/*
* 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 "SkColorPriv.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)));
}
/*
* Assumes IsIco was called and returned true
* Creates an Ico decoder
* Reads enough of the stream to determine the image format
*/
SkCodec* SkIcoCodec::NewFromStream(SkStream* stream) {
// Ensure that we do not leak the input stream
SkAutoTDelete<SkStream> inputStream(stream);
// Header size constants
static const uint32_t kIcoDirectoryBytes = 6;
static const uint32_t kIcoDirEntryBytes = 16;
// Read the directory header
SkAutoTDeleteArray<uint8_t> dirBuffer(new uint8_t[kIcoDirectoryBytes]);
if (inputStream.get()->read(dirBuffer.get(), kIcoDirectoryBytes) !=
kIcoDirectoryBytes) {
SkCodecPrintf("Error: unable to read ico directory header.\n");
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");
return nullptr;
}
// Ensure that we can read all of indicated directory entries
SkAutoTDeleteArray<uint8_t> entryBuffer(new uint8_t[numImages * kIcoDirEntryBytes]);
if (inputStream.get()->read(entryBuffer.get(), numImages*kIcoDirEntryBytes) !=
numImages*kIcoDirEntryBytes) {
SkCodecPrintf("Error: unable to read ico directory entries.\n");
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;
};
SkAutoTDeleteArray<Entry> directoryEntries(new Entry[numImages]);
// Iterate over directory entries
for (uint32_t i = 0; i < numImages; i++) {
// 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.get(), 8 + i*kIcoDirEntryBytes);
// 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.get(), 12 + i*kIcoDirEntryBytes);
// Save the vital fields
directoryEntries.get()[i].offset = offset;
directoryEntries.get()[i].size = size;
}
// 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.get(), directoryEntries.get() + numImages - 1,
lessThan);
// Now will construct a candidate codec for each of the embedded images
uint32_t bytesRead = kIcoDirectoryBytes + numImages * kIcoDirEntryBytes;
SkAutoTDelete<SkTArray<SkAutoTDelete<SkCodec>, true>> codecs(
new (SkTArray<SkAutoTDelete<SkCodec>, true>)(numImages));
for (uint32_t i = 0; i < numImages; i++) {
uint32_t offset = directoryEntries.get()[i].offset;
uint32_t size = directoryEntries.get()[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 (inputStream.get()->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
SkAutoTUnref<SkData> data(
SkData::NewFromStream(inputStream.get(), size));
if (nullptr == data.get()) {
SkCodecPrintf("Warning: could not create embedded stream.\n");
break;
}
SkAutoTDelete<SkMemoryStream> embeddedStream(new SkMemoryStream(data.get()));
bytesRead += size;
// Check if the embedded codec is bmp or png and create the codec
SkCodec* codec = nullptr;
if (SkPngCodec::IsPng((const char*) data->bytes(), data->size())) {
codec = SkPngCodec::NewFromStream(embeddedStream.detach());
} else {
codec = SkBmpCodec::NewFromIco(embeddedStream.detach());
}
// Save a valid codec
if (nullptr != codec) {
codecs->push_back().reset(codec);
}
}
// 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
uint32_t maxSize = 0;
uint32_t maxIndex = 0;
for (int32_t i = 0; i < codecs->count(); i++) {
SkImageInfo info = codecs->operator[](i)->getInfo();
uint32_t size = info.width() * info.height();
if (size > maxSize) {
maxSize = size;
maxIndex = i;
}
}
SkImageInfo info = codecs->operator[](maxIndex)->getInfo();
// Note that stream is owned by the embedded codec, the ico does not need
// direct access to the stream.
return new SkIcoCodec(info, codecs.detach());
}
/*
* Creates an instance of the decoder
* Called only by NewFromStream
*/
SkIcoCodec::SkIcoCodec(const SkImageInfo& info,
SkTArray<SkAutoTDelete<SkCodec>, true>* codecs)
: INHERITED(info, nullptr)
, fEmbeddedCodecs(codecs)
, fCurrScanlineCodec(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->getInfo().width();
int origHeight = this->getInfo().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++) {
int width = fEmbeddedCodecs->operator[](i)->getInfo().width();
int height = fEmbeddedCodecs->operator[](i)->getInfo().height();
float error = SkTAbs(((float) (width * height)) - desiredSize);
if (error < minError) {
minError = error;
minIndex = i;
}
}
SkASSERT(minIndex >= 0);
return fEmbeddedCodecs->operator[](minIndex)->getInfo().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)->getInfo().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, SkPMColor* colorTable,
int* colorCount, 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);
result = embeddedCodec->getPixels(dstInfo, dst, dstRowBytes, &opts, colorTable,
colorCount);
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, SkPMColor colorTable[], int* colorCount) {
int index = 0;
SkCodec::Result result = kInvalidScale;
while (true) {
index = this->chooseCodec(dstInfo.dimensions(), index);
if (index < 0) {
break;
}
SkCodec* embeddedCodec = fEmbeddedCodecs->operator[](index);
result = embeddedCodec->startScanlineDecode(dstInfo, &options, colorTable, colorCount);
if (kSuccess == result) {
fCurrScanlineCodec = 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(fCurrScanlineCodec);
return fCurrScanlineCodec->getScanlines(dst, count, rowBytes);
}
bool SkIcoCodec::onSkipScanlines(int count) {
SkASSERT(fCurrScanlineCodec);
return fCurrScanlineCodec->skipScanlines(count);
}
SkCodec::SkScanlineOrder SkIcoCodec::onGetScanlineOrder() const {
// FIXME: This function will possibly return the wrong value if it is called
// before startScanlineDecode().
return fCurrScanlineCodec ? fCurrScanlineCodec->getScanlineOrder() :
INHERITED::onGetScanlineOrder();
}
SkSampler* SkIcoCodec::getSampler(bool createIfNecessary) {
return fCurrScanlineCodec ? fCurrScanlineCodec->getSampler(createIfNecessary) : nullptr;
}