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264 lines
11 KiB
264 lines
11 KiB
/*
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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 SkAndroidCodec_DEFINED
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#define SkAndroidCodec_DEFINED
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#include "include/codec/SkCodec.h"
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#include "include/core/SkEncodedImageFormat.h"
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#include "include/core/SkStream.h"
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#include "include/core/SkTypes.h"
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/**
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* Abstract interface defining image codec functionality that is necessary for
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* Android.
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*/
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class SK_API SkAndroidCodec : SkNoncopyable {
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public:
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/**
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* Deprecated.
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*
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* Now that SkAndroidCodec supports multiframe images, there are multiple
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* ways to handle compositing an oriented frame on top of an oriented frame
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* with different tradeoffs. SkAndroidCodec now ignores the orientation and
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* forces the client to handle it.
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*/
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enum class ExifOrientationBehavior {
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kIgnore,
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kRespect,
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};
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/**
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* Pass ownership of an SkCodec to a newly-created SkAndroidCodec.
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*/
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static std::unique_ptr<SkAndroidCodec> MakeFromCodec(std::unique_ptr<SkCodec>);
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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 SkAndroidCodec that can decode it. Otherwise return NULL.
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*
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* The SkPngChunkReader handles unknown chunks in PNGs.
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* See SkCodec.h for more details.
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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 std::unique_ptr<SkAndroidCodec> MakeFromStream(std::unique_ptr<SkStream>,
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SkPngChunkReader* = nullptr);
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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 SkAndroidCodec that can decode it. Otherwise return NULL.
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*
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* The SkPngChunkReader handles unknown chunks in PNGs.
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* See SkCodec.h for more details.
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*/
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static std::unique_ptr<SkAndroidCodec> MakeFromData(sk_sp<SkData>, SkPngChunkReader* = nullptr);
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virtual ~SkAndroidCodec();
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// TODO: fInfo is now just a cache of SkCodec's SkImageInfo. No need to
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// cache and return a reference here, once Android call-sites are updated.
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const SkImageInfo& getInfo() const { return fInfo; }
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/**
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* Return the ICC profile of the encoded data.
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*/
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const skcms_ICCProfile* getICCProfile() const {
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return fCodec->getEncodedInfo().profile();
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}
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/**
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* Format of the encoded data.
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*/
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SkEncodedImageFormat getEncodedFormat() const { return fCodec->getEncodedFormat(); }
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/**
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* @param requestedColorType Color type requested by the client
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*
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* |requestedColorType| may be overriden. We will default to kF16
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* for high precision images.
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*
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* In the general case, if it is possible to decode to
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* |requestedColorType|, this returns |requestedColorType|.
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* Otherwise, this returns a color type that is an appropriate
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* match for the the encoded data.
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*/
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SkColorType computeOutputColorType(SkColorType requestedColorType);
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/**
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* @param requestedUnpremul Indicates if the client requested
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* unpremultiplied output
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*
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* Returns the appropriate alpha type to decode to. If the image
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* has alpha, the value of requestedUnpremul will be honored.
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*/
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SkAlphaType computeOutputAlphaType(bool requestedUnpremul);
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/**
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* @param outputColorType Color type that the client will decode to.
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* @param prefColorSpace Preferred color space to decode to.
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* This may not return |prefColorSpace| for a couple reasons.
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* (1) Android Principles: 565 must be sRGB, F16 must be
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* linear sRGB, transfer function must be parametric.
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* (2) Codec Limitations: F16 requires a linear color space.
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*
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* Returns the appropriate color space to decode to.
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*/
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sk_sp<SkColorSpace> computeOutputColorSpace(SkColorType outputColorType,
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sk_sp<SkColorSpace> prefColorSpace = nullptr);
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/**
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* Compute the appropriate sample size to get to |size|.
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*
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* @param size As an input parameter, the desired output size of
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* the decode. As an output parameter, the smallest sampled size
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* larger than the input.
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* @return the sample size to set AndroidOptions::fSampleSize to decode
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* to the output |size|.
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*/
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int computeSampleSize(SkISize* size) const;
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/**
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* Returns the dimensions of the scaled output image, for an input
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* sampleSize.
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*
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* When the sample size divides evenly into the original dimensions, the
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* scaled output dimensions will simply be equal to the original
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* dimensions divided by the sample size.
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*
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* When the sample size does not divide even into the original
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* dimensions, the codec may round up or down, depending on what is most
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* efficient to decode.
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*
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* Finally, the codec will always recommend a non-zero output, so the output
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* dimension will always be one if the sampleSize is greater than the
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* original dimension.
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*/
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SkISize getSampledDimensions(int sampleSize) const;
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/**
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* Return (via desiredSubset) a subset which can decoded from this codec,
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* or false if the input subset is invalid.
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*
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* @param desiredSubset in/out parameter
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* As input, a desired subset of the original bounds
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* (as specified by getInfo).
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* As output, if true is returned, desiredSubset may
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* have been modified to a subset which is
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* supported. Although a particular change may have
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* been made to desiredSubset to create something
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* supported, it is possible other changes could
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* result in a valid subset. If false is returned,
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* desiredSubset's value is undefined.
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* @return true If the input desiredSubset is valid.
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* desiredSubset may be modified to a subset
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* supported by the codec.
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* false If desiredSubset is invalid (NULL or not fully
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* contained within the image).
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*/
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bool getSupportedSubset(SkIRect* desiredSubset) const;
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// TODO: Rename SkCodec::getValidSubset() to getSupportedSubset()
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/**
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* Returns the dimensions of the scaled, partial output image, for an
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* input sampleSize and subset.
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*
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* @param sampleSize Factor to scale down by.
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* @param subset Must be a valid subset of the original image
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* dimensions and a subset supported by SkAndroidCodec.
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* getSubset() can be used to obtain a subset supported
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* by SkAndroidCodec.
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* @return Size of the scaled partial image. Or zero size
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* if either of the inputs is invalid.
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*/
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SkISize getSampledSubsetDimensions(int sampleSize, const SkIRect& subset) const;
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/**
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* Additional options to pass to getAndroidPixels().
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*/
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// FIXME: It's a bit redundant to name these AndroidOptions when this class is already
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// called SkAndroidCodec. On the other hand, it's may be a bit confusing to call
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// these Options when SkCodec has a slightly different set of Options. Maybe these
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// should be DecodeOptions or SamplingOptions?
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struct AndroidOptions : public SkCodec::Options {
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AndroidOptions()
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: SkCodec::Options()
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, fSampleSize(1)
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{}
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/**
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* The client may provide an integer downscale factor for the decode.
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* The codec may implement this downscaling by sampling or another
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* method if it is more efficient.
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*
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* The default is 1, representing no downscaling.
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*/
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int fSampleSize;
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};
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/**
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* Decode into the given pixels, a block of memory of size at
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* least (info.fHeight - 1) * rowBytes + (info.fWidth *
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* bytesPerPixel)
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*
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* Repeated calls to this function should give the same results,
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* allowing the PixelRef to be immutable.
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*
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* @param info A description of the format (config, size)
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* expected by the caller. This can simply be identical
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* to the info returned by getInfo().
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*
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* This contract also allows the caller to specify
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* different output-configs, which the implementation can
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* decide to support or not.
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*
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* A size that does not match getInfo() implies a request
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* to scale or subset. If the codec cannot perform this
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* scaling or subsetting, it will return an error code.
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*
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* The AndroidOptions object is also used to specify any requested scaling or subsetting
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* using options->fSampleSize and options->fSubset. If NULL, the defaults (as specified above
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* for AndroidOptions) are used.
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*
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* @return Result kSuccess, or another value explaining the type of failure.
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*/
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// FIXME: It's a bit redundant to name this getAndroidPixels() when this class is already
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// called SkAndroidCodec. On the other hand, it's may be a bit confusing to call
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// this getPixels() when it is a slightly different API than SkCodec's getPixels().
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// Maybe this should be decode() or decodeSubset()?
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SkCodec::Result getAndroidPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
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const AndroidOptions* options);
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/**
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* Simplified version of getAndroidPixels() where we supply the default AndroidOptions as
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* specified above for AndroidOptions. It will not perform any scaling or subsetting.
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*/
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SkCodec::Result getAndroidPixels(const SkImageInfo& info, void* pixels, size_t rowBytes);
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SkCodec::Result getPixels(const SkImageInfo& info, void* pixels, size_t rowBytes) {
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return this->getAndroidPixels(info, pixels, rowBytes);
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}
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SkCodec* codec() const { return fCodec.get(); }
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protected:
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SkAndroidCodec(SkCodec*);
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virtual SkISize onGetSampledDimensions(int sampleSize) const = 0;
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virtual bool onGetSupportedSubset(SkIRect* desiredSubset) const = 0;
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virtual SkCodec::Result onGetAndroidPixels(const SkImageInfo& info, void* pixels,
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size_t rowBytes, const AndroidOptions& options) = 0;
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private:
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const SkImageInfo fInfo;
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std::unique_ptr<SkCodec> fCodec;
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};
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#endif // SkAndroidCodec_DEFINED
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