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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 "vdmx.h"
#include <set>
// VDMX - Vertical Device Metrics
// http://www.microsoft.com/typography/otspec/vdmx.htm
namespace ots {
#define TABLE_NAME "VDMX"
bool OpenTypeVDMX::Parse(const uint8_t *data, size_t length) {
Buffer table(data, length);
ots::Font* font = this->GetFont();
if (!table.ReadU16(&this->version) ||
!table.ReadU16(&this->num_recs) ||
!table.ReadU16(&this->num_ratios)) {
return Drop("Failed to read table header");
}
if (this->version > 1) {
return Drop("Unsupported table version: %u", this->version);
}
this->rat_ranges.reserve(this->num_ratios);
for (unsigned i = 0; i < this->num_ratios; ++i) {
OpenTypeVDMXRatioRecord rec;
if (!table.ReadU8(&rec.charset) ||
!table.ReadU8(&rec.x_ratio) ||
!table.ReadU8(&rec.y_start_ratio) ||
!table.ReadU8(&rec.y_end_ratio)) {
return Drop("Failed to read RatioRange record %d", i);
}
if (rec.charset > 1) {
return Drop("Unsupported character set: %u", rec.charset);
}
if (rec.y_start_ratio > rec.y_end_ratio) {
return Drop("Bad y ratio");
}
// All values set to zero signal the default grouping to use;
// if present, this must be the last Ratio group in the table.
if ((i < this->num_ratios - 1u) &&
(rec.x_ratio == 0) &&
(rec.y_start_ratio == 0) &&
(rec.y_end_ratio == 0)) {
// workaround for fonts which have 2 or more {0, 0, 0} terminators.
return Drop("Superfluous terminator found");
}
this->rat_ranges.push_back(rec);
}
this->offsets.reserve(this->num_ratios);
const size_t current_offset = table.offset();
std::set<uint16_t> unique_offsets;
// current_offset is less than (2 bytes * 3) + (4 bytes * USHRT_MAX) = 256k.
for (unsigned i = 0; i < this->num_ratios; ++i) {
uint16_t offset;
if (!table.ReadU16(&offset)) {
return Drop("Failed to read ratio offset %d", i);
}
if (current_offset + offset >= length) { // thus doesn't overflow.
return Drop("Bad ratio offset %d for ration %d", offset, i);
}
this->offsets.push_back(offset);
unique_offsets.insert(offset);
}
// Check that num_recs is sufficient to provide as many VDMXGroup records
// as there are unique offsets; if not, update it (we'll return an error
// below if they're not actually present).
if (unique_offsets.size() > this->num_recs) {
OTS_WARNING("increasing num_recs (%u is too small for %u unique offsets)",
this->num_recs, unique_offsets.size());
this->num_recs = unique_offsets.size();
}
this->groups.reserve(this->num_recs);
for (unsigned i = 0; i < this->num_recs; ++i) {
OpenTypeVDMXGroup group;
if (!table.ReadU16(&group.recs) ||
!table.ReadU8(&group.startsz) ||
!table.ReadU8(&group.endsz)) {
return Drop("Failed to read record header %d", i);
}
group.entries.reserve(group.recs);
for (unsigned j = 0; j < group.recs; ++j) {
OpenTypeVDMXVTable vt;
if (!table.ReadU16(&vt.y_pel_height) ||
!table.ReadS16(&vt.y_max) ||
!table.ReadS16(&vt.y_min)) {
return Drop("Failed to read record %d group %d", i, j);
}
if (vt.y_max < vt.y_min) {
return Drop("bad y min/max");
}
// This table must appear in sorted order (sorted by yPelHeight),
// but need not be continuous.
if ((j != 0) && (group.entries[j - 1].y_pel_height >= vt.y_pel_height)) {
return Drop("The table is not sorted");
}
group.entries.push_back(vt);
}
this->groups.push_back(group);
}
return true;
}
bool OpenTypeVDMX::ShouldSerialize() {
return Table::ShouldSerialize() &&
// this table is not for CFF fonts.
GetFont()->GetTable(OTS_TAG_GLYF) != NULL;
}
bool OpenTypeVDMX::Serialize(OTSStream *out) {
if (!out->WriteU16(this->version) ||
!out->WriteU16(this->num_recs) ||
!out->WriteU16(this->num_ratios)) {
return Error("Failed to write table header");
}
for (unsigned i = 0; i < this->rat_ranges.size(); ++i) {
const OpenTypeVDMXRatioRecord& rec = this->rat_ranges[i];
if (!out->Write(&rec.charset, 1) ||
!out->Write(&rec.x_ratio, 1) ||
!out->Write(&rec.y_start_ratio, 1) ||
!out->Write(&rec.y_end_ratio, 1)) {
return Error("Failed to write RatioRange record %d", i);
}
}
for (unsigned i = 0; i < this->offsets.size(); ++i) {
if (!out->WriteU16(this->offsets[i])) {
return Error("Failed to write ratio offset %d", i);
}
}
for (unsigned i = 0; i < this->groups.size(); ++i) {
const OpenTypeVDMXGroup& group = this->groups[i];
if (!out->WriteU16(group.recs) ||
!out->Write(&group.startsz, 1) ||
!out->Write(&group.endsz, 1)) {
return Error("Failed to write group %d", i);
}
for (unsigned j = 0; j < group.entries.size(); ++j) {
const OpenTypeVDMXVTable& vt = group.entries[j];
if (!out->WriteU16(vt.y_pel_height) ||
!out->WriteS16(vt.y_max) ||
!out->WriteS16(vt.y_min)) {
return Error("Failed to write group %d entry %d", i, j);
}
}
}
return true;
}
#undef TABLE_NAME
} // namespace ots
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