icuSources/layout/MarkToLigaturePosnSubtables.cpp

   1 /*
   2  * (C) Copyright IBM Corp. 1998-2013 - All Rights Reserved
   3  *
   4  */
   5
   6 #include "LETypes.h"
   7 #include "LEFontInstance.h"
   8 #include "OpenTypeTables.h"
   9 #include "AnchorTables.h"
  10 #include "MarkArrays.h"
  11 #include "GlyphPositioningTables.h"
  12 #include "AttachmentPosnSubtables.h"
  13 #include "MarkToLigaturePosnSubtables.h"
  14 #include "GlyphIterator.h"
  15 #include "LESwaps.h"
  16
  17 U_NAMESPACE_BEGIN
  18
  19 LEGlyphID MarkToLigaturePositioningSubtable::findLigatureGlyph(GlyphIterator *glyphIterator) const
  20 {
  21     if (glyphIterator->prev()) {
  22         return glyphIterator->getCurrGlyphID();
  23     }
  24
  25     return 0xFFFF;
  26 }
  27
  28 le_int32 MarkToLigaturePositioningSubtable::process(const LETableReference &base, GlyphIterator *glyphIterator, const LEFontInstance *fontInstance, LEErrorCode &success) const
  29 {
  30     LEGlyphID markGlyph = glyphIterator->getCurrGlyphID();
  31     le_int32 markCoverage = getGlyphCoverage(base, (LEGlyphID) markGlyph, success);
  32
  33     if (markCoverage < 0) {
  34         // markGlyph isn't a covered mark glyph
  35         return 0;
  36     }
  37
  38     LEPoint markAnchor;
  39     const MarkArray *markArray = (const MarkArray *) ((char *) this + SWAPW(markArrayOffset));
  40     le_int32 markClass = markArray->getMarkClass(markGlyph, markCoverage, fontInstance, markAnchor);
  41     le_uint16 mcCount = SWAPW(classCount);
  42
  43     if (markClass < 0 || markClass >= mcCount) {
  44         // markGlyph isn't in the mark array or its
  45         // mark class is too big. The table is mal-formed!
  46         return 0;
  47     }
  48
  49     // FIXME: we probably don't want to find a ligature before a previous base glyph...
  50     GlyphIterator ligatureIterator(*glyphIterator, (le_uint16) (lfIgnoreMarks /*| lfIgnoreBaseGlyphs*/));
  51     LEGlyphID ligatureGlyph = findLigatureGlyph(&ligatureIterator);
  52     le_int32 ligatureCoverage = getBaseCoverage(base, (LEGlyphID) ligatureGlyph, success);
  53     const LigatureArray *ligatureArray = (const LigatureArray *) ((char *) this + SWAPW(baseArrayOffset));
  54     le_uint16 ligatureCount = SWAPW(ligatureArray->ligatureCount);
  55
  56     if (ligatureCoverage < 0 || ligatureCoverage >= ligatureCount) {
  57         // The ligature glyph isn't covered, or the coverage
  58         // index is too big. The latter means that the
  59         // table is mal-formed...
  60         return 0;
  61     }
  62
  63     le_int32 markPosition = glyphIterator->getCurrStreamPosition();
  64     Offset ligatureAttachOffset = SWAPW(ligatureArray->ligatureAttachTableOffsetArray[ligatureCoverage]);
  65     const LigatureAttachTable *ligatureAttachTable = (const LigatureAttachTable *) ((char *) ligatureArray + ligatureAttachOffset);
  66     le_int32 componentCount = SWAPW(ligatureAttachTable->componentCount);
  67     le_int32 component = ligatureIterator.getMarkComponent(markPosition);
  68
  69     if (component >= componentCount) {
  70         // should really just bail at this point...
  71         component = componentCount - 1;
  72     }
  73
  74     const ComponentRecord *componentRecord = &ligatureAttachTable->componentRecordArray[component * mcCount];
  75     Offset anchorTableOffset = SWAPW(componentRecord->ligatureAnchorTableOffsetArray[markClass]);
  76     const AnchorTable *anchorTable = (const AnchorTable *) ((char *) ligatureAttachTable + anchorTableOffset);
  77     LEPoint ligatureAnchor, markAdvance, pixels;
  78
  79     anchorTable->getAnchor(ligatureGlyph, fontInstance, ligatureAnchor);
  80
  81     fontInstance->getGlyphAdvance(markGlyph, pixels);
  82     fontInstance->pixelsToUnits(pixels, markAdvance);
  83
  84     float anchorDiffX = ligatureAnchor.fX - markAnchor.fX;
  85     float anchorDiffY = ligatureAnchor.fY - markAnchor.fY;
  86
  87     glyphIterator->setCurrGlyphBaseOffset(ligatureIterator.getCurrStreamPosition());
  88
  89     if (glyphIterator->isRightToLeft()) {
  90         glyphIterator->setCurrGlyphPositionAdjustment(anchorDiffX, anchorDiffY, -markAdvance.fX, -markAdvance.fY);
  91     } else {
  92         LEPoint ligatureAdvance;
  93
  94         fontInstance->getGlyphAdvance(ligatureGlyph, pixels);
  95         fontInstance->pixelsToUnits(pixels, ligatureAdvance);
  96
  97         glyphIterator->setCurrGlyphPositionAdjustment(anchorDiffX - ligatureAdvance.fX, anchorDiffY - ligatureAdvance.fY, -markAdvance.fX, -markAdvance.fY);
  98     }
  99
 100     return 1;
 101 }
 102
 103 U_NAMESPACE_END