eColorID__moz_nativehyperlinktext },

widget/LookAndFeel.h

@@ -160,6 +160,8 @@ class LookAndFeel
 
     // 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

widget/nsXPLookAndFeel.cpp

@@ -661,6 +661,8 @@ nsXPLookAndFeel::GetStandinForNativeColor(ColorID aID)
     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:

widget/windows/nsLookAndFeel.cpp

@@ -272,6 +272,13 @@ nsLookAndFeel::NativeGetColor(ColorID aID, nscolor &aColor)
       // 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 (IsAppThemed()) {
         res = ::GetColorFromTheme(eUXMediaToolbar,
@@ -802,3 +809,28 @@ nsLookAndFeel::GetAccentColor(nscolor& aColor)
 
   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 that seem consistent with what Windows does.
+
+  float luminance = 0.2125f * NS_GET_R(accentColor) +
+                    0.7154f * NS_GET_G(accentColor) +
+                    0.0721f * NS_GET_B(accentColor);
+
+  aColor = (luminance <= 110) ? NS_RGB(255, 255, 255) : NS_RGB(0, 0, 0);
+
+  return NS_OK;
+}

widget/windows/nsLookAndFeel.h

@@ -59,6 +59,15 @@ class nsLookAndFeel: public nsXPLookAndFeel {
    */
   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);
+
   // Content process cached values that get shipped over from the browser
   // process.
   int32_t mUseAccessibilityTheme;