intl/lwbrk/nsPangoBreaker.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "nsComplexBreaker.h"
   7
   8 #include <pango/pango-break.h>
   9 #include "nsUTF8Utils.h"
  10 #include "nsString.h"
  11 #include "nsTArray.h"
  12
  13 void NS_GetComplexLineBreaks(const char16_t* aText, uint32_t aLength,
  14                              uint8_t* aBreakBefore) {
  15   NS_ASSERTION(aText, "aText shouldn't be null");
  16
  17   memset(aBreakBefore, false, aLength * sizeof(uint8_t));
  18
  19   AutoTArray<PangoLogAttr, 2000> attrBuffer;
  20   // XXX(Bug 1631371) Check if this should use a fallible operation as it
  21   // pretended earlier.
  22   attrBuffer.AppendElements(aLength + 1);
  23
  24   NS_ConvertUTF16toUTF8 aUTF8(aText, aLength);
  25
  26   const gchar* p = aUTF8.Data();
  27   const gchar* end = p + aUTF8.Length();
  28   uint32_t u16Offset = 0;
  29
  30   static PangoLanguage* language = pango_language_from_string("en");
  31
  32   while (p < end) {
  33     PangoLogAttr* attr = attrBuffer.Elements();
  34     pango_get_log_attrs(p, end - p, -1, language, attr, attrBuffer.Length());
  35
  36     while (p < end) {
  37       aBreakBefore[u16Offset] = attr->is_line_break;
  38       if (NS_IS_LOW_SURROGATE(aText[u16Offset]))
  39         aBreakBefore[++u16Offset] = false;  // Skip high surrogate
  40       ++u16Offset;
  41
  42       // We're iterating over text obtained from NS_ConvertUTF16toUTF8,
  43       // so we know we have valid UTF-8 and don't need to check for
  44       // errors.
  45       uint32_t ch = UTF8CharEnumerator::NextChar(&p, end);
  46       ++attr;
  47
  48       if (!ch) {
  49         // pango_break (pango 1.16.2) only analyses text before the
  50         // first NUL (but sets one extra attr). Workaround loop to call
  51         // pango_break again to analyse after the NUL is done somewhere else
  52         // (gfx/thebes/gfxFontconfigFonts.cpp: SetupClusterBoundaries()).
  53         // So, we do the same here for pango_get_log_attrs.
  54         break;
  55       }
  56     }
  57   }
  58 }