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// Copyright (c) 2009-2017 The OTS 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 "loca.h"
#include "head.h"
#include "maxp.h"
// loca - Index to Location
// http://www.microsoft.com/typography/otspec/loca.htm
namespace ots {
bool OpenTypeLOCA::Parse(const uint8_t *data, size_t length) {
Buffer table(data, length);
// We can't do anything useful in validating this data except to ensure that
// the values are monotonically increasing.
OpenTypeMAXP *maxp = static_cast<OpenTypeMAXP*>(
GetFont()->GetTypedTable(OTS_TAG_MAXP));
OpenTypeHEAD *head = static_cast<OpenTypeHEAD*>(
GetFont()->GetTypedTable(OTS_TAG_HEAD));
if (!maxp || !head) {
return Error("Required maxp or head tables are missing");
}
const unsigned num_glyphs = maxp->num_glyphs;
unsigned last_offset = 0;
this->offsets.resize(num_glyphs + 1);
// maxp->num_glyphs is uint16_t, thus the addition never overflows.
if (head->index_to_loc_format == 0) {
// Note that the <= here (and below) is correct. There is one more offset
// than the number of glyphs in order to give the length of the final
// glyph.
for (unsigned i = 0; i <= num_glyphs; ++i) {
uint16_t offset = 0;
if (!table.ReadU16(&offset)) {
return Error("Failed to read offset for glyph %d", i);
}
if (offset < last_offset) {
return Error("Out of order offset %d < %d for glyph %d", offset, last_offset, i);
}
last_offset = offset;
this->offsets[i] = offset * 2;
}
} else {
for (unsigned i = 0; i <= num_glyphs; ++i) {
uint32_t offset = 0;
if (!table.ReadU32(&offset)) {
return Error("Failed to read offset for glyph %d", i);
}
if (offset < last_offset) {
return Error("Out of order offset %d < %d for glyph %d", offset, last_offset, i);
}
last_offset = offset;
this->offsets[i] = offset;
}
}
return true;
}
bool OpenTypeLOCA::Serialize(OTSStream *out) {
OpenTypeHEAD *head = static_cast<OpenTypeHEAD*>(
GetFont()->GetTypedTable(OTS_TAG_HEAD));
if (!head) {
return Error("Required head table is missing");
}
if (head->index_to_loc_format == 0) {
for (unsigned i = 0; i < this->offsets.size(); ++i) {
const uint16_t offset = static_cast<uint16_t>(this->offsets[i] >> 1);
if ((offset != (this->offsets[i] >> 1)) ||
!out->WriteU16(offset)) {
return Error("Failed to write glyph offset for glyph %d", i);
}
}
} else {
for (unsigned i = 0; i < this->offsets.size(); ++i) {
if (!out->WriteU32(this->offsets[i])) {
return Error("Failed to write glyph offset for glyph %d", i);
}
}
}
return true;
}
} // namespace ots
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