dfdec78a5d
This reverts commit 3675874468.
BUG=skia:
NOTREECHECKS=true
NOTRY=true
TBR=
Review URL: https://codereview.chromium.org/1012873002
93 lines
2.7 KiB
C++
93 lines
2.7 KiB
C++
/*
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* Copyright 2015 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef SkCodec_DEFINED
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#define SkCodec_DEFINED
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#include "SkImageGenerator.h"
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#include "SkImageInfo.h"
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#include "SkSize.h"
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#include "SkTemplates.h"
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#include "SkTypes.h"
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class SkData;
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class SkStream;
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/**
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* Abstraction layer directly on top of an image codec.
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*/
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class SkCodec : public SkImageGenerator {
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public:
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/**
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* If this stream represents an encoded image that we know how to decode,
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* return an SkCodec that can decode it. Otherwise return NULL.
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*
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* If NULL is returned, the stream is deleted immediately. Otherwise, the
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* SkCodec takes ownership of it, and will delete it when done with it.
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*/
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static SkCodec* NewFromStream(SkStream*);
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/**
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* If this data represents an encoded image that we know how to decode,
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* return an SkCodec that can decode it. Otherwise return NULL.
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*
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* Will take a ref if it returns a codec, else will not affect the data.
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*/
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static SkCodec* NewFromData(SkData*);
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/**
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* Return a size that approximately supports the desired scale factor.
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* The codec may not be able to scale efficiently to the exact scale
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* factor requested, so return a size that approximates that scale.
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*
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* FIXME: Move to SkImageGenerator?
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*/
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SkISize getScaledDimensions(float desiredScale) const;
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protected:
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SkCodec(const SkImageInfo&, SkStream*);
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/**
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* The SkAlphaType is a conservative answer. i.e. it is possible that it
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* initially returns a non-opaque answer, but completing the decode
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* reveals that the image is actually opaque.
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*/
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bool onGetInfo(SkImageInfo* info) SK_OVERRIDE {
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*info = fInfo;
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return true;
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}
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// Helper for subclasses.
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const SkImageInfo& getOriginalInfo() { return fInfo; }
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virtual SkISize onGetScaledDimensions(float /* desiredScale */) const {
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// By default, scaling is not supported.
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return fInfo.dimensions();
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}
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/**
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* If the stream was previously read, attempt to rewind.
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* @returns:
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* true
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* - if the stream needed to be rewound, and the rewind
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* succeeded.
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* - if the stream did not need to be rewound.
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* false
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* - if the stream needed to be rewound, and rewind failed.
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* Subclasses MUST call this function before reading the stream (e.g. in
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* onGetPixels). If it returns false, onGetPixels should return
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* kCouldNotRewind.
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*/
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bool SK_WARN_UNUSED_RESULT rewindIfNeeded();
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private:
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const SkImageInfo fInfo;
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SkAutoTDelete<SkStream> fStream;
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bool fNeedsRewind;
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};
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#endif // SkCodec_DEFINED
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