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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 "glyf.h"
#include <algorithm>
#include <limits>
#include "head.h"
#include "loca.h"
#include "maxp.h"
// glyf - Glyph Data
// http://www.microsoft.com/typography/otspec/glyf.htm
#define TABLE_NAME "glyf"
namespace {
bool ParseFlagsForSimpleGlyph(ots::Font *font,
ots::Buffer *table,
uint32_t gly_length,
uint32_t num_flags,
uint32_t *flags_count_logical,
uint32_t *flags_count_physical,
uint32_t *xy_coordinates_length) {
uint8_t flag = 0;
if (!table->ReadU8(&flag)) {
return OTS_FAILURE_MSG("Can't read flag");
}
uint32_t delta = 0;
if (flag & (1u << 1)) { // x-Short
++delta;
} else if (!(flag & (1u << 4))) {
delta += 2;
}
if (flag & (1u << 2)) { // y-Short
++delta;
} else if (!(flag & (1u << 5))) {
delta += 2;
}
if (flag & (1u << 3)) { // repeat
if (*flags_count_logical + 1 >= num_flags) {
return OTS_FAILURE_MSG("Count too high (%d + 1 >= %d)", *flags_count_logical, num_flags);
}
uint8_t repeat = 0;
if (!table->ReadU8(&repeat)) {
return OTS_FAILURE_MSG("Can't read repeat value");
}
if (repeat == 0) {
return OTS_FAILURE_MSG("Zero repeat");
}
delta += (delta * repeat);
*flags_count_logical += repeat;
if (*flags_count_logical >= num_flags) {
return OTS_FAILURE_MSG("Count too high (%d >= %d)", *flags_count_logical, num_flags);
}
++(*flags_count_physical);
}
if ((flag & (1u << 6)) || (flag & (1u << 7))) { // reserved flags
return OTS_FAILURE_MSG("Bad glyph flag value (%d), reserved flags must be set to zero", flag);
}
*xy_coordinates_length += delta;
if (gly_length < *xy_coordinates_length) {
return OTS_FAILURE_MSG("Glyph coordinates length too low (%d < %d)", gly_length, *xy_coordinates_length);
}
return true;
}
bool ParseSimpleGlyph(ots::Font *font, const uint8_t *data,
ots::Buffer *table, int16_t num_contours,
uint32_t gly_offset, uint32_t gly_length,
uint32_t *new_size) {
ots::OpenTypeGLYF *glyf = font->glyf;
// read the end-points array
uint16_t num_flags = 0;
for (int i = 0; i < num_contours; ++i) {
uint16_t tmp_index = 0;
if (!table->ReadU16(&tmp_index)) {
return OTS_FAILURE_MSG("Can't read contour index %d", i);
}
if (tmp_index == 0xffffu) {
return OTS_FAILURE_MSG("Bad contour index %d", i);
}
// check if the indices are monotonically increasing
if (i && (tmp_index + 1 <= num_flags)) {
return OTS_FAILURE_MSG("Decreasing contour index %d + 1 <= %d", tmp_index, num_flags);
}
num_flags = tmp_index + 1;
}
uint16_t bytecode_length = 0;
if (!table->ReadU16(&bytecode_length)) {
return OTS_FAILURE_MSG("Can't read bytecode length");
}
if ((font->maxp->version_1) &&
(font->maxp->max_size_glyf_instructions < bytecode_length)) {
return OTS_FAILURE_MSG("Bytecode length too high %d", bytecode_length);
}
const uint32_t gly_header_length = 10 + num_contours * 2 + 2;
if (gly_length < (gly_header_length + bytecode_length)) {
return OTS_FAILURE_MSG("Glyph header length too high %d", gly_header_length);
}
glyf->iov.push_back(std::make_pair(
data + gly_offset,
static_cast<size_t>(gly_header_length + bytecode_length)));
if (!table->Skip(bytecode_length)) {
return OTS_FAILURE_MSG("Can't skip bytecode of length %d", bytecode_length);
}
uint32_t flags_count_physical = 0; // on memory
uint32_t xy_coordinates_length = 0;
for (uint32_t flags_count_logical = 0;
flags_count_logical < num_flags;
++flags_count_logical, ++flags_count_physical) {
if (!ParseFlagsForSimpleGlyph(font,
table,
gly_length,
num_flags,
&flags_count_logical,
&flags_count_physical,
&xy_coordinates_length)) {
return OTS_FAILURE_MSG("Failed to parse glyph flags %d", flags_count_logical);
}
}
if (gly_length < (gly_header_length + bytecode_length +
flags_count_physical + xy_coordinates_length)) {
return OTS_FAILURE_MSG("Glyph too short %d", gly_length);
}
if (gly_length - (gly_header_length + bytecode_length +
flags_count_physical + xy_coordinates_length) > 3) {
// We allow 0-3 bytes difference since gly_length is 4-bytes aligned,
// zero-padded length.
return OTS_FAILURE_MSG("Invalid glyph length %d", gly_length);
}
glyf->iov.push_back(std::make_pair(
data + gly_offset + gly_header_length + bytecode_length,
static_cast<size_t>(flags_count_physical + xy_coordinates_length)));
*new_size
= gly_header_length + flags_count_physical + xy_coordinates_length + bytecode_length;
return true;
}
} // namespace
namespace ots {
bool ots_glyf_parse(Font *font, const uint8_t *data, size_t length) {
Buffer table(data, length);
if (!font->maxp || !font->loca || !font->head) {
return OTS_FAILURE_MSG("Missing maxp or loca or head table needed by glyf table");
}
OpenTypeGLYF *glyf = new OpenTypeGLYF;
font->glyf = glyf;
const unsigned num_glyphs = font->maxp->num_glyphs;
std::vector<uint32_t> &offsets = font->loca->offsets;
if (offsets.size() != num_glyphs + 1) {
return OTS_FAILURE_MSG("Invalide glyph offsets size %ld != %d", offsets.size(), num_glyphs + 1);
}
std::vector<uint32_t> resulting_offsets(num_glyphs + 1);
uint32_t current_offset = 0;
for (unsigned i = 0; i < num_glyphs; ++i) {
const unsigned gly_offset = offsets[i];
// The LOCA parser checks that these values are monotonic
const unsigned gly_length = offsets[i + 1] - offsets[i];
if (!gly_length) {
// this glyph has no outline (e.g. the space charactor)
resulting_offsets[i] = current_offset;
continue;
}
if (gly_offset >= length) {
return OTS_FAILURE_MSG("Glyph %d offset %d too high %ld", i, gly_offset, length);
}
// Since these are unsigned types, the compiler is not allowed to assume
// that they never overflow.
if (gly_offset + gly_length < gly_offset) {
return OTS_FAILURE_MSG("Glyph %d length (%d < 0)!", i, gly_length);
}
if (gly_offset + gly_length > length) {
return OTS_FAILURE_MSG("Glyph %d length %d too high", i, gly_length);
}
table.set_offset(gly_offset);
int16_t num_contours, xmin, ymin, xmax, ymax;
if (!table.ReadS16(&num_contours) ||
!table.ReadS16(&xmin) ||
!table.ReadS16(&ymin) ||
!table.ReadS16(&xmax) ||
!table.ReadS16(&ymax)) {
return OTS_FAILURE_MSG("Can't read glyph %d header", i);
}
if (num_contours <= -2) {
// -2, -3, -4, ... are reserved for future use.
return OTS_FAILURE_MSG("Bad number of contours %d in glyph %d", num_contours, i);
}
// workaround for fonts in http://www.princexml.com/fonts/
if ((xmin == 32767) &&
(xmax == -32767) &&
(ymin == 32767) &&
(ymax == -32767)) {
OTS_WARNING("bad xmin/xmax/ymin/ymax values");
xmin = xmax = ymin = ymax = 0;
}
if (xmin > xmax || ymin > ymax) {
return OTS_FAILURE_MSG("Bad bounding box values bl=(%d, %d), tr=(%d, %d) in glyph %d", xmin, ymin, xmax, ymax, i);
}
unsigned new_size = 0;
if (num_contours >= 0) {
// this is a simple glyph and might contain bytecode
if (!ParseSimpleGlyph(font, data, &table,
num_contours, gly_offset, gly_length, &new_size)) {
return OTS_FAILURE_MSG("Failed to parse glyph %d", i);
}
} else {
// it's a composite glyph without any bytecode. Enqueue the whole thing
glyf->iov.push_back(std::make_pair(data + gly_offset,
static_cast<size_t>(gly_length)));
new_size = gly_length;
}
resulting_offsets[i] = current_offset;
// glyphs must be four byte aligned
// TODO(yusukes): investigate whether this padding is really necessary.
// Which part of the spec requires this?
const unsigned padding = (4 - (new_size & 3)) % 4;
if (padding) {
glyf->iov.push_back(std::make_pair(
reinterpret_cast<const uint8_t*>("\x00\x00\x00\x00"),
static_cast<size_t>(padding)));
new_size += padding;
}
current_offset += new_size;
}
resulting_offsets[num_glyphs] = current_offset;
const uint16_t max16 = std::numeric_limits<uint16_t>::max();
if ((*std::max_element(resulting_offsets.begin(),
resulting_offsets.end()) >= (max16 * 2u)) &&
(font->head->index_to_loc_format != 1)) {
OTS_WARNING("2-bytes indexing is not possible (due to the padding above)");
font->head->index_to_loc_format = 1;
}
font->loca->offsets = resulting_offsets;
return true;
}
bool ots_glyf_should_serialise(Font *font) {
return font->glyf != NULL;
}
bool ots_glyf_serialise(OTSStream *out, Font *font) {
const OpenTypeGLYF *glyf = font->glyf;
for (unsigned i = 0; i < glyf->iov.size(); ++i) {
if (!out->Write(glyf->iov[i].first, glyf->iov[i].second)) {
return OTS_FAILURE_MSG("Falied to write glyph %d", i);
}
}
return true;
}
void ots_glyf_reuse(Font *font, Font *other) {
font->glyf = other->glyf;
font->glyf_reused = true;
}
void ots_glyf_free(Font *font) {
delete font->glyf;
}
} // namespace ots
#undef TABLE_NAME