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Diffstat (limited to 'src/codec/SkPngCodec.cpp')
| -rw-r--r-- | src/codec/SkPngCodec.cpp | 787 |
1 files changed, 787 insertions, 0 deletions
diff --git a/src/codec/SkPngCodec.cpp b/src/codec/SkPngCodec.cpp new file mode 100644 index 0000000000..66215a6c73 --- /dev/null +++ b/src/codec/SkPngCodec.cpp @@ -0,0 +1,787 @@ +/* + * Copyright 2015 Google Inc. + * + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + */ + +#include "SkCodecPriv.h" +#include "SkColorPriv.h" +#include "SkColorTable.h" +#include "SkBitmap.h" +#include "SkMath.h" +#include "SkPngCodec.h" +#include "SkSize.h" +#include "SkStream.h" +#include "SkSwizzler.h" +#include "SkTemplates.h" + +/////////////////////////////////////////////////////////////////////////////// +// Helper macros +/////////////////////////////////////////////////////////////////////////////// + +#ifndef png_jmpbuf +# define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf) +#endif + +/* These were dropped in libpng >= 1.4 */ +#ifndef png_infopp_NULL + #define png_infopp_NULL nullptr +#endif + +#ifndef png_bytepp_NULL + #define png_bytepp_NULL nullptr +#endif + +#ifndef int_p_NULL + #define int_p_NULL nullptr +#endif + +#ifndef png_flush_ptr_NULL + #define png_flush_ptr_NULL nullptr +#endif + +/////////////////////////////////////////////////////////////////////////////// +// Callback functions +/////////////////////////////////////////////////////////////////////////////// + +static void sk_error_fn(png_structp png_ptr, png_const_charp msg) { + SkCodecPrintf("------ png error %s\n", msg); + longjmp(png_jmpbuf(png_ptr), 1); +} + +void sk_warning_fn(png_structp, png_const_charp msg) { + SkCodecPrintf("----- png warning %s\n", msg); +} + +static void sk_read_fn(png_structp png_ptr, png_bytep data, + png_size_t length) { + SkStream* stream = static_cast<SkStream*>(png_get_io_ptr(png_ptr)); + const size_t bytes = stream->read(data, length); + if (bytes != length) { + // FIXME: We want to report the fact that the stream was truncated. + // One way to do that might be to pass a enum to longjmp so setjmp can + // specify the failure. + png_error(png_ptr, "Read Error!"); + } +} + +#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED +static int sk_read_user_chunk(png_structp png_ptr, png_unknown_chunkp chunk) { + SkPngChunkReader* chunkReader = (SkPngChunkReader*)png_get_user_chunk_ptr(png_ptr); + // readChunk() returning true means continue decoding + return chunkReader->readChunk((const char*)chunk->name, chunk->data, chunk->size) ? 1 : -1; +} +#endif + +/////////////////////////////////////////////////////////////////////////////// +// Helpers +/////////////////////////////////////////////////////////////////////////////// + +class AutoCleanPng : public SkNoncopyable { +public: + AutoCleanPng(png_structp png_ptr) + : fPng_ptr(png_ptr) + , fInfo_ptr(nullptr) {} + + ~AutoCleanPng() { + // fInfo_ptr will never be non-nullptr unless fPng_ptr is. + if (fPng_ptr) { + png_infopp info_pp = fInfo_ptr ? &fInfo_ptr : nullptr; + png_destroy_read_struct(&fPng_ptr, info_pp, png_infopp_NULL); + } + } + + void setInfoPtr(png_infop info_ptr) { + SkASSERT(nullptr == fInfo_ptr); + fInfo_ptr = info_ptr; + } + + void detach() { + fPng_ptr = nullptr; + fInfo_ptr = nullptr; + } + +private: + png_structp fPng_ptr; + png_infop fInfo_ptr; +}; +#define AutoCleanPng(...) SK_REQUIRE_LOCAL_VAR(AutoCleanPng) + +//checks if there is transparency info in the tRNS chunk +//image types which could have data in the tRNS chunk include: Index8, Gray8, RGB +static bool has_transparency_in_tRNS(png_structp png_ptr, + png_infop info_ptr) { + if (!png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) { + return false; + } + + png_bytep trans; + int num_trans; + png_get_tRNS(png_ptr, info_ptr, &trans, &num_trans, nullptr); + return num_trans > 0; +} + +// Method for coverting to either an SkPMColor or a similarly packed +// unpremultiplied color. +typedef uint32_t (*PackColorProc)(U8CPU a, U8CPU r, U8CPU g, U8CPU b); + +// Note: SkColorTable claims to store SkPMColors, which is not necessarily +// the case here. +bool SkPngCodec::decodePalette(bool premultiply, int* ctableCount) { + int numPalette; + png_colorp palette; + png_bytep trans; + + if (!png_get_PLTE(fPng_ptr, fInfo_ptr, &palette, &numPalette)) { + return false; + } + + // Note: These are not necessarily SkPMColors + SkPMColor colorStorage[256]; // worst-case storage + SkPMColor* colorPtr = colorStorage; + + int numTrans; + if (png_get_valid(fPng_ptr, fInfo_ptr, PNG_INFO_tRNS)) { + png_get_tRNS(fPng_ptr, fInfo_ptr, &trans, &numTrans, nullptr); + } else { + numTrans = 0; + } + + // check for bad images that might make us crash + if (numTrans > numPalette) { + numTrans = numPalette; + } + + int index = 0; + + // Choose which function to use to create the color table. If the final destination's + // colortype is unpremultiplied, the color table will store unpremultiplied colors. + PackColorProc proc; + if (premultiply) { + proc = &SkPreMultiplyARGB; + } else { + proc = &SkPackARGB32NoCheck; + } + for (; index < numTrans; index++) { + *colorPtr++ = proc(*trans++, palette->red, palette->green, palette->blue); + palette++; + } + + for (; index < numPalette; index++) { + *colorPtr++ = SkPackARGB32(0xFF, palette->red, palette->green, palette->blue); + palette++; + } + + /* BUGGY IMAGE WORKAROUND + Invalid images could contain pixel values that are greater than the number of palette + entries. Since we use pixel values as indices into the palette this could result in reading + beyond the end of the palette which could leak the contents of uninitialized memory. To + ensure this doesn't happen, we grow the colortable to the maximum size that can be + addressed by the bitdepth of the image and fill it with the last palette color or black if + the palette is empty (really broken image). + */ + int colorCount = SkTMax(numPalette, 1 << SkTMin(fBitDepth, 8)); + SkPMColor lastColor = index > 0 ? colorPtr[-1] : SkPackARGB32(0xFF, 0, 0, 0); + for (; index < colorCount; index++) { + *colorPtr++ = lastColor; + } + + // Set the new color count + if (ctableCount != nullptr) { + *ctableCount = colorCount; + } + + fColorTable.reset(new SkColorTable(colorStorage, colorCount)); + return true; +} + +/////////////////////////////////////////////////////////////////////////////// +// Creation +/////////////////////////////////////////////////////////////////////////////// + +bool SkPngCodec::IsPng(const char* buf, size_t bytesRead) { + return !png_sig_cmp((png_bytep) buf, (png_size_t)0, bytesRead); +} + +// Reads the header and initializes the output fields, if not NULL. +// +// @param stream Input data. Will be read to get enough information to properly +// setup the codec. +// @param chunkReader SkPngChunkReader, for reading unknown chunks. May be NULL. +// If not NULL, png_ptr will hold an *unowned* pointer to it. The caller is +// expected to continue to own it for the lifetime of the png_ptr. +// @param png_ptrp Optional output variable. If non-NULL, will be set to a new +// png_structp on success. +// @param info_ptrp Optional output variable. If non-NULL, will be set to a new +// png_infop on success; +// @param imageInfo Optional output variable. If non-NULL, will be set to +// reflect the properties of the encoded image on success. +// @param bitDepthPtr Optional output variable. If non-NULL, will be set to the +// bit depth of the encoded image on success. +// @param numberPassesPtr Optional output variable. If non-NULL, will be set to +// the number_passes of the encoded image on success. +// @return true on success, in which case the caller is responsible for calling +// png_destroy_read_struct(png_ptrp, info_ptrp). +// If it returns false, the passed in fields (except stream) are unchanged. +static bool read_header(SkStream* stream, SkPngChunkReader* chunkReader, + png_structp* png_ptrp, png_infop* info_ptrp, + SkImageInfo* imageInfo, int* bitDepthPtr, int* numberPassesPtr) { + // The image is known to be a PNG. Decode enough to know the SkImageInfo. + png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, nullptr, + sk_error_fn, sk_warning_fn); + if (!png_ptr) { + return false; + } + + AutoCleanPng autoClean(png_ptr); + + png_infop info_ptr = png_create_info_struct(png_ptr); + if (info_ptr == nullptr) { + return false; + } + + autoClean.setInfoPtr(info_ptr); + + // FIXME: Could we use the return value of setjmp to specify the type of + // error? + if (setjmp(png_jmpbuf(png_ptr))) { + return false; + } + + png_set_read_fn(png_ptr, static_cast<void*>(stream), sk_read_fn); + +#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED + // Hookup our chunkReader so we can see any user-chunks the caller may be interested in. + // This needs to be installed before we read the png header. Android may store ninepatch + // chunks in the header. + if (chunkReader) { + png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_ALWAYS, (png_byte*)"", 0); + png_set_read_user_chunk_fn(png_ptr, (png_voidp) chunkReader, sk_read_user_chunk); + } +#endif + + // The call to png_read_info() gives us all of the information from the + // PNG file before the first IDAT (image data chunk). + png_read_info(png_ptr, info_ptr); + png_uint_32 origWidth, origHeight; + int bitDepth, colorType; + png_get_IHDR(png_ptr, info_ptr, &origWidth, &origHeight, &bitDepth, + &colorType, int_p_NULL, int_p_NULL, int_p_NULL); + + if (bitDepthPtr) { + *bitDepthPtr = bitDepth; + } + + // sanity check for size + { + int64_t size = sk_64_mul(origWidth, origHeight); + // now check that if we are 4-bytes per pixel, we also don't overflow + if (size < 0 || size > (0x7FFFFFFF >> 2)) { + return false; + } + } + + // Tell libpng to strip 16 bit/color files down to 8 bits/color + if (bitDepth == 16) { + png_set_strip_16(png_ptr); + } +#ifdef PNG_READ_PACK_SUPPORTED + // Extract multiple pixels with bit depths of 1, 2, and 4 from a single + // byte into separate bytes (useful for paletted and grayscale images). + if (bitDepth < 8) { + png_set_packing(png_ptr); + } +#endif + // Expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel. + if (colorType == PNG_COLOR_TYPE_GRAY && bitDepth < 8) { + png_set_expand_gray_1_2_4_to_8(png_ptr); + } + + // Now determine the default SkColorType and SkAlphaType and set required transforms + SkColorType skColorType = kUnknown_SkColorType; + SkAlphaType skAlphaType = kUnknown_SkAlphaType; + switch (colorType) { + case PNG_COLOR_TYPE_PALETTE: + skColorType = kIndex_8_SkColorType; + skAlphaType = has_transparency_in_tRNS(png_ptr, info_ptr) ? + kUnpremul_SkAlphaType : kOpaque_SkAlphaType; + break; + case PNG_COLOR_TYPE_RGB: + if (has_transparency_in_tRNS(png_ptr, info_ptr)) { + //convert to RGBA with tranparency information in tRNS chunk if it exists + png_set_tRNS_to_alpha(png_ptr); + skAlphaType = kUnpremul_SkAlphaType; + } else { + skAlphaType = kOpaque_SkAlphaType; + } + skColorType = kN32_SkColorType; + break; + case PNG_COLOR_TYPE_GRAY: + if (has_transparency_in_tRNS(png_ptr, info_ptr)) { + //FIXME: support gray with alpha as a color type + //convert to RGBA if there is transparentcy info in the tRNS chunk + png_set_tRNS_to_alpha(png_ptr); + png_set_gray_to_rgb(png_ptr); + skColorType = kN32_SkColorType; + skAlphaType = kUnpremul_SkAlphaType; + } else { + skColorType = kGray_8_SkColorType; + skAlphaType = kOpaque_SkAlphaType; + } + break; + case PNG_COLOR_TYPE_GRAY_ALPHA: + //FIXME: support gray with alpha as a color type + //convert to RGBA + png_set_gray_to_rgb(png_ptr); + skColorType = kN32_SkColorType; + skAlphaType = kUnpremul_SkAlphaType; + break; + case PNG_COLOR_TYPE_RGBA: + skColorType = kN32_SkColorType; + skAlphaType = kUnpremul_SkAlphaType; + break; + default: + //all the color types have been covered above + SkASSERT(false); + } + + int numberPasses = png_set_interlace_handling(png_ptr); + if (numberPassesPtr) { + *numberPassesPtr = numberPasses; + } + + // FIXME: Also need to check for sRGB ( https://bug.skia.org/3471 ). + + if (imageInfo) { + *imageInfo = SkImageInfo::Make(origWidth, origHeight, skColorType, skAlphaType); + } + autoClean.detach(); + if (png_ptrp) { + *png_ptrp = png_ptr; + } + if (info_ptrp) { + *info_ptrp = info_ptr; + } + + return true; +} + +SkPngCodec::SkPngCodec(const SkImageInfo& info, SkStream* stream, SkPngChunkReader* chunkReader, + png_structp png_ptr, png_infop info_ptr, int bitDepth, int numberPasses) + : INHERITED(info, stream) + , fPngChunkReader(SkSafeRef(chunkReader)) + , fPng_ptr(png_ptr) + , fInfo_ptr(info_ptr) + , fSrcConfig(SkSwizzler::kUnknown) + , fNumberPasses(numberPasses) + , fBitDepth(bitDepth) +{} + +SkPngCodec::~SkPngCodec() { + this->destroyReadStruct(); +} + +void SkPngCodec::destroyReadStruct() { + if (fPng_ptr) { + // We will never have a nullptr fInfo_ptr with a non-nullptr fPng_ptr + SkASSERT(fInfo_ptr); + png_destroy_read_struct(&fPng_ptr, &fInfo_ptr, png_infopp_NULL); + fPng_ptr = nullptr; + fInfo_ptr = nullptr; + } +} + +/////////////////////////////////////////////////////////////////////////////// +// Getting the pixels +/////////////////////////////////////////////////////////////////////////////// + +SkCodec::Result SkPngCodec::initializeSwizzler(const SkImageInfo& requestedInfo, + const Options& options, + SkPMColor ctable[], + int* ctableCount) { + // FIXME: Could we use the return value of setjmp to specify the type of + // error? + if (setjmp(png_jmpbuf(fPng_ptr))) { + SkCodecPrintf("setjmp long jump!\n"); + return kInvalidInput; + } + png_read_update_info(fPng_ptr, fInfo_ptr); + + //srcColorType was determined in read_header() which determined png color type + const SkColorType srcColorType = this->getInfo().colorType(); + + switch (srcColorType) { + case kIndex_8_SkColorType: + //decode palette to Skia format + fSrcConfig = SkSwizzler::kIndex; + if (!this->decodePalette(kPremul_SkAlphaType == requestedInfo.alphaType(), + ctableCount)) { + return kInvalidInput; + } + break; + case kGray_8_SkColorType: + fSrcConfig = SkSwizzler::kGray; + break; + case kN32_SkColorType: + if (this->getInfo().alphaType() == kOpaque_SkAlphaType) { + fSrcConfig = SkSwizzler::kRGB; + } else { + fSrcConfig = SkSwizzler::kRGBA; + } + break; + default: + //would have exited before now if the colorType was supported by png + SkASSERT(false); + } + + // Copy the color table to the client if they request kIndex8 mode + copy_color_table(requestedInfo, fColorTable, ctable, ctableCount); + + // Create the swizzler. SkPngCodec retains ownership of the color table. + const SkPMColor* colors = get_color_ptr(fColorTable.get()); + fSwizzler.reset(SkSwizzler::CreateSwizzler(fSrcConfig, colors, requestedInfo, options)); + if (!fSwizzler) { + // FIXME: CreateSwizzler could fail for another reason. + return kUnimplemented; + } + return kSuccess; +} + + +bool SkPngCodec::onRewind() { + // This sets fPng_ptr and fInfo_ptr to nullptr. If read_header + // succeeds, they will be repopulated, and if it fails, they will + // remain nullptr. Any future accesses to fPng_ptr and fInfo_ptr will + // come through this function which will rewind and again attempt + // to reinitialize them. + this->destroyReadStruct(); + + png_structp png_ptr; + png_infop info_ptr; + if (!read_header(this->stream(), fPngChunkReader.get(), &png_ptr, &info_ptr, + nullptr, nullptr, nullptr)) { + return false; + } + + fPng_ptr = png_ptr; + fInfo_ptr = info_ptr; + return true; +} + +SkCodec::Result SkPngCodec::onGetPixels(const SkImageInfo& requestedInfo, void* dst, + size_t dstRowBytes, const Options& options, + SkPMColor ctable[], int* ctableCount, + int* rowsDecoded) { + if (!conversion_possible(requestedInfo, this->getInfo())) { + return kInvalidConversion; + } + if (options.fSubset) { + // Subsets are not supported. + return kUnimplemented; + } + + // Note that ctable and ctableCount may be modified if there is a color table + const Result result = this->initializeSwizzler(requestedInfo, options, ctable, ctableCount); + if (result != kSuccess) { + return result; + } + // FIXME: Could we use the return value of setjmp to specify the type of + // error? + int row = 0; + // This must be declared above the call to setjmp to avoid memory leaks on incomplete images. + SkAutoTMalloc<uint8_t> storage; + if (setjmp(png_jmpbuf(fPng_ptr))) { + // Assume that any error that occurs while reading rows is caused by an incomplete input. + if (fNumberPasses > 1) { + // FIXME (msarett): Handle incomplete interlaced pngs. + return kInvalidInput; + } + // FIXME: We do a poor job on incomplete pngs compared to other decoders (ex: Chromium, + // Ubuntu Image Viewer). This is because we use the default buffer size in libpng (8192 + // bytes), and if we can't fill the buffer, we immediately fail. + // For example, if we try to read 8192 bytes, and the image (incorrectly) only contains + // half that, which may have been enough to contain a non-zero number of lines, we fail + // when we could have decoded a few more lines and then failed. + // The read function that we provide for libpng has no way of indicating that we have + // made a partial read. + // Making our buffer size smaller improves our incomplete decodes, but what impact does + // it have on regular decode performance? Should we investigate using a different API + // instead of png_read_row(s)? Chromium uses png_process_data. + *rowsDecoded = row; + return kIncompleteInput; + } + + // FIXME: We could split these out based on subclass. + void* dstRow = dst; + if (fNumberPasses > 1) { + const int width = requestedInfo.width(); + const int height = requestedInfo.height(); + const int bpp = SkSwizzler::BytesPerPixel(fSrcConfig); + const size_t srcRowBytes = width * bpp; + + storage.reset(width * height * bpp); + uint8_t* const base = storage.get(); + + for (int i = 0; i < fNumberPasses; i++) { + uint8_t* srcRow = base; + for (int y = 0; y < height; y++) { + uint8_t* bmRow = srcRow; + png_read_rows(fPng_ptr, &bmRow, png_bytepp_NULL, 1); + srcRow += srcRowBytes; + } + } + + // Now swizzle it. + uint8_t* srcRow = base; + for (int y = 0; y < height; y++) { + fSwizzler->swizzle(dstRow, srcRow); + dstRow = SkTAddOffset<void>(dstRow, dstRowBytes); + srcRow += srcRowBytes; + } + } else { + storage.reset(requestedInfo.width() * SkSwizzler::BytesPerPixel(fSrcConfig)); + uint8_t* srcRow = storage.get(); + for (; row < requestedInfo.height(); row++) { + png_read_rows(fPng_ptr, &srcRow, png_bytepp_NULL, 1); + // FIXME: Only call IsOpaque once, outside the loop. Same for onGetScanlines. + fSwizzler->swizzle(dstRow, srcRow); + dstRow = SkTAddOffset<void>(dstRow, dstRowBytes); + } + } + + // FIXME: do we need substituteTranspColor? Note that we cannot do it for + // scanline decoding, but we could do it here. Alternatively, we could do + // it as we go, instead of in post-processing like SkPNGImageDecoder. + + if (setjmp(png_jmpbuf(fPng_ptr))) { + // We've already read all the scanlines. This is a success. + return kSuccess; + } + + // read rest of file, and get additional comment and time chunks in info_ptr + png_read_end(fPng_ptr, fInfo_ptr); + + return kSuccess; +} + +uint32_t SkPngCodec::onGetFillValue(SkColorType colorType, SkAlphaType alphaType) const { + const SkPMColor* colorPtr = get_color_ptr(fColorTable.get()); + if (colorPtr) { + return get_color_table_fill_value(colorType, colorPtr, 0); + } + return INHERITED::onGetFillValue(colorType, alphaType); +} + +// Subclass of SkPngCodec which supports scanline decoding +class SkPngScanlineDecoder : public SkPngCodec { +public: + SkPngScanlineDecoder(const SkImageInfo& srcInfo, SkStream* stream, + SkPngChunkReader* chunkReader, png_structp png_ptr, png_infop info_ptr, int bitDepth) + : INHERITED(srcInfo, stream, chunkReader, png_ptr, info_ptr, bitDepth, 1) + , fSrcRow(nullptr) + {} + + Result onStartScanlineDecode(const SkImageInfo& dstInfo, const Options& options, + SkPMColor ctable[], int* ctableCount) override { + if (!conversion_possible(dstInfo, this->getInfo())) { + return kInvalidConversion; + } + + const Result result = this->initializeSwizzler(dstInfo, options, ctable, + ctableCount); + if (result != kSuccess) { + return result; + } + + fStorage.reset(this->getInfo().width() * SkSwizzler::BytesPerPixel(this->srcConfig())); + fSrcRow = fStorage.get(); + + return kSuccess; + } + + int onGetScanlines(void* dst, int count, size_t rowBytes) override { + // Assume that an error in libpng indicates an incomplete input. + int row = 0; + if (setjmp(png_jmpbuf(this->png_ptr()))) { + SkCodecPrintf("setjmp long jump!\n"); + return row; + } + + void* dstRow = dst; + for (; row < count; row++) { + png_read_rows(this->png_ptr(), &fSrcRow, png_bytepp_NULL, 1); + this->swizzler()->swizzle(dstRow, fSrcRow); + dstRow = SkTAddOffset<void>(dstRow, rowBytes); + } + + return row; + } + + bool onSkipScanlines(int count) override { + // Assume that an error in libpng indicates an incomplete input. + if (setjmp(png_jmpbuf(this->png_ptr()))) { + SkCodecPrintf("setjmp long jump!\n"); + return false; + } + //there is a potential tradeoff of memory vs speed created by putting this in a loop. + //calling png_read_rows in a loop is insignificantly slower than calling it once with count + //as png_read_rows has it's own loop which calls png_read_row count times. + for (int row = 0; row < count; row++) { + png_read_rows(this->png_ptr(), &fSrcRow, png_bytepp_NULL, 1); + } + return true; + } + +private: + SkAutoTMalloc<uint8_t> fStorage; + uint8_t* fSrcRow; + + typedef SkPngCodec INHERITED; +}; + + +class SkPngInterlacedScanlineDecoder : public SkPngCodec { +public: + SkPngInterlacedScanlineDecoder(const SkImageInfo& srcInfo, SkStream* stream, + SkPngChunkReader* chunkReader, png_structp png_ptr, png_infop info_ptr, + int bitDepth, int numberPasses) + : INHERITED(srcInfo, stream, chunkReader, png_ptr, info_ptr, bitDepth, numberPasses) + , fHeight(-1) + , fCanSkipRewind(false) + { + SkASSERT(numberPasses != 1); + } + + Result onStartScanlineDecode(const SkImageInfo& dstInfo, const Options& options, + SkPMColor ctable[], int* ctableCount) override { + if (!conversion_possible(dstInfo, this->getInfo())) { + return kInvalidConversion; + } + + const Result result = this->initializeSwizzler(dstInfo, options, ctable, + ctableCount); + if (result != kSuccess) { + return result; + } + + fHeight = dstInfo.height(); + // FIXME: This need not be called on a second call to onStartScanlineDecode. + fSrcRowBytes = this->getInfo().width() * SkSwizzler::BytesPerPixel(this->srcConfig()); + fGarbageRow.reset(fSrcRowBytes); + fGarbageRowPtr = static_cast<uint8_t*>(fGarbageRow.get()); + fCanSkipRewind = true; + + return SkCodec::kSuccess; + } + + int onGetScanlines(void* dst, int count, size_t dstRowBytes) override { + // rewind stream if have previously called onGetScanlines, + // since we need entire progressive image to get scanlines + if (fCanSkipRewind) { + // We already rewound in onStartScanlineDecode, so there is no reason to rewind. + // Next time onGetScanlines is called, we will need to rewind. + fCanSkipRewind = false; + } else { + // rewindIfNeeded resets fCurrScanline, since it assumes that start + // needs to be called again before scanline decoding. PNG scanline + // decoding is the exception, since it needs to rewind between + // calls to getScanlines. Keep track of fCurrScanline, to undo the + // reset. + const int currScanline = this->nextScanline(); + // This method would never be called if currScanline is -1 + SkASSERT(currScanline != -1); + + if (!this->rewindIfNeeded()) { + return kCouldNotRewind; + } + this->updateCurrScanline(currScanline); + } + + if (setjmp(png_jmpbuf(this->png_ptr()))) { + SkCodecPrintf("setjmp long jump!\n"); + // FIXME (msarett): Returning 0 is pessimistic. If we can complete a single pass, + // we may be able to report that all of the memory has been initialized. Even if we + // fail on the first pass, we can still report than some scanlines are initialized. + return 0; + } + SkAutoTMalloc<uint8_t> storage(count * fSrcRowBytes); + uint8_t* storagePtr = storage.get(); + uint8_t* srcRow; + const int startRow = this->nextScanline(); + for (int i = 0; i < this->numberPasses(); i++) { + // read rows we planned to skip into garbage row + for (int y = 0; y < startRow; y++){ + png_read_rows(this->png_ptr(), &fGarbageRowPtr, png_bytepp_NULL, 1); + } + // read rows we care about into buffer + srcRow = storagePtr; + for (int y = 0; y < count; y++) { + png_read_rows(this->png_ptr(), &srcRow, png_bytepp_NULL, 1); + srcRow += fSrcRowBytes; + } + // read rows we don't want into garbage buffer + for (int y = 0; y < fHeight - startRow - count; y++) { + png_read_rows(this->png_ptr(), &fGarbageRowPtr, png_bytepp_NULL, 1); + } + } + //swizzle the rows we care about + srcRow = storagePtr; + void* dstRow = dst; + for (int y = 0; y < count; y++) { + this->swizzler()->swizzle(dstRow, srcRow); + dstRow = SkTAddOffset<void>(dstRow, dstRowBytes); + srcRow += fSrcRowBytes; + } + + return count; + } + + bool onSkipScanlines(int count) override { + // The non-virtual version will update fCurrScanline. + return true; + } + + SkScanlineOrder onGetScanlineOrder() const override { + return kNone_SkScanlineOrder; + } + +private: + int fHeight; + size_t fSrcRowBytes; + SkAutoMalloc fGarbageRow; + uint8_t* fGarbageRowPtr; + // FIXME: This imitates behavior in SkCodec::rewindIfNeeded. That function + // is called whenever some action is taken that reads the stream and + // therefore the next call will require a rewind. So it modifies a boolean + // to note that the *next* time it is called a rewind is needed. + // SkPngInterlacedScanlineDecoder has an extra wrinkle - calling + // onStartScanlineDecode followed by onGetScanlines does *not* require a + // rewind. Since rewindIfNeeded does not have this flexibility, we need to + // add another layer. + bool fCanSkipRewind; + + typedef SkPngCodec INHERITED; +}; + +SkCodec* SkPngCodec::NewFromStream(SkStream* stream, SkPngChunkReader* chunkReader) { + SkAutoTDelete<SkStream> streamDeleter(stream); + png_structp png_ptr; + png_infop info_ptr; + SkImageInfo imageInfo; + int bitDepth; + int numberPasses; + + if (!read_header(stream, chunkReader, &png_ptr, &info_ptr, &imageInfo, &bitDepth, + &numberPasses)) { + return nullptr; + } + + if (1 == numberPasses) { + return new SkPngScanlineDecoder(imageInfo, streamDeleter.detach(), chunkReader, + png_ptr, info_ptr, bitDepth); + } + + return new SkPngInterlacedScanlineDecoder(imageInfo, streamDeleter.detach(), chunkReader, + png_ptr, info_ptr, bitDepth, numberPasses); +} |