1 /*
2 * Copyright (C) 2017 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <stdint.h>
18 #include <stdlib.h>
19
20 #include "FontUtils.h"
21
22 namespace minikin {
23
readU16(const uint8_t * data,size_t offset)24 static uint16_t readU16(const uint8_t* data, size_t offset) {
25 return data[offset] << 8 | data[offset + 1];
26 }
27
readU32(const uint8_t * data,size_t offset)28 static uint32_t readU32(const uint8_t* data, size_t offset) {
29 return ((uint32_t)data[offset]) << 24 | ((uint32_t)data[offset + 1]) << 16 |
30 ((uint32_t)data[offset + 2]) << 8 | ((uint32_t)data[offset + 3]);
31 }
32
analyzeStyle(const uint8_t * os2_data,size_t os2_size,int * weight,bool * italic)33 bool analyzeStyle(const uint8_t* os2_data,
34 size_t os2_size,
35 int* weight,
36 bool* italic) {
37 const size_t kUsWeightClassOffset = 4;
38 const size_t kFsSelectionOffset = 62;
39 const uint16_t kItalicFlag = (1 << 0);
40 if (os2_size < kFsSelectionOffset + 2) {
41 return false;
42 }
43 uint16_t weightClass = readU16(os2_data, kUsWeightClassOffset);
44 *weight = weightClass / 100;
45 uint16_t fsSelection = readU16(os2_data, kFsSelectionOffset);
46 *italic = (fsSelection & kItalicFlag) != 0;
47 return true;
48 }
49
analyzeAxes(const uint8_t * fvar_data,size_t fvar_size,std::unordered_set<uint32_t> * axes)50 void analyzeAxes(const uint8_t* fvar_data,
51 size_t fvar_size,
52 std::unordered_set<uint32_t>* axes) {
53 const size_t kMajorVersionOffset = 0;
54 const size_t kMinorVersionOffset = 2;
55 const size_t kOffsetToAxesArrayOffset = 4;
56 const size_t kAxisCountOffset = 8;
57 const size_t kAxisSizeOffset = 10;
58
59 axes->clear();
60
61 if (fvar_size < kAxisSizeOffset + 2) {
62 return;
63 }
64 const uint16_t majorVersion = readU16(fvar_data, kMajorVersionOffset);
65 const uint16_t minorVersion = readU16(fvar_data, kMinorVersionOffset);
66 const uint32_t axisOffset = readU16(fvar_data, kOffsetToAxesArrayOffset);
67 const uint32_t axisCount = readU16(fvar_data, kAxisCountOffset);
68 const uint32_t axisSize = readU16(fvar_data, kAxisSizeOffset);
69
70 if (majorVersion != 1 || minorVersion != 0 || axisOffset != 0x10 ||
71 axisSize != 0x14) {
72 return; // Unsupported version.
73 }
74 if (fvar_size < axisOffset + axisOffset * axisCount) {
75 return; // Invalid table size.
76 }
77 for (uint32_t i = 0; i < axisCount; ++i) {
78 size_t axisRecordOffset = axisOffset + i * axisSize;
79 uint32_t tag = readU32(fvar_data, axisRecordOffset);
80 axes->insert(tag);
81 }
82 }
83 } // namespace minikin
84