cpp/src/sfntly/data/font_data.cc

/*
 * Copyright 2011 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "sfntly/data/font_data.h"

#include <algorithm>
#include <functional>
#include <limits>

#include "sfntly/port/logging.h"

namespace sfntly {

int32_t FontData::Size() const {
  return std::min<int32_t>(array_->Size() - bound_offset_, bound_length_);
}

void FontData::Bound(int32_t offset, int32_t length) {
  // Inputs should not be negative.
  CHECK(offset >= 0);
  CHECK(length >= 0);

  // Check to make sure |bound_offset_| will not overflow.
  CHECK(bound_offset_ <= std::numeric_limits<int32_t>::max() - offset);
  const int32_t new_offset = bound_offset_ + offset;

  if (length == GROWABLE_SIZE) {
    // When |length| has the special value of GROWABLE_SIZE, it means the size
    // should not have any artificial limits, thus it is just the underlying
    // |array_|'s size. Just make sure |new_offset| is still within bounds.
    CHECK(new_offset <= array_->Size());
  } else {
    // When |length| has any other value, |new_offset| + |length| points to the
    // end of the array. Make sure that is within bounds, but use subtraction to
    // avoid an integer overflow.
    CHECK(new_offset <= array_->Size() - length);
  }

  bound_offset_ = new_offset;
  bound_length_ = length;
}

int32_t FontData::Length() const {
  return std::min<int32_t>(array_->Length() - bound_offset_, bound_length_);
}

FontData::FontData(ByteArray* ba) {
  Init(ba);
}

FontData::FontData(FontData* data, int32_t offset, int32_t length) {
  Init(data->array_);
  Bound(data->bound_offset_ + offset, length);
}

FontData::FontData(FontData* data, int32_t offset) {
  Init(data->array_);
  Bound(data->bound_offset_ + offset,
        (data->bound_length_ == GROWABLE_SIZE)
        ? GROWABLE_SIZE : data->bound_length_ - offset);
}

FontData::~FontData() {}

void FontData::Init(ByteArray* ba) {
  array_ = ba;
  bound_offset_ = 0;
  bound_length_ = GROWABLE_SIZE;
}

int32_t FontData::BoundOffset(int32_t offset) {
  return offset + bound_offset_;
}

int32_t FontData::BoundLength(int32_t offset, int32_t length) {
  return std::min<int32_t>(length, bound_length_ - offset);
}

}  // namespace sfntly