source/layout/CoverageTables.cpp

   1 /*
   2  *
   3  * (C) Copyright IBM Corp. 1998-2006 - 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 (count == 0) {
  52                 return -1;
  53         }
  54
  55     if (SWAPW(glyphArray[extra]) <= ttGlyphID) {
  56         index = extra;
  57     }
  58
  59     while (probe > (1 << 0)) {
  60         probe >>= 1;
  61
  62         if (SWAPW(glyphArray[index + probe]) <= ttGlyphID) {
  63             index += probe;
  64         }
  65     }
  66
  67     if (SWAPW(glyphArray[index]) == ttGlyphID) {
  68         return index;
  69     }
  70
  71     return -1;
  72 }
  73
  74 le_int32 CoverageFormat2Table::getGlyphCoverage(LEGlyphID glyphID) const
  75 {
  76     TTGlyphID ttGlyphID = (TTGlyphID) LE_GET_GLYPH(glyphID);
  77     le_uint16 count = SWAPW(rangeCount);
  78     le_int32 rangeIndex =
  79         OpenTypeUtilities::getGlyphRangeIndex(ttGlyphID, rangeRecordArray, count);
  80
  81     if (rangeIndex < 0) {
  82         return -1;
  83     }
  84
  85     TTGlyphID firstInRange = SWAPW(rangeRecordArray[rangeIndex].firstGlyph);
  86     le_uint16  startCoverageIndex = SWAPW(rangeRecordArray[rangeIndex].rangeValue);
  87
  88     return startCoverageIndex + (ttGlyphID - firstInRange);
  89 }
  90
  91 U_NAMESPACE_END