/*

  * @(#)KernTable.cpp	1.1 04/10/13

  *

  * (C) Copyright IBM Corp. 2004-2005 - All Rights Reserved

  *

  */

 #include "KernTable.h"

 #include "LESwaps.h"

 #include <stdio.h>

 #define DEBUG 0

 U_NAMESPACE_BEGIN

 struct PairInfo {

   le_uint32 key;   // sigh, MSVC compiler gags on union here

   le_int16  value; // fword, kern value in funits

 };

 #define KERN_PAIRINFO_SIZE 6

 struct Subtable_0 {

   le_uint16 nPairs;

   le_uint16 searchRange;

   le_uint16 entrySelector;

   le_uint16 rangeShift;

 };

 #define KERN_SUBTABLE_0_HEADER_SIZE 8

 // Kern table version 0 only

 struct SubtableHeader {

   le_uint16 version;

   le_uint16 length;

   le_uint16 coverage;

 };

 #define KERN_SUBTABLE_HEADER_SIZE 6

 // Version 0 only, version 1 has different layout

 struct KernTableHeader {

   le_uint16 version;

   le_uint16 nTables;

 };

 #define KERN_TABLE_HEADER_SIZE 4

 #define COVERAGE_HORIZONTAL 0x1

 #define COVERAGE_MINIMUM 0x2

 #define COVERAGE_CROSS 0x4

 #define COVERAGE_OVERRIDE 0x8

 KernTable::KernTable(const LEFontInstance* font, const void* tableData) 

   : pairs(0), font(font)

 {

   const KernTableHeader* header = (const KernTableHeader*)tableData;

   if (header == 0) {

 #if DEBUG

     fprintf(stderr, "no kern data\n");

     fflush(stderr);

 #endif

     return;

   }

 #if DEBUG

   // dump first 32 bytes of header

   for (int i = 0; i < 64; ++i) {

     fprintf(stderr, "%0.2x ", ((const char*)tableData)[i]&0xff);

     if (((i+1)&0xf) == 0) {

       fprintf(stderr, "\n");

     } else if (((i+1)&0x7) == 0) {

       fprintf(stderr, "  ");

     }

   }

   fflush(stderr);

 #endif

   if (header->version == 0 && SWAPW(header->nTables) > 0) {

     const SubtableHeader* subhead = (const SubtableHeader*)((char*)tableData + KERN_TABLE_HEADER_SIZE);

     if (subhead->version == 0) {

       coverage = SWAPW(subhead->coverage);

       if (coverage & COVERAGE_HORIZONTAL) { // only handle horizontal kerning

 	const Subtable_0* table = (const Subtable_0*)((char*)subhead + KERN_SUBTABLE_HEADER_SIZE);

 	nPairs = SWAPW(table->nPairs);

 	searchRange = SWAPW(table->searchRange);

 	entrySelector = SWAPW(table->entrySelector);

 	rangeShift = SWAPW(table->rangeShift);

 	pairs = (const PairInfo*)((char*)table + KERN_SUBTABLE_0_HEADER_SIZE);

 #if DEBUG

 	fprintf(stderr, "coverage: %0.4x nPairs: %d pairs 0x%x\n", coverage, nPairs, pairs);

 	fprintf(stderr, "  searchRange: %d entrySelector: %d rangeShift: %d\n", searchRange, entrySelector, rangeShift);

 	fflush(stderr);

 	{

 	  // dump part of the pair list

 	  char ids[256];

 	  for (int i = 256; --i >= 0;) {

 	    LEGlyphID id = font->mapCharToGlyph(i);

 	    if (id < 256) {

 	      ids[id] = (char)i;

 	    }

 	  }

 	  const PairInfo* p = pairs;

 	  for (i = 0; i < nPairs; ++i, p = (const PairInfo*)((char*)p+KERN_PAIRINFO_SIZE)) {

   	    le_uint32 k = SWAPL(p->key);

 	    le_uint16 left = (k >> 16) & 0xffff;

 	    le_uint16 right = k & 0xffff;

 	    if (left < 256 && right < 256) {

 	      char c = ids[left];

 	      if (c > 0x20 && c < 0x7f) {

 		fprintf(stderr, "%c/", c & 0xff);

 	      } else {

 		fprintf(stderr, "%0.2x/", c & 0xff);

 	      }

 	      c = ids[right];

 	      if (c > 0x20 && c < 0x7f) {

 		fprintf(stderr, "%c ", c & 0xff);

 	      } else {

 		fprintf(stderr, "%0.2x ", c & 0xff);

 	      }

 	    }

 	  }

 	  fflush(stderr);

 	}

 #endif

       }

     }

   }

 }

 /*

  * Process the glyph positions.  The positions array has two floats for each

  * glyph, plus a trailing pair to mark the end of the last glyph.

  */

 //void KernTable::process(const LEGlyphID glyphs[], float* positions, le_int32 glyphCount) 

 void KernTable::process(LEGlyphStorage& storage) 

 {

   if (pairs) {

     LEErrorCode success = LE_NO_ERROR;

     le_uint32 key = storage[0]; // no need to mask off high bits

     float adjust = 0;

     for (int i = 1, e = storage.getGlyphCount(); i < e; ++i) {

       key = key << 16 | (storage[i] & 0xffff);

       // argh, to do a binary search, we need to have the pair list in sorted order

       // but it is not in sorted order on win32 platforms because of the endianness difference

       // so either I have to swap the element each time I examine it, or I have to swap

       // all the elements ahead of time and store them in the font

       const PairInfo* p = pairs;

       const PairInfo* tp = (const PairInfo*)((char*)p + rangeShift);

       if (key > SWAPL(tp->key)) {

 	p = tp;

       }

 #if DEBUG

       fprintf(stderr, "binary search for %0.8x\n", key);

       fflush(stderr);

 #endif

       le_uint32 probe = searchRange;

       while (probe > KERN_PAIRINFO_SIZE) {

         probe >>= 1;

         tp = (const PairInfo*)((char*)p + probe);

 	le_uint32 tkey = SWAPL(tp->key);

 #if DEBUG

 	fprintf(stdout, "   %.3d (%0.8x)\n", ((char*)tp - (char*)pairs)/KERN_PAIRINFO_SIZE, tkey);

 	fflush(stdout);

 #endif

         if (tkey <= key) {

 	  if (tkey == key) {

 	    le_int16 value = SWAPW(tp->value);

 #if DEBUG

 	    fprintf(stdout, "binary found kerning pair %x:%x at %d, value: 0x%x (%g)\n", 

 		    storage[i-1], storage[i], i, value & 0xffff, font->xUnitsToPoints(value));

 	    fflush(stdout);

 #endif

 	    adjust += font->xUnitsToPoints(value);

 	    break;

 	  }

 	  p = tp;

         }

       }

       storage.adjustPosition(i, adjust, 0, success);

     }

     storage.adjustPosition(storage.getGlyphCount(), adjust, 0, success);

   }

 }

 U_NAMESPACE_END