1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/skia/trunk/src/core/SkFontStream.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,210 @@
1.4 +/*
1.5 + * Copyright 2011 Google Inc.
1.6 + *
1.7 + * Use of this source code is governed by a BSD-style license that can be
1.8 + * found in the LICENSE file.
1.9 + */
1.10 +
1.11 +#include "SkEndian.h"
1.12 +#include "SkFontStream.h"
1.13 +#include "SkStream.h"
1.14 +
1.15 +struct SkSFNTHeader {
1.16 + uint32_t fVersion;
1.17 + uint16_t fNumTables;
1.18 + uint16_t fSearchRange;
1.19 + uint16_t fEntrySelector;
1.20 + uint16_t fRangeShift;
1.21 +};
1.22 +
1.23 +struct SkTTCFHeader {
1.24 + uint32_t fTag;
1.25 + uint32_t fVersion;
1.26 + uint32_t fNumOffsets;
1.27 + uint32_t fOffset0; // the first of N (fNumOffsets)
1.28 +};
1.29 +
1.30 +union SkSharedTTHeader {
1.31 + SkSFNTHeader fSingle;
1.32 + SkTTCFHeader fCollection;
1.33 +};
1.34 +
1.35 +struct SkSFNTDirEntry {
1.36 + uint32_t fTag;
1.37 + uint32_t fChecksum;
1.38 + uint32_t fOffset;
1.39 + uint32_t fLength;
1.40 +};
1.41 +
1.42 +static bool read(SkStream* stream, void* buffer, size_t amount) {
1.43 + return stream->read(buffer, amount) == amount;
1.44 +}
1.45 +
1.46 +static bool skip(SkStream* stream, size_t amount) {
1.47 + return stream->skip(amount) == amount;
1.48 +}
1.49 +
1.50 +/** Return the number of tables, or if this is a TTC (collection), return the
1.51 + number of tables in the first element of the collection. In either case,
1.52 + if offsetToDir is not-null, set it to the offset to the beginning of the
1.53 + table headers (SkSFNTDirEntry), relative to the start of the stream.
1.54 +
1.55 + On an error, return 0 for number of tables, and ignore offsetToDir
1.56 + */
1.57 +static int count_tables(SkStream* stream, int ttcIndex, size_t* offsetToDir) {
1.58 + SkASSERT(ttcIndex >= 0);
1.59 +
1.60 + SkAutoSMalloc<1024> storage(sizeof(SkSharedTTHeader));
1.61 + SkSharedTTHeader* header = (SkSharedTTHeader*)storage.get();
1.62 +
1.63 + if (!read(stream, header, sizeof(SkSharedTTHeader))) {
1.64 + return 0;
1.65 + }
1.66 +
1.67 + // by default, SkSFNTHeader is at the start of the stream
1.68 + size_t offset = 0;
1.69 +
1.70 + // if we're really a collection, the first 4-bytes will be 'ttcf'
1.71 + uint32_t tag = SkEndian_SwapBE32(header->fCollection.fTag);
1.72 + if (SkSetFourByteTag('t', 't', 'c', 'f') == tag) {
1.73 + unsigned count = SkEndian_SwapBE32(header->fCollection.fNumOffsets);
1.74 + if ((unsigned)ttcIndex >= count) {
1.75 + return 0;
1.76 + }
1.77 +
1.78 + if (ttcIndex > 0) { // need to read more of the shared header
1.79 + stream->rewind();
1.80 + size_t amount = sizeof(SkSharedTTHeader) + ttcIndex * sizeof(uint32_t);
1.81 + header = (SkSharedTTHeader*)storage.reset(amount);
1.82 + if (!read(stream, header, amount)) {
1.83 + return 0;
1.84 + }
1.85 + }
1.86 + // this is the offset to the local SkSFNTHeader
1.87 + offset = SkEndian_SwapBE32((&header->fCollection.fOffset0)[ttcIndex]);
1.88 + stream->rewind();
1.89 + if (!skip(stream, offset)) {
1.90 + return 0;
1.91 + }
1.92 + if (!read(stream, header, sizeof(SkSFNTHeader))) {
1.93 + return 0;
1.94 + }
1.95 + }
1.96 +
1.97 + if (offsetToDir) {
1.98 + // add the size of the header, so we will point to the DirEntries
1.99 + *offsetToDir = offset + sizeof(SkSFNTHeader);
1.100 + }
1.101 + return SkEndian_SwapBE16(header->fSingle.fNumTables);
1.102 +}
1.103 +
1.104 +///////////////////////////////////////////////////////////////////////////////
1.105 +
1.106 +struct SfntHeader {
1.107 + SfntHeader() : fCount(0), fDir(NULL) {}
1.108 + ~SfntHeader() { sk_free(fDir); }
1.109 +
1.110 + /** If it returns true, then fCount and fDir are properly initialized.
1.111 + Note: fDir will point to the raw array of SkSFNTDirEntry values,
1.112 + meaning they will still be in the file's native endianness (BE).
1.113 +
1.114 + fDir will be automatically freed when this object is destroyed
1.115 + */
1.116 + bool init(SkStream* stream, int ttcIndex) {
1.117 + stream->rewind();
1.118 +
1.119 + size_t offsetToDir;
1.120 + fCount = count_tables(stream, ttcIndex, &offsetToDir);
1.121 + if (0 == fCount) {
1.122 + return false;
1.123 + }
1.124 +
1.125 + stream->rewind();
1.126 + if (!skip(stream, offsetToDir)) {
1.127 + return false;
1.128 + }
1.129 +
1.130 + size_t size = fCount * sizeof(SkSFNTDirEntry);
1.131 + fDir = reinterpret_cast<SkSFNTDirEntry*>(sk_malloc_throw(size));
1.132 + return read(stream, fDir, size);
1.133 + }
1.134 +
1.135 + int fCount;
1.136 + SkSFNTDirEntry* fDir;
1.137 +};
1.138 +
1.139 +///////////////////////////////////////////////////////////////////////////////
1.140 +
1.141 +int SkFontStream::CountTTCEntries(SkStream* stream) {
1.142 + stream->rewind();
1.143 +
1.144 + SkSharedTTHeader shared;
1.145 + if (!read(stream, &shared, sizeof(shared))) {
1.146 + return 0;
1.147 + }
1.148 +
1.149 + // if we're really a collection, the first 4-bytes will be 'ttcf'
1.150 + uint32_t tag = SkEndian_SwapBE32(shared.fCollection.fTag);
1.151 + if (SkSetFourByteTag('t', 't', 'c', 'f') == tag) {
1.152 + return SkEndian_SwapBE32(shared.fCollection.fNumOffsets);
1.153 + } else {
1.154 + return 1; // normal 'sfnt' has 1 dir entry
1.155 + }
1.156 +}
1.157 +
1.158 +int SkFontStream::GetTableTags(SkStream* stream, int ttcIndex,
1.159 + SkFontTableTag tags[]) {
1.160 + SfntHeader header;
1.161 + if (!header.init(stream, ttcIndex)) {
1.162 + return 0;
1.163 + }
1.164 +
1.165 + if (tags) {
1.166 + for (int i = 0; i < header.fCount; i++) {
1.167 + tags[i] = SkEndian_SwapBE32(header.fDir[i].fTag);
1.168 + }
1.169 + }
1.170 + return header.fCount;
1.171 +}
1.172 +
1.173 +size_t SkFontStream::GetTableData(SkStream* stream, int ttcIndex,
1.174 + SkFontTableTag tag,
1.175 + size_t offset, size_t length, void* data) {
1.176 + SfntHeader header;
1.177 + if (!header.init(stream, ttcIndex)) {
1.178 + return 0;
1.179 + }
1.180 +
1.181 + for (int i = 0; i < header.fCount; i++) {
1.182 + if (SkEndian_SwapBE32(header.fDir[i].fTag) == tag) {
1.183 + size_t realOffset = SkEndian_SwapBE32(header.fDir[i].fOffset);
1.184 + size_t realLength = SkEndian_SwapBE32(header.fDir[i].fLength);
1.185 + // now sanity check the caller's offset/length
1.186 + if (offset >= realLength) {
1.187 + return 0;
1.188 + }
1.189 + // if the caller is trusting the length from the file, then a
1.190 + // hostile file might choose a value which would overflow offset +
1.191 + // length.
1.192 + if (offset + length < offset) {
1.193 + return 0;
1.194 + }
1.195 + if (length > realLength - offset) {
1.196 + length = realLength - offset;
1.197 + }
1.198 + if (data) {
1.199 + // skip the stream to the part of the table we want to copy from
1.200 + stream->rewind();
1.201 + size_t bytesToSkip = realOffset + offset;
1.202 + if (!skip(stream, bytesToSkip)) {
1.203 + return 0;
1.204 + }
1.205 + if (!read(stream, data, length)) {
1.206 + return 0;
1.207 + }
1.208 + }
1.209 + return length;
1.210 + }
1.211 + }
1.212 + return 0;
1.213 +}
