/// <summary>
/// Reads atom data from <paramref name="stream"/>, invoking <paramref name="handler"/> for each atom encountered.
/// </summary>
/// <param name="stream">The stream to read atoms from.</param>
/// <param name="handler">A callback function to handle each atom.</param>
/// <param name="stopByBytes">The maximum number of bytes to process before discontinuing.</param>
public static void ProcessAtoms([NotNull] Stream stream, [NotNull] Action <AtomCallbackArgs> handler, long stopByBytes = -1)
{
var reader = new SequentialStreamReader(stream);
var seriesStartPos = stream.Position;
while (stopByBytes == -1 || stream.Position < seriesStartPos + stopByBytes)
{
var atomStartPos = stream.Position;
// Length of the atom's data, in bytes, including size bytes
long atomSize;
try
{
atomSize = reader.GetUInt32();
}
catch (IOException)
{
// TODO don't use exception to trap end of stream
return;
}
// Typically four ASCII characters, but may be non-printable.
// By convention, lowercase 4CCs are reserved by Apple.
var atomType = reader.GetUInt32();
if (atomSize == 1)
{
// Size doesn't fit in 32 bits so read the 64 bit size here
atomSize = checked ((long)reader.GetUInt64());
}
else
{
Debug.Assert(atomSize >= 8, "Atom should be at least 8 bytes long");
}
var args = new AtomCallbackArgs(atomType, atomSize, stream, atomStartPos, reader);
handler(args);
if (args.Cancel)
{
return;
}
if (atomSize == 0)
{
return;
}
var toSkip = atomStartPos + atomSize - stream.Position;
if (toSkip < 0)
{
throw new Exception("Handler moved stream beyond end of atom");
}
reader.TrySkip(toSkip);
}
}
/// <summary>
/// Reads atom data from <paramref name="stream"/>, invoking <paramref name="handler"/> for each atom encountered.
/// </summary>
/// <param name="stream">The stream to read atoms from.</param>
/// <param name="handler">A callback function to handle each atom.</param>
/// <param name="stopByBytes">The maximum number of bytes to process before discontinuing.</param>
public static void ProcessAtoms([NotNull] Stream stream, [NotNull] Action <AtomCallbackArgs> handler, long stopByBytes = -1)
{
var reader = new SequentialStreamReader(stream);
var seriesStartPos = stream.Position;
while (stopByBytes == -1 || stream.Position < seriesStartPos + stopByBytes)
{
var atomStartPos = stream.Position;
try
{
// Check if the end of the stream is closer then 8 bytes to current position (Length of the atom's data + atom type)
if (reader.IsCloserToEnd(8))
{
return;
}
// Length of the atom's data, in bytes, including size bytes
long atomSize = reader.GetUInt32();
// Typically four ASCII characters, but may be non-printable.
// By convention, lowercase 4CCs are reserved by Apple.
var atomType = reader.GetUInt32();
if (atomSize == 1)
{
// Check if the end of the stream is closer then 8 bytes
if (reader.IsCloserToEnd(8))
{
return;
}
// Size doesn't fit in 32 bits so read the 64 bit size here
atomSize = checked ((long)reader.GetUInt64());
}
else if (atomSize < 8)
{
// Atom should be at least 8 bytes long
return;
}
var args = new AtomCallbackArgs(atomType, atomSize, stream, atomStartPos, reader);
handler(args);
if (args.Cancel)
{
return;
}
if (atomSize == 0)
{
return;
}
var toSkip = atomStartPos + atomSize - stream.Position;
if (toSkip < 0)
{
throw new Exception("Handler moved stream beyond end of atom");
}
// To avoid exception handling we can check if needed number of bytes are available
if (!reader.IsCloserToEnd(toSkip))
{
reader.TrySkip(toSkip);
}
}
catch (IOException)
{
// Exception trapping is used when stream doesn't support stream length method only
return;
}
}
}
protected override void Populate(Stream stream, int offset, TgaExtensionDirectory directory)
{
var reader = new SequentialStreamReader(stream, isMotorolaByteOrder: false);
var size = reader.GetUInt16();
if (size < ExtensionSize)
{
throw new ImageProcessingException("Invalid TGA extension size");
}
var authorName = GetString(41);
if (authorName.Length > 0)
{
directory.Set(TgaExtensionDirectory.TagAuthorName, authorName);
}
var comments = GetString(324);
if (comments.Length > 0)
{
directory.Set(TgaExtensionDirectory.TagComments, comments);
}
if (TryGetDateTime(out var dateTime))
{
directory.Set(TgaExtensionDirectory.TagDateTime, dateTime);
}
var jobName = GetString(41);
if (jobName.Length > 0)
{
directory.Set(TgaExtensionDirectory.TagJobName, jobName);
}
if (TryGetTimeSpan(out var jobTime))
{
directory.Set(TgaExtensionDirectory.TagJobTime, jobTime);
}
var softwareName = GetString(41);
if (softwareName.Length > 0)
{
directory.Set(TgaExtensionDirectory.TagSoftwareName, softwareName);
}
var softwareVersion = GetSoftwareVersion(softwareName);
if (softwareVersion.Length > 0)
{
directory.Set(TgaExtensionDirectory.TagSoftwareVersion, softwareVersion);
}
var keyColor = reader.GetUInt32();
if (keyColor != 0)
{
directory.Set(TgaExtensionDirectory.TagKeyColor, keyColor);
}
if (TryGetRational(out var aspectRatio))
{
directory.Set(TgaExtensionDirectory.TagAspectRatio, aspectRatio);
}
if (TryGetRational(out var gamma))
{
directory.Set(TgaExtensionDirectory.TagGamma, gamma);
}
var colorCorrectionOffset = reader.GetInt32();
if (colorCorrectionOffset != 0)
{
directory.Set(TgaExtensionDirectory.TagColorCorrectionOffset, colorCorrectionOffset);
}
var thumbnailOffset = reader.GetInt32();
if (thumbnailOffset != 0)
{
directory.Set(TgaExtensionDirectory.TagThumbnailOffset, thumbnailOffset);
}
var scanLineOffset = reader.GetInt32();
if (scanLineOffset != 0)
{
directory.Set(TgaExtensionDirectory.TagScanLineOffset, scanLineOffset);
}
var attributesType = reader.GetByte();
directory.Set(TgaExtensionDirectory.TagAttributesType, attributesType);
string GetString(int length)
{
var buffer = new byte[length];
reader.GetBytes(buffer, 0, length);
int i = 0;
while (i < buffer.Length && buffer[i] != '\0')
{
++i;
}
return(Encoding.ASCII.GetString(buffer, 0, i).TrimEnd());
}
bool TryGetDateTime(out DateTime dateTime)
{
var month = reader.GetInt16();
var day = reader.GetInt16();
var year = reader.GetInt16();
var hour = reader.GetInt16();
var minute = reader.GetInt16();
var second = reader.GetInt16();
if (month == 0 && day == 0 && year == 0)
{
dateTime = DateTime.MinValue;
return(false);
}
dateTime = new DateTime(year, month, day, hour, minute, second);
return(true);
}
bool TryGetTimeSpan(out TimeSpan timeSpan)
{
var hours = reader.GetInt16();
var minutes = reader.GetInt16();
var seconds = reader.GetInt16();
if (hours == 0 && minutes == 0 && seconds == 0)
{
timeSpan = TimeSpan.Zero;
return(false);
}
timeSpan = new TimeSpan(hours, minutes, seconds);
return(true);
}
string GetSoftwareVersion(string softwareName)
{
var number = reader.GetUInt16();
var letter = reader.GetByte();
if (number == 0)
{
return(string.Empty);
}
var sb = new StringBuilder();
var denom = softwareName != "Paint Shop Pro" ? 100 : 0x100;
sb.Append(number / denom);
sb.Append('.');
sb.Append(number % denom);
if (letter != 0 && letter != 0x20)
{
sb.Append((char)letter);
}
return(sb.ToString());
}
bool TryGetRational(out Rational value)
{
var num = reader.GetUInt16();
var denom = reader.GetUInt16();
if (denom == 0)
{
value = default;
return(false);
}
value = new Rational(num, denom);
return(true);
}
}
