/*
* @(#)KernTable.cpp 1.1 04/10/13
*
* (C) Copyright IBM Corp. 2004-2014 - All Rights Reserved
*
*/
#include "KernTable.h"
#include "LEFontInstance.h"
#include "LEGlyphStorage.h"
#include "LESwaps.h"
#include "OpenTypeUtilities.h"
#include <stdio.h>
#define KERNTABLE_DEBUG 0
U_NAMESPACE_BEGIN
struct PairInfo {
le_uint16 left; // left glyph of kern pair
le_uint16 right; // right glyph of kern pair
le_int16 value; // fword, kern value in funits
};
#define KERN_PAIRINFO_SIZE 6
LE_CORRECT_SIZE(PairInfo, KERN_PAIRINFO_SIZE)
#define SWAP_KEY(p) (((le_uint32) SWAPW((p)->left) << 16) | SWAPW((p)->right))
struct Subtable_0 {
le_uint16 nPairs;
le_uint16 searchRange;
le_uint16 entrySelector;
le_uint16 rangeShift;
};
#define KERN_SUBTABLE_0_HEADER_SIZE 8
LE_CORRECT_SIZE(Subtable_0, KERN_SUBTABLE_0_HEADER_SIZE)
// Kern table version 0 only
struct SubtableHeader {
le_uint16 version;
le_uint16 length;
le_uint16 coverage;
};
#define KERN_SUBTABLE_HEADER_SIZE 6
LE_CORRECT_SIZE(SubtableHeader, KERN_SUBTABLE_HEADER_SIZE)
// Version 0 only, version 1 has different layout
struct KernTableHeader {
le_uint16 version;
le_uint16 nTables;
};
#define KERN_TABLE_HEADER_SIZE 4
LE_CORRECT_SIZE(KernTableHeader, KERN_TABLE_HEADER_SIZE)
#define COVERAGE_HORIZONTAL 0x1
#define COVERAGE_MINIMUM 0x2
#define COVERAGE_CROSS 0x4
#define COVERAGE_OVERRIDE 0x8
/*
* This implementation has support for only one subtable, so if the font has
* multiple subtables, only the first will be used. If this turns out to
* be a problem in practice we should add it.
*
* This also supports only version 0 of the kern table header, only
* Apple supports the latter.
*
* This implementation isn't careful about the kern table flags, and
* might invoke kerning when it is not supposed to. That too I'm
* leaving for a bug fix.
*
* TODO: support multiple subtables
* TODO: respect header flags
*/
KernTable::KernTable(const LETableReference& base, LEErrorCode &success)
: pairs(), fTable(base)
{
if(LE_FAILURE(success) || fTable.isEmpty()) {
#if KERNTABLE_DEBUG
fprintf(stderr, "no kern data\n");
#endif
return;
}
LEReferenceTo<KernTableHeader> header(fTable, success);
#if KERNTABLE_DEBUG
// dump first 32 bytes of header
for (int i = 0; i < 64; ++i) {
fprintf(stderr, "%0.2x ", ((const char*)header.getAlias())[i]&0xff);
if (((i+1)&0xf) == 0) {
fprintf(stderr, "\n");
} else if (((i+1)&0x7) == 0) {
fprintf(stderr, " ");
}
}
#endif
if(LE_FAILURE(success)) return;
if (!header.isEmpty() && header->version == 0 && SWAPW(header->nTables) > 0) {
LEReferenceTo<SubtableHeader> subhead(header, success, KERN_TABLE_HEADER_SIZE);
if (LE_SUCCESS(success) && !subhead.isEmpty() && subhead->version == 0) {
coverage = SWAPW(subhead->coverage);
if (coverage & COVERAGE_HORIZONTAL) { // only handle horizontal kerning
LEReferenceTo<Subtable_0> table(subhead, success, KERN_SUBTABLE_HEADER_SIZE);
if(table.isEmpty() || LE_FAILURE(success)) return;
nPairs = SWAPW(table->nPairs);
#if 0 // some old fonts have bad values here...
searchRange = SWAPW(table->searchRange);
entrySelector = SWAPW(table->entrySelector);
rangeShift = SWAPW(table->rangeShift);
#else
entrySelector = OpenTypeUtilities::highBit(nPairs);
searchRange = (1 << entrySelector) * KERN_PAIRINFO_SIZE;
rangeShift = (nPairs * KERN_PAIRINFO_SIZE) - searchRange;
#endif
if(LE_SUCCESS(success) && nPairs>0) {
// pairs is an instance member, and table is on the stack.
// set 'pairs' based on table.getAlias(). This will range check it.
pairs = LEReferenceToArrayOf<PairInfo>(fTable, // based on overall table
success,
(const PairInfo*)table.getAlias(), // subtable 0 + ..
KERN_SUBTABLE_0_HEADER_SIZE, // .. offset of header size
nPairs); // count
}
#if 0
fprintf(stderr, "coverage: %0.4x nPairs: %d pairs %p\n", coverage, nPairs, pairs.getAlias());
fprintf(stderr, " searchRange: %d entrySelector: %d rangeShift: %d\n", searchRange, entrySelector, rangeShift);
fprintf(stderr, "[[ ignored font table entries: range %d selector %d shift %d ]]\n", SWAPW(table->searchRange), SWAPW(table->entrySelector), SWAPW(table->rangeShift));
#endif
#if KERNTABLE_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);
if(LE_SUCCESS(success) {
// 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;
}
}
for (i = 0; i < nPairs; ++i) {
const PairInfo& p = pairs[i, success];
le_uint16 left = p->left;
le_uint16 right = p->right;
if (left < 256 && right < 256) {
char c = ids[left];
if (c > 0x20 && c < 0x7f) {
fprintf(stderr, "%c/", c & 0xff);
} else {
printf(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);
}
}
}
}
#endif
}
}
}
}
/*
* Process the glyph positions. The positions array has two floats for each
g * glyph, plus a trailing pair to mark the end of the last glyph.
*/
void KernTable::process(LEGlyphStorage& storage, LEErrorCode &success)
{
if (LE_SUCCESS(success) && !pairs.isEmpty()) {
le_uint32 key = storage[0]; // no need to mask off high bits
float adjust = 0;
for (int i = 1, e = storage.getGlyphCount(); LE_SUCCESS(success)&& 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.getAlias(0, success);
LEReferenceTo<PairInfo> tpRef(pairs, success, rangeShift); // ((char*)pairs) + rangeShift
const PairInfo *tp = tpRef.getAlias();
if(LE_FAILURE(success)) return; // get out.
if (key > SWAP_KEY(tp)) {
p = tp;
}
#if KERNTABLE_DEBUG
fprintf(stderr, "binary search for %0.8x\n", key);
#endif
le_uint32 probe = searchRange;
while (probe > KERN_PAIRINFO_SIZE && LE_SUCCESS(success)) {
probe >>= 1;
tpRef = LEReferenceTo<PairInfo>(pairs, success, p, probe); // (char*)p + probe
tp = tpRef.getAlias();
le_uint32 tkey = SWAP_KEY(tp);
if(LE_FAILURE(success)) break;
#if KERNTABLE_DEBUG
fprintf(stdout, " %.3d (%0.8x)\n", ((char*)tp - (char*)pairs)/KERN_PAIRINFO_SIZE, tkey);
#endif
if (tkey <= key && LE_SUCCESS(success)) {
if (tkey == key) {
le_int16 value = SWAPW(tp->value);
#if KERNTABLE_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 += fTable.getFont()->xUnitsToPoints(value);
break;
}
p = tp;
}
}
storage.adjustPosition(i, adjust, 0, success);
}
storage.adjustPosition(storage.getGlyphCount(), adjust, 0, success);
}
}
U_NAMESPACE_END