source/layout/LigatureSubstProc.cpp

   1 /*
   2  *
   3  * (C) Copyright IBM Corp. 1998-2013 - All Rights Reserved
   4  *
   5  */
   6
   7 #include "LETypes.h"
   8 #include "MorphTables.h"
   9 #include "StateTables.h"
  10 #include "MorphStateTables.h"
  11 #include "SubtableProcessor.h"
  12 #include "StateTableProcessor.h"
  13 #include "LigatureSubstProc.h"
  14 #include "LEGlyphStorage.h"
  15 #include "LESwaps.h"
  16
  17 U_NAMESPACE_BEGIN
  18
  19 #define ExtendedComplement(m) ((le_int32) (~((le_uint32) (m))))
  20 #define SignBit(m) ((ExtendedComplement(m) >> 1) & (le_int32)(m))
  21 #define SignExtend(v,m) (((v) & SignBit(m))? ((v) | ExtendedComplement(m)): (v))
  22
  23 UOBJECT_DEFINE_RTTI_IMPLEMENTATION(LigatureSubstitutionProcessor)
  24
  25   LigatureSubstitutionProcessor::LigatureSubstitutionProcessor(const LEReferenceTo<MorphSubtableHeader> &morphSubtableHeader, LEErrorCode &success)
  26 : StateTableProcessor(morphSubtableHeader, success), ligatureSubstitutionHeader(morphSubtableHeader, success)
  27 {
  28     if(LE_FAILURE(success)) return;
  29     ligatureActionTableOffset = SWAPW(ligatureSubstitutionHeader->ligatureActionTableOffset);
  30     componentTableOffset = SWAPW(ligatureSubstitutionHeader->componentTableOffset);
  31     ligatureTableOffset = SWAPW(ligatureSubstitutionHeader->ligatureTableOffset);
  32
  33     entryTable = LEReferenceToArrayOf<LigatureSubstitutionStateEntry>(stHeader, success, entryTableOffset, LE_UNBOUNDED_ARRAY);
  34 }
  35
  36 LigatureSubstitutionProcessor::~LigatureSubstitutionProcessor()
  37 {
  38 }
  39
  40 void LigatureSubstitutionProcessor::beginStateTable()
  41 {
  42     m = -1;
  43 }
  44
  45 ByteOffset LigatureSubstitutionProcessor::processStateEntry(LEGlyphStorage &glyphStorage, le_int32 &currGlyph, EntryTableIndex index)
  46 {
  47   LEErrorCode success = LE_NO_ERROR;
  48   const LigatureSubstitutionStateEntry *entry = entryTable.getAlias(index, success);
  49
  50     ByteOffset newState = SWAPW(entry->newStateOffset);
  51     le_int16 flags = SWAPW(entry->flags);
  52
  53     if (flags & lsfSetComponent) {
  54         if (++m >= nComponents) {
  55             m = 0;
  56         }
  57
  58         componentStack[m] = currGlyph;
  59     } else if ( m == -1) {
  60         // bad font- skip this glyph.
  61         currGlyph++;
  62         return newState;
  63     }
  64
  65     ByteOffset actionOffset = flags & lsfActionOffsetMask;
  66
  67     if (actionOffset != 0) {
  68       LEReferenceTo<LigatureActionEntry> ap(stHeader, success, actionOffset);
  69         LigatureActionEntry action;
  70         le_int32 offset, i = 0;
  71         le_int32 stack[nComponents];
  72         le_int16 mm = -1;
  73
  74         do {
  75             le_uint32 componentGlyph = componentStack[m--];
  76
  77             action = SWAPL(*ap.getAlias());
  78             ap.addObject(success); // ap++
  79
  80             if (m < 0) {
  81                 m = nComponents - 1;
  82             }
  83
  84             offset = action & lafComponentOffsetMask;
  85             if (offset != 0) {
  86               LEReferenceToArrayOf<le_int16> offsetTable(stHeader, success, 2 * SignExtend(offset, lafComponentOffsetMask), LE_UNBOUNDED_ARRAY);
  87
  88               if(LE_FAILURE(success)) {
  89                   currGlyph++;
  90                   LE_DEBUG_BAD_FONT("off end of ligature substitution header");
  91                   return newState; // get out! bad font
  92               }
  93               if(componentGlyph > (le_uint32)glyphStorage.getGlyphCount()) {
  94                 LE_DEBUG_BAD_FONT("preposterous componentGlyph");
  95                 currGlyph++;
  96                 return newState; // get out! bad font
  97               }
  98               i += SWAPW(offsetTable.getObject(LE_GET_GLYPH(glyphStorage[componentGlyph]), success));
  99
 100                 if (action & (lafLast | lafStore))  {
 101                   LEReferenceTo<TTGlyphID> ligatureOffset(stHeader, success, i);
 102                   TTGlyphID ligatureGlyph = SWAPW(*ligatureOffset.getAlias());
 103
 104                   glyphStorage[componentGlyph] = LE_SET_GLYPH(glyphStorage[componentGlyph], ligatureGlyph);
 105                   if(mm==nComponents) {
 106                     LE_DEBUG_BAD_FONT("exceeded nComponents");
 107                     mm--; // don't overrun the stack.
 108                   }
 109                   stack[++mm] = componentGlyph;
 110                   i = 0;
 111                 } else {
 112                   glyphStorage[componentGlyph] = LE_SET_GLYPH(glyphStorage[componentGlyph], 0xFFFF);
 113                 }
 114             }
 115 #if LE_ASSERT_BAD_FONT
 116             if(m<0) {
 117               LE_DEBUG_BAD_FONT("m<0")
 118             }
 119 #endif
 120         } while (!(action & lafLast)  && (m>=0) ); // stop if last bit is set, or if run out of items
 121
 122         while (mm >= 0) {
 123           if (++m >= nComponents) {
 124             m = 0;
 125           }
 126
 127           componentStack[m] = stack[mm--];
 128         }
 129     }
 130
 131     if (!(flags & lsfDontAdvance)) {
 132         // should handle reverse too!
 133         currGlyph += 1;
 134     }
 135
 136     return newState;
 137 }
 138
 139 void LigatureSubstitutionProcessor::endStateTable()
 140 {
 141 }
 142
 143 U_NAMESPACE_END