private void ReadzTXtChunk(int data_length)
{
long position = Tell;
ByteVector data = ReadChunkData(data_length);
CheckCRC(zTXt_CHUNK_TYPE, data, ReadCRC());
int terminator_index;
string keyword = ReadKeyword(data, 0, out terminator_index);
if (terminator_index + 1 >= data_length)
{
throw new CorruptFileException("Compression Method byte expected");
}
byte compression_method = data[terminator_index + 1];
ByteVector plain_data = Decompress(compression_method, data.Mid(terminator_index + 2));
if (plain_data == null)
{
return;
}
string value = plain_data.ToString();
PngTag png_tag = GetTag(TagTypes.Png, true)
as PngTag;
if (png_tag.GetKeyword(keyword) == null)
{
png_tag.SetKeyword(keyword, value);
}
AddMetadataBlock(position - 8, data_length + 8 + 4);
}
/// <summary>
/// Creates a list of Chunks containing the PNG keywords
/// </summary>
/// <returns>
/// A <see cref="ByteVector"/> with the list of chunks, or
/// or <see langword="null" /> if no PNG Keywords are contained.
/// </returns>
private ByteVector RenderKeywordChunks()
{
// Check, if PngTag is contained
PngTag png_tag = GetTag(TagTypes.Png, true) as PngTag;
if (png_tag == null)
{
return(null);
}
ByteVector chunks = new ByteVector();
foreach (KeyValuePair <string, string> keyword in png_tag)
{
ByteVector data = new ByteVector();
data.Add(keyword.Key);
data.Add("\0");
data.Add(keyword.Value);
chunks.Add(ByteVector.FromUInt((uint)data.Count));
chunks.Add(tEXt_CHUNK_TYPE);
chunks.Add(data);
chunks.Add(ComputeCRC(tEXt_CHUNK_TYPE, data));
}
return(chunks);
}
/// <summary>
/// Reads an tEXt Chunk from file. The current position must be set
/// to the start of the Chunk Data. Such a Chunk contains plain
/// keywords.
/// </summary>
/// <param name="data_length">
/// A <see cref="System.Int32"/> with the length of the Chunk Data.
/// </param>
private void ReadtEXtChunk(int data_length)
{
long position = Tell;
// tEXt Chunk
//
// N Bytes Keyword
// 1 Byte Null Separator
// N Bytes Txt
//
// Followed by 4 Bytes CRC data
ByteVector data = ReadChunkData(data_length);
CheckCRC(tEXt_CHUNK_TYPE, data, ReadCRC());
int keyword_terminator;
string keyword = ReadKeyword(data, 0, out keyword_terminator);
string value = data.Mid(keyword_terminator + 1).ToString();
PngTag png_tag = GetTag(TagTypes.Png, true) as PngTag;
if (png_tag.GetKeyword(keyword) == null)
{
png_tag.SetKeyword(keyword, value);
}
AddMetadataBlock(position - 8, data_length + 8 + 4);
}
/// <summary>
/// Reads an zTXt Chunk from file. The current position must be set
/// to the start of the Chunk Data. Such a Chunk contains compressed
/// keywords.
/// </summary>
/// <param name="data_length">
/// A <see cref="System.Int32"/> with the length of the Chunk Data.
/// </param>
/// <remarks>
/// The Chunk may also contain compressed Exif data which is written
/// by other tools. But, since the PNG specification does not support
/// Exif data, we ignore it here.
/// </remarks>
private void ReadzTXtChunk(int data_length)
{
long position = Tell;
// zTXt Chunk
//
// N Bytes Keyword
// 1 Byte Null Separator
// 1 Byte Compression Method
// N Bytes Txt
//
// Followed by 4 Bytes CRC data
ByteVector data = ReadChunkData(data_length);
CheckCRC(zTXt_CHUNK_TYPE, data, ReadCRC());
int terminator_index;
string keyword = ReadKeyword(data, 0, out terminator_index);
if (terminator_index + 1 >= data_length)
{
throw new CorruptFileException("Compression Method byte expected");
}
byte compression_method = data [terminator_index + 1];
ByteVector plain_data = Decompress(compression_method, data.Mid(terminator_index + 2));
// ignore unknown compression methods
if (plain_data == null)
{
return;
}
string value = plain_data.ToString();
RawProfile rawProfile = null;
if (keyword.StartsWith("Raw profile type"))
{
rawProfile = ProcessRawProfile(value);
value = rawProfile.ToString();
}
// handle XMP, which has a fixed header
if (keyword == "xmp" || rawProfile != null && string.Compare(rawProfile.Name, "xmp", StringComparison.InvariantCultureIgnoreCase) == 0)
{
ImageTag.AddTag(new XmpTag(string.Join("", rawProfile.Data.ToArray()), this));
}
else
{
PngTag png_tag = GetTag(TagTypes.Png, true) as PngTag;
if (png_tag.GetKeyword(keyword) == null)
{
png_tag.SetKeyword(keyword, value);
}
}
AddMetadataBlock(position - 8, data_length + 8 + 4);
}
private void ReadiTXtChunk(int data_length)
{
long position = Tell;
ByteVector data = ReadChunkData(data_length);
CheckCRC(iTXt_CHUNK_TYPE, data, ReadCRC());
if (data.StartsWith(XMP_CHUNK_HEADER))
{
ImageTag.AddTag(new XmpTag(data.Mid(XMP_CHUNK_HEADER.Length).ToString(StringType.UTF8), this));
AddMetadataBlock(position - 8, data_length + 8 + 4);
return;
}
int terminator_index;
string keyword = ReadKeyword(data, 0, out terminator_index);
if (terminator_index + 2 >= data_length)
{
throw new CorruptFileException("Compression Flag and Compression Method byte expected");
}
byte compression_flag = data[terminator_index + 1];
byte compression_method = data[terminator_index + 2];
ByteVector txt_data = data.Mid(terminator_index + 1);
if (compression_flag != 0x00)
{
txt_data = Decompress(compression_method, txt_data);
if (txt_data == null)
{
return;
}
}
string value = txt_data.ToString();
PngTag png_tag = GetTag(TagTypes.Png, true)
as PngTag;
if (png_tag.GetKeyword(keyword) == null)
{
png_tag.SetKeyword(keyword, value);
}
AddMetadataBlock(position - 8, data_length + 8 + 4);
}
/// <summary>
/// Gets a tag of a specified type from the current instance,
/// optionally creating a new tag if possible.
/// </summary>
/// <param name="type">
/// A <see cref="TagLib.TagTypes" /> value indicating the
/// type of tag to read.
/// </param>
/// <param name="create">
/// A <see cref="bool" /> value specifying whether or not to
/// try and create the tag if one is not found.
/// </param>
/// <returns>
/// A <see cref="Tag" /> object containing the tag that was
/// found in or added to the current instance. If no
/// matching tag was found and none was created, <see
/// langword="null" /> is returned.
/// </returns>
public override TagLib.Tag GetTag (TagLib.TagTypes type,
bool create)
{
foreach (Tag tag in ImageTag.AllTags) {
if ((tag.TagTypes & type) == type)
return tag;
}
if (!create || (type & ImageTag.AllowedTypes) == 0)
return null;
ImageTag new_tag = null;
switch (type) {
case TagTypes.JpegComment:
new_tag = new JpegCommentTag ();
break;
case TagTypes.GifComment:
new_tag = new GifCommentTag ();
break;
case TagTypes.Png:
new_tag = new PngTag ();
break;
case TagTypes.TiffIFD:
new_tag = new IFDTag ();
break;
case TagTypes.XMP:
new_tag = new XmpTag ();
break;
}
if (new_tag != null) {
ImageTag.AddTag (new_tag);
return new_tag;
}
throw new NotImplementedException (String.Format ("Adding tag of type {0} not supported!", type));
}
/// <summary>
/// Reads an iTXt Chunk from file. The current position must be set
/// to the start of the Chunk Data. Such a Chunk may contain XMP data
/// or translated keywords.
/// </summary>
/// <param name="data_length">
/// A <see cref="System.Int32"/> with the length of the Chunk Data.
/// </param>
private void ReadiTXtChunk(int data_length)
{
long position = Tell;
// iTXt Chunk
//
// N Bytes Keyword
// 1 Byte Null Separator
// 1 Byte Compression Flag (0 for uncompressed data)
// 1 Byte Compression Method
// N Bytes Language Tag
// 1 Byte Null Separator
// N Bytes Translated Keyword
// 1 Byte Null Terminator
// N Bytes Txt
//
// Followed by 4 Bytes CRC data
ByteVector data = ReadChunkData(data_length);
CheckCRC(iTXt_CHUNK_TYPE, data, ReadCRC());
// handle XMP, which has a fixed header
if (data.StartsWith(XMP_CHUNK_HEADER))
{
ImageTag.AddTag(new XmpTag(data.Mid(XMP_CHUNK_HEADER.Length).ToString(StringType.UTF8), this));
AddMetadataBlock(position - 8, data_length + 8 + 4);
return;
}
int terminator_index;
string keyword = ReadKeyword(data, 0, out terminator_index);
if (terminator_index + 2 >= data_length)
{
throw new CorruptFileException("Compression Flag and Compression Method byte expected");
}
byte compression_flag = data[terminator_index + 1];
byte compression_method = data[terminator_index + 2];
//string language = ReadTerminatedString (data, terminator_index + 3, out terminator_index);
//string translated_keyword = ReadTerminatedString (data, terminator_index + 1, out terminator_index);
ByteVector txt_data = data.Mid(terminator_index + 1);
if (compression_flag != 0x00)
{
txt_data = Decompress(compression_method, txt_data);
// ignore unknown compression methods
if (txt_data == null)
{
return;
}
}
string value = txt_data.ToString();
PngTag png_tag = GetTag(TagTypes.Png, true) as PngTag;
if (png_tag.GetKeyword(keyword) == null)
{
png_tag.SetKeyword(keyword, value);
}
AddMetadataBlock(position - 8, data_length + 8 + 4);
}