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// Copyright (c) 2009 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "gasp.h"
// gasp - Grid-fitting And Scan-conversion Procedure
// http://www.microsoft.com/typography/otspec/gasp.htm
#define TABLE_NAME "gasp"
#define DROP_THIS_TABLE(...) \
do { \
OTS_FAILURE_MSG_(font->file, TABLE_NAME ": " __VA_ARGS__); \
OTS_FAILURE_MSG("Table discarded"); \
delete font->gasp; \
font->gasp = 0; \
} while (0)
namespace ots {
bool ots_gasp_parse(Font *font, const uint8_t *data, size_t length) {
Buffer table(data, length);
OpenTypeGASP *gasp = new OpenTypeGASP;
font->gasp = gasp;
uint16_t num_ranges = 0;
if (!table.ReadU16(&gasp->version) ||
!table.ReadU16(&num_ranges)) {
return OTS_FAILURE_MSG("Failed to read table header");
}
if (gasp->version > 1) {
// Lots of Linux fonts have bad version numbers...
DROP_THIS_TABLE("bad version: %u", gasp->version);
return true;
}
if (num_ranges == 0) {
DROP_THIS_TABLE("num_ranges is zero");
return true;
}
gasp->gasp_ranges.reserve(num_ranges);
for (unsigned i = 0; i < num_ranges; ++i) {
uint16_t max_ppem = 0;
uint16_t behavior = 0;
if (!table.ReadU16(&max_ppem) ||
!table.ReadU16(&behavior)) {
return OTS_FAILURE_MSG("Failed to read subrange %d", i);
}
if ((i > 0) && (gasp->gasp_ranges[i - 1].first >= max_ppem)) {
// The records in the gaspRange[] array must be sorted in order of
// increasing rangeMaxPPEM value.
DROP_THIS_TABLE("ranges are not sorted");
return true;
}
if ((i == num_ranges - 1u) && // never underflow.
(max_ppem != 0xffffu)) {
DROP_THIS_TABLE("The last record should be 0xFFFF as a sentinel value "
"for rangeMaxPPEM");
return true;
}
if (behavior >> 8) {
OTS_WARNING("undefined bits are used: %x", behavior);
// mask undefined bits.
behavior &= 0x000fu;
}
if (gasp->version == 0 && (behavior >> 2) != 0) {
OTS_WARNING("changed the version number to 1");
gasp->version = 1;
}
gasp->gasp_ranges.push_back(std::make_pair(max_ppem, behavior));
}
return true;
}
bool ots_gasp_should_serialise(Font *font) {
return font->gasp != NULL;
}
bool ots_gasp_serialise(OTSStream *out, Font *font) {
const OpenTypeGASP *gasp = font->gasp;
const uint16_t num_ranges = static_cast<uint16_t>(gasp->gasp_ranges.size());
if (num_ranges != gasp->gasp_ranges.size() ||
!out->WriteU16(gasp->version) ||
!out->WriteU16(num_ranges)) {
return OTS_FAILURE_MSG("failed to write gasp header");
}
for (uint16_t i = 0; i < num_ranges; ++i) {
if (!out->WriteU16(gasp->gasp_ranges[i].first) ||
!out->WriteU16(gasp->gasp_ranges[i].second)) {
return OTS_FAILURE_MSG("Failed to write gasp subtable %d", i);
}
}
return true;
}
void ots_gasp_reuse(Font *font, Font *other) {
font->gasp = other->gasp;
font->gasp_reused = true;
}
void ots_gasp_free(Font *font) {
delete font->gasp;
}
} // namespace ots
#undef TABLE_NAME
#undef DROP_THIS_TABLE
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