/*
* 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 "SkBitmap.h"
#include "SkCodecPriv.h"
#include "SkColorPriv.h"
#include "SkColorSpace.h"
#include "SkColorSpacePriv.h"
#include "SkColorTable.h"
#include "SkMath.h"
#include "SkOpts.h"
#include "SkPngCodec.h"
#include "SkPoint3.h"
#include "SkSize.h"
#include "SkStream.h"
#include "SkSwizzler.h"
#include "SkTemplates.h"
#include "SkUtils.h"
#include "png.h"
#include <algorithm>
// This warning triggers false postives way too often in here.
#if defined(__GNUC__) && !defined(__clang__)
#pragma GCC diagnostic ignored "-Wclobbered"
#endif
// FIXME (scroggo): We can use png_jumpbuf directly once Google3 is on 1.6
#define PNG_JMPBUF(x) png_jmpbuf((png_structp) x)
///////////////////////////////////////////////////////////////////////////////
// Callback functions
///////////////////////////////////////////////////////////////////////////////
// When setjmp is first called, it returns 0, meaning longjmp was not called.
constexpr int kSetJmpOkay = 0;
// An error internal to libpng.
constexpr int kPngError = 1;
// Passed to longjmp when we have decoded as many lines as we need.
constexpr int kStopDecoding = 2;
static void sk_error_fn(png_structp png_ptr, png_const_charp msg) {
SkCodecPrintf("------ png error %s\n", msg);
longjmp(PNG_JMPBUF(png_ptr), kPngError);
}
void sk_warning_fn(png_structp, png_const_charp msg) {
SkCodecPrintf("----- png warning %s\n", msg);
}
#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:
/*
* This class does not take ownership of stream or reader, but if codecPtr
* is non-NULL, and decodeBounds succeeds, it will have created a new
* SkCodec (pointed to by *codecPtr) which will own/ref them, as well as
* the png_ptr and info_ptr.
*/
AutoCleanPng(png_structp png_ptr, SkStream* stream, SkPngChunkReader* reader,
SkCodec** codecPtr)
: fPng_ptr(png_ptr)
, fInfo_ptr(nullptr)
, fStream(stream)
, fChunkReader(reader)
, fOutCodec(codecPtr)
{}
~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, nullptr);
}
}
void setInfoPtr(png_infop info_ptr) {
SkASSERT(nullptr == fInfo_ptr);
fInfo_ptr = info_ptr;
}
/**
* Reads enough of the input stream to decode the bounds.
* @return false if the stream is not a valid PNG (or too short).
* true if it read enough of the stream to determine the bounds.
* In the latter case, the stream may have been read beyond the
* point to determine the bounds, and the png_ptr will have saved
* any extra data. Further, if the codecPtr supplied to the
* constructor was not NULL, it will now point to a new SkCodec,
* which owns (or refs, in the case of the SkPngChunkReader) the
* inputs. If codecPtr was NULL, the png_ptr and info_ptr are
* unowned, and it is up to the caller to destroy them.
*/
bool decodeBounds();
private:
png_structp fPng_ptr;
png_infop fInfo_ptr;
SkStream* fStream;
SkPngChunkReader* fChunkReader;
SkCodec** fOutCodec;
void infoCallback(size_t idatLength);
void releasePngPtrs() {
fPng_ptr = nullptr;
fInfo_ptr = nullptr;
}
};
#define AutoCleanPng(...) SK_REQUIRE_LOCAL_VAR(AutoCleanPng)
static inline bool is_chunk(const png_byte* chunk, const char* tag) {
return memcmp(chunk + 4, tag, 4) == 0;
}
static inline bool process_data(png_structp png_ptr, png_infop info_ptr,
SkStream* stream, void* buffer, size_t bufferSize, size_t length) {
while (length > 0) {
const size_t bytesToProcess = std::min(bufferSize, length);
const size_t bytesRead = stream->read(buffer, bytesToProcess);
png_process_data(png_ptr, info_ptr, (png_bytep) buffer, bytesRead);
if (bytesRead < bytesToProcess) {
return false;
}
length -= bytesToProcess;
}
return true;
}
bool AutoCleanPng::decodeBounds() {
if (setjmp(PNG_JMPBUF(fPng_ptr))) {
return false;
}
png_set_progressive_read_fn(fPng_ptr, nullptr, nullptr, nullptr, nullptr);
// Arbitrary buffer size, though note that it matches (below)
// SkPngCodec::processData(). FIXME: Can we better suit this to the size of
// the PNG header?
constexpr size_t kBufferSize = 4096;
char buffer[kBufferSize];
{
// Parse the signature.
if (fStream->read(buffer, 8) < 8) {
return false;
}
png_process_data(fPng_ptr, fInfo_ptr, (png_bytep) buffer, 8);
}
while (true) {
// Parse chunk length and type.
if (fStream->read(buffer, 8) < 8) {
// We have read to the end of the input without decoding bounds.
break;
}
png_byte* chunk = reinterpret_cast<png_byte*>(buffer);
const size_t length = png_get_uint_32(chunk);
if (is_chunk(chunk, "IDAT")) {
this->infoCallback(length);
return true;
}
png_process_data(fPng_ptr, fInfo_ptr, chunk, 8);
// Process the full chunk + CRC.
if (!process_data(fPng_ptr, fInfo_ptr, fStream, buffer, kBufferSize, length + 4)) {
return false;
}
}
return false;
}
void SkPngCodec::processData() {
switch (setjmp(PNG_JMPBUF(fPng_ptr))) {
case kPngError:
// There was an error. Stop processing data.
// FIXME: Do we need to discard png_ptr?
return;
case kStopDecoding:
// We decoded all the lines we want.
return;
case kSetJmpOkay:
// Everything is okay.
break;
default:
// No other values should be passed to longjmp.
SkASSERT(false);
}
// Arbitrary buffer size
constexpr size_t kBufferSize = 4096;
char buffer[kBufferSize];
bool iend = false;
while (true) {
size_t length;
if (fDecodedIdat) {
// Parse chunk length and type.
if (this->stream()->read(buffer, 8) < 8) {
break;
}
png_byte* chunk = reinterpret_cast<png_byte*>(buffer);
png_process_data(fPng_ptr, fInfo_ptr, chunk, 8);
if (is_chunk(chunk, "IEND")) {
iend = true;
}
length = png_get_uint_32(chunk);
} else {
length = fIdatLength;
png_byte idat[] = {0, 0, 0, 0, 'I', 'D', 'A', 'T'};
png_save_uint_32(idat, length);
png_process_data(fPng_ptr, fInfo_ptr, idat, 8);
fDecodedIdat = true;
}
// Process the full chunk + CRC.
if (!process_data(fPng_ptr, fInfo_ptr, this->stream(), buffer, kBufferSize, length + 4)
|| iend) {
break;
}
}
}
static const SkColorType kXformSrcColorType = kRGBA_8888_SkColorType;
// Note: SkColorTable claims to store SkPMColors, which is not necessarily the case here.
bool SkPngCodec::createColorTable(const SkImageInfo& dstInfo, int* ctableCount) {
int numColors;
png_color* palette;
if (!png_get_PLTE(fPng_ptr, fInfo_ptr, &palette, &numColors)) {
return false;
}
// Contents depend on tableColorType and our choice of if/when to premultiply:
// { kPremul, kUnpremul, kOpaque } x { RGBA, BGRA }
SkPMColor colorTable[256];
SkColorType tableColorType = this->colorXform() ? kXformSrcColorType : dstInfo.colorType();
png_bytep alphas;
int numColorsWithAlpha = 0;
if (png_get_tRNS(fPng_ptr, fInfo_ptr, &alphas, &numColorsWithAlpha, nullptr)) {
// If we are performing a color xform, it will handle the premultiply. Otherwise,
// we'll do it here.
bool premultiply = !this->colorXform() && needs_premul(dstInfo, this->getEncodedInfo());
// 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 = choose_pack_color_proc(premultiply, tableColorType);
for (int i = 0; i < numColorsWithAlpha; i++) {
// We don't have a function in SkOpts that combines a set of alphas with a set
// of RGBs. We could write one, but it's hardly worth it, given that this
// is such a small fraction of the total decode time.
colorTable[i] = proc(alphas[i], palette->red, palette->green, palette->blue);
palette++;
}
}
if (numColorsWithAlpha < numColors) {
// The optimized code depends on a 3-byte png_color struct with the colors
// in RGB order. These checks make sure it is safe to use.
static_assert(3 == sizeof(png_color), "png_color struct has changed. Opts are broken.");
#ifdef SK_DEBUG
SkASSERT(&palette->red < &palette->green);
SkASSERT(&palette->green < &palette->blue);
#endif
if (is_rgba(tableColorType)) {
SkOpts::RGB_to_RGB1(colorTable + numColorsWithAlpha, palette,
numColors - numColorsWithAlpha);
} else {
SkOpts::RGB_to_BGR1(colorTable + numColorsWithAlpha, palette,
numColors - numColorsWithAlpha);
}
}
if (this->colorXform() &&
!apply_xform_on_decode(dstInfo.colorType(), this->getEncodedInfo().color())) {
const SkColorSpaceXform::ColorFormat dstFormat =
select_xform_format_ct(dstInfo.colorType());
const SkColorSpaceXform::ColorFormat srcFormat = select_xform_format(kXformSrcColorType);
const SkAlphaType xformAlphaType = select_xform_alpha(dstInfo.alphaType(),
this->getInfo().alphaType());
SkAssertResult(this->colorXform()->apply(dstFormat, colorTable, srcFormat, colorTable,
numColors, xformAlphaType));
}
// Pad the color table with the last color in the table (or black) in the case that
// invalid pixel indices exceed the number of colors in the table.
const int maxColors = 1 << fBitDepth;
if (numColors < maxColors) {
SkPMColor lastColor = numColors > 0 ? colorTable[numColors - 1] : SK_ColorBLACK;
sk_memset32(colorTable + numColors, lastColor, maxColors - numColors);
}
// Set the new color count.
if (ctableCount != nullptr) {
*ctableCount = maxColors;
}
fColorTable.reset(new SkColorTable(colorTable, maxColors));
return true;
}
///////////////////////////////////////////////////////////////////////////////
// Creation
///////////////////////////////////////////////////////////////////////////////
bool SkPngCodec::IsPng(const char* buf, size_t bytesRead) {
return !png_sig_cmp((png_bytep) buf, (png_size_t)0, bytesRead);
}
#if (PNG_LIBPNG_VER_MAJOR > 1) || (PNG_LIBPNG_VER_MAJOR == 1 && PNG_LIBPNG_VER_MINOR >= 6)
static float png_fixed_point_to_float(png_fixed_point x) {
// We multiply by the same factor that libpng used to convert
// fixed point -> double. Since we want floats, we choose to
// do the conversion ourselves rather than convert
// fixed point -> double -> float.
return ((float) x) * 0.00001f;
}
static float png_inverted_fixed_point_to_float(png_fixed_point x) {
// This is necessary because the gAMA chunk actually stores 1/gamma.
return 1.0f / png_fixed_point_to_float(x);
}
#endif // LIBPNG >= 1.6
// Returns a colorSpace object that represents any color space information in
// the encoded data. If the encoded data contains an invalid/unsupported color space,
// this will return NULL. If there is no color space information, it will guess sRGB
sk_sp<SkColorSpace> read_color_space(png_structp png_ptr, png_infop info_ptr,
SkColorSpace_Base::ICCTypeFlag iccType) {
#if (PNG_LIBPNG_VER_MAJOR > 1) || (PNG_LIBPNG_VER_MAJOR == 1 && PNG_LIBPNG_VER_MINOR >= 6)
// First check for an ICC profile
png_bytep profile;
png_uint_32 length;
// The below variables are unused, however, we need to pass them in anyway or
// png_get_iCCP() will return nothing.
// Could knowing the |name| of the profile ever be interesting? Maybe for debugging?
png_charp name;
// The |compression| is uninteresting since:
// (1) libpng has already decompressed the profile for us.
// (2) "deflate" is the only mode of decompression that libpng supports.
int compression;
if (PNG_INFO_iCCP == png_get_iCCP(png_ptr, info_ptr, &name, &compression, &profile,
&length)) {
return SkColorSpace_Base::MakeICC(profile, length, iccType);
}
// Second, check for sRGB.
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_sRGB)) {
// sRGB chunks also store a rendering intent: Absolute, Relative,
// Perceptual, and Saturation.
// FIXME (msarett): Extract this information from the sRGB chunk once
// we are able to handle this information in
// SkColorSpace.
return SkColorSpace::MakeSRGB();
}
// Next, check for chromaticities.
png_fixed_point chrm[8];
png_fixed_point gamma;
if (png_get_cHRM_fixed(png_ptr, info_ptr, &chrm[0], &chrm[1], &chrm[2], &chrm[3], &chrm[4],
&chrm[5], &chrm[6], &chrm[7]))
{
SkColorSpacePrimaries primaries;
primaries.fRX = png_fixed_point_to_float(chrm[2]);
primaries.fRY = png_fixed_point_to_float(chrm[3]);
primaries.fGX = png_fixed_point_to_float(chrm[4]);
primaries.fGY = png_fixed_point_to_float(chrm[5]);
primaries.fBX = png_fixed_point_to_float(chrm[6]);
primaries.fBY = png_fixed_point_to_float(chrm[7]);
primaries.fWX = png_fixed_point_to_float(chrm[0]);
primaries.fWY = png_fixed_point_to_float(chrm[1]);
SkMatrix44 toXYZD50(SkMatrix44::kUninitialized_Constructor);
if (!primaries.toXYZD50(&toXYZD50)) {
toXYZD50.set3x3RowMajorf(gSRGB_toXYZD50);
}
if (PNG_INFO_gAMA == png_get_gAMA_fixed(png_ptr, info_ptr, &gamma)) {
SkColorSpaceTransferFn fn;
fn.fA = 1.0f;
fn.fB = fn.fC = fn.fD = fn.fE = fn.fF = 0.0f;
fn.fG = png_inverted_fixed_point_to_float(gamma);
return SkColorSpace::MakeRGB(fn, toXYZD50);
}
// Default to sRGB gamma if the image has color space information,
// but does not specify gamma.
return SkColorSpace::MakeRGB(SkColorSpace::kSRGB_RenderTargetGamma, toXYZD50);
}
// Last, check for gamma.
if (PNG_INFO_gAMA == png_get_gAMA_fixed(png_ptr, info_ptr, &gamma)) {
SkColorSpaceTransferFn fn;
fn.fA = 1.0f;
fn.fB = fn.fC = fn.fD = fn.fE = fn.fF = 0.0f;
fn.fG = png_inverted_fixed_point_to_float(gamma);
// Since there is no cHRM, we will guess sRGB gamut.
SkMatrix44 toXYZD50(SkMatrix44::kUninitialized_Constructor);
toXYZD50.set3x3RowMajorf(gSRGB_toXYZD50);
return SkColorSpace::MakeRGB(fn, toXYZD50);
}
#endif // LIBPNG >= 1.6
// Report that there is no color space information in the PNG.
// Guess sRGB in this case.
return SkColorSpace::MakeSRGB();
}
void SkPngCodec::allocateStorage(const SkImageInfo& dstInfo) {
switch (fXformMode) {
case kSwizzleOnly_XformMode:
break;
case kColorOnly_XformMode:
// Intentional fall through. A swizzler hasn't been created yet, but one will
// be created later if we are sampling. We'll go ahead and allocate
// enough memory to swizzle if necessary.
case kSwizzleColor_XformMode: {
const int bitsPerPixel = this->getEncodedInfo().bitsPerPixel();
// If we have more than 8-bits (per component) of precision, we will keep that
// extra precision. Otherwise, we will swizzle to RGBA_8888 before transforming.
const size_t bytesPerPixel = (bitsPerPixel > 32) ? bitsPerPixel / 8 : 4;
const size_t colorXformBytes = dstInfo.width() * bytesPerPixel;
fStorage.reset(colorXformBytes);
fColorXformSrcRow = fStorage.get();
break;
}
}
}
static SkColorSpaceXform::ColorFormat png_select_xform_format(const SkEncodedInfo& info) {
// We use kRGB and kRGBA formats because color PNGs are always RGB or RGBA.
if (16 == info.bitsPerComponent()) {
if (SkEncodedInfo::kRGBA_Color == info.color()) {
return SkColorSpaceXform::kRGBA_U16_BE_ColorFormat;
} else if (SkEncodedInfo::kRGB_Color == info.color()) {
return SkColorSpaceXform::kRGB_U16_BE_ColorFormat;
}
}
return SkColorSpaceXform::kRGBA_8888_ColorFormat;
}
void SkPngCodec::applyXformRow(void* dst, const void* src) {
const SkColorSpaceXform::ColorFormat srcColorFormat =
png_select_xform_format(this->getEncodedInfo());
switch (fXformMode) {
case kSwizzleOnly_XformMode:
fSwizzler->swizzle(dst, (const uint8_t*) src);
break;
case kColorOnly_XformMode:
SkAssertResult(this->colorXform()->apply(fXformColorFormat, dst, srcColorFormat, src,
fXformWidth, fXformAlphaType));
break;
case kSwizzleColor_XformMode:
fSwizzler->swizzle(fColorXformSrcRow, (const uint8_t*) src);
SkAssertResult(this->colorXform()->apply(fXformColorFormat, dst, srcColorFormat,
fColorXformSrcRow, fXformWidth, fXformAlphaType));
break;
}
}
class SkPngNormalDecoder : public SkPngCodec {
public:
SkPngNormalDecoder(const SkEncodedInfo& info, const SkImageInfo& imageInfo, SkStream* stream,
SkPngChunkReader* reader, png_structp png_ptr, png_infop info_ptr, int bitDepth)
: INHERITED(info, imageInfo, stream, reader, png_ptr, info_ptr, bitDepth)
, fRowsWrittenToOutput(0)
, fDst(nullptr)
, fRowBytes(0)
, fFirstRow(0)
, fLastRow(0)
{}
static void AllRowsCallback(png_structp png_ptr, png_bytep row, png_uint_32 rowNum, int /*pass*/) {
GetDecoder(png_ptr)->allRowsCallback(row, rowNum);
}
static void RowCallback(png_structp png_ptr, png_bytep row, png_uint_32 rowNum, int /*pass*/) {
GetDecoder(png_ptr)->rowCallback(row, rowNum);
}
private:
int fRowsWrittenToOutput;
void* fDst;
size_t fRowBytes;
// Variables for partial decode
int fFirstRow; // FIXME: Move to baseclass?
int fLastRow;
int fRowsNeeded;
typedef SkPngCodec INHERITED;
static SkPngNormalDecoder* GetDecoder(png_structp png_ptr) {
return static_cast<SkPngNormalDecoder*>(png_get_progressive_ptr(png_ptr));
}
Result decodeAllRows(void* dst, size_t rowBytes, int* rowsDecoded) override {
const int height = this->getInfo().height();
png_set_progressive_read_fn(this->png_ptr(), this, nullptr, AllRowsCallback, nullptr);
fDst = dst;
fRowBytes = rowBytes;
fRowsWrittenToOutput = 0;
fFirstRow = 0;
fLastRow = height - 1;
this->processData();
if (fRowsWrittenToOutput == height) {
return SkCodec::kSuccess;
}
if (rowsDecoded) {
*rowsDecoded = fRowsWrittenToOutput;
}
return SkCodec::kIncompleteInput;
}
void allRowsCallback(png_bytep row, int rowNum) {
SkASSERT(rowNum == fRowsWrittenToOutput);
fRowsWrittenToOutput++;
this->applyXformRow(fDst, row);
fDst = SkTAddOffset<void>(fDst, fRowBytes);
}
void setRange(int firstRow, int lastRow, void* dst, size_t rowBytes) override {
png_set_progressive_read_fn(this->png_ptr(), this, nullptr, RowCallback, nullptr);
fFirstRow = firstRow;
fLastRow = lastRow;
fDst = dst;
fRowBytes = rowBytes;
fRowsWrittenToOutput = 0;
fRowsNeeded = fLastRow - fFirstRow + 1;
}
SkCodec::Result decode(int* rowsDecoded) override {
if (this->swizzler()) {
const int sampleY = this->swizzler()->sampleY();
fRowsNeeded = get_scaled_dimension(fLastRow - fFirstRow + 1, sampleY);
}
this->processData();
if (fRowsWrittenToOutput == fRowsNeeded) {
return SkCodec::kSuccess;
}
if (rowsDecoded) {
*rowsDecoded = fRowsWrittenToOutput;
}
return SkCodec::kIncompleteInput;
}
void rowCallback(png_bytep row, int rowNum) {
if (rowNum < fFirstRow) {
// Ignore this row.
return;
}
SkASSERT(rowNum <= fLastRow);
SkASSERT(fRowsWrittenToOutput < fRowsNeeded);
// If there is no swizzler, all rows are needed.
if (!this->swizzler() || this->swizzler()->rowNeeded(rowNum - fFirstRow)) {
this->applyXformRow(fDst, row);
fDst = SkTAddOffset<void>(fDst, fRowBytes);
fRowsWrittenToOutput++;
}
if (fRowsWrittenToOutput == fRowsNeeded) {
// Fake error to stop decoding scanlines.
longjmp(PNG_JMPBUF(this->png_ptr()), kStopDecoding);
}
}
};
class SkPngInterlacedDecoder : public SkPngCodec {
public:
SkPngInterlacedDecoder(const SkEncodedInfo& info, const SkImageInfo& imageInfo,
SkStream* stream, SkPngChunkReader* reader, png_structp png_ptr, png_infop info_ptr,
int bitDepth, int numberPasses)
: INHERITED(info, imageInfo, stream, reader, png_ptr, info_ptr, bitDepth)
, fNumberPasses(numberPasses)
, fFirstRow(0)
, fLastRow(0)
, fLinesDecoded(0)
, fInterlacedComplete(false)
, fPng_rowbytes(0)
{}
static void InterlacedRowCallback(png_structp png_ptr, png_bytep row, png_uint_32 rowNum, int pass) {
auto decoder = static_cast<SkPngInterlacedDecoder*>(png_get_progressive_ptr(png_ptr));
decoder->interlacedRowCallback(row, rowNum, pass);
}
private:
const int fNumberPasses;
int fFirstRow;
int fLastRow;
void* fDst;
size_t fRowBytes;
int fLinesDecoded;
bool fInterlacedComplete;
size_t fPng_rowbytes;
SkAutoTMalloc<png_byte> fInterlaceBuffer;
typedef SkPngCodec INHERITED;
// FIXME: Currently sharing interlaced callback for all rows and subset. It's not
// as expensive as the subset version of non-interlaced, but it still does extra
// work.
void interlacedRowCallback(png_bytep row, int rowNum, int pass) {
if (rowNum < fFirstRow || rowNum > fLastRow || fInterlacedComplete) {
// Ignore this row
return;
}
png_bytep oldRow = fInterlaceBuffer.get() + (rowNum - fFirstRow) * fPng_rowbytes;
png_progressive_combine_row(this->png_ptr(), oldRow, row);
if (0 == pass) {
// The first pass initializes all rows.
SkASSERT(row);
SkASSERT(fLinesDecoded == rowNum - fFirstRow);
fLinesDecoded++;
} else {
SkASSERT(fLinesDecoded == fLastRow - fFirstRow + 1);
if (fNumberPasses - 1 == pass && rowNum == fLastRow) {
// Last pass, and we have read all of the rows we care about.
fInterlacedComplete = true;
if (fLastRow != this->getInfo().height() - 1 ||
(this->swizzler() && this->swizzler()->sampleY() != 1)) {
// Fake error to stop decoding scanlines. Only stop if we're not decoding the
// whole image, in which case processing the rest of the image might be
// expensive. When decoding the whole image, read through the IEND chunk to
// preserve Android behavior of leaving the input stream in the right place.
longjmp(PNG_JMPBUF(this->png_ptr()), kStopDecoding);
}
}
}
}
SkCodec::Result decodeAllRows(void* dst, size_t rowBytes, int* rowsDecoded) override {
const int height = this->getInfo().height();
this->setUpInterlaceBuffer(height);
png_set_progressive_read_fn(this->png_ptr(), this, nullptr, InterlacedRowCallback,
nullptr);
fFirstRow = 0;
fLastRow = height - 1;
fLinesDecoded = 0;
this->processData();
png_bytep srcRow = fInterlaceBuffer.get();
// FIXME: When resuming, this may rewrite rows that did not change.
for (int rowNum = 0; rowNum < fLinesDecoded; rowNum++) {
this->applyXformRow(dst, srcRow);
dst = SkTAddOffset<void>(dst, rowBytes);
srcRow = SkTAddOffset<png_byte>(srcRow, fPng_rowbytes);
}
if (fInterlacedComplete) {
return SkCodec::kSuccess;
}
if (rowsDecoded) {
*rowsDecoded = fLinesDecoded;
}
return SkCodec::kIncompleteInput;
}
void setRange(int firstRow, int lastRow, void* dst, size_t rowBytes) override {
// FIXME: We could skip rows in the interlace buffer that we won't put in the output.
this->setUpInterlaceBuffer(lastRow - firstRow + 1);
png_set_progressive_read_fn(this->png_ptr(), this, nullptr, InterlacedRowCallback, nullptr);
fFirstRow = firstRow;
fLastRow = lastRow;
fDst = dst;
fRowBytes = rowBytes;
fLinesDecoded = 0;
}
SkCodec::Result decode(int* rowsDecoded) override {
this->processData();
// Now apply Xforms on all the rows that were decoded.
if (!fLinesDecoded) {
if (rowsDecoded) {
*rowsDecoded = 0;
}
return SkCodec::kIncompleteInput;
}
const int sampleY = this->swizzler() ? this->swizzler()->sampleY() : 1;
const int rowsNeeded = get_scaled_dimension(fLastRow - fFirstRow + 1, sampleY);
int rowsWrittenToOutput = 0;
// FIXME: For resuming interlace, we may swizzle a row that hasn't changed. But it
// may be too tricky/expensive to handle that correctly.
// Offset srcRow by get_start_coord rows. We do not need to account for fFirstRow,
// since the first row in fInterlaceBuffer corresponds to fFirstRow.
png_bytep srcRow = SkTAddOffset<png_byte>(fInterlaceBuffer.get(),
fPng_rowbytes * get_start_coord(sampleY));
void* dst = fDst;
for (; rowsWrittenToOutput < rowsNeeded; rowsWrittenToOutput++) {
this->applyXformRow(dst, srcRow);
dst = SkTAddOffset<void>(dst, fRowBytes);
srcRow = SkTAddOffset<png_byte>(srcRow, fPng_rowbytes * sampleY);
}
if (fInterlacedComplete) {
return SkCodec::kSuccess;
}
if (rowsDecoded) {
*rowsDecoded = rowsWrittenToOutput;
}
return SkCodec::kIncompleteInput;
}
void setUpInterlaceBuffer(int height) {
fPng_rowbytes = png_get_rowbytes(this->png_ptr(), this->info_ptr());
fInterlaceBuffer.reset(fPng_rowbytes * height);
fInterlacedComplete = false;
}
};
// 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 outCodec Optional output variable. If non-NULL, will be set to a new
// SkPngCodec on success.
// @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;
// @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, SkCodec** outCodec,
png_structp* png_ptrp, png_infop* info_ptrp) {
// 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, stream, chunkReader, outCodec);
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;
}
#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
const bool decodedBounds = autoClean.decodeBounds();
if (!decodedBounds) {
return false;
}
// On success, decodeBounds releases ownership of png_ptr and info_ptr.
if (png_ptrp) {
*png_ptrp = png_ptr;
}
if (info_ptrp) {
*info_ptrp = info_ptr;
}
// decodeBounds takes care of setting outCodec
if (outCodec) {
SkASSERT(*outCodec);
}
return true;
}
void AutoCleanPng::infoCallback(size_t idatLength) {
png_uint_32 origWidth, origHeight;
int bitDepth, encodedColorType;
png_get_IHDR(fPng_ptr, fInfo_ptr, &origWidth, &origHeight, &bitDepth,
&encodedColorType, nullptr, nullptr, nullptr);
// TODO: Should we support 16-bits of precision for gray images?
if (bitDepth == 16 && (PNG_COLOR_TYPE_GRAY == encodedColorType ||
PNG_COLOR_TYPE_GRAY_ALPHA == encodedColorType)) {
bitDepth = 8;
png_set_strip_16(fPng_ptr);
}
// Now determine the default colorType and alphaType and set the required transforms.
// Often, we depend on SkSwizzler to perform any transforms that we need. However, we
// still depend on libpng for many of the rare and PNG-specific cases.
SkEncodedInfo::Color color;
SkEncodedInfo::Alpha alpha;
switch (encodedColorType) {
case PNG_COLOR_TYPE_PALETTE:
// 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) {
// TODO: Should we use SkSwizzler here?
bitDepth = 8;
png_set_packing(fPng_ptr);
}
color = SkEncodedInfo::kPalette_Color;
// Set the alpha depending on if a transparency chunk exists.
alpha = png_get_valid(fPng_ptr, fInfo_ptr, PNG_INFO_tRNS) ?
SkEncodedInfo::kUnpremul_Alpha : SkEncodedInfo::kOpaque_Alpha;
break;
case PNG_COLOR_TYPE_RGB:
if (png_get_valid(fPng_ptr, fInfo_ptr, PNG_INFO_tRNS)) {
// Convert to RGBA if transparency chunk exists.
png_set_tRNS_to_alpha(fPng_ptr);
color = SkEncodedInfo::kRGBA_Color;
alpha = SkEncodedInfo::kBinary_Alpha;
} else {
color = SkEncodedInfo::kRGB_Color;
alpha = SkEncodedInfo::kOpaque_Alpha;
}
break;
case PNG_COLOR_TYPE_GRAY:
// Expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel.
if (bitDepth < 8) {
// TODO: Should we use SkSwizzler here?
bitDepth = 8;
png_set_expand_gray_1_2_4_to_8(fPng_ptr);
}
if (png_get_valid(fPng_ptr, fInfo_ptr, PNG_INFO_tRNS)) {
png_set_tRNS_to_alpha(fPng_ptr);
color = SkEncodedInfo::kGrayAlpha_Color;
alpha = SkEncodedInfo::kBinary_Alpha;
} else {
color = SkEncodedInfo::kGray_Color;
alpha = SkEncodedInfo::kOpaque_Alpha;
}
break;
case PNG_COLOR_TYPE_GRAY_ALPHA:
color = SkEncodedInfo::kGrayAlpha_Color;
alpha = SkEncodedInfo::kUnpremul_Alpha;
break;
case PNG_COLOR_TYPE_RGBA:
color = SkEncodedInfo::kRGBA_Color;
alpha = SkEncodedInfo::kUnpremul_Alpha;
break;
default:
// All the color types have been covered above.
SkASSERT(false);
color = SkEncodedInfo::kRGBA_Color;
alpha = SkEncodedInfo::kUnpremul_Alpha;
}
const int numberPasses = png_set_interlace_handling(fPng_ptr);
if (fOutCodec) {
SkASSERT(nullptr == *fOutCodec);
SkColorSpace_Base::ICCTypeFlag iccType = SkColorSpace_Base::kRGB_ICCTypeFlag;
if (SkEncodedInfo::kGray_Color == color || SkEncodedInfo::kGrayAlpha_Color == color) {
iccType |= SkColorSpace_Base::kGray_ICCTypeFlag;
}
sk_sp<SkColorSpace> colorSpace = read_color_space(fPng_ptr, fInfo_ptr, iccType);
const bool unsupportedICC = !colorSpace;
if (!colorSpace) {
// Treat unsupported/invalid color spaces as sRGB.
colorSpace = SkColorSpace::MakeSRGB();
}
SkEncodedInfo encodedInfo = SkEncodedInfo::Make(color, alpha, bitDepth);
SkImageInfo imageInfo = encodedInfo.makeImageInfo(origWidth, origHeight, colorSpace);
if (SkEncodedInfo::kOpaque_Alpha == alpha) {
png_color_8p sigBits;
if (png_get_sBIT(fPng_ptr, fInfo_ptr, &sigBits)) {
if (5 == sigBits->red && 6 == sigBits->green && 5 == sigBits->blue) {
// Recommend a decode to 565 if the sBIT indicates 565.
imageInfo = imageInfo.makeColorType(kRGB_565_SkColorType);
}
}
}
if (1 == numberPasses) {
*fOutCodec = new SkPngNormalDecoder(encodedInfo, imageInfo, fStream,
fChunkReader, fPng_ptr, fInfo_ptr, bitDepth);
} else {
*fOutCodec = new SkPngInterlacedDecoder(encodedInfo, imageInfo, fStream,
fChunkReader, fPng_ptr, fInfo_ptr, bitDepth, numberPasses);
}
(*fOutCodec)->setUnsupportedICC(unsupportedICC);
static_cast<SkPngCodec*>(*fOutCodec)->setIdatLength(idatLength);
}
// Release the pointers, which are now owned by the codec or the caller is expected to
// take ownership.
this->releasePngPtrs();
}
SkPngCodec::SkPngCodec(const SkEncodedInfo& encodedInfo, const SkImageInfo& imageInfo,
SkStream* stream, SkPngChunkReader* chunkReader, void* png_ptr,
void* info_ptr, int bitDepth)
: INHERITED(encodedInfo, imageInfo, stream)
, fPngChunkReader(SkSafeRef(chunkReader))
, fPng_ptr(png_ptr)
, fInfo_ptr(info_ptr)
, fColorXformSrcRow(nullptr)
, fBitDepth(bitDepth)
, fIdatLength(0)
, fDecodedIdat(false)
{}
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((png_struct**)&fPng_ptr, (png_info**)&fInfo_ptr, nullptr);
fPng_ptr = nullptr;
fInfo_ptr = nullptr;
}
}
///////////////////////////////////////////////////////////////////////////////
// Getting the pixels
///////////////////////////////////////////////////////////////////////////////
bool SkPngCodec::initializeXforms(const SkImageInfo& dstInfo, const Options& options,
SkPMColor ctable[], int* ctableCount) {
if (setjmp(PNG_JMPBUF((png_struct*)fPng_ptr))) {
SkCodecPrintf("Failed on png_read_update_info.\n");
return false;
}
png_read_update_info(fPng_ptr, fInfo_ptr);
// Reset fSwizzler and this->colorXform(). We can't do this in onRewind() because the
// interlaced scanline decoder may need to rewind.
fSwizzler.reset(nullptr);
if (!this->initializeColorXform(dstInfo, options.fPremulBehavior)) {
return false;
}
// If SkColorSpaceXform directly supports the encoded PNG format, we should skip format
// conversion in the swizzler (or skip swizzling altogether).
bool skipFormatConversion = false;
switch (this->getEncodedInfo().color()) {
case SkEncodedInfo::kRGB_Color:
if (this->getEncodedInfo().bitsPerComponent() != 16) {
break;
}
// Fall through
case SkEncodedInfo::kRGBA_Color:
skipFormatConversion = this->colorXform();
break;
default:
break;
}
if (skipFormatConversion && !options.fSubset) {
fXformMode = kColorOnly_XformMode;
return true;
}
if (SkEncodedInfo::kPalette_Color == this->getEncodedInfo().color()) {
if (!this->createColorTable(dstInfo, ctableCount)) {
return false;
}
}
// Copy the color table to the client if they request kIndex8 mode.
copy_color_table(dstInfo, fColorTable.get(), ctable, ctableCount);
this->initializeSwizzler(dstInfo, options, skipFormatConversion);
return true;
}
void SkPngCodec::initializeXformParams() {
switch (fXformMode) {
case kColorOnly_XformMode:
fXformColorFormat = select_xform_format(this->dstInfo().colorType());
fXformAlphaType = select_xform_alpha(this->dstInfo().alphaType(),
this->getInfo().alphaType());
fXformWidth = this->dstInfo().width();
break;
case kSwizzleColor_XformMode:
fXformColorFormat = select_xform_format(this->dstInfo().colorType());
fXformAlphaType = select_xform_alpha(this->dstInfo().alphaType(),
this->getInfo().alphaType());
fXformWidth = this->swizzler()->swizzleWidth();
break;
default:
break;
}
}
void SkPngCodec::initializeSwizzler(const SkImageInfo& dstInfo, const Options& options,
bool skipFormatConversion) {
SkImageInfo swizzlerInfo = dstInfo;
Options swizzlerOptions = options;
fXformMode = kSwizzleOnly_XformMode;
if (this->colorXform() &&
apply_xform_on_decode(dstInfo.colorType(), this->getEncodedInfo().color()))
{
swizzlerInfo = swizzlerInfo.makeColorType(kXformSrcColorType);
if (kPremul_SkAlphaType == dstInfo.alphaType()) {
swizzlerInfo = swizzlerInfo.makeAlphaType(kUnpremul_SkAlphaType);
}
fXformMode = kSwizzleColor_XformMode;
// Here, we swizzle into temporary memory, which is not zero initialized.
// FIXME (msarett):
// Is this a problem?
swizzlerOptions.fZeroInitialized = kNo_ZeroInitialized;
}
const SkPMColor* colors = get_color_ptr(fColorTable.get());
fSwizzler.reset(SkSwizzler::CreateSwizzler(this->getEncodedInfo(), colors, swizzlerInfo,
swizzlerOptions, nullptr, skipFormatConversion));
SkASSERT(fSwizzler);
}
SkSampler* SkPngCodec::getSampler(bool createIfNecessary) {
if (fSwizzler || !createIfNecessary) {
return fSwizzler.get();
}
this->initializeSwizzler(this->dstInfo(), this->options(), true);
return fSwizzler.get();
}
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(), nullptr, &png_ptr, &info_ptr)) {
return false;
}
fPng_ptr = png_ptr;
fInfo_ptr = info_ptr;
fDecodedIdat = false;
return true;
}
SkCodec::Result SkPngCodec::onGetPixels(const SkImageInfo& dstInfo, void* dst,
size_t rowBytes, const Options& options,
SkPMColor ctable[], int* ctableCount,
int* rowsDecoded) {
if (!conversion_possible(dstInfo, this->getInfo()) ||
!this->initializeXforms(dstInfo, options, ctable, ctableCount))
{
return kInvalidConversion;
}
if (options.fSubset) {
return kUnimplemented;
}
this->allocateStorage(dstInfo);
this->initializeXformParams();
return this->decodeAllRows(dst, rowBytes, rowsDecoded);
}
SkCodec::Result SkPngCodec::onStartIncrementalDecode(const SkImageInfo& dstInfo,
void* dst, size_t rowBytes, const SkCodec::Options& options,
SkPMColor* ctable, int* ctableCount) {
if (!conversion_possible(dstInfo, this->getInfo()) ||
!this->initializeXforms(dstInfo, options, ctable, ctableCount))
{
return kInvalidConversion;
}
this->allocateStorage(dstInfo);
int firstRow, lastRow;
if (options.fSubset) {
firstRow = options.fSubset->top();
lastRow = options.fSubset->bottom() - 1;
} else {
firstRow = 0;
lastRow = dstInfo.height() - 1;
}
this->setRange(firstRow, lastRow, dst, rowBytes);
return kSuccess;
}
SkCodec::Result SkPngCodec::onIncrementalDecode(int* rowsDecoded) {
// FIXME: Only necessary on the first call.
this->initializeXformParams();
return this->decode(rowsDecoded);
}
uint64_t SkPngCodec::onGetFillValue(const SkImageInfo& dstInfo) const {
const SkPMColor* colorPtr = get_color_ptr(fColorTable.get());
if (colorPtr) {
SkAlphaType alphaType = select_xform_alpha(dstInfo.alphaType(),
this->getInfo().alphaType());
return get_color_table_fill_value(dstInfo.colorType(), alphaType, colorPtr, 0,
this->colorXform(), true);
}
return INHERITED::onGetFillValue(dstInfo);
}
SkCodec* SkPngCodec::NewFromStream(SkStream* stream, SkPngChunkReader* chunkReader) {
std::unique_ptr<SkStream> streamDeleter(stream);
SkCodec* outCodec = nullptr;
if (read_header(streamDeleter.get(), chunkReader, &outCodec, nullptr, nullptr)) {
// Codec has taken ownership of the stream.
SkASSERT(outCodec);
streamDeleter.release();
return outCodec;
}
return nullptr;
}