icuSources/layout/CoverageTables.cpp

   1 /*
   2  *
   3  * (C) Copyright IBM Corp. 1998-2004 - All Rights Reserved
   4  *
   5  */
   6
   7 #include "LETypes.h"
   8 #include "OpenTypeTables.h"
   9 #include "OpenTypeUtilities.h"
  10 #include "CoverageTables.h"
  11 #include "LESwaps.h"
  12
  13 U_NAMESPACE_BEGIN
  14
  15 le_int32 CoverageTable::getGlyphCoverage(LEGlyphID glyphID) const
  16 {
  17     switch(SWAPW(coverageFormat))
  18     {
  19     case 0:
  20         return -1;
  21
  22     case 1:
  23     {
  24         const CoverageFormat1Table *f1Table = (const CoverageFormat1Table *) this;
  25
  26         return f1Table->getGlyphCoverage(glyphID);
  27     }
  28
  29     case 2:
  30     {
  31         const CoverageFormat2Table *f2Table = (const CoverageFormat2Table *) this;
  32
  33         return f2Table->getGlyphCoverage(glyphID);
  34     }
  35
  36     default:
  37         return -1;
  38     }
  39 }
  40
  41 le_int32 CoverageFormat1Table::getGlyphCoverage(LEGlyphID glyphID) const
  42 {
  43     TTGlyphID ttGlyphID = (TTGlyphID) LE_GET_GLYPH(glyphID);
  44     le_uint16 count = SWAPW(glyphCount);
  45     le_uint8 bit = OpenTypeUtilities::highBit(count);
  46     le_uint16 power = 1 << bit;
  47     le_uint16 extra = count - power;
  48     le_uint16 probe = power;
  49     le_uint16 index = 0;
  50
  51     if (SWAPW(glyphArray[extra]) <= ttGlyphID) {
  52         index = extra;
  53     }
  54
  55     while (probe > (1 << 0)) {
  56         probe >>= 1;
  57
  58         if (SWAPW(glyphArray[index + probe]) <= ttGlyphID) {
  59             index += probe;
  60         }
  61     }
  62
  63     if (SWAPW(glyphArray[index]) == ttGlyphID) {
  64         return index;
  65     }
  66
  67     return -1;
  68 }
  69
  70 le_int32 CoverageFormat2Table::getGlyphCoverage(LEGlyphID glyphID) const
  71 {
  72     TTGlyphID ttGlyphID = (TTGlyphID) LE_GET_GLYPH(glyphID);
  73     le_uint16 count = SWAPW(rangeCount);
  74     le_int32 rangeIndex =
  75         OpenTypeUtilities::getGlyphRangeIndex(ttGlyphID, rangeRecordArray, count);
  76
  77     if (rangeIndex < 0) {
  78         return -1;
  79     }
  80
  81     TTGlyphID firstInRange = SWAPW(rangeRecordArray[rangeIndex].firstGlyph);
  82     le_uint16  startCoverageIndex = SWAPW(rangeRecordArray[rangeIndex].rangeValue);
  83
  84     return startCoverageIndex + (ttGlyphID - firstInRange);
  85 }
  86
  87 U_NAMESPACE_END