Bug 639134 - change document color pref to tristate, r=dbaron

layout/base/nsPresContext.cpp

@@ -614,6 +614,14 @@ nsPresContext::GetDocumentColorPreferences()
   int32_t useAccessibilityTheme = 0;
   bool usePrefColors = true;
   bool isChromeDocShell = false;
+  static int32_t sDocumentColorsSetting;
+  static bool sDocumentColorsSettingPrefCached = false;
+  if (!sDocumentColorsSettingPrefCached) {
+    sDocumentColorsSettingPrefCached = true;
+    Preferences::AddIntVarCache(&sDocumentColorsSetting,
+                                "browser.display.document_color_use",
+                                0);
+  }
 
   nsIDocument* doc = mDocument->GetDisplayDocument();
   if (doc && doc->GetDocShell()) {
@@ -669,9 +677,21 @@ nsPresContext::GetDocumentColorPreferences()
   mBackgroundColor = NS_ComposeColors(NS_RGB(0xFF, 0xFF, 0xFF),
                                       mBackgroundColor);
 
-  mUseDocumentColors = !useAccessibilityTheme &&
-    Preferences::GetBool("browser.display.use_document_colors",
-                         mUseDocumentColors);
+
+  // Now deal with the pref:
+  // 0 = default: always, except in high contrast mode
+  // 1 = always
+  // 2 = never
+  if (sDocumentColorsSetting == 1) {
+    mUseDocumentColors = true;
+  } else if (sDocumentColorsSetting == 2) {
+    mUseDocumentColors = isChromeDocShell || mIsChromeOriginImage;
+  } else {
+    MOZ_ASSERT(!useAccessibilityTheme ||
+               !(isChromeDocShell || mIsChromeOriginImage),
+               "The accessibility theme should only be on for non-chrome");
+    mUseDocumentColors = !useAccessibilityTheme;
+  }
 }
 
 void

layout/base/nsPresContext.h

@@ -80,8 +80,7 @@ class ContainerLayer;
 
 // supported values for cached bool types
 enum nsPresContext_CachedBoolPrefType {
-  kPresContext_UseDocumentColors = 1,
-  kPresContext_UseDocumentFonts,
+  kPresContext_UseDocumentFonts = 1,
   kPresContext_UnderlineLinks
 };
 
@@ -378,8 +377,6 @@ public:
     switch (aPrefType) {
     case kPresContext_UseDocumentFonts:
       return mUseDocumentFonts;
-    case kPresContext_UseDocumentColors:
-      return mUseDocumentColors;
     case kPresContext_UnderlineLinks:
       return mUnderlineLinks;
     default:
@@ -846,7 +843,9 @@ public:
 
   // Is it OK to let the page specify colors and backgrounds?
   bool UseDocumentColors() const {
-    return GetCachedBoolPref(kPresContext_UseDocumentColors) || IsChrome() || IsChromeOriginImage();
+    MOZ_ASSERT(mUseDocumentColors || !(IsChrome() || IsChromeOriginImage()),
+               "We should never have a chrome doc or image that can't use its colors.");
+    return mUseDocumentColors;
   }
 
   // Explicitly enable and disable paint flashing.

layout/style/test/test_dont_use_document_colors.html

@@ -50,7 +50,7 @@ var cs5 = getComputedStyle(document.getElementById("five"), "");
 var cs6 = getComputedStyle(document.getElementById("six"), "");
 var cs7 = getComputedStyle(document.getElementById("seven"), "");
 
-SpecialPowers.pushPrefEnv({'set': [['browser.display.use_document_colors', true]]}, part1);
+SpecialPowers.pushPrefEnv({'set': [['browser.display.document_color_use', 1]]}, part1);
 
 var transparentBackgroundColor;
 var inputBackgroundColor, inputColor, inputBorderTopColor;
@@ -121,7 +121,7 @@ function part1()
     inputBorderRightColor = cs4.borderRightColor;
     inputBorderLeftColor = cs4.borderLeftColor;
     inputBorderBottomColor = cs4.borderBottomColor;
-    SpecialPowers.pushPrefEnv({'set': [['browser.display.use_document_colors', false]]}, part2);
+    SpecialPowers.pushPrefEnv({'set': [['browser.display.document_color_use', 2]]}, part2);
 }
 
 function part2()

modules/libpref/init/all.js

@@ -177,7 +177,10 @@ pref("browser.sessionhistory.max_total_viewers", -1);
 pref("ui.use_native_colors", true);
 pref("ui.click_hold_context_menus", false);
 pref("browser.display.use_document_fonts",  1);  // 0 = never, 1 = quick, 2 = always
-pref("browser.display.use_document_colors", true);
+// 0 = default: always, except in high contrast mode
+// 1 = always
+// 2 = never
+pref("browser.display.document_color_use", 0);
 pref("browser.display.use_system_colors",   false);
 pref("browser.display.foreground_color",    "#000000");
 pref("browser.display.background_color",    "#FFFFFF");