Improve shaping segmentation for grapheme cluster based font fallback

third_party/WebKit/Source/platform/fonts/SimpleFontData.cpp

 /*
  * Copyright (C) 2005, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 434 matching lines @@
 
     m_platformData.setupPaint(&paint);
 
     paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
     SkScalar width = paint.measureText(&glyph, 2);
     if (!paint.isSubpixelText())
         width = SkScalarRoundToInt(width);
     return SkScalarToFloat(width);
 }
 
-bool SimpleFontData::canRenderCombiningCharacterSequence(const UChar* characters, size_t length) const
-{
-    if (!m_combiningCharacterSequenceSupport)

[eae, 2015/10/14 08:12:00]

This also means we can remove m_combiningCharacterSequenceSupport from
SimpleFontData.h, right?

-        m_combiningCharacterSequenceSupport = adoptPtr(new HashMap<String, bool>);
-
-    WTF::HashMap<String, bool>::AddResult addResult = m_combiningCharacterSequenceSupport->add(String(characters, length), false);
-    if (!addResult.isNewEntry)
-        return addResult.storedValue->value;
-
-    UErrorCode error = U_ZERO_ERROR;
-    Vector<UChar, 4> normalizedCharacters(length);
-    size_t normalizedLength = unorm_normalize(characters, length, UNORM_NFC, UNORM_UNICODE_3_2, &normalizedCharacters[0], length, &error);
-    // Can't render if we have an error or no composition occurred.
-    if (U_FAILURE(error) || normalizedLength == length)
-        return false;
-
-    for (size_t offset = 0; offset < normalizedLength;) {
-        UChar32 character;
-        U16_NEXT(normalizedCharacters, offset, normalizedLength, character);
-        if (!glyphForCharacter(character))
-            return false;
-    }
-
-    addResult.storedValue->value = true;
-    return true;
-}
-
 bool SimpleFontData::fillGlyphPage(GlyphPage* pageToFill, unsigned offset, unsigned length, UChar* buffer, unsigned bufferLength) const
 {
     if (SkUTF16_IsHighSurrogate(buffer[bufferLength-1])) {
         SkDebugf("%s last char is high-surrogate", __FUNCTION__);
         return false;
     }
 
     SkTypeface* typeface = platformData().typeface();
     if (!typeface) {
         WTF_LOG_ERROR("fillGlyphPage called on an empty Skia typeface.");
         return false;
     }
 
     SkAutoSTMalloc<GlyphPage::size, uint16_t> glyphStorage(length);
     uint16_t* glyphs = glyphStorage.get();
     typeface->charsToGlyphs(buffer, SkTypeface::kUTF16_Encoding, glyphs, length);
 
     bool haveGlyphs = false;
     for (unsigned i = 0; i < length; i++) {
         if (glyphs[i]) {
             pageToFill->setGlyphDataForIndex(offset + i, glyphs[i], this);
             haveGlyphs = true;
         }
     }
 
     return haveGlyphs;
 }
 
 } // namespace blink