/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Novell code.
 *
 * The Initial Developer of the Original Code is Novell Corporation.
 * Portions created by the Initial Developer are Copyright (C) 2006
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   robert@ocallahan.org
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#include "nsTextRunTransformations.h"

#include "nsTextFrameUtils.h"
#include "gfxSkipChars.h"
#include "nsGkAtoms.h"

#include "nsStyleConsts.h"
#include "nsStyleContext.h"
#include "gfxContext.h"
#include "nsContentUtils.h"
#include "nsUnicharUtils.h"
#include "nsUnicodeProperties.h"
#include "nsSpecialCasingData.h"

// Unicode characters needing special casing treatment in tr/az languages
#define LATIN_CAPITAL_LETTER_I_WITH_DOT_ABOVE  0x0130
#define LATIN_SMALL_LETTER_DOTLESS_I           0x0131

// Greek sigma needs custom handling for the lowercase transform; for details
// see comments under "case NS_STYLE_TEXT_TRANSFORM_LOWERCASE" within
// nsCaseTransformTextRunFactory::RebuildTextRun(), and bug 740120.
#define GREEK_CAPITAL_LETTER_SIGMA      0x03A3
#define GREEK_SMALL_LETTER_FINAL_SIGMA  0x03C2
#define GREEK_SMALL_LETTER_SIGMA        0x03C3

nsTransformedTextRun *
nsTransformedTextRun::Create(const gfxTextRunFactory::Parameters* aParams,
                             nsTransformingTextRunFactory* aFactory,
                             gfxFontGroup* aFontGroup,
                             const PRUnichar* aString, PRUint32 aLength,
                             const PRUint32 aFlags, nsStyleContext** aStyles,
                             bool aOwnsFactory)
{
  NS_ASSERTION(!(aFlags & gfxTextRunFactory::TEXT_IS_8BIT),
               "didn't expect text to be marked as 8-bit here");

  void *storage = AllocateStorageForTextRun(sizeof(nsTransformedTextRun), aLength);
  if (!storage) {
    return nsnull;
  }

  return new (storage) nsTransformedTextRun(aParams, aFactory, aFontGroup,
                                            aString, aLength,
                                            aFlags, aStyles, aOwnsFactory);
}

void
nsTransformedTextRun::SetCapitalization(PRUint32 aStart, PRUint32 aLength,
                                        bool* aCapitalization,
                                        gfxContext* aRefContext)
{
  if (mCapitalize.IsEmpty()) {
    if (!mCapitalize.AppendElements(GetLength()))
      return;
    memset(mCapitalize.Elements(), 0, GetLength()*sizeof(bool));
  }
  memcpy(mCapitalize.Elements() + aStart, aCapitalization, aLength*sizeof(bool));
  mNeedsRebuild = true;
}

bool
nsTransformedTextRun::SetPotentialLineBreaks(PRUint32 aStart, PRUint32 aLength,
                                             PRUint8* aBreakBefore,
                                             gfxContext* aRefContext)
{
  bool changed = gfxTextRun::SetPotentialLineBreaks(aStart, aLength,
      aBreakBefore, aRefContext);
  if (changed) {
    mNeedsRebuild = true;
  }
  return changed;
}

size_t
nsTransformedTextRun::SizeOfExcludingThis(nsMallocSizeOfFun aMallocSizeOf)
{
  size_t total = gfxTextRun::SizeOfExcludingThis(aMallocSizeOf);
  total += mStyles.SizeOfExcludingThis(aMallocSizeOf);
  total += mCapitalize.SizeOfExcludingThis(aMallocSizeOf);
  if (mOwnsFactory) {
    total += aMallocSizeOf(mFactory);
  }
  return total;
}

size_t
nsTransformedTextRun::SizeOfIncludingThis(nsMallocSizeOfFun aMallocSizeOf)
{
  return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
}

nsTransformedTextRun*
nsTransformingTextRunFactory::MakeTextRun(const PRUnichar* aString, PRUint32 aLength,
                                          const gfxTextRunFactory::Parameters* aParams,
                                          gfxFontGroup* aFontGroup, PRUint32 aFlags,
                                          nsStyleContext** aStyles, bool aOwnsFactory)
{
  return nsTransformedTextRun::Create(aParams, this, aFontGroup,
                                      aString, aLength, aFlags, aStyles, aOwnsFactory);
}

nsTransformedTextRun*
nsTransformingTextRunFactory::MakeTextRun(const PRUint8* aString, PRUint32 aLength,
                                          const gfxTextRunFactory::Parameters* aParams,
                                          gfxFontGroup* aFontGroup, PRUint32 aFlags,
                                          nsStyleContext** aStyles, bool aOwnsFactory)
{
  // We'll only have a Unicode code path to minimize the amount of code needed
  // for these rarely used features
  NS_ConvertASCIItoUTF16 unicodeString(reinterpret_cast<const char*>(aString), aLength);
  return MakeTextRun(unicodeString.get(), aLength, aParams, aFontGroup,
                     aFlags & ~(gfxFontGroup::TEXT_IS_PERSISTENT | gfxFontGroup::TEXT_IS_8BIT),
                     aStyles, aOwnsFactory);
}

/**
 * Copy a given textrun, but merge certain characters into a single logical
 * character. Glyphs for a character are added to the glyph list for the previous
 * character and then the merged character is eliminated. Visually the results
 * are identical.
 * 
 * This is used for text-transform:uppercase when we encounter a SZLIG,
 * whose uppercase form is "SS", or other ligature or precomposed form
 * that expands to multiple codepoints during case transformation.
 * 
 * This function is unable to merge characters when they occur in different
 * glyph runs. This only happens in tricky edge cases where a character was
 * decomposed by case-mapping (e.g. there's no precomposed uppercase version
 * of an accented lowercase letter), and then font-matching caused the
 * diacritics to be assigned to a different font than the base character.
 * In this situation, the diacritic(s) get discarded, which is less than
 * ideal, but they probably weren't going to render very well anyway.
 * Bug 543200 will improve this by making font-matching operate on entire
 * clusters instead of individual codepoints.
 * 
 * For simplicity, this produces a textrun containing all DetailedGlyphs,
 * no simple glyphs. So don't call it unless you really have merging to do.
 * 
 * @param aCharsToMerge when aCharsToMerge[i] is true, this character is
 * merged into the previous character
 */
static void
MergeCharactersInTextRun(gfxTextRun* aDest, gfxTextRun* aSrc,
                         bool* aCharsToMerge)
{
  aDest->ResetGlyphRuns();

  gfxTextRun::GlyphRunIterator iter(aSrc, 0, aSrc->GetLength());
  PRUint32 offset = 0;
  nsAutoTArray<gfxTextRun::DetailedGlyph,2> glyphs;
  while (iter.NextRun()) {
    gfxTextRun::GlyphRun* run = iter.GetGlyphRun();
    nsresult rv = aDest->AddGlyphRun(run->mFont, run->mMatchType,
                                     offset, false);
    if (NS_FAILED(rv))
      return;

    bool anyMissing = false;
    PRUint32 mergeRunStart = iter.GetStringStart();
    const gfxTextRun::CompressedGlyph *srcGlyphs = aSrc->GetCharacterGlyphs();
    gfxTextRun::CompressedGlyph mergedGlyph = srcGlyphs[mergeRunStart];
    PRUint32 stringEnd = iter.GetStringEnd();
    for (PRUint32 k = iter.GetStringStart(); k < stringEnd; ++k) {
      const gfxTextRun::CompressedGlyph g = srcGlyphs[k];
      if (g.IsSimpleGlyph()) {
        if (!anyMissing) {
          gfxTextRun::DetailedGlyph details;
          details.mGlyphID = g.GetSimpleGlyph();
          details.mAdvance = g.GetSimpleAdvance();
          details.mXOffset = 0;
          details.mYOffset = 0;
          glyphs.AppendElement(details);
        }
      } else {
        if (g.IsMissing()) {
          anyMissing = true;
          glyphs.Clear();
        }
        if (g.GetGlyphCount() > 0) {
          glyphs.AppendElements(aSrc->GetDetailedGlyphs(k), g.GetGlyphCount());
        }
      }

      if (k + 1 < iter.GetStringEnd() && aCharsToMerge[k + 1]) {
        // next char is supposed to merge with current, so loop without
        // writing current merged glyph to the destination
        continue;
      }

      // If the start of the merge run is actually a character that should
      // have been merged with the previous character (this can happen
      // if there's a font change in the middle of a case-mapped character,
      // that decomposed into a sequence of base+diacritics, for example),
      // just discard the entire merge run. See comment at start of this
      // function.
      NS_WARN_IF_FALSE(!aCharsToMerge[mergeRunStart],
                       "unable to merge across a glyph run boundary, "
                       "glyph(s) discarded");
      if (!aCharsToMerge[mergeRunStart]) {
        if (anyMissing) {
          mergedGlyph.SetMissing(glyphs.Length());
        } else {
          mergedGlyph.SetComplex(mergedGlyph.IsClusterStart(),
                                 mergedGlyph.IsLigatureGroupStart(),
                                 glyphs.Length());
        }
        aDest->SetGlyphs(offset, mergedGlyph, glyphs.Elements());
        ++offset;
      }

      glyphs.Clear();
      anyMissing = false;
      mergeRunStart = k + 1;
      if (mergeRunStart < stringEnd) {
        mergedGlyph = srcGlyphs[mergeRunStart];
      }
    }
    NS_ASSERTION(glyphs.Length() == 0,
                 "Leftover glyphs, don't request merging of the last character with its next!");  
  }
  NS_ASSERTION(offset == aDest->GetLength(), "Bad offset calculations");
}

static gfxTextRunFactory::Parameters
GetParametersForInner(nsTransformedTextRun* aTextRun, PRUint32* aFlags,
    gfxContext* aRefContext)
{
  gfxTextRunFactory::Parameters params =
    { aRefContext, nsnull, nsnull,
      nsnull, 0, aTextRun->GetAppUnitsPerDevUnit()
    };
  *aFlags = aTextRun->GetFlags() & ~gfxFontGroup::TEXT_IS_PERSISTENT;
  return params;
}

void
nsFontVariantTextRunFactory::RebuildTextRun(nsTransformedTextRun* aTextRun,
    gfxContext* aRefContext)
{
  gfxFontGroup* fontGroup = aTextRun->GetFontGroup();
  gfxFontStyle fontStyle = *fontGroup->GetStyle();
  fontStyle.size *= 0.8;
  nsRefPtr<gfxFontGroup> smallFont = fontGroup->Copy(&fontStyle);
  if (!smallFont)
    return;

  PRUint32 flags;
  gfxTextRunFactory::Parameters innerParams =
      GetParametersForInner(aTextRun, &flags, aRefContext);

  PRUint32 length = aTextRun->GetLength();
  const PRUnichar* str = aTextRun->mString.BeginReading();
  nsRefPtr<nsStyleContext>* styles = aTextRun->mStyles.Elements();
  // Create a textrun so we can check cluster-start properties
  nsAutoPtr<gfxTextRun> inner(fontGroup->MakeTextRun(str, length, &innerParams, flags));
  if (!inner.get())
    return;

  nsCaseTransformTextRunFactory uppercaseFactory(nsnull, true);

  aTextRun->ResetGlyphRuns();

  PRUint32 runStart = 0;
  bool runIsLowercase = false;
  nsAutoTArray<nsStyleContext*,50> styleArray;
  nsAutoTArray<PRUint8,50> canBreakBeforeArray;

  PRUint32 i;
  for (i = 0; i <= length; ++i) {
    bool isLowercase = false;
    if (i < length) {
      // Characters that aren't the start of a cluster are ignored here. They
      // get added to whatever lowercase/non-lowercase run we're in.
      if (!inner->IsClusterStart(i)) {
        isLowercase = runIsLowercase;
      } else {
        if (styles[i]->GetStyleFont()->mFont.variant == NS_STYLE_FONT_VARIANT_SMALL_CAPS) {
          PRUint32 ch = str[i];
          if (NS_IS_HIGH_SURROGATE(ch) && i < length - 1 && NS_IS_LOW_SURROGATE(str[i + 1])) {
            ch = SURROGATE_TO_UCS4(ch, str[i + 1]);
          }
          PRUint32 ch2 = ToUpperCase(ch);
          isLowercase = ch != ch2 || mozilla::unicode::SpecialUpper(ch);
        } else {
          // Don't transform the character! I.e., pretend that it's not lowercase
        }
      }
    }

    if ((i == length || runIsLowercase != isLowercase) && runStart < i) {
      nsAutoPtr<nsTransformedTextRun> transformedChild;
      nsAutoPtr<gfxTextRun> cachedChild;
      gfxTextRun* child;

      if (runIsLowercase) {
        transformedChild = uppercaseFactory.MakeTextRun(str + runStart, i - runStart,
            &innerParams, smallFont, flags, styleArray.Elements(), false);
        child = transformedChild;
      } else {
        cachedChild =
          fontGroup->MakeTextRun(str + runStart, i - runStart,
                                 &innerParams, flags);
        child = cachedChild.get();
      }
      if (!child)
        return;
      // Copy potential linebreaks into child so they're preserved
      // (and also child will be shaped appropriately)
      NS_ASSERTION(canBreakBeforeArray.Length() == i - runStart,
                   "lost some break-before values?");
      child->SetPotentialLineBreaks(0, canBreakBeforeArray.Length(),
          canBreakBeforeArray.Elements(), aRefContext);
      if (transformedChild) {
        transformedChild->FinishSettingProperties(aRefContext);
      }
      aTextRun->CopyGlyphDataFrom(child, 0, child->GetLength(), runStart);

      runStart = i;
      styleArray.Clear();
      canBreakBeforeArray.Clear();
    }

    if (i < length) {
      runIsLowercase = isLowercase;
      styleArray.AppendElement(styles[i]);
      canBreakBeforeArray.AppendElement(aTextRun->CanBreakLineBefore(i));
    }
  }
}

void
nsCaseTransformTextRunFactory::RebuildTextRun(nsTransformedTextRun* aTextRun,
    gfxContext* aRefContext)
{
  PRUint32 length = aTextRun->GetLength();
  const PRUnichar* str = aTextRun->mString.BeginReading();
  nsRefPtr<nsStyleContext>* styles = aTextRun->mStyles.Elements();

  nsAutoString convertedString;
  nsAutoTArray<bool,50> charsToMergeArray;
  nsAutoTArray<nsStyleContext*,50> styleArray;
  nsAutoTArray<PRUint8,50> canBreakBeforeArray;
  PRUint32 extraCharsCount = 0;

  // Some languages have special casing conventions that differ from the
  // default Unicode mappings.
  // The enum values here are named for well-known exemplar languages that
  // exhibit the behavior in question; multiple lang tags may map to the
  // same setting here, if the behavior is shared by other languages.
  enum {
    eNone,    // default non-lang-specific behavior
    eTurkish, // preserve dotted/dotless-i distinction in uppercase
    eDutch    // treat "ij" digraph as a unit for capitalization
  } languageSpecificCasing = eNone;

  const nsIAtom* lang = nsnull;
  bool capitalizeDutchIJ = false;
  bool prevIsLetter = false;
  PRUint32 sigmaIndex = PRUint32(-1);
  nsIUGenCategory::nsUGenCategory cat;
  PRUint32 i;
  for (i = 0; i < length; ++i) {
    PRUint32 ch = str[i];
    nsStyleContext* styleContext = styles[i];

    charsToMergeArray.AppendElement(false);
    styleArray.AppendElement(styleContext);
    canBreakBeforeArray.AppendElement(aTextRun->CanBreakLineBefore(i));

    PRUint8 style = mAllUppercase ? NS_STYLE_TEXT_TRANSFORM_UPPERCASE
      : styleContext->GetStyleText()->mTextTransform;
    int extraChars = 0;
    const mozilla::unicode::MultiCharMapping *mcm;

    if (NS_IS_HIGH_SURROGATE(ch) && i < length - 1 && NS_IS_LOW_SURROGATE(str[i + 1])) {
      ch = SURROGATE_TO_UCS4(ch, str[i + 1]);
    }

    if (lang != styleContext->GetStyleFont()->mLanguage) {
      lang = styleContext->GetStyleFont()->mLanguage;
      if (lang == nsGkAtoms::tr || lang == nsGkAtoms::az ||
          lang == nsGkAtoms::ba || lang == nsGkAtoms::crh ||
          lang == nsGkAtoms::tt) {
        languageSpecificCasing = eTurkish;
      } else if (lang == nsGkAtoms::nl) {
        languageSpecificCasing = eDutch;
      } else {
        languageSpecificCasing = eNone;
      }
    }

    switch (style) {
    case NS_STYLE_TEXT_TRANSFORM_LOWERCASE:
      if (languageSpecificCasing == eTurkish) {
        if (ch == 'I') {
          ch = LATIN_SMALL_LETTER_DOTLESS_I;
          prevIsLetter = true;
          sigmaIndex = PRUint32(-1);
          break;
        }
        if (ch == LATIN_CAPITAL_LETTER_I_WITH_DOT_ABOVE) {
          ch = 'i';
          prevIsLetter = true;
          sigmaIndex = PRUint32(-1);
          break;
        }
      }

      // Special lowercasing behavior for Greek Sigma: note that this is listed
      // as context-sensitive in Unicode's SpecialCasing.txt, but is *not* a
      // language-specific mapping; it applies regardless of the language of
      // the element.
      //
      // The lowercase mapping for CAPITAL SIGMA should be to SMALL SIGMA (i.e.
      // the non-final form) whenever there is a following letter, or when the
      // CAPITAL SIGMA occurs in isolation (neither preceded nor followed by a
      // LETTER); and to FINAL SIGMA when it is preceded by another letter but
      // not followed by one.
      //
      // To implement the context-sensitive nature of this mapping, we keep
      // track of whether the previous character was a letter. If not, CAPITAL
      // SIGMA will map directly to SMALL SIGMA. If the previous character
      // was a letter, CAPITAL SIGMA maps to FINAL SIGMA and we record the
      // position in the converted string; if we then encounter another letter,
      // that FINAL SIGMA is replaced with a standard SMALL SIGMA.

      cat = mozilla::unicode::GetGenCategory(ch);

      // If sigmaIndex is not -1, it marks where we have provisionally mapped
      // a CAPITAL SIGMA to FINAL SIGMA; if we now find another letter, we
      // need to change it to SMALL SIGMA.
      if (sigmaIndex != PRUint32(-1)) {
        if (cat == nsIUGenCategory::kLetter) {
          convertedString.SetCharAt(GREEK_SMALL_LETTER_SIGMA, sigmaIndex);
        }
      }

      if (ch == GREEK_CAPITAL_LETTER_SIGMA) {
        // If preceding char was a letter, map to FINAL instead of SMALL,
        // and note where it occurred by setting sigmaIndex; we'll change it
        // to standard SMALL SIGMA later if another letter follows
        if (prevIsLetter) {
          ch = GREEK_SMALL_LETTER_FINAL_SIGMA;
          sigmaIndex = convertedString.Length();
        } else {
          // CAPITAL SIGMA not preceded by a letter is unconditionally mapped
          // to SMALL SIGMA
          ch = GREEK_SMALL_LETTER_SIGMA;
          sigmaIndex = PRUint32(-1);
        }
        prevIsLetter = true;
        break;
      }

      // ignore diacritics for the purpose of contextual sigma mapping;
      // otherwise, reset prevIsLetter appropriately and clear the
      // sigmaIndex marker
      if (cat != nsIUGenCategory::kMark) {
        prevIsLetter = (cat == nsIUGenCategory::kLetter);
        sigmaIndex = PRUint32(-1);
      }

      mcm = mozilla::unicode::SpecialLower(ch);
      if (mcm) {
        int j = 0;
        while (j < 2 && mcm->mMappedChars[j + 1]) {
          convertedString.Append(mcm->mMappedChars[j]);
          ++extraChars;
          ++j;
        }
        ch = mcm->mMappedChars[j];
        break;
      }

      ch = ToLowerCase(ch);
      break;

    case NS_STYLE_TEXT_TRANSFORM_UPPERCASE:
      if (languageSpecificCasing == eTurkish && ch == 'i') {
        ch = LATIN_CAPITAL_LETTER_I_WITH_DOT_ABOVE;
        break;
      }

      mcm = mozilla::unicode::SpecialUpper(ch);
      if (mcm) {
        int j = 0;
        while (j < 2 && mcm->mMappedChars[j + 1]) {
          convertedString.Append(mcm->mMappedChars[j]);
          ++extraChars;
          ++j;
        }
        ch = mcm->mMappedChars[j];
        break;
      }

      ch = ToUpperCase(ch);
      break;

    case NS_STYLE_TEXT_TRANSFORM_CAPITALIZE:
      if (capitalizeDutchIJ && ch == 'j') {
        ch = 'J';
        capitalizeDutchIJ = false;
        break;
      }
      capitalizeDutchIJ = false;
      if (i < aTextRun->mCapitalize.Length() && aTextRun->mCapitalize[i]) {
        if (languageSpecificCasing == eTurkish && ch == 'i') {
          ch = LATIN_CAPITAL_LETTER_I_WITH_DOT_ABOVE;
          break;
        }
        if (languageSpecificCasing == eDutch && ch == 'i') {
          ch = 'I';
          capitalizeDutchIJ = true;
          break;
        }

        mcm = mozilla::unicode::SpecialTitle(ch);
        if (mcm) {
          int j = 0;
          while (j < 2 && mcm->mMappedChars[j + 1]) {
            convertedString.Append(mcm->mMappedChars[j]);
            ++extraChars;
            ++j;
          }
          ch = mcm->mMappedChars[j];
          break;
        }

        ch = ToTitleCase(ch);
      }
      break;

    default:
      break;
    }

    if (IS_IN_BMP(ch)) {
      convertedString.Append(ch);
    } else {
      convertedString.Append(H_SURROGATE(ch));
      convertedString.Append(L_SURROGATE(ch));
      i++;
      charsToMergeArray.AppendElement(false);
      styleArray.AppendElement(styleContext);
      canBreakBeforeArray.AppendElement(false);
    }

    while (extraChars > 0) {
      ++extraCharsCount;
      charsToMergeArray.AppendElement(true);
      styleArray.AppendElement(styleContext);
      canBreakBeforeArray.AppendElement(false);
      --extraChars;
    }
  }

  PRUint32 flags;
  gfxTextRunFactory::Parameters innerParams =
      GetParametersForInner(aTextRun, &flags, aRefContext);
  gfxFontGroup* fontGroup = aTextRun->GetFontGroup();

  nsAutoPtr<nsTransformedTextRun> transformedChild;
  nsAutoPtr<gfxTextRun> cachedChild;
  gfxTextRun* child;

  if (mInnerTransformingTextRunFactory) {
    transformedChild = mInnerTransformingTextRunFactory->MakeTextRun(
        convertedString.BeginReading(), convertedString.Length(),
        &innerParams, fontGroup, flags, styleArray.Elements(), false);
    child = transformedChild.get();
  } else {
    cachedChild = fontGroup->MakeTextRun(
        convertedString.BeginReading(), convertedString.Length(),
        &innerParams, flags);
    child = cachedChild.get();
  }
  if (!child)
    return;
  // Copy potential linebreaks into child so they're preserved
  // (and also child will be shaped appropriately)
  NS_ASSERTION(convertedString.Length() == canBreakBeforeArray.Length(),
               "Dropped characters or break-before values somewhere!");
  child->SetPotentialLineBreaks(0, canBreakBeforeArray.Length(),
      canBreakBeforeArray.Elements(), aRefContext);
  if (transformedChild) {
    transformedChild->FinishSettingProperties(aRefContext);
  }

  if (extraCharsCount > 0) {
    // Now merge multiple characters into one multi-glyph character as required
    MergeCharactersInTextRun(aTextRun, child, charsToMergeArray.Elements());
  } else {
    // No merging to do, so just copy; this produces a more optimized textrun.
    // We can't steal the data because the child may be cached and stealing
    // the data would break the cache.
    aTextRun->ResetGlyphRuns();
    aTextRun->CopyGlyphDataFrom(child, 0, child->GetLength(), 0);
  }
}