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skia2/include/codec/SkCodec.h
Brian Osman b62f50cf76 Replace nearly all kRespect with kIgnore 
- Encoders and decoders always assume kIgnore.
- They are less opinionated about F16 and color space,
  we just trust the color space that's passed in, and
  put that directly in the image (no sRGB encoding).
- SkBitmap and SkPixmap read/write pixels functions were
  defaulting to kResepct, those are now always kIgnore.
- Many other bits of plumbing are simplified, and I
  added a default of kIgnore to SkImage::makeColorSpace,
  so we can phase out that argument entirely.
- Still need to add defaults to other public APIs that
  take SkTransferFunctionBehavior.

- This makes gold think that we've dramatically changed
  the contents of all F16 images, but that's because
  it doesn't understand the (now linear) color space
  that's embedded. Once we triage them all once, they
  will work fine (and they'll look perfect in the browser).

Bug: skia:
Change-Id: I62fa090f96cae1b67d181ce14bd91f34ff2ed747
Reviewed-on: https://skia-review.googlesource.com/140570
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
2018-07-12 20:54:14 +00:00

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/*
* Copyright 2015 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkCodec_DEFINED
#define SkCodec_DEFINED
#include "../private/SkTemplates.h"
#include "../private/SkEncodedInfo.h"
#include "SkCodecAnimation.h"
#include "SkColor.h"
#include "SkColorSpaceXform.h"
#include "SkEncodedImageFormat.h"
#include "SkEncodedOrigin.h"
#include "SkImageInfo.h"
#include "SkPixmap.h"
#include "SkSize.h"
#include "SkStream.h"
#include "SkTypes.h"
#include "SkYUVSizeInfo.h"
#include <vector>
class SkColorSpace;
class SkData;
class SkFrameHolder;
class SkPngChunkReader;
class SkSampler;
namespace DM {
class CodecSrc;
class ColorCodecSrc;
}
/**
* Abstraction layer directly on top of an image codec.
*/
class SK_API SkCodec : SkNoncopyable {
public:
/**
* Minimum number of bytes that must be buffered in SkStream input.
*
* An SkStream passed to NewFromStream must be able to use this many
* bytes to determine the image type. Then the same SkStream must be
* passed to the correct decoder to read from the beginning.
*
* This can be accomplished by implementing peek() to support peeking
* this many bytes, or by implementing rewind() to be able to rewind()
* after reading this many bytes.
*/
static constexpr size_t MinBufferedBytesNeeded() { return 32; }
/**
* Error codes for various SkCodec methods.
*/
enum Result {
/**
* General return value for success.
*/
kSuccess,
/**
* The input is incomplete. A partial image was generated.
*/
kIncompleteInput,
/**
* Like kIncompleteInput, except the input had an error.
*
* If returned from an incremental decode, decoding cannot continue,
* even with more data.
*/
kErrorInInput,
/**
* The generator cannot convert to match the request, ignoring
* dimensions.
*/
kInvalidConversion,
/**
* The generator cannot scale to requested size.
*/
kInvalidScale,
/**
* Parameters (besides info) are invalid. e.g. NULL pixels, rowBytes
* too small, etc.
*/
kInvalidParameters,
/**
* The input did not contain a valid image.
*/
kInvalidInput,
/**
* Fulfilling this request requires rewinding the input, which is not
* supported for this input.
*/
kCouldNotRewind,
/**
* An internal error, such as OOM.
*/
kInternalError,
/**
* This method is not implemented by this codec.
* FIXME: Perhaps this should be kUnsupported?
*/
kUnimplemented,
};
/**
* Readable string representing the error code.
*/
static const char* ResultToString(Result);
/**
* If this stream represents an encoded image that we know how to decode,
* return an SkCodec that can decode it. Otherwise return NULL.
*
* As stated above, this call must be able to peek or read
* MinBufferedBytesNeeded to determine the correct format, and then start
* reading from the beginning. First it will attempt to peek, and it
* assumes that if less than MinBufferedBytesNeeded bytes (but more than
* zero) are returned, this is because the stream is shorter than this,
* so falling back to reading would not provide more data. If peek()
* returns zero bytes, this call will instead attempt to read(). This
* will require that the stream can be rewind()ed.
*
* If Result is not NULL, it will be set to either kSuccess if an SkCodec
* is returned or a reason for the failure if NULL is returned.
*
* If SkPngChunkReader is not NULL, take a ref and pass it to libpng if
* the image is a png.
*
* If the SkPngChunkReader is not NULL then:
* If the image is not a PNG, the SkPngChunkReader will be ignored.
* If the image is a PNG, the SkPngChunkReader will be reffed.
* If the PNG has unknown chunks, the SkPngChunkReader will be used
* to handle these chunks. SkPngChunkReader will be called to read
* any unknown chunk at any point during the creation of the codec
* or the decode. Note that if SkPngChunkReader fails to read a
* chunk, this could result in a failure to create the codec or a
* failure to decode the image.
* If the PNG does not contain unknown chunks, the SkPngChunkReader
* will not be used or modified.
*
* If NULL is returned, the stream is deleted immediately. Otherwise, the
* SkCodec takes ownership of it, and will delete it when done with it.
*/
static std::unique_ptr<SkCodec> MakeFromStream(std::unique_ptr<SkStream>, Result* = nullptr,
SkPngChunkReader* = nullptr);
/**
* If this data represents an encoded image that we know how to decode,
* return an SkCodec that can decode it. Otherwise return NULL.
*
* If the SkPngChunkReader is not NULL then:
* If the image is not a PNG, the SkPngChunkReader will be ignored.
* If the image is a PNG, the SkPngChunkReader will be reffed.
* If the PNG has unknown chunks, the SkPngChunkReader will be used
* to handle these chunks. SkPngChunkReader will be called to read
* any unknown chunk at any point during the creation of the codec
* or the decode. Note that if SkPngChunkReader fails to read a
* chunk, this could result in a failure to create the codec or a
* failure to decode the image.
* If the PNG does not contain unknown chunks, the SkPngChunkReader
* will not be used or modified.
*/
static std::unique_ptr<SkCodec> MakeFromData(sk_sp<SkData>, SkPngChunkReader* = nullptr);
virtual ~SkCodec();
/**
* Return the ImageInfo associated with this codec.
*/
const SkImageInfo& getInfo() const { return fSrcInfo; }
/**
* Returns the image orientation stored in the EXIF data.
* If there is no EXIF data, or if we cannot read the EXIF data, returns kTopLeft.
*/
SkEncodedOrigin getOrigin() const { return fOrigin; }
/**
* Return a size that approximately supports the desired scale factor.
* The codec may not be able to scale efficiently to the exact scale
* factor requested, so return a size that approximates that scale.
* The returned value is the codec's suggestion for the closest valid
* scale that it can natively support
*/
SkISize getScaledDimensions(float desiredScale) const {
// Negative and zero scales are errors.
SkASSERT(desiredScale > 0.0f);
if (desiredScale <= 0.0f) {
return SkISize::Make(0, 0);
}
// Upscaling is not supported. Return the original size if the client
// requests an upscale.
if (desiredScale >= 1.0f) {
return this->getInfo().dimensions();
}
return this->onGetScaledDimensions(desiredScale);
}
/**
* Return (via desiredSubset) a subset which can decoded from this codec,
* or false if this codec cannot decode subsets or anything similar to
* desiredSubset.
*
* @param desiredSubset In/out parameter. As input, a desired subset of
* the original bounds (as specified by getInfo). If true is returned,
* desiredSubset may have been modified to a subset which is
* supported. Although a particular change may have been made to
* desiredSubset to create something supported, it is possible other
* changes could result in a valid subset.
* If false is returned, desiredSubset's value is undefined.
* @return true if this codec supports decoding desiredSubset (as
* returned, potentially modified)
*/
bool getValidSubset(SkIRect* desiredSubset) const {
return this->onGetValidSubset(desiredSubset);
}
/**
* Format of the encoded data.
*/
SkEncodedImageFormat getEncodedFormat() const { return this->onGetEncodedFormat(); }
/**
* Whether or not the memory passed to getPixels is zero initialized.
*/
enum ZeroInitialized {
/**
* The memory passed to getPixels is zero initialized. The SkCodec
* may take advantage of this by skipping writing zeroes.
*/
kYes_ZeroInitialized,
/**
* The memory passed to getPixels has not been initialized to zero,
* so the SkCodec must write all zeroes to memory.
*
* This is the default. It will be used if no Options struct is used.
*/
kNo_ZeroInitialized,
};
/**
* Additional options to pass to getPixels.
*/
struct Options {
Options()
: fZeroInitialized(kNo_ZeroInitialized)
, fSubset(nullptr)
, fFrameIndex(0)
, fPriorFrame(kNone)
, fPremulBehavior(SkTransferFunctionBehavior::kIgnore)
{}
ZeroInitialized fZeroInitialized;
/**
* If not NULL, represents a subset of the original image to decode.
* Must be within the bounds returned by getInfo().
* If the EncodedFormat is SkEncodedImageFormat::kWEBP (the only one which
* currently supports subsets), the top and left values must be even.
*
* In getPixels and incremental decode, we will attempt to decode the
* exact rectangular subset specified by fSubset.
*
* In a scanline decode, it does not make sense to specify a subset
* top or subset height, since the client already controls which rows
* to get and which rows to skip. During scanline decodes, we will
* require that the subset top be zero and the subset height be equal
* to the full height. We will, however, use the values of
* subset left and subset width to decode partial scanlines on calls
* to getScanlines().
*/
const SkIRect* fSubset;
/**
* The frame to decode.
*
* Only meaningful for multi-frame images.
*/
int fFrameIndex;
/**
* If not kNone, the dst already contains the prior frame at this index.
*
* Only meaningful for multi-frame images.
*
* If fFrameIndex needs to be blended with a prior frame (as reported by
* getFrameInfo[fFrameIndex].fRequiredFrame), the client can set this to
* any non-kRestorePrevious frame in [fRequiredFrame, fFrameIndex) to
* indicate that that frame is already in the dst. Options.fZeroInitialized
* is ignored in this case.
*
* If set to kNone, the codec will decode any necessary required frame(s) first.
*/
int fPriorFrame;
/**
* Indicates whether we should do a linear premultiply or a legacy premultiply.
*
* In the case where the dst SkColorSpace is nullptr, this flag is ignored and
* we will always do a legacy premultiply.
*/
SkTransferFunctionBehavior fPremulBehavior;
};
/**
* Decode into the given pixels, a block of memory of size at
* least (info.fHeight - 1) * rowBytes + (info.fWidth *
* bytesPerPixel)
*
* Repeated calls to this function should give the same results,
* allowing the PixelRef to be immutable.
*
* @param info A description of the format (config, size)
* expected by the caller. This can simply be identical
* to the info returned by getInfo().
*
* This contract also allows the caller to specify
* different output-configs, which the implementation can
* decide to support or not.
*
* A size that does not match getInfo() implies a request
* to scale. If the generator cannot perform this scale,
* it will return kInvalidScale.
*
* If the info contains a non-null SkColorSpace, the codec
* will perform the appropriate color space transformation.
* If the caller passes in the same color space that was
* reported by the codec, the color space transformation is
* a no-op.
*
* If a scanline decode is in progress, scanline mode will end, requiring the client to call
* startScanlineDecode() in order to return to decoding scanlines.
*
* @return Result kSuccess, or another value explaining the type of failure.
*/
Result getPixels(const SkImageInfo& info, void* pixels, size_t rowBytes, const Options*);
/**
* Simplified version of getPixels() that uses the default Options.
*/
Result getPixels(const SkImageInfo& info, void* pixels, size_t rowBytes) {
return this->getPixels(info, pixels, rowBytes, nullptr);
}
Result getPixels(const SkPixmap& pm, const Options* opts = nullptr) {
return this->getPixels(pm.info(), pm.writable_addr(), pm.rowBytes(), opts);
}
/**
* If decoding to YUV is supported, this returns true. Otherwise, this
* returns false and does not modify any of the parameters.
*
* @param sizeInfo Output parameter indicating the sizes and required
* allocation widths of the Y, U, and V planes.
* @param colorSpace Output parameter. If non-NULL this is set to kJPEG,
* otherwise this is ignored.
*/
bool queryYUV8(SkYUVSizeInfo* sizeInfo, SkYUVColorSpace* colorSpace) const {
if (nullptr == sizeInfo) {
return false;
}
return this->onQueryYUV8(sizeInfo, colorSpace);
}
/**
* Returns kSuccess, or another value explaining the type of failure.
* This always attempts to perform a full decode. If the client only
* wants size, it should call queryYUV8().
*
* @param sizeInfo Needs to exactly match the values returned by the
* query, except the WidthBytes may be larger than the
* recommendation (but not smaller).
* @param planes Memory for each of the Y, U, and V planes.
*/
Result getYUV8Planes(const SkYUVSizeInfo& sizeInfo, void* planes[3]) {
if (nullptr == planes || nullptr == planes[0] || nullptr == planes[1] ||
nullptr == planes[2]) {
return kInvalidInput;
}
if (!this->rewindIfNeeded()) {
return kCouldNotRewind;
}
return this->onGetYUV8Planes(sizeInfo, planes);
}
/**
* Prepare for an incremental decode with the specified options.
*
* This may require a rewind.
*
* @param dstInfo Info of the destination. If the dimensions do not match
* those of getInfo, this implies a scale.
* @param dst Memory to write to. Needs to be large enough to hold the subset,
* if present, or the full image as described in dstInfo.
* @param options Contains decoding options, including if memory is zero
* initialized and whether to decode a subset.
* @return Enum representing success or reason for failure.
*/
Result startIncrementalDecode(const SkImageInfo& dstInfo, void* dst, size_t rowBytes,
const Options*);
Result startIncrementalDecode(const SkImageInfo& dstInfo, void* dst, size_t rowBytes) {
return this->startIncrementalDecode(dstInfo, dst, rowBytes, nullptr);
}
/**
* Start/continue the incremental decode.
*
* Not valid to call before calling startIncrementalDecode().
*
* After the first call, should only be called again if more data has been
* provided to the source SkStream.
*
* Unlike getPixels and getScanlines, this does not do any filling. This is
* left up to the caller, since they may be skipping lines or continuing the
* decode later. In the latter case, they may choose to initialize all lines
* first, or only initialize the remaining lines after the first call.
*
* @param rowsDecoded Optional output variable returning the total number of
* lines initialized. Only meaningful if this method returns kIncompleteInput.
* Otherwise the implementation may not set it.
* Note that some implementations may have initialized this many rows, but
* not necessarily finished those rows (e.g. interlaced PNG). This may be
* useful for determining what rows the client needs to initialize.
* @return kSuccess if all lines requested in startIncrementalDecode have
* been completely decoded. kIncompleteInput otherwise.
*/
Result incrementalDecode(int* rowsDecoded = nullptr) {
if (!fStartedIncrementalDecode) {
return kInvalidParameters;
}
return this->onIncrementalDecode(rowsDecoded);
}
/**
* The remaining functions revolve around decoding scanlines.
*/
/**
* Prepare for a scanline decode with the specified options.
*
* After this call, this class will be ready to decode the first scanline.
*
* This must be called in order to call getScanlines or skipScanlines.
*
* This may require rewinding the stream.
*
* Not all SkCodecs support this.
*
* @param dstInfo Info of the destination. If the dimensions do not match
* those of getInfo, this implies a scale.
* @param options Contains decoding options, including if memory is zero
* initialized.
* @return Enum representing success or reason for failure.
*/
Result startScanlineDecode(const SkImageInfo& dstInfo, const Options* options);
/**
* Simplified version of startScanlineDecode() that uses the default Options.
*/
Result startScanlineDecode(const SkImageInfo& dstInfo) {
return this->startScanlineDecode(dstInfo, nullptr);
}
/**
* Write the next countLines scanlines into dst.
*
* Not valid to call before calling startScanlineDecode().
*
* @param dst Must be non-null, and large enough to hold countLines
* scanlines of size rowBytes.
* @param countLines Number of lines to write.
* @param rowBytes Number of bytes per row. Must be large enough to hold
* a scanline based on the SkImageInfo used to create this object.
* @return the number of lines successfully decoded. If this value is
* less than countLines, this will fill the remaining lines with a
* default value.
*/
int getScanlines(void* dst, int countLines, size_t rowBytes);
/**
* Skip count scanlines.
*
* Not valid to call before calling startScanlineDecode().
*
* The default version just calls onGetScanlines and discards the dst.
* NOTE: If skipped lines are the only lines with alpha, this default
* will make reallyHasAlpha return true, when it could have returned
* false.
*
* @return true if the scanlines were successfully skipped
* false on failure, possible reasons for failure include:
* An incomplete input image stream.
* Calling this function before calling startScanlineDecode().
* If countLines is less than zero or so large that it moves
* the current scanline past the end of the image.
*/
bool skipScanlines(int countLines);
/**
* The order in which rows are output from the scanline decoder is not the
* same for all variations of all image types. This explains the possible
* output row orderings.
*/
enum SkScanlineOrder {
/*
* By far the most common, this indicates that the image can be decoded
* reliably using the scanline decoder, and that rows will be output in
* the logical order.
*/
kTopDown_SkScanlineOrder,
/*
* This indicates that the scanline decoder reliably outputs rows, but
* they will be returned in reverse order. If the scanline format is
* kBottomUp, the nextScanline() API can be used to determine the actual
* y-coordinate of the next output row, but the client is not forced
* to take advantage of this, given that it's not too tough to keep
* track independently.
*
* For full image decodes, it is safe to get all of the scanlines at
* once, since the decoder will handle inverting the rows as it
* decodes.
*
* For subset decodes and sampling, it is simplest to get and skip
* scanlines one at a time, using the nextScanline() API. It is
* possible to ask for larger chunks at a time, but this should be used
* with caution. As with full image decodes, the decoder will handle
* inverting the requested rows, but rows will still be delivered
* starting from the bottom of the image.
*
* Upside down bmps are an example.
*/
kBottomUp_SkScanlineOrder,
};
/**
* An enum representing the order in which scanlines will be returned by
* the scanline decoder.
*
* This is undefined before startScanlineDecode() is called.
*/
SkScanlineOrder getScanlineOrder() const { return this->onGetScanlineOrder(); }
/**
* Returns the y-coordinate of the next row to be returned by the scanline
* decoder.
*
* This will equal fCurrScanline, except in the case of strangely
* encoded image types (bottom-up bmps).
*
* Results are undefined when not in scanline decoding mode.
*/
int nextScanline() const { return this->outputScanline(fCurrScanline); }
/**
* Returns the output y-coordinate of the row that corresponds to an input
* y-coordinate. The input y-coordinate represents where the scanline
* is located in the encoded data.
*
* This will equal inputScanline, except in the case of strangely
* encoded image types (bottom-up bmps, interlaced gifs).
*/
int outputScanline(int inputScanline) const;
/**
* Return the number of frames in the image.
*
* May require reading through the stream.
*/
int getFrameCount() {
return this->onGetFrameCount();
}
// The required frame for an independent frame is marked as
// kNone.
static constexpr int kNone = -1;
/**
* Information about individual frames in a multi-framed image.
*/
struct FrameInfo {
/**
* The frame that this frame needs to be blended with, or
* kNone if this frame is independent.
*
* Note that this is the *earliest* frame that can be used
* for blending. Any frame from [fRequiredFrame, i) can be
* used, unless its fDisposalMethod is kRestorePrevious.
*/
int fRequiredFrame;
/**
* Number of milliseconds to show this frame.
*/
int fDuration;
/**
* Whether the end marker for this frame is contained in the stream.
*
* Note: this does not guarantee that an attempt to decode will be complete.
* There could be an error in the stream.
*/
bool fFullyReceived;
/**
* This is conservative; it will still return non-opaque if e.g. a
* color index-based frame has a color with alpha but does not use it.
*/
SkAlphaType fAlphaType;
/**
* How this frame should be modified before decoding the next one.
*/
SkCodecAnimation::DisposalMethod fDisposalMethod;
};
/**
* Return info about a single frame.
*
* Only supported by multi-frame images. Does not read through the stream,
* so it should be called after getFrameCount() to parse any frames that
* have not already been parsed.
*/
bool getFrameInfo(int index, FrameInfo* info) const {
if (index < 0) {
return false;
}
return this->onGetFrameInfo(index, info);
}
/**
* Return info about all the frames in the image.
*
* May require reading through the stream to determine info about the
* frames (including the count).
*
* As such, future decoding calls may require a rewind.
*
* For single-frame images, this will return an empty vector.
*/
std::vector<FrameInfo> getFrameInfo();
static constexpr int kRepetitionCountInfinite = -1;
/**
* Return the number of times to repeat, if this image is animated.
*
* May require reading the stream to find the repetition count.
*
* As such, future decoding calls may require a rewind.
*
* For single-frame images, this will return 0.
*/
int getRepetitionCount() {
return this->onGetRepetitionCount();
}
protected:
const SkEncodedInfo& getEncodedInfo() const { return fEncodedInfo; }
using XformFormat = SkColorSpaceXform::ColorFormat;
SkCodec(int width,
int height,
const SkEncodedInfo&,
XformFormat srcFormat,
std::unique_ptr<SkStream>,
sk_sp<SkColorSpace>,
SkEncodedOrigin = kTopLeft_SkEncodedOrigin);
/**
* Allows the subclass to set the recommended SkImageInfo
*/
SkCodec(const SkEncodedInfo&,
const SkImageInfo&,
XformFormat srcFormat,
std::unique_ptr<SkStream>,
SkEncodedOrigin = kTopLeft_SkEncodedOrigin);
virtual SkISize onGetScaledDimensions(float /*desiredScale*/) const {
// By default, scaling is not supported.
return this->getInfo().dimensions();
}
// FIXME: What to do about subsets??
/**
* Subclasses should override if they support dimensions other than the
* srcInfo's.
*/
virtual bool onDimensionsSupported(const SkISize&) {
return false;
}
virtual SkEncodedImageFormat onGetEncodedFormat() const = 0;
/**
* @param rowsDecoded When the encoded image stream is incomplete, this function
* will return kIncompleteInput and rowsDecoded will be set to
* the number of scanlines that were successfully decoded.
* This will allow getPixels() to fill the uninitialized memory.
*/
virtual Result onGetPixels(const SkImageInfo& info,
void* pixels, size_t rowBytes, const Options&,
int* rowsDecoded) = 0;
virtual bool onQueryYUV8(SkYUVSizeInfo*, SkYUVColorSpace*) const {
return false;
}
virtual Result onGetYUV8Planes(const SkYUVSizeInfo&, void*[3] /*planes*/) {
return kUnimplemented;
}
virtual bool onGetValidSubset(SkIRect* /*desiredSubset*/) const {
// By default, subsets are not supported.
return false;
}
/**
* If the stream was previously read, attempt to rewind.
*
* If the stream needed to be rewound, call onRewind.
* @returns true if the codec is at the right position and can be used.
* false if there was a failure to rewind.
*
* This is called by getPixels() and start(). Subclasses may call if they
* need to rewind at another time.
*/
bool SK_WARN_UNUSED_RESULT rewindIfNeeded();
/**
* Called by rewindIfNeeded, if the stream needed to be rewound.
*
* Subclasses should do any set up needed after a rewind.
*/
virtual bool onRewind() {
return true;
}
/**
* On an incomplete input, getPixels() and getScanlines() will fill any uninitialized
* scanlines. This allows the subclass to indicate what value to fill with.
*
* @param dstInfo Describes the destination.
* @return The value with which to fill uninitialized pixels.
*
* Note that we can interpret the return value as a 64-bit Float16 color, a SkPMColor,
* a 16-bit 565 color, an 8-bit gray color, or an 8-bit index into a color table,
* depending on the color type.
*/
uint64_t getFillValue(const SkImageInfo& dstInfo) const {
return this->onGetFillValue(dstInfo);
}
/**
* Some subclasses will override this function, but this is a useful default for the color
* types that we support. Note that for color types that do not use the full 64-bits,
* we will simply take the low bits of the fill value.
*
* The defaults are:
* kRGBA_F16_SkColorType: Transparent or Black, depending on the src alpha type
* kN32_SkColorType: Transparent or Black, depending on the src alpha type
* kRGB_565_SkColorType: Black
* kGray_8_SkColorType: Black
*/
virtual uint64_t onGetFillValue(const SkImageInfo& dstInfo) const;
/**
* Get method for the input stream
*/
SkStream* stream() {
return fStream.get();
}
/**
* The remaining functions revolve around decoding scanlines.
*/
/**
* Most images types will be kTopDown and will not need to override this function.
*/
virtual SkScanlineOrder onGetScanlineOrder() const { return kTopDown_SkScanlineOrder; }
const SkImageInfo& dstInfo() const { return fDstInfo; }
const Options& options() const { return fOptions; }
/**
* Returns the number of scanlines that have been decoded so far.
* This is unaffected by the SkScanlineOrder.
*
* Returns -1 if we have not started a scanline decode.
*/
int currScanline() const { return fCurrScanline; }
virtual int onOutputScanline(int inputScanline) const;
bool initializeColorXform(const SkImageInfo& dstInfo, SkEncodedInfo::Alpha);
// Some classes never need a colorXform e.g.
// - ICO uses its embedded codec's colorXform
// - WBMP is just Black/White
virtual bool usesColorXform() const { return true; }
void applyColorXform(void* dst, const void* src, int count, SkAlphaType) const;
void applyColorXform(void* dst, const void* src, int count) const;
SkColorSpaceXform* colorXform() const { return fColorXform.get(); }
bool xformOnDecode() const { return fXformOnDecode; }
virtual int onGetFrameCount() {
return 1;
}
virtual bool onGetFrameInfo(int, FrameInfo*) const {
return false;
}
virtual int onGetRepetitionCount() {
return 0;
}
private:
const SkEncodedInfo fEncodedInfo;
const SkImageInfo fSrcInfo;
const XformFormat fSrcXformFormat;
std::unique_ptr<SkStream> fStream;
bool fNeedsRewind;
const SkEncodedOrigin fOrigin;
SkImageInfo fDstInfo;
Options fOptions;
XformFormat fDstXformFormat; // Based on fDstInfo.
std::unique_ptr<SkColorSpaceXform> fColorXform;
bool fXformOnDecode;
// Only meaningful during scanline decodes.
int fCurrScanline;
bool fStartedIncrementalDecode;
/**
* Return whether {srcColor, srcIsOpaque, srcCS} can convert to dst.
*
* Will be called for the appropriate frame, prior to initializing the colorXform.
*/
virtual bool conversionSupported(const SkImageInfo& dst, SkColorType srcColor,
bool srcIsOpaque, const SkColorSpace* srcCS) const;
/**
* Return whether these dimensions are supported as a scale.
*
* The codec may choose to cache the information about scale and subset.
* Either way, the same information will be passed to onGetPixels/onStart
* on success.
*
* This must return true for a size returned from getScaledDimensions.
*/
bool dimensionsSupported(const SkISize& dim) {
return dim == fSrcInfo.dimensions() || this->onDimensionsSupported(dim);
}
/**
* For multi-framed images, return the object with information about the frames.
*/
virtual const SkFrameHolder* getFrameHolder() const {
return nullptr;
}
/**
* Check for a valid Options.fFrameIndex, and decode prior frames if necessary.
*/
Result handleFrameIndex(const SkImageInfo&, void* pixels, size_t rowBytes, const Options&);
// Methods for scanline decoding.
virtual Result onStartScanlineDecode(const SkImageInfo& /*dstInfo*/,
const Options& /*options*/) {
return kUnimplemented;
}
virtual Result onStartIncrementalDecode(const SkImageInfo& /*dstInfo*/, void*, size_t,
const Options&) {
return kUnimplemented;
}
virtual Result onIncrementalDecode(int*) {
return kUnimplemented;
}
virtual bool onSkipScanlines(int /*countLines*/) { return false; }
virtual int onGetScanlines(void* /*dst*/, int /*countLines*/, size_t /*rowBytes*/) { return 0; }
/**
* On an incomplete decode, getPixels() and getScanlines() will call this function
* to fill any uinitialized memory.
*
* @param dstInfo Contains the destination color type
* Contains the destination alpha type
* Contains the destination width
* The height stored in this info is unused
* @param dst Pointer to the start of destination pixel memory
* @param rowBytes Stride length in destination pixel memory
* @param zeroInit Indicates if memory is zero initialized
* @param linesRequested Number of lines that the client requested
* @param linesDecoded Number of lines that were successfully decoded
*/
void fillIncompleteImage(const SkImageInfo& dstInfo, void* dst, size_t rowBytes,
ZeroInitialized zeroInit, int linesRequested, int linesDecoded);
/**
* Return an object which will allow forcing scanline decodes to sample in X.
*
* May create a sampler, if one is not currently being used. Otherwise, does
* not affect ownership.
*
* Only valid during scanline decoding or incremental decoding.
*/
virtual SkSampler* getSampler(bool /*createIfNecessary*/) { return nullptr; }
friend class DM::CodecSrc; // for fillIncompleteImage
friend class SkSampledCodec;
friend class SkIcoCodec;
friend class SkAndroidCodec; // for fEncodedInfo
};
#endif // SkCodec_DEFINED
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