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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"
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;
}
bool ReadFont(const uint8_t* data, size_t len, Font* font) {
Buffer file(data, len);
// 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.ReadU32(&font->flavor) ||
!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;
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;
}
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;
}
bool WriteFont(const Font& font, uint8_t* dst, size_t dst_size) {
if (dst_size < 12ULL + 16ULL * font.num_tables) {
return FONT_COMPRESSION_FAILURE();
}
size_t offset = 0;
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) {
const Font::Table& table = i.second;
StoreU32(table.tag, &offset, dst);
StoreU32(table.checksum, &offset, dst);
StoreU32(table.offset, &offset, dst);
StoreU32(table.length, &offset, dst);
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;
}
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 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
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