/*
* 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 "SkBmpCodec.h"
#include "SkCodecPriv.h"
#include "SkColorData.h"
#include "SkData.h"
#include "SkIcoCodec.h"
#include "SkPngCodec.h"
#include "SkStream.h"
#include "SkTDArray.h"
#include "SkTSort.h"
/*
* Checks the start of the stream to see if the image is an Ico or Cur
*/
bool SkIcoCodec::IsIco(const void* buffer, size_t bytesRead) {
const char icoSig[] = { '\x00', '\x00', '\x01', '\x00' };
const char curSig[] = { '\x00', '\x00', '\x02', '\x00' };
return bytesRead >= sizeof(icoSig) &&
(!memcmp(buffer, icoSig, sizeof(icoSig)) ||
!memcmp(buffer, curSig, sizeof(curSig)));
}
std::unique_ptr<SkCodec> SkIcoCodec::MakeFromStream(std::unique_ptr<SkStream> stream,
Result* result) {
// Header size constants
constexpr uint32_t kIcoDirectoryBytes = 6;
constexpr uint32_t kIcoDirEntryBytes = 16;
// Read the directory header
std::unique_ptr<uint8_t[]> dirBuffer(new uint8_t[kIcoDirectoryBytes]);
if (stream->read(dirBuffer.get(), kIcoDirectoryBytes) != kIcoDirectoryBytes) {
SkCodecPrintf("Error: unable to read ico directory header.\n");
*result = kIncompleteInput;
return nullptr;
}
// Process the directory header
const uint16_t numImages = get_short(dirBuffer.get(), 4);
if (0 == numImages) {
SkCodecPrintf("Error: No images embedded in ico.\n");
*result = kInvalidInput;
return nullptr;
}
// This structure is used to represent the vital information about entries
// in the directory header. We will obtain this information for each
// directory entry.
struct Entry {
uint32_t offset;
uint32_t size;
};
SkAutoFree dirEntryBuffer(sk_malloc_canfail(sizeof(Entry) * numImages));
if (!dirEntryBuffer) {
SkCodecPrintf("Error: OOM allocating ICO directory for %i images.\n",
numImages);
*result = kInternalError;
return nullptr;
}
auto* directoryEntries = reinterpret_cast<Entry*>(dirEntryBuffer.get());
// Iterate over directory entries
for (uint32_t i = 0; i < numImages; i++) {
uint8_t entryBuffer[kIcoDirEntryBytes];
if (stream->read(entryBuffer, kIcoDirEntryBytes) != kIcoDirEntryBytes) {
SkCodecPrintf("Error: Dir entries truncated in ico.\n");
*result = kIncompleteInput;
return nullptr;
}
// The directory entry contains information such as width, height,
// bits per pixel, and number of colors in the color palette. We will
// ignore these fields since they are repeated in the header of the
// embedded image. In the event of an inconsistency, we would always
// defer to the value in the embedded header anyway.
// Specifies the size of the embedded image, including the header
uint32_t size = get_int(entryBuffer, 8);
// Specifies the offset of the embedded image from the start of file.
// It does not indicate the start of the pixel data, but rather the
// start of the embedded image header.
uint32_t offset = get_int(entryBuffer, 12);
// Save the vital fields
directoryEntries[i].offset = offset;
directoryEntries[i].size = size;
}
// Default Result, if no valid embedded codecs are found.
*result = kInvalidInput;
// It is "customary" that the embedded images will be stored in order of
// increasing offset. However, the specification does not indicate that
// they must be stored in this order, so we will not trust that this is the
// case. Here we sort the embedded images by increasing offset.
struct EntryLessThan {
bool operator() (Entry a, Entry b) const {
return a.offset < b.offset;
}
};
EntryLessThan lessThan;
SkTQSort(directoryEntries, &directoryEntries[numImages - 1], lessThan);
// Now will construct a candidate codec for each of the embedded images
uint32_t bytesRead = kIcoDirectoryBytes + numImages * kIcoDirEntryBytes;
std::unique_ptr<SkTArray<std::unique_ptr<SkCodec>, true>> codecs(
new SkTArray<std::unique_ptr<SkCodec>, true>(numImages));
for (uint32_t i = 0; i < numImages; i++) {
uint32_t offset = directoryEntries[i].offset;
uint32_t size = directoryEntries[i].size;
// Ensure that the offset is valid
if (offset < bytesRead) {
SkCodecPrintf("Warning: invalid ico offset.\n");
continue;
}
// If we cannot skip, assume we have reached the end of the stream and
// stop trying to make codecs
if (stream->skip(offset - bytesRead) != offset - bytesRead) {
SkCodecPrintf("Warning: could not skip to ico offset.\n");
break;
}
bytesRead = offset;
// Create a new stream for the embedded codec
SkAutoFree buffer(sk_malloc_canfail(size));
if (!buffer) {
SkCodecPrintf("Warning: OOM trying to create embedded stream.\n");
break;
}
if (stream->read(buffer.get(), size) != size) {
SkCodecPrintf("Warning: could not create embedded stream.\n");
*result = kIncompleteInput;
break;
}
sk_sp<SkData> data(SkData::MakeFromMalloc(buffer.release(), size));
auto embeddedStream = SkMemoryStream::Make(data);
bytesRead += size;
// Check if the embedded codec is bmp or png and create the codec
std::unique_ptr<SkCodec> codec;
Result dummyResult;
if (SkPngCodec::IsPng((const char*) data->bytes(), data->size())) {
codec = SkPngCodec::MakeFromStream(std::move(embeddedStream), &dummyResult);
} else {
codec = SkBmpCodec::MakeFromIco(std::move(embeddedStream), &dummyResult);
}
// Save a valid codec
if (nullptr != codec) {
codecs->push_back().reset(codec.release());
}
}
// Recognize if there are no valid codecs
if (0 == codecs->count()) {
SkCodecPrintf("Error: could not find any valid embedded ico codecs.\n");
return nullptr;
}
// Use the largest codec as a "suggestion" for image info
size_t maxSize = 0;
int maxIndex = 0;
for (int i = 0; i < codecs->count(); i++) {
SkImageInfo info = codecs->operator[](i)->getInfo();
size_t size = info.computeMinByteSize();
if (size > maxSize) {
maxSize = size;
maxIndex = i;
}
}
auto maxInfo = codecs->operator[](maxIndex)->getEncodedInfo().copy();
*result = kSuccess;
// The original stream is no longer needed, because the embedded codecs own their
// own streams.
return std::unique_ptr<SkCodec>(new SkIcoCodec(std::move(maxInfo), codecs.release()));
}
SkIcoCodec::SkIcoCodec(SkEncodedInfo&& info, SkTArray<std::unique_ptr<SkCodec>, true>* codecs)
// The source skcms_PixelFormat will not be used. The embedded
// codec's will be used instead.
: INHERITED(std::move(info), skcms_PixelFormat(), nullptr)
, fEmbeddedCodecs(codecs)
, fCurrCodec(nullptr)
{}
/*
* Chooses the best dimensions given the desired scale
*/
SkISize SkIcoCodec::onGetScaledDimensions(float desiredScale) const {
// We set the dimensions to the largest candidate image by default.
// Regardless of the scale request, this is the largest image that we
// will decode.
int origWidth = this->dimensions().width();
int origHeight = this->dimensions().height();
float desiredSize = desiredScale * origWidth * origHeight;
// At least one image will have smaller error than this initial value
float minError = ((float) (origWidth * origHeight)) - desiredSize + 1.0f;
int32_t minIndex = -1;
for (int32_t i = 0; i < fEmbeddedCodecs->count(); i++) {
auto dimensions = fEmbeddedCodecs->operator[](i)->dimensions();
int width = dimensions.width();
int height = dimensions.height();
float error = SkTAbs(((float) (width * height)) - desiredSize);
if (error < minError) {
minError = error;
minIndex = i;
}
}
SkASSERT(minIndex >= 0);
return fEmbeddedCodecs->operator[](minIndex)->dimensions();
}
int SkIcoCodec::chooseCodec(const SkISize& requestedSize, int startIndex) {
SkASSERT(startIndex >= 0);
// FIXME: Cache the index from onGetScaledDimensions?
for (int i = startIndex; i < fEmbeddedCodecs->count(); i++) {
if (fEmbeddedCodecs->operator[](i)->dimensions() == requestedSize) {
return i;
}
}
return -1;
}
bool SkIcoCodec::onDimensionsSupported(const SkISize& dim) {
return this->chooseCodec(dim, 0) >= 0;
}
/*
* Initiates the Ico decode
*/
SkCodec::Result SkIcoCodec::onGetPixels(const SkImageInfo& dstInfo,
void* dst, size_t dstRowBytes,
const Options& opts,
int* rowsDecoded) {
if (opts.fSubset) {
// Subsets are not supported.
return kUnimplemented;
}
int index = 0;
SkCodec::Result result = kInvalidScale;
while (true) {
index = this->chooseCodec(dstInfo.dimensions(), index);
if (index < 0) {
break;
}
SkCodec* embeddedCodec = fEmbeddedCodecs->operator[](index).get();
result = embeddedCodec->getPixels(dstInfo, dst, dstRowBytes, &opts);
switch (result) {
case kSuccess:
case kIncompleteInput:
// The embedded codec will handle filling incomplete images, so we will indicate
// that all of the rows are initialized.
*rowsDecoded = dstInfo.height();
return result;
default:
// Continue trying to find a valid embedded codec on a failed decode.
break;
}
index++;
}
SkCodecPrintf("Error: No matching candidate image in ico.\n");
return result;
}
SkCodec::Result SkIcoCodec::onStartScanlineDecode(const SkImageInfo& dstInfo,
const SkCodec::Options& options) {
int index = 0;
SkCodec::Result result = kInvalidScale;
while (true) {
index = this->chooseCodec(dstInfo.dimensions(), index);
if (index < 0) {
break;
}
SkCodec* embeddedCodec = fEmbeddedCodecs->operator[](index).get();
result = embeddedCodec->startScanlineDecode(dstInfo, &options);
if (kSuccess == result) {
fCurrCodec = embeddedCodec;
return result;
}
index++;
}
SkCodecPrintf("Error: No matching candidate image in ico.\n");
return result;
}
int SkIcoCodec::onGetScanlines(void* dst, int count, size_t rowBytes) {
SkASSERT(fCurrCodec);
return fCurrCodec->getScanlines(dst, count, rowBytes);
}
bool SkIcoCodec::onSkipScanlines(int count) {
SkASSERT(fCurrCodec);
return fCurrCodec->skipScanlines(count);
}
SkCodec::Result SkIcoCodec::onStartIncrementalDecode(const SkImageInfo& dstInfo,
void* pixels, size_t rowBytes, const SkCodec::Options& options) {
int index = 0;
while (true) {
index = this->chooseCodec(dstInfo.dimensions(), index);
if (index < 0) {
break;
}
SkCodec* embeddedCodec = fEmbeddedCodecs->operator[](index).get();
switch (embeddedCodec->startIncrementalDecode(dstInfo,
pixels, rowBytes, &options)) {
case kSuccess:
fCurrCodec = embeddedCodec;
return kSuccess;
case kUnimplemented:
// FIXME: embeddedCodec is a BMP. If scanline decoding would work,
// return kUnimplemented so that SkSampledCodec will fall through
// to use the scanline decoder.
// Note that calling startScanlineDecode will require an extra
// rewind. The embedded codec has an SkMemoryStream, which is
// cheap to rewind, though it will do extra work re-reading the
// header.
// Also note that we pass nullptr for Options. This is because
// Options that are valid for incremental decoding may not be
// valid for scanline decoding.
// Once BMP supports incremental decoding this workaround can go
// away.
if (embeddedCodec->startScanlineDecode(dstInfo) == kSuccess) {
return kUnimplemented;
}
// Move on to the next embedded codec.
break;
default:
break;
}
index++;
}
SkCodecPrintf("Error: No matching candidate image in ico.\n");
return kInvalidScale;
}
SkCodec::Result SkIcoCodec::onIncrementalDecode(int* rowsDecoded) {
SkASSERT(fCurrCodec);
return fCurrCodec->incrementalDecode(rowsDecoded);
}
SkCodec::SkScanlineOrder SkIcoCodec::onGetScanlineOrder() const {
// FIXME: This function will possibly return the wrong value if it is called
// before startScanlineDecode()/startIncrementalDecode().
if (fCurrCodec) {
return fCurrCodec->getScanlineOrder();
}
return INHERITED::onGetScanlineOrder();
}
SkSampler* SkIcoCodec::getSampler(bool createIfNecessary) {
if (fCurrCodec) {
return fCurrCodec->getSampler(createIfNecessary);
}
return nullptr;
}