/*

 * @(#)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