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
  14 NS_GetComplexLineBreaks(const char16_t* aText, uint32_t aLength,
  15                         uint8_t* aBreakBefore)
  16 {
  17   NS_ASSERTION(aText, "aText shouldn't be null");
  18
  19   memset(aBreakBefore, false, aLength * sizeof(uint8_t));
  20
  21   nsAutoTArray<PangoLogAttr, 2000> attrBuffer;
  22   if (!attrBuffer.AppendElements(aLength + 1))
  23     return;
  24
  25   NS_ConvertUTF16toUTF8 aUTF8(aText, aLength);
  26
  27   const gchar* p = aUTF8.Data();
  28   const gchar* end = p + aUTF8.Length();
  29   uint32_t     u16Offset = 0;
  30
  31   static PangoLanguage* language = pango_language_from_string("en");
  32
  33   while (p < end)
  34   {
  35     PangoLogAttr* attr = attrBuffer.Elements();
  36     pango_get_log_attrs(p, end - p, -1, language, attr, attrBuffer.Length());
  37
  38     while (p < end)
  39     {
  40       aBreakBefore[u16Offset] = attr->is_line_break;
  41       if (NS_IS_LOW_SURROGATE(aText[u16Offset]))
  42         aBreakBefore[++u16Offset] = false; // Skip high surrogate
  43       ++u16Offset;
  44
  45       bool err;
  46       uint32_t ch = UTF8CharEnumerator::NextChar(&p, end, &err);
  47       ++attr;
  48
  49       if (ch == 0 || err) {
  50         // pango_break (pango 1.16.2) only analyses text before the
  51         // first NUL (but sets one extra attr). Workaround loop to call
  52         // pango_break again to analyse after the NUL is done somewhere else
  53         // (gfx/thebes/gfxPangoFonts.cpp: SetupClusterBoundaries()).
  54         // So, we do the same here for pango_get_log_attrs.
  55         break;
  56       }
  57     }
  58   }
  59 }
  60