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 <stdlib.h>
18#include <stdint.h>
19
20#include "FontUtils.h"
21
22namespace minikin {
23
24static uint16_t readU16(const uint8_t* data, size_t offset) {
25    return data[offset] << 8 | data[offset + 1];
26}
27
28static 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
33bool analyzeStyle(const uint8_t* os2_data, size_t os2_size, int* weight, bool* italic) {
34    const size_t kUsWeightClassOffset = 4;
35    const size_t kFsSelectionOffset = 62;
36    const uint16_t kItalicFlag = (1 << 0);
37    if (os2_size < kFsSelectionOffset + 2) {
38        return false;
39    }
40    uint16_t weightClass = readU16(os2_data, kUsWeightClassOffset);
41    *weight = weightClass / 100;
42    uint16_t fsSelection = readU16(os2_data, kFsSelectionOffset);
43    *italic = (fsSelection & kItalicFlag) != 0;
44    return true;
45}
46
47void analyzeAxes(const uint8_t* fvar_data, size_t fvar_size, std::unordered_set<uint32_t>* axes) {
48    const size_t kMajorVersionOffset = 0;
49    const size_t kMinorVersionOffset = 2;
50    const size_t kOffsetToAxesArrayOffset = 4;
51    const size_t kAxisCountOffset = 8;
52    const size_t kAxisSizeOffset = 10;
53
54    axes->clear();
55
56    if (fvar_size < kAxisSizeOffset + 2) {
57        return;
58    }
59    const uint16_t majorVersion = readU16(fvar_data, kMajorVersionOffset);
60    const uint16_t minorVersion = readU16(fvar_data, kMinorVersionOffset);
61    const uint32_t axisOffset = readU16(fvar_data, kOffsetToAxesArrayOffset);
62    const uint32_t axisCount = readU16(fvar_data, kAxisCountOffset);
63    const uint32_t axisSize = readU16(fvar_data, kAxisSizeOffset);
64
65    if (majorVersion != 1 || minorVersion != 0 || axisOffset != 0x10 || axisSize != 0x14) {
66        return;  // Unsupported version.
67    }
68    if (fvar_size < axisOffset + axisOffset * axisCount) {
69        return;  // Invalid table size.
70    }
71    for (uint32_t i = 0; i < axisCount; ++i) {
72        size_t axisRecordOffset = axisOffset + i * axisSize;
73        uint32_t tag = readU32(fvar_data, axisRecordOffset);
74        axes->insert(tag);
75    }
76}
77}  // namespace minikin
78