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| -rw-r--r-- | gfx/skia/skia/include/codec/SkCodec.h | 954 |
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diff --git a/gfx/skia/skia/include/codec/SkCodec.h b/gfx/skia/skia/include/codec/SkCodec.h new file mode 100644 index 0000000000..2f9f93c0e7 --- /dev/null +++ b/gfx/skia/skia/include/codec/SkCodec.h @@ -0,0 +1,954 @@ +/* + * 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 "include/codec/SkCodecAnimation.h" +#include "include/codec/SkEncodedOrigin.h" +#include "include/core/SkColor.h" +#include "include/core/SkEncodedImageFormat.h" +#include "include/core/SkImageInfo.h" +#include "include/core/SkPixmap.h" +#include "include/core/SkSize.h" +#include "include/core/SkStream.h" +#include "include/core/SkTypes.h" +#include "include/core/SkYUVASizeInfo.h" +#include "include/private/SkEncodedInfo.h" +#include "include/private/SkNoncopyable.h" +#include "include/private/SkTemplates.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); + + /** + * For container formats that contain both still images and image sequences, + * instruct the decoder how the output should be selected. (Refer to comments + * for each value for more details.) + */ + enum class SelectionPolicy { + /** + * If the container format contains both still images and image sequences, + * SkCodec should choose one of the still images. This is the default. + */ + kPreferStillImage, + /** + * If the container format contains both still images and image sequences, + * SkCodec should choose one of the image sequences for animation. + */ + kPreferAnimation, + }; + + /** + * 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, + SelectionPolicy selectionPolicy = SelectionPolicy::kPreferStillImage); + + /** + * 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 a reasonable SkImageInfo to decode into. + */ + SkImageInfo getInfo() const { return fEncodedInfo.makeImageInfo(); } + + SkISize dimensions() const { return {fEncodedInfo.width(), fEncodedInfo.height()}; } + SkIRect bounds() const { + return SkIRect::MakeWH(fEncodedInfo.width(), fEncodedInfo.height()); + } + + /** + * 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->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(kNoFrame) + {} + + 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 kNoFrame, 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 kNoFrame, the codec will decode any necessary required frame(s) first. + */ + int fPriorFrame; + }; + + /** + * 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, V, and A planes. Given current codec + * limitations the size of the A plane will always be 0 and the Y, U, V + * channels will always be planar. + * @param colorSpace Output parameter. If non-NULL this is set to kJPEG, + * otherwise this is ignored. + */ + bool queryYUV8(SkYUVASizeInfo* sizeInfo, SkYUVColorSpace* colorSpace) const { + if (nullptr == sizeInfo) { + return false; + } + + bool result = this->onQueryYUV8(sizeInfo, colorSpace); + if (result) { + for (int i = 0; i <= 2; ++i) { + SkASSERT(sizeInfo->fSizes[i].fWidth > 0 && sizeInfo->fSizes[i].fHeight > 0 && + sizeInfo->fWidthBytes[i] > 0); + } + SkASSERT(!sizeInfo->fSizes[3].fWidth && + !sizeInfo->fSizes[3].fHeight && + !sizeInfo->fWidthBytes[3]); + } + return result; + } + + /** + * 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 SkYUVASizeInfo& sizeInfo, void* planes[SkYUVASizeInfo::kMaxCount]) { + if (!planes || !planes[0] || !planes[1] || !planes[2]) { + return kInvalidInput; + } + SkASSERT(!planes[3]); // TODO: is this a fair assumption? + + if (!this->rewindIfNeeded()) { + return kCouldNotRewind; + } + + return this->onGetYUV8Planes(sizeInfo, planes); + } + + /** + * Prepare for an incremental decode with the specified options. + * + * This may require a rewind. + * + * If kIncompleteInput is returned, may be called again after more data has + * been provided to the source SkStream. + * + * @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 a call to startIncrementalDecode() returns + * kSuccess. + * + * If kIncompleteInput is returned, may be called again after 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(); + } + + // Sentinel value used when a frame index implies "no frame": + // - FrameInfo::fRequiredFrame set to this value means the frame + // is independent. + // - Options::fPriorFrame set to this value means no (relevant) prior frame + // is residing in dst's memory. + static constexpr int kNoFrame = -1; + + // This transitional definition was added in August 2018, and will eventually be removed. +#ifdef SK_LEGACY_SKCODEC_NONE_ENUM + static constexpr int kNone = kNoFrame; +#endif + + /** + * Information about individual frames in a multi-framed image. + */ + struct FrameInfo { + /** + * The frame that this frame needs to be blended with, or + * kNoFrame if this frame is independent (so it can be + * drawn over an uninitialized buffer). + * + * 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 still (non-animated) image codecs, 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. This number does not + * include the first play through of each frame. For example, a repetition count of 4 means + * that each frame is played 5 times and then the animation stops. + * + * It can return kRepetitionCountInfinite, a negative number, meaning that the animation + * should loop forever. + * + * May require reading the stream to find the repetition count. + * + * As such, future decoding calls may require a rewind. + * + * For still (non-animated) image codecs, this will return 0. + */ + int getRepetitionCount() { + return this->onGetRepetitionCount(); + } + + // Register a decoder at runtime by passing two function pointers: + // - peek() to return true if the span of bytes appears to be your encoded format; + // - make() to attempt to create an SkCodec from the given stream. + // Not thread safe. + static void Register( + bool (*peek)(const void*, size_t), + std::unique_ptr<SkCodec> (*make)(std::unique_ptr<SkStream>, SkCodec::Result*)); + +protected: + const SkEncodedInfo& getEncodedInfo() const { return fEncodedInfo; } + + using XformFormat = skcms_PixelFormat; + + SkCodec(SkEncodedInfo&&, + XformFormat srcFormat, + std::unique_ptr<SkStream>, + SkEncodedOrigin = kTopLeft_SkEncodedOrigin); + + virtual SkISize onGetScaledDimensions(float /*desiredScale*/) const { + // By default, scaling is not supported. + return this->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(SkYUVASizeInfo*, SkYUVColorSpace*) const { + return false; + } + + virtual Result onGetYUV8Planes(const SkYUVASizeInfo&, + void*[SkYUVASizeInfo::kMaxCount] /*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(), getYUV8Planes(), startIncrementalDecode() and + * startScanlineDecode(). 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; + } + + /** + * 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; + + /** + * Return whether we can convert to dst. + * + * Will be called for the appropriate frame, prior to initializing the colorXform. + */ + virtual bool conversionSupported(const SkImageInfo& dst, bool srcIsOpaque, + bool needsColorXform); + + // 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) const; + + bool colorXform() const { return fXformTime != kNo_XformTime; } + bool xformOnDecode() const { return fXformTime == kDecodeRow_XformTime; } + + virtual int onGetFrameCount() { + return 1; + } + + virtual bool onGetFrameInfo(int, FrameInfo*) const { + return false; + } + + virtual int onGetRepetitionCount() { + return 0; + } + +private: + const SkEncodedInfo fEncodedInfo; + const XformFormat fSrcXformFormat; + std::unique_ptr<SkStream> fStream; + bool fNeedsRewind; + const SkEncodedOrigin fOrigin; + + SkImageInfo fDstInfo; + Options fOptions; + + enum XformTime { + kNo_XformTime, + kPalette_XformTime, + kDecodeRow_XformTime, + }; + XformTime fXformTime; + XformFormat fDstXformFormat; // Based on fDstInfo. + skcms_ICCProfile fDstProfile; + skcms_AlphaFormat fDstXformAlphaFormat; + + // Only meaningful during scanline decodes. + int fCurrScanline; + + bool fStartedIncrementalDecode; + + bool initializeColorXform(const SkImageInfo& dstInfo, SkEncodedInfo::Alpha, bool srcIsOpaque); + + /** + * 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 == this->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 |