Bug 276079 - add layout support for CSS text-justify property. r=xidorn

MozReview-Commit-ID: Kiwu8UNfbSj

--HG--
extra : rebase_source : 7673c42f8d401832437b0bb891f87aa22acabe15

layout/base/nsLayoutUtils.cpp

@@ -6974,7 +6974,8 @@ nsLayoutUtils::GetTextRunFlagsForStyle(nsStyleContext* aStyleContext,
                                        nscoord aLetterSpacing)
 {
   uint32_t result = 0;
-  if (aLetterSpacing != 0) {
+  if (aLetterSpacing != 0 ||
+      aStyleText->mTextJustify == StyleTextJustify::InterCharacter) {
     result |= gfxTextRunFactory::TEXT_DISABLE_OPTIONAL_LIGATURES;
   }
   if (aStyleText->mControlCharacterVisibility == NS_STYLE_CONTROL_CHARACTER_VISIBILITY_HIDDEN) {

layout/generic/nsTextFrame.cpp

@@ -2964,10 +2964,17 @@ nsTextFrame::GetTrimmedOffsets(const nsTextFragment* aFrag,
   return offsets;
 }
 
-static bool IsJustifiableCharacter(const nsTextFragment* aFrag, int32_t aPos,
+static bool IsJustifiableCharacter(const nsStyleText* aTextStyle,
+                                   const nsTextFragment* aFrag, int32_t aPos,
                                    bool aLangIsCJ)
 {
   NS_ASSERTION(aPos >= 0, "negative position?!");
+
+  StyleTextJustify justifyStyle = aTextStyle->mTextJustify;
+  if (justifyStyle == StyleTextJustify::None) {
+    return false;
+  }
+
   char16_t ch = aFrag->CharAt(aPos);
   if (ch == '\n' || ch == '\t' || ch == '\r') {
     return true;
@@ -2980,6 +2987,14 @@ static bool IsJustifiableCharacter(const nsTextFragment* aFrag, int32_t aPos,
     return !nsTextFrameUtils::IsSpaceCombiningSequenceTail(
       aFrag->Get2b() + aPos + 1, aFrag->GetLength() - (aPos + 1));
   }
+
+  if (justifyStyle == StyleTextJustify::InterCharacter) {
+    return true;
+  } else if (justifyStyle == StyleTextJustify::InterWord) {
+    return false;
+  }
+
+  // text-justify: auto
   if (ch < 0x2150u) {
     return false;
   }
@@ -3310,7 +3325,7 @@ PropertyProvider::ComputeJustification(
     gfxSkipCharsIterator iter = run.GetPos();
     for (uint32_t i = 0; i < length; ++i) {
       uint32_t offset = originalOffset + i;
-      if (!IsJustifiableCharacter(mFrag, offset, isCJ)) {
+      if (!IsJustifiableCharacter(mTextStyle, mFrag, offset, isCJ)) {
         continue;
       }