/* Copyright 2014 Google Inc. All Rights Reserved.
Distributed under MIT license.
See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
*/
/* Library for converting TTF format font files to their WOFF2 versions. */
#include <woff2/encode.h>
#include <stdlib.h>
#include <complex>
#include <cstring>
#include <limits>
#include <string>
#include <vector>
#include <brotli/encode.h>
#include "./buffer.h"
#include "./font.h"
#include "./normalize.h"
#include "./round.h"
#include "./store_bytes.h"
#include "./table_tags.h"
#include "./transform.h"
#include "./variable_length.h"
#include "./woff2_common.h"
namespace woff2 {
namespace {
const size_t kWoff2HeaderSize = 48;
const size_t kWoff2EntrySize = 20;
bool Compress(const uint8_t* data, const size_t len, uint8_t* result,
uint32_t* result_len, BrotliEncoderMode mode, int quality) {
size_t compressed_len = *result_len;
if (BrotliEncoderCompress(quality, BROTLI_DEFAULT_WINDOW, mode, len, data,
&compressed_len, result) == 0) {
return false;
}
*result_len = compressed_len;
return true;
}
bool Woff2Compress(const uint8_t* data, const size_t len,
uint8_t* result, uint32_t* result_len,
int quality) {
return Compress(data, len, result, result_len,
BROTLI_MODE_FONT, quality);
}
bool TextCompress(const uint8_t* data, const size_t len,
uint8_t* result, uint32_t* result_len,
int quality) {
return Compress(data, len, result, result_len,
BROTLI_MODE_TEXT, quality);
}
int KnownTableIndex(uint32_t tag) {
for (int i = 0; i < 63; ++i) {
if (tag == kKnownTags[i]) return i;
}
return 63;
}
void StoreTableEntry(const Table& table, size_t* offset, uint8_t* dst) {
uint8_t flag_byte = (table.flags & 0xC0) | KnownTableIndex(table.tag);
dst[(*offset)++] = flag_byte;
// The index here is treated as a set of flag bytes because
// bits 6 and 7 of the byte are reserved for future use as flags.
// 0x3f or 63 means an arbitrary table tag.
if ((flag_byte & 0x3f) == 0x3f) {
StoreU32(table.tag, offset, dst);
}
StoreBase128(table.src_length, offset, dst);
if ((table.flags & kWoff2FlagsTransform) != 0) {
StoreBase128(table.transform_length, offset, dst);
}
}
size_t TableEntrySize(const Table& table) {
uint8_t flag_byte = KnownTableIndex(table.tag);
size_t size = ((flag_byte & 0x3f) != 0x3f) ? 1 : 5;
size += Base128Size(table.src_length);
if ((table.flags & kWoff2FlagsTransform) != 0) {
size += Base128Size(table.transform_length);
}
return size;
}
size_t ComputeWoff2Length(const FontCollection& font_collection,
const std::vector<Table>& tables,
std::map<std::pair<uint32_t, uint32_t>, uint16_t>
index_by_tag_offset,
size_t compressed_data_length,
size_t extended_metadata_length) {
size_t size = kWoff2HeaderSize;
for (const auto& table : tables) {
size += TableEntrySize(table);
}
// for collections only, collection tables
if (font_collection.flavor == kTtcFontFlavor) {
size += 4; // UInt32 Version of TTC Header
size += Size255UShort(font_collection.fonts.size()); // 255UInt16 numFonts
size += 4 * font_collection.fonts.size(); // UInt32 flavor for each
for (const auto& font : font_collection.fonts) {
size += Size255UShort(font.tables.size()); // 255UInt16 numTables
for (const auto& entry : font.tables) {
const Font::Table& table = entry.second;
// no collection entry for xform table
if (table.tag & 0x80808080) continue;
std::pair<uint32_t, uint32_t> tag_offset(table.tag, table.offset);
uint16_t table_index = index_by_tag_offset[tag_offset];
size += Size255UShort(table_index); // 255UInt16 index entry
}
}
}
// compressed data
size += compressed_data_length;
size = Round4(size);
size += extended_metadata_length;
return size;
}
size_t ComputeUncompressedLength(const Font& font) {
// sfnt header + offset table
size_t size = 12 + 16 * font.num_tables;
for (const auto& entry : font.tables) {
const Font::Table& table = entry.second;
if (table.tag & 0x80808080) continue; // xform tables don't stay
if (table.IsReused()) continue; // don't have to pay twice
size += Round4(table.length);
}
return size;
}
size_t ComputeUncompressedLength(const FontCollection& font_collection) {
if (font_collection.flavor != kTtcFontFlavor) {
return ComputeUncompressedLength(font_collection.fonts[0]);
}
size_t size = CollectionHeaderSize(font_collection.header_version,
font_collection.fonts.size());
for (const auto& font : font_collection.fonts) {
size += ComputeUncompressedLength(font);
}
return size;
}
size_t ComputeTotalTransformLength(const Font& font) {
size_t total = 0;
for (const auto& i : font.tables) {
const Font::Table& table = i.second;
if (table.IsReused()) {
continue;
}
if (table.tag & 0x80808080 || !font.FindTable(table.tag ^ 0x80808080)) {
// Count transformed tables and non-transformed tables that do not have
// transformed versions.
total += table.length;
}
}
return total;
}
} // namespace
size_t MaxWOFF2CompressedSize(const uint8_t* data, size_t length) {
return MaxWOFF2CompressedSize(data, length, "");
}
size_t MaxWOFF2CompressedSize(const uint8_t* data, size_t length,
const std::string& extended_metadata) {
// Except for the header size, which is 32 bytes larger in woff2 format,
// all other parts should be smaller (table header in short format,
// transformations and compression). Just to be sure, we will give some
// headroom anyway.
return length + 1024 + extended_metadata.length();
}
uint32_t CompressedBufferSize(uint32_t original_size) {
return 1.2 * original_size + 10240;
}
bool TransformFontCollection(FontCollection* font_collection) {
for (auto& font : font_collection->fonts) {
if (!TransformGlyfAndLocaTables(&font)) {
#ifdef FONT_COMPRESSION_BIN
fprintf(stderr, "glyf/loca transformation failed.\n");
#endif
return FONT_COMPRESSION_FAILURE();
}
}
return true;
}
bool ConvertTTFToWOFF2(const uint8_t *data, size_t length,
uint8_t *result, size_t *result_length) {
WOFF2Params params;
return ConvertTTFToWOFF2(data, length, result, result_length,
params);
}
bool ConvertTTFToWOFF2(const uint8_t *data, size_t length,
uint8_t *result, size_t *result_length,
const WOFF2Params& params) {
FontCollection font_collection;
if (!ReadFontCollection(data, length, &font_collection)) {
#ifdef FONT_COMPRESSION_BIN
fprintf(stderr, "Parsing of the input font failed.\n");
#endif
return FONT_COMPRESSION_FAILURE();
}
if (!NormalizeFontCollection(&font_collection)) {
return FONT_COMPRESSION_FAILURE();
}
if (params.allow_transforms && !TransformFontCollection(&font_collection)) {
return FONT_COMPRESSION_FAILURE();
} else {
// glyf/loca use 11 to flag "not transformed"
for (auto& font : font_collection.fonts) {
Font::Table* glyf_table = font.FindTable(kGlyfTableTag);
Font::Table* loca_table = font.FindTable(kLocaTableTag);
if (glyf_table) {
glyf_table->flag_byte |= 0xc0;
}
if (loca_table) {
loca_table->flag_byte |= 0xc0;
}
}
}
// Although the compressed size of each table in the final woff2 file won't
// be larger than its transform_length, we have to allocate a large enough
// buffer for the compressor, since the compressor can potentially increase
// the size. If the compressor overflows this, it should return false and
// then this function will also return false.
size_t total_transform_length = 0;
for (const auto& font : font_collection.fonts) {
total_transform_length += ComputeTotalTransformLength(font);
}
size_t compression_buffer_size = CompressedBufferSize(total_transform_length);
std::vector<uint8_t> compression_buf(compression_buffer_size);
uint32_t total_compressed_length = compression_buffer_size;
// Collect all transformed data into one place in output order.
std::vector<uint8_t> transform_buf(total_transform_length);
size_t transform_offset = 0;
for (const auto& font : font_collection.fonts) {
for (const auto tag : font.OutputOrderedTags()) {
const Font::Table& original = font.tables.at(tag);
if (original.IsReused()) continue;
if (tag & 0x80808080) continue;
const Font::Table* table_to_store = font.FindTable(tag ^ 0x80808080);
if (table_to_store == NULL) table_to_store = &original;
StoreBytes(table_to_store->data, table_to_store->length,
&transform_offset, &transform_buf[0]);
}
}
// Compress all transformed data in one stream.
if (!Woff2Compress(transform_buf.data(), total_transform_length,
&compression_buf[0],
&total_compressed_length,
params.brotli_quality)) {
#ifdef FONT_COMPRESSION_BIN
fprintf(stderr, "Compression of combined table failed.\n");
#endif
return FONT_COMPRESSION_FAILURE();
}
#ifdef FONT_COMPRESSION_BIN
fprintf(stderr, "Compressed %zu to %u.\n", total_transform_length,
total_compressed_length);
#endif
// Compress the extended metadata
// TODO(user): how does this apply to collections
uint32_t compressed_metadata_buf_length =
CompressedBufferSize(params.extended_metadata.length());
std::vector<uint8_t> compressed_metadata_buf(compressed_metadata_buf_length);
if (params.extended_metadata.length() > 0) {
if (!TextCompress((const uint8_t*)params.extended_metadata.data(),
params.extended_metadata.length(),
compressed_metadata_buf.data(),
&compressed_metadata_buf_length,
params.brotli_quality)) {
#ifdef FONT_COMPRESSION_BIN
fprintf(stderr, "Compression of extended metadata failed.\n");
#endif
return FONT_COMPRESSION_FAILURE();
}
} else {
compressed_metadata_buf_length = 0;
}
std::vector<Table> tables;
std::map<std::pair<uint32_t, uint32_t>, uint16_t> index_by_tag_offset;
for (const auto& font : font_collection.fonts) {
for (const auto tag : font.OutputOrderedTags()) {
const Font::Table& src_table = font.tables.at(tag);
if (src_table.IsReused()) {
continue;
}
std::pair<uint32_t, uint32_t> tag_offset(src_table.tag, src_table.offset);
if (index_by_tag_offset.find(tag_offset) == index_by_tag_offset.end()) {
index_by_tag_offset[tag_offset] = tables.size();
} else {
return false;
}
Table table;
table.tag = src_table.tag;
table.flags = src_table.flag_byte;
table.src_length = src_table.length;
table.transform_length = src_table.length;
const uint8_t* transformed_data = src_table.data;
const Font::Table* transformed_table =
font.FindTable(src_table.tag ^ 0x80808080);
if (transformed_table != NULL) {
table.flags = transformed_table->flag_byte;
table.flags |= kWoff2FlagsTransform;
table.transform_length = transformed_table->length;
transformed_data = transformed_table->data;
}
tables.push_back(table);
}
}
size_t woff2_length = ComputeWoff2Length(font_collection, tables,
index_by_tag_offset, total_compressed_length,
compressed_metadata_buf_length);
if (woff2_length > *result_length) {
#ifdef FONT_COMPRESSION_BIN
fprintf(stderr, "Result allocation was too small (%zd vs %zd bytes).\n",
*result_length, woff2_length);
#endif
return FONT_COMPRESSION_FAILURE();
}
*result_length = woff2_length;
size_t offset = 0;
// start of woff2 header (http://www.w3.org/TR/WOFF2/#woff20Header)
StoreU32(kWoff2Signature, &offset, result);
if (font_collection.flavor != kTtcFontFlavor) {
StoreU32(font_collection.fonts[0].flavor, &offset, result);
} else {
StoreU32(kTtcFontFlavor, &offset, result);
}
StoreU32(woff2_length, &offset, result);
Store16(tables.size(), &offset, result);
Store16(0, &offset, result); // reserved
// totalSfntSize
StoreU32(ComputeUncompressedLength(font_collection), &offset, result);
StoreU32(total_compressed_length, &offset, result); // totalCompressedSize
// Let's just all be v1.0
Store16(1, &offset, result); // majorVersion
Store16(0, &offset, result); // minorVersion
if (compressed_metadata_buf_length > 0) {
StoreU32(woff2_length - compressed_metadata_buf_length,
&offset, result); // metaOffset
StoreU32(compressed_metadata_buf_length, &offset, result); // metaLength
StoreU32(params.extended_metadata.length(),
&offset, result); // metaOrigLength
} else {
StoreU32(0, &offset, result); // metaOffset
StoreU32(0, &offset, result); // metaLength
StoreU32(0, &offset, result); // metaOrigLength
}
StoreU32(0, &offset, result); // privOffset
StoreU32(0, &offset, result); // privLength
// end of woff2 header
// table directory (http://www.w3.org/TR/WOFF2/#table_dir_format)
for (const auto& table : tables) {
StoreTableEntry(table, &offset, result);
}
// for collections only, collection table directory
if (font_collection.flavor == kTtcFontFlavor) {
StoreU32(font_collection.header_version, &offset, result);
Store255UShort(font_collection.fonts.size(), &offset, result);
for (const Font& font : font_collection.fonts) {
uint16_t num_tables = 0;
for (const auto& entry : font.tables) {
const Font::Table& table = entry.second;
if (table.tag & 0x80808080) continue; // don't write xform tables
num_tables++;
}
Store255UShort(num_tables, &offset, result);
StoreU32(font.flavor, &offset, result);
for (const auto& entry : font.tables) {
const Font::Table& table = entry.second;
if (table.tag & 0x80808080) continue; // don't write xform tables
// for reused tables, only the original has an updated offset
uint32_t table_offset =
table.IsReused() ? table.reuse_of->offset : table.offset;
uint32_t table_length =
table.IsReused() ? table.reuse_of->length : table.length;
std::pair<uint32_t, uint32_t> tag_offset(table.tag, table_offset);
if (index_by_tag_offset.find(tag_offset) == index_by_tag_offset.end()) {
#ifdef FONT_COMPRESSION_BIN
fprintf(stderr, "Missing table index for offset 0x%08x\n",
table_offset);
#endif
return FONT_COMPRESSION_FAILURE();
}
uint16_t index = index_by_tag_offset[tag_offset];
Store255UShort(index, &offset, result);
}
}
}
// compressed data format (http://www.w3.org/TR/WOFF2/#table_format)
StoreBytes(&compression_buf[0], total_compressed_length, &offset, result);
offset = Round4(offset);
StoreBytes(compressed_metadata_buf.data(), compressed_metadata_buf_length,
&offset, result);
if (*result_length != offset) {
#ifdef FONT_COMPRESSION_BIN
fprintf(stderr, "Mismatch between computed and actual length "
"(%zd vs %zd)\n", *result_length, offset);
#endif
return FONT_COMPRESSION_FAILURE();
}
return true;
}
} // namespace woff2
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