/// <summary>
/// Copies an App1 segment and may replace it with Xmp.
/// </summary>
/// <param name="xmp">Xmp content that shall be used</param>
/// <param name="input">Stream of bytes in the original file</param>
/// <param name="output">Stream of bytes in the newly composed file</param>
/// <param name="wroteXmp"></param>
/// <returns>indicates if the Xmp content was written to this segment</returns>
private static bool CopyOrUpdateApp1Segment(XDocument xmp, SequentialByteArrayReader input, MemoryStream output, bool wroteXmp)
{
// 1. read the segment index that encodes the segment length
byte highByte = input.GetByte();
byte lowByte = input.GetByte();
int segmentLength = SegmentLengthFromBytes(highByte, lowByte, input.IsMotorolaByteOrder);
// 2. read the rest of the segment
byte[] segmentBytes = input.GetBytes(segmentLength);
// 3. if this is the XMP segment, overwrite it with the new segment
int preambleLength = XmpReader.JpegSegmentPreamble.Length;
if (segmentBytes.Length >= preambleLength && XmpReader.JpegSegmentPreamble.Equals(Encoding.UTF8.GetString(segmentBytes, 0, preambleLength), StringComparison.OrdinalIgnoreCase))
{
// overwrite the payload
segmentBytes = ByteArrayFromXmpXDocument(xmp);
// and update the segment length!!
byte[] lengthMark = BytesFromSegmentLength(segmentBytes.Length, input.IsMotorolaByteOrder);
highByte = lengthMark[0];
lowByte = lengthMark[1];
// indicate that the Xmp was written to this segment
wroteXmp = true;
}
// 4. only now write the entire segment (index + payload)
output.WriteByte(highByte);
output.WriteByte(lowByte);
output.Write(segmentBytes, 0, segmentBytes.Length);
return(wroteXmp);
}
/// <exception cref="PngProcessingException"/>
public PngHeader([NotNull] byte[] bytes)
{
if (bytes.Length != 13)
{
throw new PngProcessingException("PNG header chunk must have exactly 13 data bytes");
}
var reader = new SequentialByteArrayReader(bytes);
ImageWidth = reader.GetInt32();
ImageHeight = reader.GetInt32();
BitsPerSample = reader.GetByte();
var colorTypeNumber = reader.GetByte();
var colorType = PngColorType.FromNumericValue(colorTypeNumber);
if (colorType == null)
{
throw new PngProcessingException("Unexpected PNG color type: " + colorTypeNumber);
}
ColorType = colorType;
CompressionType = reader.GetByte();
FilterMethod = reader.GetByte();
InterlaceMethod = reader.GetByte();
}
public string GetBackgroundColorDescription()
{
var bytes = Directory.GetByteArray(PngDirectory.TagBackgroundColor);
if (bytes == null || !Directory.TryGetInt32(PngDirectory.TagColorType, out int colorType))
{
return(null);
}
var reader = new SequentialByteArrayReader(bytes);
try
{
switch (colorType)
{
case 0:
case 4:
// TODO do we need to normalise these based upon the bit depth?
return($"Greyscale Level {reader.GetUInt16()}");
case 2:
case 6:
return($"R {reader.GetUInt16()}, G {reader.GetUInt16()}, B {reader.GetUInt16()}");
case 3:
return($"Palette Index {reader.GetByte()}");
}
}
catch (IOException)
{
return(null);
}
return(null);
}
public string GetBackgroundColorDescription()
{
var bytes = Directory.GetByteArray(PngDirectory.TagBackgroundColor);
if (bytes == null)
{
return(null);
}
var reader = new SequentialByteArrayReader(bytes);
try
{
// TODO do we need to normalise these based upon the bit depth?
switch (bytes.Length)
{
case 1:
return($"Palette Index {reader.GetByte()}");
case 2:
return($"Greyscale Level {reader.GetUInt16()}");
case 6:
return($"R {reader.GetUInt16()}, G {reader.GetUInt16()}, B {reader.GetUInt16()}");
}
}
catch (IOException)
{
return(null);
}
return(null);
}
/// <exception cref="PngProcessingException"/>
public PngHeader(byte[] bytes)
{
if (bytes.Length != 13)
{
throw new PngProcessingException("PNG header chunk must have exactly 13 data bytes");
}
var reader = new SequentialByteArrayReader(bytes);
ImageWidth = reader.GetInt32();
ImageHeight = reader.GetInt32();
BitsPerSample = reader.GetByte();
ColorType = PngColorType.FromNumericValue(reader.GetByte());
CompressionType = reader.GetByte();
FilterMethod = reader.GetByte();
InterlaceMethod = reader.GetByte();
}
/// <summary>Reads JPEG SOF values and returns them in a <see cref="JpegDirectory"/>.</summary>
public JpegDirectory Extract(JpegSegment segment)
{
var directory = new JpegDirectory();
// The value of TagCompressionType is determined by the segment type found
directory.Set(JpegDirectory.TagCompressionType, (int)segment.Type - (int)JpegSegmentType.Sof0);
SequentialReader reader = new SequentialByteArrayReader(segment.Bytes);
try
{
directory.Set(JpegDirectory.TagDataPrecision, reader.GetByte());
directory.Set(JpegDirectory.TagImageHeight, reader.GetUInt16());
directory.Set(JpegDirectory.TagImageWidth, reader.GetUInt16());
var componentCount = reader.GetByte();
directory.Set(JpegDirectory.TagNumberOfComponents, componentCount);
// For each component, there are three bytes of data:
// 1 - Component ID: 1 = Y, 2 = Cb, 3 = Cr, 4 = I, 5 = Q
// 2 - Sampling factors: bit 0-3 vertical, 4-7 horizontal
// 3 - Quantization table number
for (var i = 0; i < componentCount; i++)
{
var componentId = reader.GetByte();
var samplingFactorByte = reader.GetByte();
var quantizationTableNumber = reader.GetByte();
var component = new JpegComponent(componentId, samplingFactorByte, quantizationTableNumber);
directory.Set(JpegDirectory.TagComponentData1 + i, component);
}
}
catch (IOException ex)
{
directory.AddError(ex.Message);
}
return(directory);
}
/// <exception cref="PngProcessingException"/>
/// <exception cref="System.IO.IOException"/>
private static IEnumerable <Directory> ProcessChunk([NotNull] PngChunk chunk)
{
var chunkType = chunk.ChunkType;
var bytes = chunk.Bytes;
if (chunkType == PngChunkType.IHDR)
{
var header = new PngHeader(bytes);
var directory = new PngDirectory(PngChunkType.IHDR);
directory.Set(PngDirectory.TagImageWidth, header.ImageWidth);
directory.Set(PngDirectory.TagImageHeight, header.ImageHeight);
directory.Set(PngDirectory.TagBitsPerSample, header.BitsPerSample);
directory.Set(PngDirectory.TagColorType, header.ColorType.NumericValue);
directory.Set(PngDirectory.TagCompressionType, header.CompressionType);
directory.Set(PngDirectory.TagFilterMethod, header.FilterMethod);
directory.Set(PngDirectory.TagInterlaceMethod, header.InterlaceMethod);
yield return(directory);
}
else if (chunkType == PngChunkType.PLTE)
{
var directory = new PngDirectory(PngChunkType.PLTE);
directory.Set(PngDirectory.TagPaletteSize, bytes.Length / 3);
yield return(directory);
}
else if (chunkType == PngChunkType.tRNS)
{
var directory = new PngDirectory(PngChunkType.tRNS);
directory.Set(PngDirectory.TagPaletteHasTransparency, 1);
yield return(directory);
}
else if (chunkType == PngChunkType.sRGB)
{
int srgbRenderingIntent = unchecked ((sbyte)bytes[0]);
var directory = new PngDirectory(PngChunkType.sRGB);
directory.Set(PngDirectory.TagSrgbRenderingIntent, srgbRenderingIntent);
yield return(directory);
}
else if (chunkType == PngChunkType.cHRM)
{
var chromaticities = new PngChromaticities(bytes);
var directory = new PngChromaticitiesDirectory();
directory.Set(PngChromaticitiesDirectory.TagWhitePointX, chromaticities.WhitePointX);
directory.Set(PngChromaticitiesDirectory.TagWhitePointY, chromaticities.WhitePointY);
directory.Set(PngChromaticitiesDirectory.TagRedX, chromaticities.RedX);
directory.Set(PngChromaticitiesDirectory.TagRedY, chromaticities.RedY);
directory.Set(PngChromaticitiesDirectory.TagGreenX, chromaticities.GreenX);
directory.Set(PngChromaticitiesDirectory.TagGreenY, chromaticities.GreenY);
directory.Set(PngChromaticitiesDirectory.TagBlueX, chromaticities.BlueX);
directory.Set(PngChromaticitiesDirectory.TagBlueY, chromaticities.BlueY);
yield return(directory);
}
else if (chunkType == PngChunkType.gAMA)
{
var gammaInt = ByteConvert.ToInt32BigEndian(bytes);
var directory = new PngDirectory(PngChunkType.gAMA);
directory.Set(PngDirectory.TagGamma, gammaInt / 100000.0);
yield return(directory);
}
else if (chunkType == PngChunkType.iCCP)
{
var reader = new SequentialByteArrayReader(bytes);
var profileName = reader.GetNullTerminatedStringValue(maxLengthBytes: 79);
var directory = new PngDirectory(PngChunkType.iCCP);
directory.Set(PngDirectory.TagIccProfileName, profileName);
var compressionMethod = reader.GetSByte();
if (compressionMethod == 0)
{
// Only compression method allowed by the spec is zero: deflate
// This assumes 1-byte-per-char, which it is by spec.
var bytesLeft = bytes.Length - profileName.Bytes.Length - 2;
// http://george.chiramattel.com/blog/2007/09/deflatestream-block-length-does-not-match.html
// First two bytes are part of the zlib specification (RFC 1950), not the deflate specification (RFC 1951).
reader.GetByte(); reader.GetByte();
bytesLeft -= 2;
var compressedProfile = reader.GetBytes(bytesLeft);
IccDirectory iccDirectory = null;
Exception ex = null;
try
{
using (var inflaterStream = new DeflateStream(new MemoryStream(compressedProfile), CompressionMode.Decompress))
{
iccDirectory = new IccReader().Extract(new IndexedCapturingReader(inflaterStream));
iccDirectory.Parent = directory;
}
}
catch (Exception e)
{
ex = e;
}
if (ex == null)
{
yield return(iccDirectory);
}
else
{
directory.AddError($"Exception decompressing {nameof(PngChunkType.iCCP)} chunk: {ex.Message}");
}
}
else
{
directory.AddError("Invalid compression method value");
}
yield return(directory);
}
else if (chunkType == PngChunkType.bKGD)
{
var directory = new PngDirectory(PngChunkType.bKGD);
directory.Set(PngDirectory.TagBackgroundColor, bytes);
yield return(directory);
}
else if (chunkType == PngChunkType.tEXt)
{
var reader = new SequentialByteArrayReader(bytes);
var keyword = reader.GetNullTerminatedStringValue(maxLengthBytes: 79).ToString(_latin1Encoding);
var bytesLeft = bytes.Length - keyword.Length - 1;
var value = reader.GetNullTerminatedStringValue(bytesLeft, _latin1Encoding);
var textPairs = new List <KeyValuePair> {
new KeyValuePair(keyword, value)
};
var directory = new PngDirectory(PngChunkType.tEXt);
directory.Set(PngDirectory.TagTextualData, textPairs);
yield return(directory);
}
else if (chunkType == PngChunkType.zTXt)
{
var reader = new SequentialByteArrayReader(bytes);
var keyword = reader.GetNullTerminatedStringValue(maxLengthBytes: 79).ToString(_latin1Encoding);
var compressionMethod = reader.GetSByte();
var bytesLeft = bytes.Length - keyword.Length - 1 - 1 - 1 - 1;
byte[] textBytes = null;
if (compressionMethod == 0)
{
using (var inflaterStream = new DeflateStream(new MemoryStream(bytes, bytes.Length - bytesLeft, bytesLeft), CompressionMode.Decompress))
{
Exception ex = null;
try
{
textBytes = ReadStreamToBytes(inflaterStream);
}
catch (Exception e)
{
ex = e;
}
// Work-around no yield-return from catch blocks
if (ex != null)
{
var directory = new PngDirectory(PngChunkType.zTXt);
directory.AddError($"Exception decompressing {nameof(PngChunkType.zTXt)} chunk with keyword \"{keyword}\": {ex.Message}");
yield return(directory);
}
}
}
else
{
var directory = new PngDirectory(PngChunkType.zTXt);
directory.AddError("Invalid compression method value");
yield return(directory);
}
if (textBytes != null)
{
if (keyword == "XML:com.adobe.xmp")
{
// NOTE in testing images, the XMP has parsed successfully, but we are not extracting tags from it as necessary
yield return(new XmpReader().Extract(textBytes));
}
else
{
var textPairs = new List <KeyValuePair> {
new KeyValuePair(keyword, new StringValue(textBytes, _latin1Encoding))
};
var directory = new PngDirectory(PngChunkType.zTXt);
directory.Set(PngDirectory.TagTextualData, textPairs);
yield return(directory);
}
}
}
else if (chunkType == PngChunkType.iTXt)
{
var reader = new SequentialByteArrayReader(bytes);
var keyword = reader.GetNullTerminatedStringValue(maxLengthBytes: 79).ToString(_latin1Encoding);
var compressionFlag = reader.GetSByte();
var compressionMethod = reader.GetSByte();
// TODO we currently ignore languageTagBytes and translatedKeywordBytes
var languageTagBytes = reader.GetNullTerminatedBytes(bytes.Length);
var translatedKeywordBytes = reader.GetNullTerminatedBytes(bytes.Length);
var bytesLeft = bytes.Length - keyword.Length - 1 - 1 - 1 - languageTagBytes.Length - 1 - translatedKeywordBytes.Length - 1;
byte[] textBytes = null;
if (compressionFlag == 0)
{
textBytes = reader.GetNullTerminatedBytes(bytesLeft);
}
else if (compressionFlag == 1)
{
if (compressionMethod == 0)
{
using (var inflaterStream = new DeflateStream(new MemoryStream(bytes, bytes.Length - bytesLeft, bytesLeft), CompressionMode.Decompress))
{
Exception ex = null;
try
{
textBytes = ReadStreamToBytes(inflaterStream);
}
catch (Exception e)
{
ex = e;
}
// Work-around no yield-return from catch blocks
if (ex != null)
{
var directory = new PngDirectory(PngChunkType.iTXt);
directory.AddError($"Exception decompressing {nameof(PngChunkType.iTXt)} chunk with keyword \"{keyword}\": {ex.Message}");
yield return(directory);
}
}
}
else
{
var directory = new PngDirectory(PngChunkType.iTXt);
directory.AddError("Invalid compression method value");
yield return(directory);
}
}
else
{
var directory = new PngDirectory(PngChunkType.iTXt);
directory.AddError("Invalid compression flag value");
yield return(directory);
}
if (textBytes != null)
{
if (keyword == "XML:com.adobe.xmp")
{
// NOTE in testing images, the XMP has parsed successfully, but we are not extracting tags from it as necessary
yield return(new XmpReader().Extract(textBytes));
}
else
{
var textPairs = new List <KeyValuePair> {
new KeyValuePair(keyword, new StringValue(textBytes, _latin1Encoding))
};
var directory = new PngDirectory(PngChunkType.iTXt);
directory.Set(PngDirectory.TagTextualData, textPairs);
yield return(directory);
}
}
}
else if (chunkType == PngChunkType.tIME)
{
var reader = new SequentialByteArrayReader(bytes);
var year = reader.GetUInt16();
var month = reader.GetByte();
int day = reader.GetByte();
int hour = reader.GetByte();
int minute = reader.GetByte();
int second = reader.GetByte();
var directory = new PngDirectory(PngChunkType.tIME);
if (DateUtil.IsValidDate(year, month, day) && DateUtil.IsValidTime(hour, minute, second))
{
var time = new DateTime(year, month, day, hour, minute, second, DateTimeKind.Unspecified);
directory.Set(PngDirectory.TagLastModificationTime, time);
}
else
{
directory.AddError($"PNG tIME data describes an invalid date/time: year={year} month={month} day={day} hour={hour} minute={minute} second={second}");
}
yield return(directory);
}
else if (chunkType == PngChunkType.pHYs)
{
var reader = new SequentialByteArrayReader(bytes);
var pixelsPerUnitX = reader.GetInt32();
var pixelsPerUnitY = reader.GetInt32();
var unitSpecifier = reader.GetSByte();
var directory = new PngDirectory(PngChunkType.pHYs);
directory.Set(PngDirectory.TagPixelsPerUnitX, pixelsPerUnitX);
directory.Set(PngDirectory.TagPixelsPerUnitY, pixelsPerUnitY);
directory.Set(PngDirectory.TagUnitSpecifier, unitSpecifier);
yield return(directory);
}
else if (chunkType.Equals(PngChunkType.sBIT))
{
var directory = new PngDirectory(PngChunkType.sBIT);
directory.Set(PngDirectory.TagSignificantBits, bytes);
yield return(directory);
}
}
/// <exception cref="PngProcessingException"/>
/// <exception cref="System.IO.IOException"/>
private static IEnumerable <Directory> ProcessChunk([NotNull] PngChunk chunk)
{
var chunkType = chunk.ChunkType;
var bytes = chunk.Bytes;
if (chunkType == PngChunkType.IHDR)
{
var header = new PngHeader(bytes);
var directory = new PngDirectory(PngChunkType.IHDR);
directory.Set(PngDirectory.TagImageWidth, header.ImageWidth);
directory.Set(PngDirectory.TagImageHeight, header.ImageHeight);
directory.Set(PngDirectory.TagBitsPerSample, header.BitsPerSample);
directory.Set(PngDirectory.TagColorType, header.ColorType.NumericValue);
directory.Set(PngDirectory.TagCompressionType, header.CompressionType);
directory.Set(PngDirectory.TagFilterMethod, header.FilterMethod);
directory.Set(PngDirectory.TagInterlaceMethod, header.InterlaceMethod);
yield return(directory);
}
else if (chunkType == PngChunkType.PLTE)
{
var directory = new PngDirectory(PngChunkType.PLTE);
directory.Set(PngDirectory.TagPaletteSize, bytes.Length / 3);
yield return(directory);
}
else if (chunkType == PngChunkType.tRNS)
{
var directory = new PngDirectory(PngChunkType.tRNS);
directory.Set(PngDirectory.TagPaletteHasTransparency, 1);
yield return(directory);
}
else if (chunkType == PngChunkType.sRGB)
{
int srgbRenderingIntent = unchecked ((sbyte)bytes[0]);
var directory = new PngDirectory(PngChunkType.sRGB);
directory.Set(PngDirectory.TagSrgbRenderingIntent, srgbRenderingIntent);
yield return(directory);
}
else if (chunkType == PngChunkType.cHRM)
{
var chromaticities = new PngChromaticities(bytes);
var directory = new PngChromaticitiesDirectory();
directory.Set(PngChromaticitiesDirectory.TagWhitePointX, chromaticities.WhitePointX);
directory.Set(PngChromaticitiesDirectory.TagWhitePointY, chromaticities.WhitePointY);
directory.Set(PngChromaticitiesDirectory.TagRedX, chromaticities.RedX);
directory.Set(PngChromaticitiesDirectory.TagRedY, chromaticities.RedY);
directory.Set(PngChromaticitiesDirectory.TagGreenX, chromaticities.GreenX);
directory.Set(PngChromaticitiesDirectory.TagGreenY, chromaticities.GreenY);
directory.Set(PngChromaticitiesDirectory.TagBlueX, chromaticities.BlueX);
directory.Set(PngChromaticitiesDirectory.TagBlueY, chromaticities.BlueY);
yield return(directory);
}
else if (chunkType == PngChunkType.gAMA)
{
var gammaInt = ByteConvert.ToInt32BigEndian(bytes);
var directory = new PngDirectory(PngChunkType.gAMA);
directory.Set(PngDirectory.TagGamma, gammaInt / 100000.0);
yield return(directory);
}
else if (chunkType == PngChunkType.iCCP)
{
var reader = new SequentialByteArrayReader(bytes);
var profileName = reader.GetNullTerminatedStringValue(maxLengthBytes: 79);
var directory = new PngDirectory(PngChunkType.iCCP);
directory.Set(PngDirectory.TagIccProfileName, profileName);
var compressionMethod = reader.GetSByte();
if (compressionMethod == 0)
{
// Only compression method allowed by the spec is zero: deflate
// This assumes 1-byte-per-char, which it is by spec.
var bytesLeft = bytes.Length - profileName.Bytes.Length - 2;
var compressedProfile = reader.GetBytes(bytesLeft);
using (var inflaterStream = new DeflateStream(new MemoryStream(compressedProfile), CompressionMode.Decompress))
// using (var inflaterStream = new InflaterInputStream(new MemoryStream(compressedProfile)))
{
var iccDirectory = new IccReader().Extract(new IndexedCapturingReader(inflaterStream));
iccDirectory.Parent = directory;
yield return(iccDirectory);
}
}
else
{
directory.AddError("Invalid compression method value");
}
yield return(directory);
}
else if (chunkType == PngChunkType.bKGD)
{
var directory = new PngDirectory(PngChunkType.bKGD);
directory.Set(PngDirectory.TagBackgroundColor, bytes);
yield return(directory);
}
else if (chunkType == PngChunkType.tEXt)
{
var reader = new SequentialByteArrayReader(bytes);
var keyword = reader.GetNullTerminatedStringValue(maxLengthBytes: 79).ToString(_latin1Encoding);
var bytesLeft = bytes.Length - keyword.Length - 1;
var value = reader.GetNullTerminatedStringValue(bytesLeft, _latin1Encoding);
var textPairs = new List <KeyValuePair> {
new KeyValuePair(keyword, value)
};
var directory = new PngDirectory(PngChunkType.iTXt);
directory.Set(PngDirectory.TagTextualData, textPairs);
yield return(directory);
}
else if (chunkType == PngChunkType.zTXt)
{
var reader = new SequentialByteArrayReader(bytes);
var keyword = reader.GetNullTerminatedStringValue(maxLengthBytes: 79).ToString(_latin1Encoding);
var compressionMethod = reader.GetSByte();
var bytesLeft = bytes.Length - keyword.Length - 1 - 1 - 1 - 1;
byte[] textBytes = null;
if (compressionMethod == 0)
{
using (var inflaterStream = new DeflateStream(new MemoryStream(bytes, bytes.Length - bytesLeft, bytesLeft), CompressionMode.Decompress))
using (var decompStream = new MemoryStream())
{
#if !NET35
inflaterStream.CopyTo(decompStream);
#else
byte[] buffer = new byte[256];
int count;
int totalBytes = 0;
while ((count = inflaterStream.Read(buffer, 0, 256)) > 0)
{
decompStream.Write(buffer, 0, count);
totalBytes += count;
}
#endif
textBytes = decompStream.ToArray();
}
}
else
{
var directory = new PngDirectory(PngChunkType.zTXt);
directory.AddError("Invalid compression method value");
yield return(directory);
}
if (textBytes != null)
{
if (keyword == "XML:com.adobe.xmp")
{
// NOTE in testing images, the XMP has parsed successfully, but we are not extracting tags from it as necessary
yield return(new XmpReader().Extract(textBytes));
}
else
{
var textPairs = new List <KeyValuePair> {
new KeyValuePair(keyword, new StringValue(textBytes, _latin1Encoding))
};
var directory = new PngDirectory(PngChunkType.zTXt);
directory.Set(PngDirectory.TagTextualData, textPairs);
yield return(directory);
}
}
}
else if (chunkType == PngChunkType.iTXt)
{
var reader = new SequentialByteArrayReader(bytes);
var keyword = reader.GetNullTerminatedStringValue(maxLengthBytes: 79).ToString(_latin1Encoding);
var compressionFlag = reader.GetSByte();
var compressionMethod = reader.GetSByte();
// TODO we currently ignore languageTagBytes and translatedKeywordBytes
var languageTagBytes = reader.GetNullTerminatedBytes(bytes.Length);
var translatedKeywordBytes = reader.GetNullTerminatedBytes(bytes.Length);
var bytesLeft = bytes.Length - keyword.Length - 1 - 1 - 1 - languageTagBytes.Length - 1 - translatedKeywordBytes.Length - 1;
byte[] textBytes = null;
if (compressionFlag == 0)
{
textBytes = reader.GetNullTerminatedBytes(bytesLeft);
}
else if (compressionFlag == 1)
{
if (compressionMethod == 0)
{
using (var inflaterStream = new DeflateStream(new MemoryStream(bytes, bytes.Length - bytesLeft, bytesLeft), CompressionMode.Decompress))
using (var decompStream = new MemoryStream())
{
#if !NET35
inflaterStream.CopyTo(decompStream);
#else
byte[] buffer = new byte[256];
int count;
int totalBytes = 0;
while ((count = inflaterStream.Read(buffer, 0, 256)) > 0)
{
decompStream.Write(buffer, 0, count);
totalBytes += count;
}
#endif
textBytes = decompStream.ToArray();
}
}
else
{
var directory = new PngDirectory(PngChunkType.iTXt);
directory.AddError("Invalid compression method value");
yield return(directory);
}
}
else
{
var directory = new PngDirectory(PngChunkType.iTXt);
directory.AddError("Invalid compression flag value");
yield return(directory);
}
if (textBytes != null)
{
if (keyword == "XML:com.adobe.xmp")
{
// NOTE in testing images, the XMP has parsed successfully, but we are not extracting tags from it as necessary
yield return(new XmpReader().Extract(textBytes));
}
else
{
var textPairs = new List <KeyValuePair> {
new KeyValuePair(keyword, new StringValue(textBytes, _latin1Encoding))
};
var directory = new PngDirectory(PngChunkType.iTXt);
directory.Set(PngDirectory.TagTextualData, textPairs);
yield return(directory);
}
}
}
else if (chunkType == PngChunkType.tIME)
{
var reader = new SequentialByteArrayReader(bytes);
var year = reader.GetUInt16();
var month = reader.GetByte();
int day = reader.GetByte();
int hour = reader.GetByte();
int minute = reader.GetByte();
int second = reader.GetByte();
var directory = new PngDirectory(PngChunkType.tIME);
try
{
var time = new DateTime(year, month, day, hour, minute, second, DateTimeKind.Unspecified);
directory.Set(PngDirectory.TagLastModificationTime, time);
}
catch (ArgumentOutOfRangeException e)
{
directory.AddError("Error constructing DateTime: " + e.Message);
}
yield return(directory);
}
else if (chunkType == PngChunkType.pHYs)
{
var reader = new SequentialByteArrayReader(bytes);
var pixelsPerUnitX = reader.GetInt32();
var pixelsPerUnitY = reader.GetInt32();
var unitSpecifier = reader.GetSByte();
var directory = new PngDirectory(PngChunkType.pHYs);
directory.Set(PngDirectory.TagPixelsPerUnitX, pixelsPerUnitX);
directory.Set(PngDirectory.TagPixelsPerUnitY, pixelsPerUnitY);
directory.Set(PngDirectory.TagUnitSpecifier, unitSpecifier);
yield return(directory);
}
else if (chunkType.Equals(PngChunkType.sBIT))
{
var directory = new PngDirectory(PngChunkType.sBIT);
directory.Set(PngDirectory.TagSignificantBits, bytes);
yield return(directory);
}
}
public static MemoryStream SubstituteXmp([NotNull] byte[] original, [NotNull] XDocument xmp)
{
SequentialByteArrayReader input = new SequentialByteArrayReader(original);
MemoryStream output = new MemoryStream();
try
{
// The Xmp-substitution loops over the original bytes and copies them into a
// MemoryStream (ms). If an App1-segment containing Xmp data is encountered,
// the new Xmp bytes are written to the MemoryStream instead of the old bytes.
// If no Xmp-containing App1 is encountered before other segments, a new App1-
// segment with the Xmp-data is inserted.
// All non-App1-fragments are just copied as they are.
bool wroteXmp = false;
// The following loop scans over the input, copies it to the output and locks in
// when it encounters a segment marker.
// Reference: http://dev.exiv2.org/projects/exiv2/wiki/The_Metadata_in_JPEG_files
while (true)
{
// Find the segment marker. Markers are zero or more 0xFF bytes, followed
// by a 0xFF and then a byte not equal to 0x00 or 0xFF.
var segmentIdentifier = input.GetByte();
output.WriteByte(segmentIdentifier);
var segmentTypeByte = input.GetByte();
output.WriteByte(segmentTypeByte);
// Read until we have a 0xFF byte followed by a byte that is not 0xFF or 0x00
while (segmentIdentifier != 0xFF || segmentTypeByte == 0xFF || segmentTypeByte == 0)
{
segmentIdentifier = segmentTypeByte;
segmentTypeByte = input.GetByte();
output.WriteByte(segmentTypeByte);
}
var segmentType = (JpegSegmentType)segmentTypeByte;
// the algorithm above stopped at a segment marker. This may be an opportunity
// to update or insert an App1-Xmp segment
if (!wroteXmp && segmentType == JpegSegmentType.App1)
{
// An App1 segment was encountered and might be a candidate for updating the Xmp
// Copy the segment (if it already contains Xmp, it will be updated)
wroteXmp = CopyOrUpdateApp1Segment(xmp, input, output, wroteXmp);
}
else if (!wroteXmp && segmentType != JpegSegmentType.Soi && segmentType != JpegSegmentType.App0)
{
// file begins with Soi (App0) (App1) ...
// At this point we have encountered a segment that should not be earlier than an App1.
// Also, the files does not contain an App1-Xmp segment yet.
// Therefore we must insert a new App1-Xmp segment now.
wroteXmp = InsertApp1XmpSegment(xmp, input, output, segmentIdentifier, segmentTypeByte);
}
// then continues with copying until the next segment or the end of the input
}
}
catch (IOException ex)
{
// we expect a IOException when the sequential reader reaches the end of the original data
if (ex.Message != "End of data reached.")
{
throw new JpegProcessingException("An error occured while trying to write Xml to the buffer.", ex);
}
}
catch (Exception ex)
{
throw new JpegProcessingException("An error occured while trying to write Xml to the buffer.", ex);
}
return(output);
}
/// <exception cref="PngProcessingException"/>
/// <exception cref="System.IO.IOException"/>
private static IEnumerable <Directory> ProcessChunk(PngChunk chunk)
{
var chunkType = chunk.ChunkType;
var bytes = chunk.Bytes;
if (chunkType == PngChunkType.IHDR)
{
var header = new PngHeader(bytes);
var directory = new PngDirectory(PngChunkType.IHDR);
directory.Set(PngDirectory.TagImageWidth, header.ImageWidth);
directory.Set(PngDirectory.TagImageHeight, header.ImageHeight);
directory.Set(PngDirectory.TagBitsPerSample, header.BitsPerSample);
directory.Set(PngDirectory.TagColorType, header.ColorType.NumericValue);
directory.Set(PngDirectory.TagCompressionType, header.CompressionType);
directory.Set(PngDirectory.TagFilterMethod, header.FilterMethod);
directory.Set(PngDirectory.TagInterlaceMethod, header.InterlaceMethod);
yield return(directory);
}
else if (chunkType == PngChunkType.PLTE)
{
var directory = new PngDirectory(PngChunkType.PLTE);
directory.Set(PngDirectory.TagPaletteSize, bytes.Length / 3);
yield return(directory);
}
else if (chunkType == PngChunkType.tRNS)
{
var directory = new PngDirectory(PngChunkType.tRNS);
directory.Set(PngDirectory.TagPaletteHasTransparency, 1);
yield return(directory);
}
else if (chunkType == PngChunkType.sRGB)
{
int srgbRenderingIntent = unchecked ((sbyte)bytes[0]);
var directory = new PngDirectory(PngChunkType.sRGB);
directory.Set(PngDirectory.TagSrgbRenderingIntent, srgbRenderingIntent);
yield return(directory);
}
else if (chunkType == PngChunkType.cHRM)
{
var chromaticities = new PngChromaticities(bytes);
var directory = new PngChromaticitiesDirectory();
directory.Set(PngChromaticitiesDirectory.TagWhitePointX, chromaticities.WhitePointX);
directory.Set(PngChromaticitiesDirectory.TagWhitePointY, chromaticities.WhitePointY);
directory.Set(PngChromaticitiesDirectory.TagRedX, chromaticities.RedX);
directory.Set(PngChromaticitiesDirectory.TagRedY, chromaticities.RedY);
directory.Set(PngChromaticitiesDirectory.TagGreenX, chromaticities.GreenX);
directory.Set(PngChromaticitiesDirectory.TagGreenY, chromaticities.GreenY);
directory.Set(PngChromaticitiesDirectory.TagBlueX, chromaticities.BlueX);
directory.Set(PngChromaticitiesDirectory.TagBlueY, chromaticities.BlueY);
yield return(directory);
}
else if (chunkType == PngChunkType.gAMA)
{
var gammaInt = ByteConvert.ToInt32BigEndian(bytes);
var directory = new PngDirectory(PngChunkType.gAMA);
directory.Set(PngDirectory.TagGamma, gammaInt / 100000.0);
yield return(directory);
}
else if (chunkType == PngChunkType.iCCP)
{
var reader = new SequentialByteArrayReader(bytes);
var profileName = reader.GetNullTerminatedStringValue(maxLengthBytes: 79);
var directory = new PngDirectory(PngChunkType.iCCP);
directory.Set(PngDirectory.TagIccProfileName, profileName);
var compressionMethod = reader.GetSByte();
if (compressionMethod == 0)
{
// Only compression method allowed by the spec is zero: deflate
// This assumes 1-byte-per-char, which it is by spec.
var bytesLeft = bytes.Length - profileName.Bytes.Length - 2;
// http://george.chiramattel.com/blog/2007/09/deflatestream-block-length-does-not-match.html
// First two bytes are part of the zlib specification (RFC 1950), not the deflate specification (RFC 1951).
reader.Skip(2);
bytesLeft -= 2;
var compressedProfile = reader.GetBytes(bytesLeft);
IccDirectory?iccDirectory = null;
Exception? ex = null;
try
{
using var inflaterStream = new DeflateStream(new MemoryStream(compressedProfile), CompressionMode.Decompress);
iccDirectory = new IccReader().Extract(new IndexedCapturingReader(inflaterStream));
iccDirectory.Parent = directory;
}
catch (Exception e)
{
ex = e;
}
if (iccDirectory != null)
{
yield return(iccDirectory);
}
else if (ex != null)
{
directory.AddError($"Exception decompressing {nameof(PngChunkType.iCCP)} chunk: {ex.Message}");
}
}
else
{
directory.AddError("Invalid compression method value");
}
yield return(directory);
}
else if (chunkType == PngChunkType.bKGD)
{
var directory = new PngDirectory(PngChunkType.bKGD);
directory.Set(PngDirectory.TagBackgroundColor, bytes);
yield return(directory);
}
else if (chunkType == PngChunkType.tEXt)
{
var reader = new SequentialByteArrayReader(bytes);
var keyword = reader.GetNullTerminatedStringValue(maxLengthBytes: 79).ToString(_latin1Encoding);
var bytesLeft = bytes.Length - keyword.Length - 1;
var value = reader.GetNullTerminatedStringValue(bytesLeft, _latin1Encoding);
var textPairs = new List <KeyValuePair> {
new KeyValuePair(keyword, value)
};
var directory = new PngDirectory(PngChunkType.tEXt);
directory.Set(PngDirectory.TagTextualData, textPairs);
yield return(directory);
}
else if (chunkType == PngChunkType.zTXt)
{
var reader = new SequentialByteArrayReader(bytes);
var keyword = reader.GetNullTerminatedStringValue(maxLengthBytes: 79).ToString(_latin1Encoding);
var compressionMethod = reader.GetSByte();
var bytesLeft = bytes.Length - keyword.Length - 1 - 1 - 1 - 1;
byte[]? textBytes = null;
if (compressionMethod == 0)
{
if (!TryDeflate(bytes, bytesLeft, out textBytes, out string?errorMessage))
{
var directory = new PngDirectory(PngChunkType.zTXt);
directory.AddError($"Exception decompressing {nameof(PngChunkType.zTXt)} chunk with keyword \"{keyword}\": {errorMessage}");
yield return(directory);
}
}
else
{
var directory = new PngDirectory(PngChunkType.zTXt);
directory.AddError("Invalid compression method value");
yield return(directory);
}
if (textBytes != null)
{
foreach (var directory in ProcessTextChunk(keyword, textBytes))
{
yield return(directory);
}
}
}
else if (chunkType == PngChunkType.iTXt)
{
var reader = new SequentialByteArrayReader(bytes);
var keyword = reader.GetNullTerminatedStringValue(maxLengthBytes: 79).ToString(_latin1Encoding);
var compressionFlag = reader.GetSByte();
var compressionMethod = reader.GetSByte();
// TODO we currently ignore languageTagBytes and translatedKeywordBytes
var languageTagBytes = reader.GetNullTerminatedBytes(bytes.Length);
var translatedKeywordBytes = reader.GetNullTerminatedBytes(bytes.Length);
var bytesLeft = bytes.Length - keyword.Length - 1 - 1 - 1 - languageTagBytes.Length - 1 - translatedKeywordBytes.Length - 1;
byte[]? textBytes = null;
if (compressionFlag == 0)
{
textBytes = reader.GetNullTerminatedBytes(bytesLeft);
}
else if (compressionFlag == 1)
{
if (compressionMethod == 0)
{
if (!TryDeflate(bytes, bytesLeft, out textBytes, out string?errorMessage))
{
var directory = new PngDirectory(PngChunkType.iTXt);
directory.AddError($"Exception decompressing {nameof(PngChunkType.iTXt)} chunk with keyword \"{keyword}\": {errorMessage}");
yield return(directory);
}
}
else
{
var directory = new PngDirectory(PngChunkType.iTXt);
directory.AddError("Invalid compression method value");
yield return(directory);
}
}
else
{
var directory = new PngDirectory(PngChunkType.iTXt);
directory.AddError("Invalid compression flag value");
yield return(directory);
}
if (textBytes != null)
{
foreach (var directory in ProcessTextChunk(keyword, textBytes))
{
yield return(directory);
}
}
}
else if (chunkType == PngChunkType.tIME)
{
var reader = new SequentialByteArrayReader(bytes);
var year = reader.GetUInt16();
var month = reader.GetByte();
int day = reader.GetByte();
int hour = reader.GetByte();
int minute = reader.GetByte();
int second = reader.GetByte();
var directory = new PngDirectory(PngChunkType.tIME);
if (DateUtil.IsValidDate(year, month, day) && DateUtil.IsValidTime(hour, minute, second))
{
var time = new DateTime(year, month, day, hour, minute, second, DateTimeKind.Unspecified);
directory.Set(PngDirectory.TagLastModificationTime, time);
}
else
{
directory.AddError($"PNG tIME data describes an invalid date/time: year={year} month={month} day={day} hour={hour} minute={minute} second={second}");
}
yield return(directory);
}
else if (chunkType == PngChunkType.pHYs)
{
var reader = new SequentialByteArrayReader(bytes);
var pixelsPerUnitX = reader.GetInt32();
var pixelsPerUnitY = reader.GetInt32();
var unitSpecifier = reader.GetSByte();
var directory = new PngDirectory(PngChunkType.pHYs);
directory.Set(PngDirectory.TagPixelsPerUnitX, pixelsPerUnitX);
directory.Set(PngDirectory.TagPixelsPerUnitY, pixelsPerUnitY);
directory.Set(PngDirectory.TagUnitSpecifier, unitSpecifier);
yield return(directory);
}
else if (chunkType.Equals(PngChunkType.sBIT))
{
var directory = new PngDirectory(PngChunkType.sBIT);
directory.Set(PngDirectory.TagSignificantBits, bytes);
yield return(directory);
}
yield break;
IEnumerable <Directory> ProcessTextChunk(string keyword, byte[] textBytes)
{
if (keyword == "XML:com.adobe.xmp")
{
yield return(new XmpReader().Extract(textBytes));
}
else if (keyword == "Raw profile type xmp")
{
if (TryProcessRawProfile(out int byteCount))
{
yield return(new XmpReader().Extract(textBytes, 0, byteCount));
}
else
{
yield return(ReadTextDirectory(keyword, textBytes, chunkType));
}
}
else if (keyword == "Raw profile type exif" || keyword == "Raw profile type APP1")
{
if (TryProcessRawProfile(out _))
{
foreach (var exifDirectory in new ExifReader().Extract(new ByteArrayReader(textBytes)))
{
yield return(exifDirectory);
}
}
else
{
yield return(ReadTextDirectory(keyword, textBytes, chunkType));
}
}
else if (keyword == "Raw profile type icc" || keyword == "Raw profile type icm")
{
if (TryProcessRawProfile(out _))
{
yield return(new IccReader().Extract(new ByteArrayReader(textBytes)));
}
else
{
yield return(ReadTextDirectory(keyword, textBytes, chunkType));
}
}
else if (keyword == "Raw profile type iptc")
{
if (TryProcessRawProfile(out int byteCount))
{
yield return(new IptcReader().Extract(new SequentialByteArrayReader(textBytes), byteCount));
}
else
{
yield return(ReadTextDirectory(keyword, textBytes, chunkType));
}
}
else
{
yield return(ReadTextDirectory(keyword, textBytes, chunkType));
}
PngDirectory ReadTextDirectory(string keyword, byte[] textBytes, PngChunkType pngChunkType)
{
var textPairs = new[] { new KeyValuePair(keyword, new StringValue(textBytes, _latin1Encoding)) };
var directory = new PngDirectory(pngChunkType);
directory.Set(PngDirectory.TagTextualData, textPairs);
return(directory);
}
bool TryProcessRawProfile(out int byteCount)
{
// Raw profiles have form "\n<name>\n<length>\n<hex>\n"
if (textBytes.Length == 0 || textBytes[0] != '\n')
{
byteCount = default;
return(false);
}
var i = 1;
// Skip name
while (i < textBytes.Length && textBytes[i] != '\n')
{
i++;
}
if (i == textBytes.Length)
{
byteCount = default;
return(false);
}
// Read length
int length = 0;
while (true)
{
i++;
var c = (char)textBytes[i];
if (c == ' ')
{
continue;
}
if (c == '\n')
{
break;
}
if (c >= '0' && c <= '9')
{
length *= 10;
length += c - '0';
}
else
{
byteCount = default;
return(false);
}
}
i++;
// We should be at the ASCII-encoded hex data. Walk through the remaining bytes, re-writing as raw bytes
// starting at offset zero in the array. We have to skip \n characters.
// Validate the data can be correctly parsed before modifying it in-place, because if parsing fails later
// consumers may want the unmodified data.
// Each row must have 72 characters (36 bytes once decoded) separated by \n
const int rowCharCount = 72;
int charsInRow = rowCharCount;
for (int j = i; j < length + i; j++)
{
byte c = textBytes[j];
if (charsInRow-- == 0)
{
if (c != '\n')
{
byteCount = default;
return(false);
}
charsInRow = rowCharCount;
continue;
}
if ((c < '0' || c > '9') && (c < 'a' || c > 'f') && (c < 'A' || c > 'F'))
{
byteCount = default;
return(false);
}
}
byteCount = length;
var writeIndex = 0;
charsInRow = rowCharCount;
while (length > 0)
{
var c1 = textBytes[i++];
if (charsInRow-- == 0)
{
Debug.Assert(c1 == '\n');
charsInRow = rowCharCount;
continue;
}
var c2 = textBytes[i++];
charsInRow--;
var n1 = ParseHexNibble(c1);
var n2 = ParseHexNibble(c2);
length--;
textBytes[writeIndex++] = (byte)((n1 << 4) | n2);
}
return(writeIndex == byteCount);
static int ParseHexNibble(int h)
{
if (h >= '0' && h <= '9')
{
return(h - '0');
}
if (h >= 'a' && h <= 'f')
{
return(10 + (h - 'a'));
}
if (h >= 'A' && h <= 'F')
{
return(10 + (h - 'A'));
}
Debug.Fail("Should not reach here");
throw new InvalidOperationException();
}
}
