skia2/include/utils/SkFrontBufferedStream.h
scroggo a1193e4b0e Make SkStream *not* ref counted.
SkStream is a stateful object, so it does not make sense for it to have
multiple owners. Make SkStream inherit directly from SkNoncopyable.

Update methods which previously called SkStream::ref() (e.g.
SkImageDecoder::buildTileIndex() and SkFrontBufferedStream::Create(),
which required the existing owners to call SkStream::unref()) to take
ownership of their SkStream parameters and delete when done (including
on failure).

Switch all SkAutoTUnref<SkStream>s to SkAutoTDelete<SkStream>s. In some
cases this means heap allocating streams that were previously stack
allocated.

Respect ownership rules of SkTypeface::CreateFromStream() and
SkImageDecoder::buildTileIndex().

Update the comments for exceptional methods which do not affect the
ownership of their SkStream parameters (e.g.
SkPicture::CreateFromStream() and SkTypeface::Deserialize()) to be
explicit about ownership.

Remove test_stream_life, which tested that buildTileIndex() behaved
correctly when SkStream was a ref counted object. The test does not
make sense now that it is not.

In SkPDFStream, remove the SkMemoryStream member. Instead of using it,
create a new SkMemoryStream to pass to fDataStream (which is now an
SkAutoTDelete).

Make other pdf rasterizers behave like SkPDFDocumentToBitmap.

SkPDFDocumentToBitmap delete the SkStream, so do the same in the
following pdf rasterizers:

SkPopplerRasterizePDF
SkNativeRasterizePDF
SkNoRasterizePDF

Requires a change to Android, which currently treats SkStreams as ref
counted objects.

Review URL: https://codereview.chromium.org/849103004
2015-01-21 12:09:53 -08:00

38 lines
1.4 KiB
C++

/*
* Copyright 2013 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkTypes.h"
class SkStream;
class SkStreamRewindable;
/**
* Specialized stream that buffers the first X bytes of a stream,
* where X is passed in by the user. Note that unlike some buffered
* stream APIs, once more bytes than can fit in the buffer are read,
* no more buffering is done. This stream is designed for a use case
* where the caller knows that rewind will only be called from within
* X bytes (inclusive), and the wrapped stream is not necessarily
* able to rewind at all.
*/
class SkFrontBufferedStream {
public:
/**
* Creates a new stream that wraps and buffers an SkStream.
* @param stream SkStream to buffer. If stream is NULL, NULL is
* returned. When this call succeeds (i.e. returns non NULL),
* SkFrontBufferedStream is expected to be the only owner of
* stream, so it should no be longer used directly.
* SkFrontBufferedStream will delete stream upon deletion.
* @param minBufferSize Minimum size of buffer required.
* @return An SkStream that can buffer at least minBufferSize, or
* NULL on failure. The caller is required to delete when finished with
* this object.
*/
static SkStreamRewindable* Create(SkStream* stream, size_t minBufferSize);
};