font_data.cc revision de776d4ef06ca29c240de3444348894f032b03ff 
1/*
2 * Copyright 2011 Google Inc. All Rights Reserved.
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 "sfntly/data/font_data.h"
18
19#include <algorithm>
20#include <functional>
21#include <limits>
22
23#include "sfntly/port/logging.h"
24
25namespace sfntly {
26
27int32_t FontData::Size() const {
28  return std::min<int32_t>(array_->Size() - bound_offset_, bound_length_);
29}
30
31void FontData::Bound(int32_t offset, int32_t length) {
32  // Inputs should not be negative.
33  CHECK(offset >= 0);
34  CHECK(length >= 0);
35
36  // Check to make sure |bound_offset_| will not overflow.
37  CHECK(bound_offset_ <= std::numeric_limits<int32_t>::max() - offset);
38  const int32_t new_offset = bound_offset_ + offset;
39
40  if (length == GROWABLE_SIZE) {
41    // When |length| has the special value of GROWABLE_SIZE, it means the size
42    // should not have any artificial limits, thus it is just the underlying
43    // |array_|'s size. Just make sure |new_offset| is still within bounds.
44    CHECK(new_offset <= array_->Size());
45  } else {
46    // When |length| has any other value, |new_offset| + |length| points to the
47    // end of the array. Make sure that is within bounds, but use subtraction to
48    // avoid an integer overflow.
49    CHECK(new_offset <= array_->Size() - length);
50  }
51
52  bound_offset_ = new_offset;
53  bound_length_ = length;
54}
55
56int32_t FontData::Length() const {
57  return std::min<int32_t>(array_->Length() - bound_offset_, bound_length_);
58}
59
60FontData::FontData(ByteArray* ba) {
61  Init(ba);
62}
63
64FontData::FontData(FontData* data, int32_t offset, int32_t length) {
65  Init(data->array_);
66  Bound(data->bound_offset_ + offset, length);
67}
68
69FontData::FontData(FontData* data, int32_t offset) {
70  Init(data->array_);
71  Bound(data->bound_offset_ + offset,
72        (data->bound_length_ == GROWABLE_SIZE)
73        ? GROWABLE_SIZE : data->bound_length_ - offset);
74}
75
76FontData::~FontData() {}
77
78void FontData::Init(ByteArray* ba) {
79  array_ = ba;
80  bound_offset_ = 0;
81  bound_length_ = GROWABLE_SIZE;
82}
83
84int32_t FontData::BoundOffset(int32_t offset) {
85  return offset + bound_offset_;
86}
87
88int32_t FontData::BoundLength(int32_t offset, int32_t length) {
89  return std::min<int32_t>(length, bound_length_ - offset);
90}
91
92}  // namespace sfntly
93