/// <exception cref="Com.Drew.Imaging.Png.PngProcessingException"/>
/// <exception cref="System.IO.IOException"/>
public virtual Iterable <PngChunk> Extract([NotNull] SequentialReader reader, [CanBeNull] ICollection <PngChunkType> desiredChunkTypes)
{
//
// PNG DATA STREAM
//
// Starts with a PNG SIGNATURE, followed by a sequence of CHUNKS.
//
// PNG SIGNATURE
//
// Always composed of these bytes: 89 50 4E 47 0D 0A 1A 0A
//
// CHUNK
//
// 4 - length of the data field (unsigned, but always within 31 bytes), may be zero
// 4 - chunk type, restricted to [65,90] and [97,122] (A-Za-z)
// * - data field
// 4 - CRC calculated from chunk type and chunk data, but not length
//
// CHUNK TYPES
//
// Critical Chunk Types:
//
// IHDR - image header, always the first chunk in the data stream
// PLTE - palette table, associated with indexed PNG images
// IDAT - image data chunk, of which there may be many
// IEND - image trailer, always the last chunk in the data stream
//
// Ancillary Chunk Types:
//
// Transparency information: tRNS
// Colour space information: cHRM, gAMA, iCCP, sBIT, sRGB
// Textual information: iTXt, tEXt, zTXt
// Miscellaneous information: bKGD, hIST, pHYs, sPLT
// Time information: tIME
//
reader.SetMotorolaByteOrder(true);
// network byte order
if (!Arrays.Equals(PngSignatureBytes, reader.GetBytes(PngSignatureBytes.Length)))
{
throw new PngProcessingException("PNG signature mismatch");
}
bool seenImageHeader = false;
bool seenImageTrailer = false;
IList <PngChunk> chunks = new AList <PngChunk>();
ICollection <PngChunkType> seenChunkTypes = new HashSet <PngChunkType>();
while (!seenImageTrailer)
{
// Process the next chunk.
int chunkDataLength = reader.GetInt32();
PngChunkType chunkType = new PngChunkType(reader.GetBytes(4));
bool willStoreChunk = desiredChunkTypes == null || desiredChunkTypes.Contains(chunkType);
sbyte[] chunkData = reader.GetBytes(chunkDataLength);
// Skip the CRC bytes at the end of the chunk
// TODO consider verifying the CRC value to determine if we're processing bad data
reader.Skip(4);
if (willStoreChunk && seenChunkTypes.Contains(chunkType) && !chunkType.AreMultipleAllowed())
{
throw new PngProcessingException(Sharpen.Extensions.StringFormat("Observed multiple instances of PNG chunk '%s', for which multiples are not allowed", chunkType));
}
if (chunkType.Equals(PngChunkType.Ihdr))
{
seenImageHeader = true;
}
else
{
if (!seenImageHeader)
{
throw new PngProcessingException(Sharpen.Extensions.StringFormat("First chunk should be '%s', but '%s' was observed", PngChunkType.Ihdr, chunkType));
}
}
if (chunkType.Equals(PngChunkType.Iend))
{
seenImageTrailer = true;
}
if (willStoreChunk)
{
chunks.Add(new PngChunk(chunkType, chunkData));
}
seenChunkTypes.Add(chunkType);
}
return(chunks.AsIterable());
}
/// <exception cref="Com.Drew.Imaging.Png.PngProcessingException"/>
/// <exception cref="System.IO.IOException"/>
public virtual Iterable<PngChunk> Extract(SequentialReader reader, ICollection<PngChunkType> desiredChunkTypes)
{
//
// PNG DATA STREAM
//
// Starts with a PNG SIGNATURE, followed by a sequence of CHUNKS.
//
// PNG SIGNATURE
//
// Always composed of these bytes: 89 50 4E 47 0D 0A 1A 0A
//
// CHUNK
//
// 4 - length of the data field (unsigned, but always within 31 bytes), may be zero
// 4 - chunk type, restricted to [65,90] and [97,122] (A-Za-z)
// * - data field
// 4 - CRC calculated from chunk type and chunk data, but not length
//
// CHUNK TYPES
//
// Critical Chunk Types:
//
// IHDR - image header, always the first chunk in the data stream
// PLTE - palette table, associated with indexed PNG images
// IDAT - image data chunk, of which there may be many
// IEND - image trailer, always the last chunk in the data stream
//
// Ancillary Chunk Types:
//
// Transparency information: tRNS
// Colour space information: cHRM, gAMA, iCCP, sBIT, sRGB
// Textual information: iTXt, tEXt, zTXt
// Miscellaneous information: bKGD, hIST, pHYs, sPLT
// Time information: tIME
//
reader.SetMotorolaByteOrder(true);
// network byte order
if (!Arrays.Equals(PngSignatureBytes, reader.GetBytes(PngSignatureBytes.Length)))
{
throw new PngProcessingException("PNG signature mismatch");
}
bool seenImageHeader = false;
bool seenImageTrailer = false;
IList<PngChunk> chunks = new AList<PngChunk>();
ICollection<PngChunkType> seenChunkTypes = new HashSet<PngChunkType>();
while (!seenImageTrailer)
{
// Process the next chunk.
int chunkDataLength = reader.GetInt32();
PngChunkType chunkType = new PngChunkType(reader.GetBytes(4));
sbyte[] chunkData = reader.GetBytes(chunkDataLength);
// Skip the CRC bytes at the end of the chunk
// TODO consider verifying the CRC value to determine if we're processing bad data
reader.Skip(4);
if (seenChunkTypes.Contains(chunkType) && !chunkType.AreMultipleAllowed())
{
throw new PngProcessingException(Sharpen.Extensions.StringFormat("Observed multiple instances of PNG chunk '%s', for which multiples are not allowed", chunkType));
}
if (chunkType.Equals(PngChunkType.Ihdr))
{
seenImageHeader = true;
}
else
{
if (!seenImageHeader)
{
throw new PngProcessingException(Sharpen.Extensions.StringFormat("First chunk should be '%s', but '%s' was observed", PngChunkType.Ihdr, chunkType));
}
}
if (chunkType.Equals(PngChunkType.Iend))
{
seenImageTrailer = true;
}
if (desiredChunkTypes == null || desiredChunkTypes.Contains(chunkType))
{
chunks.Add(new PngChunk(chunkType, chunkData));
}
seenChunkTypes.Add(chunkType);
}
return chunks.AsIterable();
}
/// <exception cref="Com.Drew.Imaging.Png.PngProcessingException"/>
/// <exception cref="System.IO.IOException"/>
private static void ProcessChunk([NotNull] Com.Drew.Metadata.Metadata metadata, [NotNull] PngChunk chunk)
{
PngChunkType chunkType = chunk.GetChunkType();
sbyte[] bytes = chunk.GetBytes();
if (chunkType.Equals(PngChunkType.Ihdr))
{
PngHeader header = new PngHeader(bytes);
PngDirectory directory = new PngDirectory(PngChunkType.Ihdr);
directory.SetInt(PngDirectory.TagImageWidth, header.GetImageWidth());
directory.SetInt(PngDirectory.TagImageHeight, header.GetImageHeight());
directory.SetInt(PngDirectory.TagBitsPerSample, header.GetBitsPerSample());
directory.SetInt(PngDirectory.TagColorType, header.GetColorType().GetNumericValue());
directory.SetInt(PngDirectory.TagCompressionType, header.GetCompressionType());
directory.SetInt(PngDirectory.TagFilterMethod, header.GetFilterMethod());
directory.SetInt(PngDirectory.TagInterlaceMethod, header.GetInterlaceMethod());
metadata.AddDirectory(directory);
}
else
{
if (chunkType.Equals(PngChunkType.Plte))
{
PngDirectory directory = new PngDirectory(PngChunkType.Plte);
directory.SetInt(PngDirectory.TagPaletteSize, bytes.Length / 3);
metadata.AddDirectory(directory);
}
else
{
if (chunkType.Equals(PngChunkType.tRNS))
{
PngDirectory directory = new PngDirectory(PngChunkType.tRNS);
directory.SetInt(PngDirectory.TagPaletteHasTransparency, 1);
metadata.AddDirectory(directory);
}
else
{
if (chunkType.Equals(PngChunkType.sRGB))
{
int srgbRenderingIntent = new SequentialByteArrayReader(bytes).GetInt8();
PngDirectory directory = new PngDirectory(PngChunkType.sRGB);
directory.SetInt(PngDirectory.TagSrgbRenderingIntent, srgbRenderingIntent);
metadata.AddDirectory(directory);
}
else
{
if (chunkType.Equals(PngChunkType.cHRM))
{
PngChromaticities chromaticities = new PngChromaticities(bytes);
PngChromaticitiesDirectory directory = new PngChromaticitiesDirectory();
directory.SetInt(PngChromaticitiesDirectory.TagWhitePointX, chromaticities.GetWhitePointX());
directory.SetInt(PngChromaticitiesDirectory.TagWhitePointX, chromaticities.GetWhitePointX());
directory.SetInt(PngChromaticitiesDirectory.TagRedX, chromaticities.GetRedX());
directory.SetInt(PngChromaticitiesDirectory.TagRedY, chromaticities.GetRedY());
directory.SetInt(PngChromaticitiesDirectory.TagGreenX, chromaticities.GetGreenX());
directory.SetInt(PngChromaticitiesDirectory.TagGreenY, chromaticities.GetGreenY());
directory.SetInt(PngChromaticitiesDirectory.TagBlueX, chromaticities.GetBlueX());
directory.SetInt(PngChromaticitiesDirectory.TagBlueY, chromaticities.GetBlueY());
metadata.AddDirectory(directory);
}
else
{
if (chunkType.Equals(PngChunkType.gAMA))
{
int gammaInt = new SequentialByteArrayReader(bytes).GetInt32();
PngDirectory directory = new PngDirectory(PngChunkType.gAMA);
directory.SetDouble(PngDirectory.TagGamma, gammaInt / 100000.0);
metadata.AddDirectory(directory);
}
else
{
if (chunkType.Equals(PngChunkType.iCCP))
{
SequentialReader reader = new SequentialByteArrayReader(bytes);
string profileName = reader.GetNullTerminatedString(79);
PngDirectory directory = new PngDirectory(PngChunkType.iCCP);
directory.SetString(PngDirectory.TagIccProfileName, profileName);
sbyte compressionMethod = reader.GetInt8();
if (compressionMethod == 0)
{
// Only compression method allowed by the spec is zero: deflate
// This assumes 1-byte-per-char, which it is by spec.
int bytesLeft = bytes.Length - profileName.Length - 2;
sbyte[] compressedProfile = reader.GetBytes(bytesLeft);
InflaterInputStream inflateStream = new InflaterInputStream(new ByteArrayInputStream(compressedProfile));
new IccReader().Extract(new RandomAccessStreamReader(inflateStream), metadata);
inflateStream.Close();
}
metadata.AddDirectory(directory);
}
else
{
if (chunkType.Equals(PngChunkType.bKGD))
{
PngDirectory directory = new PngDirectory(PngChunkType.bKGD);
directory.SetByteArray(PngDirectory.TagBackgroundColor, bytes);
metadata.AddDirectory(directory);
}
else
{
if (chunkType.Equals(PngChunkType.tEXt))
{
SequentialReader reader = new SequentialByteArrayReader(bytes);
string keyword = reader.GetNullTerminatedString(79);
int bytesLeft = bytes.Length - keyword.Length - 1;
string value = reader.GetNullTerminatedString(bytesLeft);
IList <KeyValuePair> textPairs = new AList <KeyValuePair>();
textPairs.Add(new KeyValuePair(keyword, value));
PngDirectory directory = new PngDirectory(PngChunkType.iTXt);
directory.SetObject(PngDirectory.TagTextualData, textPairs);
metadata.AddDirectory(directory);
}
else
{
if (chunkType.Equals(PngChunkType.iTXt))
{
SequentialReader reader = new SequentialByteArrayReader(bytes);
string keyword = reader.GetNullTerminatedString(79);
sbyte compressionFlag = reader.GetInt8();
sbyte compressionMethod = reader.GetInt8();
string languageTag = reader.GetNullTerminatedString(bytes.Length);
string translatedKeyword = reader.GetNullTerminatedString(bytes.Length);
int bytesLeft = bytes.Length - keyword.Length - 1 - 1 - 1 - languageTag.Length - 1 - translatedKeyword.Length - 1;
string text = null;
if (compressionFlag == 0)
{
text = reader.GetNullTerminatedString(bytesLeft);
}
else
{
if (compressionFlag == 1)
{
if (compressionMethod == 0)
{
text = StringUtil.FromStream(new InflaterInputStream(new ByteArrayInputStream(bytes, bytes.Length - bytesLeft, bytesLeft)));
}
else
{
PngDirectory directory = new PngDirectory(PngChunkType.iTXt);
directory.AddError("Invalid compression method value");
metadata.AddDirectory(directory);
}
}
else
{
PngDirectory directory = new PngDirectory(PngChunkType.iTXt);
directory.AddError("Invalid compression flag value");
metadata.AddDirectory(directory);
}
}
if (text != null)
{
if (keyword.Equals("XML:com.adobe.xmp"))
{
// NOTE in testing images, the XMP has parsed successfully, but we are not extracting tags from it as necessary
new XmpReader().Extract(text, metadata);
}
else
{
IList <KeyValuePair> textPairs = new AList <KeyValuePair>();
textPairs.Add(new KeyValuePair(keyword, text));
PngDirectory directory = new PngDirectory(PngChunkType.iTXt);
directory.SetObject(PngDirectory.TagTextualData, textPairs);
metadata.AddDirectory(directory);
}
}
}
else
{
if (chunkType.Equals(PngChunkType.tIME))
{
SequentialByteArrayReader reader = new SequentialByteArrayReader(bytes);
int year = reader.GetUInt16();
int month = reader.GetUInt8() - 1;
int day = reader.GetUInt8();
int hour = reader.GetUInt8();
int minute = reader.GetUInt8();
int second = reader.GetUInt8();
Sharpen.Calendar calendar = Sharpen.Calendar.GetInstance(Sharpen.Extensions.GetTimeZone("UTC"));
//noinspection MagicConstant
calendar.Set(year, month, day, hour, minute, second);
PngDirectory directory = new PngDirectory(PngChunkType.tIME);
directory.SetDate(PngDirectory.TagLastModificationTime, calendar.GetTime());
metadata.AddDirectory(directory);
}
else
{
if (chunkType.Equals(PngChunkType.pHYs))
{
SequentialByteArrayReader reader = new SequentialByteArrayReader(bytes);
int pixelsPerUnitX = reader.GetInt32();
int pixelsPerUnitY = reader.GetInt32();
sbyte unitSpecifier = reader.GetInt8();
PngDirectory directory = new PngDirectory(PngChunkType.pHYs);
directory.SetInt(PngDirectory.TagPixelsPerUnitX, pixelsPerUnitX);
directory.SetInt(PngDirectory.TagPixelsPerUnitY, pixelsPerUnitY);
directory.SetInt(PngDirectory.TagUnitSpecifier, unitSpecifier);
metadata.AddDirectory(directory);
}
else
{
if (chunkType.Equals(PngChunkType.sBIT))
{
PngDirectory directory = new PngDirectory(PngChunkType.sBIT);
directory.SetByteArray(PngDirectory.TagSignificantBits, bytes);
metadata.AddDirectory(directory);
}
}
}
}
}
}
}
}
}
}
}
}
}
}