/// <summary>
/// Creates a <see cref="ByteVector"/> for the comment segment of this file
/// </summary>
/// <returns>
/// A <see cref="ByteVector"/> with the whole comment segment, if a comment tag
/// exists, otherwise null.
/// </returns>
private ByteVector RenderCOMSegment()
{
// check, if Comment is contained
JpegCommentTag com_tag = GetTag(TagTypes.JpegComment) as JpegCommentTag;
if (com_tag == null)
{
return(null);
}
// create comment data
ByteVector com_data =
ByteVector.FromString(com_tag.Value + "\0", StringType.Latin1);
uint segment_size = (uint)(2 + com_data.Count);
// do not render data segments, which cannot fit into the possible segment size
if (segment_size > ushort.MaxValue)
{
throw new Exception("Comment Segment is too big to render");
}
// create segment
ByteVector data = new ByteVector(new byte [] { 0xFF, (byte)Marker.COM });
data.Add(ByteVector.FromUShort((ushort)segment_size));
data.Add(com_data);
return(data);
}
/// <summary>
/// Reads a COM segment to find the JPEG comment.
/// </summary>
/// <param name="length">
/// The length of the segment that will be read.
/// </param>
private void ReadCOMSegment(int length)
{
if ((ImageTag.TagTypes & TagLib.TagTypes.JpegComment) != 0x00)
{
return;
}
long position = Tell;
JpegCommentTag com_tag;
if (length == 0)
{
com_tag = new JpegCommentTag();
}
else
{
ByteVector data = ReadBlock(length);
int terminator = data.Find("\0", 0);
if (terminator < 0)
{
com_tag = new JpegCommentTag(data.ToString());
}
else
{
com_tag = new JpegCommentTag(data.Mid(0, terminator).ToString());
}
}
ImageTag.AddTag(com_tag);
AddMetadataBlock(position - 4, length + 4);
}
private ByteVector RenderCOMSegment()
{
JpegCommentTag com_tag = GetTag(TagTypes.JpegComment)
as JpegCommentTag;
if (com_tag == null)
{
return(null);
}
ByteVector com_data = ByteVector.FromString(com_tag.Value + "\0", StringType.Latin1);
uint segment_size = (uint)(2 + com_data.Count);
if (segment_size > ushort.MaxValue)
{
throw new Exception("Comment Segment is too big to render");
}
ByteVector data = new ByteVector(new byte[] { 0xFF, (byte)Marker.COM });
data.Add(ByteVector.FromUShort((ushort)segment_size));
data.Add(com_data);
return(data);
}
/// <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 a COM segment to find the JPEG comment.
/// </summary>
/// <param name="length">
/// The length of the segment that will be read.
/// </param>
private void ReadCOMSegment (int length)
{
if ((ImageTag.TagTypes & TagLib.TagTypes.JpegComment) != 0x00)
return;
long position = Tell;
JpegCommentTag com_tag;
if (length == 0) {
com_tag = new JpegCommentTag ();
} else {
ByteVector data = ReadBlock (length);
int terminator = data.Find ("\0", 0);
if (terminator < 0)
com_tag = new JpegCommentTag (data.ToString ());
else
com_tag = new JpegCommentTag (data.Mid (0, terminator).ToString ());
}
ImageTag.AddTag (com_tag);
AddMetadataBlock (position - 4, length + 4);
}
/// <summary>
/// Reads a COM segment to find the JPEG comment.
/// </summary>
/// <param name="length">
/// The length of the segment that will be read.
/// </param>
private bool ReadCOMSegment (int length)
{
if (comment_position != 0)
return false;
comment_position = Tell;
JpegCommentTag com_tag;
if (length == 0)
com_tag = new JpegCommentTag ();
else
com_tag = new JpegCommentTag (ReadBlock (length - 1).ToString ());
ImageTag.AddTag (com_tag);
return true;
}
