diff options
Diffstat (limited to 'woff2/woff2_enc.cc')
| -rw-r--r-- | woff2/woff2_enc.cc | 69 |
1 files changed, 59 insertions, 10 deletions
diff --git a/woff2/woff2_enc.cc b/woff2/woff2_enc.cc index b8afd92..6150935 100644 --- a/woff2/woff2_enc.cc +++ b/woff2/woff2_enc.cc @@ -12,7 +12,7 @@ // See the License for the specific language governing permissions and // limitations under the License. // -// Library for converting WOFF2 format font files to their TTF versions. +// Library for converting TTF format font files to their WOFF2 versions. #include "./woff2_enc.h" @@ -53,7 +53,7 @@ size_t Base128Size(size_t n) { void StoreBase128(size_t len, size_t* offset, uint8_t* dst) { size_t size = Base128Size(len); for (int i = 0; i < size; ++i) { - int b = (int)(len >> (7 * (size - i - 1))) & 0x7f; + int b = static_cast<int>((len >> (7 * (size - i - 1))) & 0x7f); if (i < size - 1) { b |= 0x80; } @@ -96,6 +96,9 @@ int KnownTableIndex(uint32_t tag) { void StoreTableEntry(const Table& table, size_t* offset, uint8_t* dst) { uint8_t flag_byte = 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); } @@ -106,7 +109,8 @@ void StoreTableEntry(const Table& table, size_t* offset, uint8_t* dst) { } size_t TableEntrySize(const Table& table) { - size_t size = KnownTableIndex(table.tag) < 31 ? 1 : 5; + 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); @@ -114,7 +118,8 @@ size_t TableEntrySize(const Table& table) { return size; } -size_t ComputeWoff2Length(const std::vector<Table>& tables) { +size_t ComputeWoff2Length(const std::vector<Table>& tables, + size_t extended_metadata_length) { size_t size = kWoff2HeaderSize; for (const auto& table : tables) { size += TableEntrySize(table); @@ -123,6 +128,7 @@ size_t ComputeWoff2Length(const std::vector<Table>& tables) { size += table.dst_length; size = Round4(size); } + size += extended_metadata_length; return size; } @@ -150,15 +156,30 @@ size_t ComputeTotalTransformLength(const Font& font) { } // 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 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; + return length + 1024 + extended_metadata.length(); +} + +uint32_t CompressedBufferSize(uint32_t original_size) { + return 1.2 * original_size + 10240; } bool ConvertTTFToWOFF2(const uint8_t *data, size_t length, uint8_t *result, size_t *result_length) { + return ConvertTTFToWOFF2(data, length, result, result_length, ""); +} + +bool ConvertTTFToWOFF2(const uint8_t *data, size_t length, + uint8_t *result, size_t *result_length, + const string& extended_metadata) { Font font; if (!ReadFont(data, length, &font)) { fprintf(stderr, "Parsing of the input font failed.\n"); @@ -187,7 +208,7 @@ bool ConvertTTFToWOFF2(const uint8_t *data, size_t length, // the size. If the compressor overflows this, it should return false and // then this function will also return false. size_t total_transform_length = ComputeTotalTransformLength(font); - size_t compression_buffer_size = 1.2 * total_transform_length + 10240; + 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; @@ -209,6 +230,23 @@ bool ConvertTTFToWOFF2(const uint8_t *data, size_t length, return false; } + // Compress the extended metadata + uint32_t compressed_metadata_buf_length = + CompressedBufferSize(extended_metadata.length()); + std::vector<uint8_t> compressed_metadata_buf(compressed_metadata_buf_length); + + if (extended_metadata.length() > 0) { + if (!Woff2Compress((const uint8_t*)extended_metadata.data(), + extended_metadata.length(), + compressed_metadata_buf.data(), + &compressed_metadata_buf_length)) { + fprintf(stderr, "Compression of extended metadata failed.\n"); + return false; + } + } else { + compressed_metadata_buf_length = 0; + } + std::vector<Table> tables; for (const auto& i : font.tables) { const Font::Table& src_table = i.second; @@ -241,7 +279,8 @@ bool ConvertTTFToWOFF2(const uint8_t *data, size_t length, tables.push_back(table); } - size_t woff2_length = ComputeWoff2Length(tables); + size_t woff2_length = + ComputeWoff2Length(tables, compressed_metadata_buf_length); if (woff2_length > *result_length) { fprintf(stderr, "Result allocation was too small (%zd vs %zd bytes).\n", *result_length, woff2_length); @@ -258,9 +297,16 @@ bool ConvertTTFToWOFF2(const uint8_t *data, size_t length, StoreU32(ComputeTTFLength(tables), &offset, result); StoreU32(total_compressed_length, &offset, result); StoreBytes(head_table->data + 4, 4, &offset, result); // font revision - StoreU32(0, &offset, result); // metaOffset - StoreU32(0, &offset, result); // metaLength - StoreU32(0, &offset, result); // metaOrigLength + 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(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 for (const auto& table : tables) { @@ -270,6 +316,9 @@ bool ConvertTTFToWOFF2(const uint8_t *data, size_t length, StoreBytes(table.dst_data, table.dst_length, &offset, result); offset = Round4(offset); } + StoreBytes(compressed_metadata_buf.data(), compressed_metadata_buf_length, + &offset, result); + if (*result_length != offset) { fprintf(stderr, "Mismatch between computed and actual length " "(%zd vs %zd)\n", *result_length, offset); |