/* * 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(); // ICOs contain an alpha mask after the image which means we cannot // guarantee that an image is opaque, even if the sub-codec thinks it // is. // FIXME (msarett): The BMP decoder depends on the alpha type in order // to decode correctly, otherwise it could report kUnpremul and we would // not have to correct it here. Is there a better way? // FIXME (msarett): This is only true for BMP in ICO - could a PNG in ICO // be opaque? Is it okay that we missed out on the opportunity to mark // such an image as opaque? info = info.makeAlphaType(kUnpremul_SkAlphaType); // 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()); }
/* * 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( SkNEW_ARRAY(uint8_t, kIcoDirectoryBytes)); if (inputStream.get()->read(dirBuffer.get(), kIcoDirectoryBytes) != kIcoDirectoryBytes) { SkCodecPrintf("Error: unable to read ico directory header.\n"); return NULL; } // 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 NULL; } // Ensure that we can read all of indicated directory entries SkAutoTDeleteArray<uint8_t> entryBuffer( SkNEW_ARRAY(uint8_t, numImages*kIcoDirEntryBytes)); if (inputStream.get()->read(entryBuffer.get(), numImages*kIcoDirEntryBytes) != numImages*kIcoDirEntryBytes) { SkCodecPrintf("Error: unable to read ico directory entries.\n"); return NULL; } // 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(SkNEW_ARRAY(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( SkNEW_ARGS((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 (NULL == data.get()) { SkCodecPrintf("Warning: could not create embedded stream.\n"); break; } SkAutoTDelete<SkMemoryStream> embeddedStream(SkNEW_ARGS(SkMemoryStream, (data.get()))); bytesRead += size; // Check if the embedded codec is bmp or png and create the codec const bool isPng = SkPngCodec::IsPng(embeddedStream); SkAssertResult(embeddedStream->rewind()); SkCodec* codec = NULL; if (isPng) { codec = SkPngCodec::NewFromStream(embeddedStream.detach()); } else { codec = SkBmpCodec::NewFromIco(embeddedStream.detach()); } // Save a valid codec if (NULL != 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 NULL; } // 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 SkNEW_ARGS(SkIcoCodec, (info, codecs.detach())); }