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// Copyright 2013 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Font management utilities
#include "./font.h"
#include <algorithm>
#include "./buffer.h"
#include "./port.h"
#include "./store_bytes.h"
#include "./table_tags.h"
#include "./woff2_common.h"
namespace woff2 {
Font::Table* Font::FindTable(uint32_t tag) {
std::map<uint32_t, Font::Table>::iterator it = tables.find(tag);
return it == tables.end() ? 0 : &it->second;
}
const Font::Table* Font::FindTable(uint32_t tag) const {
std::map<uint32_t, Font::Table>::const_iterator it = tables.find(tag);
return it == tables.end() ? 0 : &it->second;
}
std::vector<uint32_t> Font::OutputOrderedTags() const {
std::vector<uint32_t> output_order;
for (const auto& i : tables) {
const Font::Table& table = i.second;
// This is a transformed table, we will write it together with the
// original version.
if (table.tag & 0x80808080) {
continue;
}
output_order.push_back(table.tag);
}
// Alphabetize and do not put loca immediately after glyf
// This violates woff2 spec but results in a font that passes OTS
std::sort(output_order.begin(), output_order.end());
// TODO(user): change to match spec once browsers are on newer OTS
/*
auto glyf_loc = std::find(output_order.begin(), output_order.end(),
kGlyfTableTag);
auto loca_loc = std::find(output_order.begin(), output_order.end(),
kLocaTableTag);
if (glyf_loc != output_order.end() && loca_loc != output_order.end()) {
output_order.erase(loca_loc);
output_order.insert(std::find(output_order.begin(), output_order.end(),
kGlyfTableTag) + 1, kLocaTableTag);
}*/
return output_order;
}
bool ReadTrueTypeFont(Buffer* file, const uint8_t* data, size_t len,
Font* font) {
// We don't care about the search_range, entry_selector and range_shift
// fields, they will always be computed upon writing the font.
if (!file->ReadU16(&font->num_tables) ||
!file->Skip(6)) {
return FONT_COMPRESSION_FAILURE();
}
std::map<uint32_t, uint32_t> intervals;
for (uint16_t i = 0; i < font->num_tables; ++i) {
Font::Table table;
table.reuse_of = NULL;
if (!file->ReadU32(&table.tag) ||
!file->ReadU32(&table.checksum) ||
!file->ReadU32(&table.offset) ||
!file->ReadU32(&table.length)) {
return FONT_COMPRESSION_FAILURE();
}
if ((table.offset & 3) != 0 ||
table.length > len ||
len - table.length < table.offset) {
return FONT_COMPRESSION_FAILURE();
}
intervals[table.offset] = table.length;
table.data = data + table.offset;
if (font->tables.find(table.tag) != font->tables.end()) {
return FONT_COMPRESSION_FAILURE();
}
font->tables[table.tag] = table;
}
// Check that tables are non-overlapping.
uint32_t last_offset = 12UL + 16UL * font->num_tables;
for (const auto& i : intervals) {
if (i.first < last_offset || i.first + i.second < i.first) {
return FONT_COMPRESSION_FAILURE();
}
last_offset = i.first + i.second;
}
return true;
}
bool ReadCollectionFont(Buffer* file, const uint8_t* data, size_t len,
Font* font,
std::map<uint32_t, Font::Table*>* all_tables) {
if (!file->ReadU32(&font->flavor)) {
return FONT_COMPRESSION_FAILURE();
}
if (!ReadTrueTypeFont(file, data, len, font)) {
return FONT_COMPRESSION_FAILURE();
}
for (auto& entry : font->tables) {
Font::Table& table = entry.second;
if (all_tables->find(table.offset) == all_tables->end()) {
(*all_tables)[table.offset] = font->FindTable(table.tag);
} else {
table.reuse_of = (*all_tables)[table.offset];
}
}
return true;
}
bool ReadTrueTypeCollection(Buffer* file, const uint8_t* data, size_t len,
FontCollection* font_collection) {
uint32_t num_fonts;
if (!file->ReadU32(&font_collection->header_version) ||
!file->ReadU32(&num_fonts)) {
return FONT_COMPRESSION_FAILURE();
}
std::vector<uint32_t> offsets;
for (auto i = 0; i < num_fonts; i++) {
uint32_t offset;
if (!file->ReadU32(&offset)) {
return FONT_COMPRESSION_FAILURE();
}
offsets.push_back(offset);
}
font_collection->fonts.resize(offsets.size());
std::vector<Font>::iterator font_it = font_collection->fonts.begin();
std::map<uint32_t, Font::Table*> all_tables;
for (const auto offset : offsets) {
file->set_offset(offset);
Font& font = *font_it++;
if (!ReadCollectionFont(file, data, len, &font, &all_tables)) {
return FONT_COMPRESSION_FAILURE();
}
}
return true;
}
bool ReadFont(const uint8_t* data, size_t len, Font* font) {
Buffer file(data, len);
if (!file.ReadU32(&font->flavor)) {
return FONT_COMPRESSION_FAILURE();
}
if (font->flavor == kTtcFontFlavor) {
return FONT_COMPRESSION_FAILURE();
}
return ReadTrueTypeFont(&file, data, len, font);
}
bool ReadFontCollection(const uint8_t* data, size_t len,
FontCollection* font_collection) {
Buffer file(data, len);
uint32_t flavor;
if (!file.ReadU32(&flavor)) {
return FONT_COMPRESSION_FAILURE();
}
if (flavor != kTtcFontFlavor) {
font_collection->fonts.resize(1);
Font& font = font_collection->fonts[0];
font.flavor = flavor;
return ReadTrueTypeFont(&file, data, len, &font);
}
return ReadTrueTypeCollection(&file, data, len, font_collection);
}
size_t FontFileSize(const Font& font) {
size_t max_offset = 12ULL + 16ULL * font.num_tables;
for (const auto& i : font.tables) {
const Font::Table& table = i.second;
size_t padding_size = (4 - (table.length & 3)) & 3;
size_t end_offset = (padding_size + table.offset) + table.length;
max_offset = std::max(max_offset, end_offset);
}
return max_offset;
}
size_t FontCollectionFileSize(const FontCollection& font_collection) {
size_t max_offset = 0;
for (auto& font : font_collection.fonts) {
// font file size actually just finds max offset
max_offset = std::max(max_offset, FontFileSize(font));
}
return max_offset;
}
bool WriteFont(const Font& font, uint8_t* dst, size_t dst_size) {
size_t offset = 0;
return WriteFont(font, &offset, dst, dst_size);
}
bool WriteTableRecord(const Font::Table* table, size_t* offset, uint8_t* dst,
size_t dst_size) {
if (dst_size < *offset + kSfntEntrySize) {
return FONT_COMPRESSION_FAILURE();
}
if (table->IsReused()) {
table = table->reuse_of;
}
StoreU32(table->tag, offset, dst);
StoreU32(table->checksum, offset, dst);
StoreU32(table->offset, offset, dst);
StoreU32(table->length, offset, dst);
return true;
}
bool WriteTable(const Font::Table& table, size_t* offset, uint8_t* dst,
size_t dst_size) {
if (!WriteTableRecord(&table, offset, dst, dst_size)) {
return false;
}
// Write the actual table data if it's the first time we've seen it
if (!table.IsReused()) {
if (table.offset + table.length < table.offset ||
dst_size < table.offset + table.length) {
return FONT_COMPRESSION_FAILURE();
}
memcpy(dst + table.offset, table.data, table.length);
size_t padding_size = (4 - (table.length & 3)) & 3;
if (table.offset + table.length + padding_size < padding_size ||
dst_size < table.offset + table.length + padding_size) {
return FONT_COMPRESSION_FAILURE();
}
memset(dst + table.offset + table.length, 0, padding_size);
}
return true;
}
bool WriteFont(const Font& font, size_t* offset, uint8_t* dst,
size_t dst_size) {
if (dst_size < 12ULL + 16ULL * font.num_tables) {
return FONT_COMPRESSION_FAILURE();
}
StoreU32(font.flavor, offset, dst);
Store16(font.num_tables, offset, dst);
uint16_t max_pow2 = font.num_tables ? Log2Floor(font.num_tables) : 0;
uint16_t search_range = max_pow2 ? 1 << (max_pow2 + 4) : 0;
uint16_t range_shift = (font.num_tables << 4) - search_range;
Store16(search_range, offset, dst);
Store16(max_pow2, offset, dst);
Store16(range_shift, offset, dst);
for (const auto& i : font.tables) {
if (!WriteTable(i.second, offset, dst, dst_size)) {
return false;
}
}
return true;
}
bool WriteFontCollection(const FontCollection& font_collection, uint8_t* dst,
size_t dst_size) {
size_t offset = 0;
// It's simpler if this just a simple sfnt
if (font_collection.fonts.size() == 1) {
return WriteFont(font_collection.fonts[0], &offset, dst, dst_size);
}
// Write TTC header
StoreU32(kTtcFontFlavor, &offset, dst);
StoreU32(font_collection.header_version, &offset, dst);
StoreU32(font_collection.fonts.size(), &offset, dst);
// Offset Table, zeroed for now
size_t offset_table = offset; // where to write offsets later
for (int i = 0; i < font_collection.fonts.size(); i++) {
StoreU32(0, &offset, dst);
}
if (font_collection.header_version == 0x00020000) {
StoreU32(0, &offset, dst); // ulDsigTag
StoreU32(0, &offset, dst); // ulDsigLength
StoreU32(0, &offset, dst); // ulDsigOffset
}
// Write fonts and their offsets.
for (int i = 0; i < font_collection.fonts.size(); i++) {
const auto& font = font_collection.fonts[i];
StoreU32(offset, &offset_table, dst);
if (!WriteFont(font, &offset, dst, dst_size)) {
return false;
}
}
return true;
}
int NumGlyphs(const Font& font) {
const Font::Table* head_table = font.FindTable(kHeadTableTag);
const Font::Table* loca_table = font.FindTable(kLocaTableTag);
if (head_table == NULL || loca_table == NULL || head_table->length < 52) {
return 0;
}
int index_fmt = IndexFormat(font);
int num_glyphs = (loca_table->length / (index_fmt == 0 ? 2 : 4)) - 1;
return num_glyphs;
}
int IndexFormat(const Font& font) {
const Font::Table* head_table = font.FindTable(kHeadTableTag);
if (head_table == NULL) {
return 0;
}
return head_table->data[51];
}
bool Font::Table::IsReused() const {
return this->reuse_of != NULL;
}
bool GetGlyphData(const Font& font, int glyph_index,
const uint8_t** glyph_data, size_t* glyph_size) {
if (glyph_index < 0) {
return FONT_COMPRESSION_FAILURE();
}
const Font::Table* head_table = font.FindTable(kHeadTableTag);
const Font::Table* loca_table = font.FindTable(kLocaTableTag);
const Font::Table* glyf_table = font.FindTable(kGlyfTableTag);
if (head_table == NULL || loca_table == NULL || glyf_table == NULL ||
head_table->length < 52) {
return FONT_COMPRESSION_FAILURE();
}
int index_fmt = IndexFormat(font);
Buffer loca_buf(loca_table->data, loca_table->length);
if (index_fmt == 0) {
uint16_t offset1, offset2;
if (!loca_buf.Skip(2 * glyph_index) ||
!loca_buf.ReadU16(&offset1) ||
!loca_buf.ReadU16(&offset2) ||
offset2 < offset1 ||
2 * offset2 > glyf_table->length) {
return FONT_COMPRESSION_FAILURE();
}
*glyph_data = glyf_table->data + 2 * offset1;
*glyph_size = 2 * (offset2 - offset1);
} else {
uint32_t offset1, offset2;
if (!loca_buf.Skip(4 * glyph_index) ||
!loca_buf.ReadU32(&offset1) ||
!loca_buf.ReadU32(&offset2) ||
offset2 < offset1 ||
offset2 > glyf_table->length) {
return FONT_COMPRESSION_FAILURE();
}
*glyph_data = glyf_table->data + offset1;
*glyph_size = offset2 - offset1;
}
return true;
}
bool RemoveDigitalSignature(Font* font) {
std::map<uint32_t, Font::Table>::iterator it =
font->tables.find(kDsigTableTag);
if (it != font->tables.end()) {
font->tables.erase(it);
font->num_tables = font->tables.size();
}
return true;
}
} // namespace woff2