Issue #1673 - Part 1: Allow tab-size to accept <length>.

Currently -moz-tab-size only accepts <number> values, and both Chrome and Firefox currently support <length> values and have for some time now. So with this you would be able to support sizes in px or em, for instance. This was implemented in Firefox 53 and was trivial to backport.

7 files changed, 124 insertions, 62 deletions

diff --git a/layout/generic/nsTextFrame.cpp b/layout/generic/nsTextFrame.cpp
index c7b55961c..749b8b944 100644
--- a/layout/generic/nsTextFrame.cpp
+++ b/layout/generic/nsTextFrame.cpp
@@ -3178,7 +3178,7 @@ public:
     return mFontMetrics;
   }
 
-  void CalcTabWidths(Range aTransformedRange);
+  void CalcTabWidths(Range aTransformedRange, gfxFloat aTabWidth);
 
   const gfxSkipCharsIterator& GetEndHint() { return mTempIterator; }
 
@@ -3364,6 +3364,28 @@ CanAddSpacingAfter(const gfxTextRun* aTextRun, uint32_t aOffset)
     aTextRun->IsLigatureGroupStart(aOffset + 1);
 }
 
+static gfxFloat
+ComputeTabWidthAppUnits(nsIFrame* aFrame, gfxTextRun* aTextRun)
+{
+  const nsStyleText* textStyle = aFrame->StyleText();
+  if (textStyle->mTabSize.GetUnit() != eStyleUnit_Factor) {
+    nscoord w = textStyle->mTabSize.GetCoordValue();
+    MOZ_ASSERT(w >= 0);
+    return w;
+  }
+
+  gfxFloat spaces = textStyle->mTabSize.GetFactorValue();
+  MOZ_ASSERT(spaces >= 0);
+
+  // Round the space width when converting to appunits the same way
+  // textruns do.
+  gfxFloat spaceWidthAppUnits =
+    NS_round(GetFirstFontMetrics(aTextRun->GetFontGroup(),
+                                 aTextRun->IsVertical()).spaceWidth *
+             aTextRun->GetAppUnitsPerDevUnit());
+  return spaces * spaceWidthAppUnits;
+}
+
 void
 PropertyProvider::GetSpacingInternal(Range aRange, Spacing* aSpacing,
                                      bool aIgnoreTabs)
@@ -3411,17 +3433,16 @@ PropertyProvider::GetSpacingInternal(Range aRange, Spacing* aSpacing,
     }
   }
 
-  // Ignore tab spacing rather than computing it, if the tab size is 0
-  if (!aIgnoreTabs)
-    aIgnoreTabs = mFrame->StyleText()->mTabSize == 0;
-
   // Now add tab spacing, if there is any
   if (!aIgnoreTabs) {
-    CalcTabWidths(aRange);
-    if (mTabWidths) {
-      mTabWidths->ApplySpacing(aSpacing,
-                               aRange.start - mStart.GetSkippedOffset(),
-                               aRange.Length());
+    gfxFloat tabWidth = ComputeTabWidthAppUnits(mFrame, mTextRun);
+    if (tabWidth > 0) {
+      CalcTabWidths(aRange);
+      if (mTabWidths) {
+        mTabWidths->ApplySpacing(aSpacing,
+                                 aRange.start - mStart.GetSkippedOffset(),
+                                 aRange.Length());
+      }
     }
   }
 
@@ -3444,33 +3465,23 @@ PropertyProvider::GetSpacingInternal(Range aRange, Spacing* aSpacing,
   }
 }
 
-static gfxFloat
-ComputeTabWidthAppUnits(nsIFrame* aFrame, const gfxTextRun* aTextRun)
-{
-  // Get the number of spaces from CSS -moz-tab-size
-  const nsStyleText* textStyle = aFrame->StyleText();
-
-  return textStyle->mTabSize * GetSpaceWidthAppUnits(aTextRun);
-}
-
 // aX and the result are in whole appunits.
 static gfxFloat
 AdvanceToNextTab(gfxFloat aX, nsIFrame* aFrame,
-                 const gfxTextRun* aTextRun, gfxFloat* aCachedTabWidth)
+                 gfxTextRun* aTextRun, gfxFloat* aTabWidth)
 {
-  if (*aCachedTabWidth < 0) {
-    *aCachedTabWidth = ComputeTabWidthAppUnits(aFrame, aTextRun);
-  }
 
   // Advance aX to the next multiple of *aCachedTabWidth. We must advance
   // by at least 1 appunit.
   // XXX should we make this 1 CSS pixel?
-  return ceil((aX + 1)/(*aCachedTabWidth))*(*aCachedTabWidth);
+  return ceil((aX + 1)/ aTabWidth) * aTabWidth;
 }
 
 void
-PropertyProvider::CalcTabWidths(Range aRange)
+PropertyProvider::CalcTabWidths(Range aRange, gfxFloat aTabWidth)
 {
+  MOZ_ASSERT(aTabWidth > 0);
+
   if (!mTabWidths) {
     if (mReflowing && !mLineContainer) {
       // Intrinsic width computation does its own tab processing. We
@@ -3505,7 +3516,6 @@ PropertyProvider::CalcTabWidths(Range aRange)
     NS_ASSERTION(mReflowing,
                  "We need precomputed tab widths, but don't have enough.");
 
-    gfxFloat tabWidth = -1;
     for (uint32_t i = tabsEnd; i < aRange.end; ++i) {
       Spacing spacing;
       GetSpacingInternal(Range(i, i + 1), &spacing, true);
@@ -3527,7 +3537,7 @@ PropertyProvider::CalcTabWidths(Range aRange)
           mFrame->SetProperty(TabWidthProperty(), mTabWidths);
         }
         double nextTab = AdvanceToNextTab(mOffsetFromBlockOriginForTabs,
-                mFrame, mTextRun, &tabWidth);
+                mFrame, mTextRun, aTabWidth);
         mTabWidths->mWidths.AppendElement(TabWidth(i - startOffset, 
                 NSToIntRound(nextTab - mOffsetFromBlockOriginForTabs)));
         mOffsetFromBlockOriginForTabs = nextTab;
@@ -8321,9 +8331,12 @@ nsTextFrame::AddInlineMinISizeForFlow(nsRenderingContext *aRenderingContext,
       PropertyProvider::Spacing spacing;
       provider.GetSpacing(Range(i, i + 1), &spacing);
       aData->mCurrentLine += nscoord(spacing.mBefore);
+      if (tabWidth < 0) {
+	tabWidth = ComputeTabWidthAppUnits(this, textRun);
+      }
       gfxFloat afterTab =
         AdvanceToNextTab(aData->mCurrentLine, this,
-                         textRun, &tabWidth);
+                         textRun, tabWidth);
       aData->mCurrentLine = nscoord(afterTab + spacing.mAfter);
       wordStart = i + 1;
     } else if (i < flowEndInTextRun ||
@@ -8480,9 +8493,12 @@ nsTextFrame::AddInlinePrefISizeForFlow(nsRenderingContext *aRenderingContext,
       PropertyProvider::Spacing spacing;
       provider.GetSpacing(Range(i, i + 1), &spacing);
       aData->mCurrentLine += nscoord(spacing.mBefore);
+      if (tabWidth < 0) {
+	tabWidth = ComputeTabWidthAppUnits(this, textRun);
+      }
       gfxFloat afterTab =
         AdvanceToNextTab(aData->mCurrentLine, this,
-                         textRun, &tabWidth);
+                         textRun, tabWidth);
       aData->mCurrentLine = nscoord(afterTab + spacing.mAfter);
       lineStart = i + 1;
     } else if (preformattedNewline) {
diff --git a/layout/style/nsCSSPropList.h b/layout/style/nsCSSPropList.h
index 4f79db5a5..5c5cfcda1 100644
--- a/layout/style/nsCSSPropList.h
+++ b/layout/style/nsCSSPropList.h
@@ -3885,7 +3885,7 @@ CSS_PROP_TEXT(
     CSS_PROPERTY_PARSE_VALUE |
         CSS_PROPERTY_VALUE_NONNEGATIVE,
     "",
-    VARIANT_HI,
+    VARIANT_INHERIT | VARIANT_LNCALC,
     nullptr,
     offsetof(nsStyleText, mTabSize),
     eStyleAnimType_Discrete)
diff --git a/layout/style/nsComputedDOMStyle.cpp b/layout/style/nsComputedDOMStyle.cpp
index 08c2846f7..bbad9c371 100644
--- a/layout/style/nsComputedDOMStyle.cpp
+++ b/layout/style/nsComputedDOMStyle.cpp
@@ -3972,7 +3972,7 @@ already_AddRefed<CSSValue>
 nsComputedDOMStyle::DoGetTabSize()
 {
   RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
-  val->SetNumber(StyleText()->mTabSize);
+  SetValueToCoord(val, StyleText()->mTabSize, true);
   return val.forget();
 }
 
diff --git a/layout/style/nsRuleNode.cpp b/layout/style/nsRuleNode.cpp
index 1136edee2..c2fd70879 100644
--- a/layout/style/nsRuleNode.cpp
+++ b/layout/style/nsRuleNode.cpp
@@ -4508,20 +4508,20 @@ TruncateStringToSingleGrapheme(nsAString& aStr)
   }
 }
 
-struct LineHeightCalcObj
+struct LengthNumberCalcObj
 {
-  float mLineHeight;
+  float LengthNumberCalcObj;
   bool mIsNumber;
 };
 
-struct SetLineHeightCalcOps : public css::NumbersAlreadyNormalizedOps
+struct LengthNumberCalcOps : public css::FloatCoeffsAlreadyNormalizedOps
 {
-  typedef LineHeightCalcObj result_type;
+  typedef LengthNumberCalcObj result_type;
   nsStyleContext* const mStyleContext;
   nsPresContext* const mPresContext;
   RuleNodeCacheConditions& mConditions;
 
-  SetLineHeightCalcOps(nsStyleContext* aStyleContext,
+  LengthNumberCalcOps(nsStyleContext* aStyleContext,
                        nsPresContext* aPresContext,
                        RuleNodeCacheConditions& aConditions)
     : mStyleContext(aStyleContext),
@@ -4536,15 +4536,15 @@ struct SetLineHeightCalcOps : public css::NumbersAlreadyNormalizedOps
   {
     MOZ_ASSERT(aValue1.mIsNumber == aValue2.mIsNumber);
 
-    LineHeightCalcObj result;
+    LengthNumberCalcObj result;
     result.mIsNumber = aValue1.mIsNumber;
     if (aCalcFunction == eCSSUnit_Calc_Plus) {
-      result.mLineHeight = aValue1.mLineHeight + aValue2.mLineHeight;
+      result.mValue = aValue1.mValue + aValue2.mValue;
       return result;
     }
     MOZ_ASSERT(aCalcFunction == eCSSUnit_Calc_Minus,
                "unexpected unit");
-    result.mLineHeight = aValue1.mLineHeight - aValue2.mLineHeight;
+    result.mValue = aValue1.mValue - aValue2.mValue;
     return result;
   }
 
@@ -4554,9 +4554,9 @@ struct SetLineHeightCalcOps : public css::NumbersAlreadyNormalizedOps
   {
     MOZ_ASSERT(aCalcFunction == eCSSUnit_Calc_Times_L,
                "unexpected unit");
-    LineHeightCalcObj result;
+    LengthNumberCalcObj result;
     result.mIsNumber = aValue2.mIsNumber;
-    result.mLineHeight = aValue1 * aValue2.mLineHeight;
+    result.mValue = aValue1 * aValue2.mValue;
     return result;
   }
 
@@ -4564,39 +4564,69 @@ struct SetLineHeightCalcOps : public css::NumbersAlreadyNormalizedOps
   MergeMultiplicativeR(nsCSSUnit aCalcFunction,
                        result_type aValue1, float aValue2)
   {
-    LineHeightCalcObj result;
+    LengthNumberCalcObj result;
     result.mIsNumber = aValue1.mIsNumber;
     if (aCalcFunction == eCSSUnit_Calc_Times_R) {
-      result.mLineHeight = aValue1.mLineHeight * aValue2;
+      result.mValue = aValue1.mValue * aValue2;
       return result;
     }
     MOZ_ASSERT(aCalcFunction == eCSSUnit_Calc_Divided,
                "unexpected unit");
-    result.mLineHeight = aValue1.mLineHeight / aValue2;
+    result.mValue = aValue1.mValue / aValue2;
     return result;
   }
 
   result_type ComputeLeafValue(const nsCSSValue& aValue)
   {
-    LineHeightCalcObj result;
+    LengthNumberCalcObj result;
     if (aValue.IsLengthUnit()) {
       result.mIsNumber = false;
-      result.mLineHeight = CalcLength(aValue, mStyleContext,
+      result.mValue = CalcLength(aValue, mStyleContext,
+                                      mPresContext, mConditions);
+    }
+    else if (eCSSUnit_Number == aValue.GetUnit()) {
+      result.mIsNumber = true;
+      result.mValue = aValue.GetFloatValue();
+    } else {
+      MOZ_ASSERT(false, "unexpected value");
+      result.mIsNumber = true;
+      result.mValue = 1.0f;
+    }
+
+    return result;
+  }
+};
+
+struct SetLineHeightCalcOps : public LengthNumberCalcOps
+{
+  SetLineHeightCalcOps(nsStyleContext* aStyleContext,
+                       nsPresContext* aPresContext,
+                       RuleNodeCacheConditions& aConditions)
+    : LengthNumberCalcOps(aStyleContext, aPresContext, aConditions)
+  {
+  }
+
+  result_type ComputeLeafValue(const nsCSSValue& aValue)
+  {
+    LengthNumberCalcObj result;
+    if (aValue.IsLengthUnit()) {
+      result.mIsNumber = false;
+      result.mValue = CalcLength(aValue, mStyleContext,
                                       mPresContext, mConditions);
     }
     else if (eCSSUnit_Percent == aValue.GetUnit()) {
       mConditions.SetUncacheable();
       result.mIsNumber = false;
       nscoord fontSize = mStyleContext->StyleFont()->mFont.size;
-      result.mLineHeight = fontSize * aValue.GetPercentValue();
+      result.mValue = fontSize * aValue.GetPercentValue();
     }
     else if (eCSSUnit_Number == aValue.GetUnit()) {
       result.mIsNumber = true;
-      result.mLineHeight = aValue.GetFloatValue();
+      result.mValue = aValue.GetFloatValue();
     } else {
       MOZ_ASSERT(false, "unexpected value");
       result.mIsNumber = true;
-      result.mLineHeight = 1.0f;
+      result.mValue = 1.0f;
     }
 
     return result;
@@ -4620,11 +4650,25 @@ nsRuleNode::ComputeTextData(void* aStartStruct,
                                    mPresContext, text->*aField, conditions);
   };
 
-  // tab-size: integer, inherit
-  SetValue(*aRuleData->ValueForTabSize(),
-           text->mTabSize, conditions,
-           SETVAL_INTEGER | SETVAL_UNSET_INHERIT, parentText->mTabSize,
-           NS_STYLE_TABSIZE_INITIAL);
+  // tab-size: number, length, calc, inherit
+  const nsCSSValue* tabSizeValue = aRuleData->ValueForTabSize();
+  if (tabSizeValue->GetUnit() == eCSSUnit_Initial) {
+    text->mTabSize = nsStyleCoord(float(NS_STYLE_TABSIZE_INITIAL), eStyleUnit_Factor);
+  } else if (eCSSUnit_Calc == tabSizeValue->GetUnit()) {
+    LengthNumberCalcOps ops(aContext, mPresContext, conditions);
+    LengthNumberCalcObj obj = css::ComputeCalc(*tabSizeValue, ops);
+    float value = obj.mValue < 0 ? 0 : obj.mValue;
+    if (obj.mIsNumber) {
+      text->mTabSize.SetFactorValue(value);
+    } else {
+      text->mTabSize.SetCoordValue(
+        NSToCoordRoundWithClamp(value));
+    }
+  } else {
+    SetCoord(*tabSizeValue, text->mTabSize, parentText->mTabSize,
+             SETCOORD_LH | SETCOORD_FACTOR | SETCOORD_UNSET_INHERIT,
+             aContext, mPresContext, conditions);
+  }
 
   // letter-spacing: normal, length, inherit
   SetCoord(*aRuleData->ValueForLetterSpacing(),
@@ -4667,12 +4711,12 @@ nsRuleNode::ComputeTextData(void* aStartStruct,
   }
   else if (eCSSUnit_Calc == lineHeightValue->GetUnit()) {
     SetLineHeightCalcOps ops(aContext, mPresContext, conditions);
-    LineHeightCalcObj obj = css::ComputeCalc(*lineHeightValue, ops);
+    LengthNumberCalcObj obj = css::ComputeCalc(*lineHeightValue, ops);
     if (obj.mIsNumber) {
-      text->mLineHeight.SetFactorValue(obj.mLineHeight);
+      text->mLineHeight.SetFactorValue(obj.mValue);
     } else {
       text->mLineHeight.SetCoordValue(
-        NSToCoordRoundWithClamp(obj.mLineHeight));
+        NSToCoordRoundWithClamp(obj.mValue));
     }
   }
   else {
diff --git a/layout/style/nsStyleStruct.cpp b/layout/style/nsStyleStruct.cpp
index 4c610cf08..a2b6833ac 100644
--- a/layout/style/nsStyleStruct.cpp
+++ b/layout/style/nsStyleStruct.cpp
@@ -3807,10 +3807,10 @@ nsStyleText::nsStyleText(StyleStructContext aContext)
   , mControlCharacterVisibility(nsCSSParser::ControlCharVisibilityDefault())
   , mTextEmphasisStyle(NS_STYLE_TEXT_EMPHASIS_STYLE_NONE)
   , mTextRendering(NS_STYLE_TEXT_RENDERING_AUTO)
-  , mTabSize(NS_STYLE_TABSIZE_INITIAL)
   , mTextEmphasisColor(StyleComplexColor::CurrentColor())
   , mWebkitTextFillColor(StyleComplexColor::CurrentColor())
   , mWebkitTextStrokeColor(StyleComplexColor::CurrentColor())
+  , mTabSize(float(NS_STYLE_TABSIZE_INITIAL), eStyleUnit_Factor)
   , mWordSpacing(0, nsStyleCoord::CoordConstructor)
   , mLetterSpacing(eStyleUnit_Normal)
   , mLineHeight(eStyleUnit_Normal)
@@ -3845,10 +3845,10 @@ nsStyleText::nsStyleText(const nsStyleText& aSource)
   , mTextEmphasisPosition(aSource.mTextEmphasisPosition)
   , mTextEmphasisStyle(aSource.mTextEmphasisStyle)
   , mTextRendering(aSource.mTextRendering)
-  , mTabSize(aSource.mTabSize)
   , mTextEmphasisColor(aSource.mTextEmphasisColor)
   , mWebkitTextFillColor(aSource.mWebkitTextFillColor)
   , mWebkitTextStrokeColor(aSource.mWebkitTextStrokeColor)
+  , mTabSize(aSource.mTabSize)
   , mWordSpacing(aSource.mWordSpacing)
   , mLetterSpacing(aSource.mLetterSpacing)
   , mLineHeight(aSource.mLineHeight)
diff --git a/layout/style/nsStyleStruct.h b/layout/style/nsStyleStruct.h
index 97724571d..c948d6056 100644
--- a/layout/style/nsStyleStruct.h
+++ b/layout/style/nsStyleStruct.h
@@ -2088,11 +2088,11 @@ struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleText
   uint8_t mTextEmphasisPosition;        // [inherited] see nsStyleConsts.h
   uint8_t mTextEmphasisStyle;           // [inherited] see nsStyleConsts.h
   uint8_t mTextRendering;               // [inherited] see nsStyleConsts.h
-  int32_t mTabSize;                     // [inherited] see nsStyleConsts.h
   mozilla::StyleComplexColor mTextEmphasisColor;      // [inherited]
   mozilla::StyleComplexColor mWebkitTextFillColor;    // [inherited]
   mozilla::StyleComplexColor mWebkitTextStrokeColor;  // [inherited]
 
+  nsStyleCoord mTabSize;                // [inherited] coord, factor, calc
   nsStyleCoord mWordSpacing;            // [inherited] coord, percent, calc
   nsStyleCoord mLetterSpacing;          // [inherited] coord, normal
   nsStyleCoord mLineHeight;             // [inherited] coord, factor, normal
diff --git a/layout/style/test/property_database.js b/layout/style/test/property_database.js
index a7014c043..8624e17dd 100644
--- a/layout/style/test/property_database.js
+++ b/layout/style/test/property_database.js
@@ -2033,8 +2033,10 @@ var gCSSProperties = {
     inherited: true,
     type: CSS_TYPE_LONGHAND,
     initial_values: [ "8" ],
-    other_values: [ "0", "3", "99", "12000" ],
-    invalid_values: [ "-1", "-808", "3.0", "17.5" ]
+    other_values: [ "0", "2.5", "3", "99", "12000", "0px", "1em",
+	    "calc(1px + 1em)", "calc(1px - 2px)", "calc(1 + 1)", "calc(-2.5)" ],
+    invalid_values: [ "9%", "calc(9% + 1px)", "calc(1 + 1em)", "-1", "-808",
+	    "auto" ]
   },
   "-moz-text-size-adjust": {
     domProp: "MozTextSizeAdjust",