[WIP] Move ImageDecoders to SkCodec

third_party/WebKit/Source/platform/image-decoders/FastSharedBufferReader.cpp

-/*
- * Copyright (C) 2015 Google Inc. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include "platform/image-decoders/FastSharedBufferReader.h"
-
-namespace blink {
-
-FastSharedBufferReader::FastSharedBufferReader(PassRefPtr<SegmentReader> data)
-    : data_(std::move(data)),
-      segment_(0),
-      segment_length_(0),
-      data_position_(0) {}
-
-void FastSharedBufferReader::SetData(PassRefPtr<SegmentReader> data) {
-  if (data == data_)
-    return;
-  data_ = std::move(data);
-  ClearCache();
-}
-
-void FastSharedBufferReader::ClearCache() {
-  segment_ = 0;
-  segment_length_ = 0;
-  data_position_ = 0;
-}
-
-const char* FastSharedBufferReader::GetConsecutiveData(size_t data_position,
-                                                       size_t length,
-                                                       char* buffer) const {
-  CHECK_LE(data_position + length, data_->size());
-
-  // Use the cached segment if it can serve the request.
-  if (data_position >= data_position_ &&
-      data_position + length <= data_position_ + segment_length_)
-    return segment_ + data_position - data_position_;
-
-  // Return a pointer into |data_| if the request doesn't span segments.
-  GetSomeDataInternal(data_position);
-  if (length <= segment_length_)
-    return segment_;
-
-  for (char* dest = buffer;;) {
-    size_t copy = std::min(length, segment_length_);
-    memcpy(dest, segment_, copy);
-    length -= copy;
-    if (!length)
-      return buffer;
-
-    // Continue reading the next segment.
-    dest += copy;
-    GetSomeDataInternal(data_position_ + copy);
-  }
-}
-
-size_t FastSharedBufferReader::GetSomeData(const char*& some_data,
-                                           size_t data_position) const {
-  GetSomeDataInternal(data_position);
-  some_data = segment_;
-  return segment_length_;
-}
-
-void FastSharedBufferReader::GetSomeDataInternal(size_t data_position) const {
-  data_position_ = data_position;
-  segment_length_ = data_->GetSomeData(segment_, data_position);
-  DCHECK(segment_length_);
-}
-
-}  // namespace blink