private void SaveData(DataBlock identificationBlock,
Collection <DataBlock> applicationData)
{
_identificationBlock = identificationBlock;
StringBuilder sb;
if (_identificationBlock.Data.Length < 11)
{
string message
= "The identification block should be 11 bytes long but "
+ "is only " + _identificationBlock.Data.Length + " bytes.";
throw new ArgumentException(message, "identificationBlock");
}
if (_identificationBlock.Data.Length > 11)
{
string message
= "The identification block should be 11 bytes long but "
+ "is " + _identificationBlock.Data.Length + " bytes long. "
+ "Additional bytes are ignored.";
SetStatus(ErrorState.IdentificationBlockTooLong, message);
}
// Read application identifer
sb = new StringBuilder();
for (int i = 0; i < 8; i++)
{
sb.Append((char)_identificationBlock[i]);
}
_applicationIdentifier = sb.ToString();
// Read application authentication code
sb = new StringBuilder();
for (int i = 8; i < 11; i++)
{
sb.Append((char)_identificationBlock[i]);
}
_applicationAuthenticationCode = sb.ToString();
_applicationData = applicationData;
if (XmlDebugging)
{
WriteDebugXmlStartElement("IdentificationData");
WriteDebugXmlNode(identificationBlock.DebugXmlReader);
WriteDebugXmlElement("ApplicationIdentifier",
_applicationIdentifier);
WriteDebugXmlElement("ApplicationAuthenticationCode",
_applicationAuthenticationCode);
WriteDebugXmlEndElement();
WriteDebugXmlStartElement("ApplicationData");
foreach (DataBlock db in applicationData)
{
WriteDebugXmlNode(db.DebugXmlReader);
}
WriteDebugXmlEndElement();
WriteDebugXmlFinish();
}
}
/// <summary>
/// Constructor.
/// </summary>
/// <param name="identificationBlock">
/// Sets the <see cref="IdentificationBlock"/>
/// </param>
/// <param name="applicationData">
/// Sets the <see cref="ApplicationData"/>
/// </param>
public ApplicationExtension(DataBlock identificationBlock,
Collection <DataBlock> applicationData)
{
SaveData(identificationBlock, applicationData);
}
/// <summary>
/// Constructor.
/// </summary>
/// <param name="identificationBlock">
/// Sets the <see cref="IdentificationBlock"/>
/// </param>
/// <param name="applicationData">
/// Sets the <see cref="ApplicationData"/>
/// </param>
public ApplicationExtension( DataBlock identificationBlock,
Collection<DataBlock> applicationData )
{
SaveData( identificationBlock, applicationData );
}
/// <summary>
/// Skips variable length blocks up to and including next zero length
/// block (block terminator).
/// </summary>
/// <param name="inputStream">
/// The input stream to read.
/// </param>
protected void SkipBlocks( Stream inputStream )
{
DataBlock block;
do
{
block = new DataBlock( inputStream, _xmlDebugging );
}
while( block.DeclaredBlockSize > 0 && block.ErrorState == ErrorState.Ok );
}
public void WriteToStreamTest()
{
ReportStart();
MemoryStream s = new MemoryStream();
_block.WriteToStream( s );
s.Seek( 0, SeekOrigin.Begin );
DataBlock d = new DataBlock( s );
Assert.AreEqual( ErrorState.Ok, d.ConsolidatedState );
Assert.AreEqual( _block.DeclaredBlockSize, d.DeclaredBlockSize );
Assert.AreEqual( _block.ActualBlockSize, d.ActualBlockSize );
for( int i = 0; i < _block.ActualBlockSize; i++ )
{
Assert.AreEqual( _block.Data[i], d.Data[i], "byte " + i );
}
ReportEnd();
}
private void ConstructorStreamTestEmptyBlock( bool xmlDebugging )
{
Stream s = new MemoryStream();
s.WriteByte( 0 ); // write length (0 bytes)
s.Seek( 0, SeekOrigin.Begin ); // go to start of stream
_block = new DataBlock( s, xmlDebugging );
Assert.AreEqual( 0, _block.DeclaredBlockSize );
Assert.AreEqual( 0, _block.ActualBlockSize );
Assert.AreEqual( 0, _block.Data.Length );
Assert.AreEqual( ErrorState.Ok, _block.ConsolidatedState );
if( xmlDebugging )
{
Assert.AreEqual( ExpectedDebugXml, _block.DebugXml );
}
}
public void SkipBlocksTest()
{
ReportStart();
byte[] data1 = new byte[] { 24, 38, 53 };
byte[] data2 = new byte[] { 66, 23, 58, 56, 23 };
byte[] data3 = new byte[] { }; // block terminator
byte[] data4 = new byte[] { 43 };
byte[] data5 = new byte[] { }; // block terminator
MemoryStream s = new MemoryStream();
s.WriteByte( (byte) data1.Length );
s.Write( data1, 0, data1.Length );
s.WriteByte( (byte) data2.Length );
s.Write( data2, 0, data2.Length );
s.WriteByte( (byte) data3.Length );
s.Write( data3, 0, data3.Length );
s.WriteByte( (byte) data4.Length );
s.Write( data4, 0, data4.Length );
s.WriteByte( (byte) data5.Length );
s.Write( data5, 0, data5.Length );
s.Seek( 0, SeekOrigin.Begin );
_component.CallSkipBlocks( s );
DataBlock db;
db = new DataBlock( s );
Assert.AreEqual( data4.Length, db.DeclaredBlockSize );
Assert.AreEqual( data4.Length, db.ActualBlockSize );
Assert.AreEqual( data4, db.Data );
db = new DataBlock( s );
Assert.AreEqual( data5.Length, db.DeclaredBlockSize );
Assert.AreEqual( data5.Length, db.ActualBlockSize );
Assert.AreEqual( data5, db.Data );
ReportEnd();
}
public void ConstructorTestNullArgument()
{
ReportStart();
try
{
_block = new DataBlock( 1, null );
}
catch( ArgumentNullException ex )
{
Assert.AreEqual( "data", ex.ParamName );
ReportEnd();
throw;
}
}
/// <summary>
/// Constructor.
/// </summary>
/// <param name="inputStream">
/// The stream from which the image data is to be read, starting with
/// the LZW minimum code size, and ending with a block terminator.
/// </param>
/// <param name="pixelCount">
/// Number of pixels in the image.
/// </param>
/// <param name="xmlDebugging">Whether or not to create debug XML</param>
/// <remarks>
/// The input stream is read, first into the LZW minimum code size, then
/// into data blocks. Bytes are extracted from the data blocks into a
/// datum until the datum contains enough bits to form a code; this code
/// is then extracted from the datum and decoded into a pixel index.
/// Once all data has been read, or a block terminator,
/// end-of-information code or error condition is encountered, any
/// remaining pixel indices not already populated default to zero.
/// </remarks>
public TableBasedImageData( Stream inputStream,
int pixelCount,
bool xmlDebugging )
: base( xmlDebugging )
{
#region guard against silly image sizes
if( pixelCount < 1 )
{
string message
= "The pixel count must be greater than zero. "
+ "Supplied value was " + pixelCount;
throw new ArgumentOutOfRangeException( "pixelCount", message );
}
#endregion
#region declare / initialise local variables
_pixels = new IndexedPixels( pixelCount );
_dataBlocks = new Collection<DataBlock>();
int nextAvailableCode; // the next code to be added to the dictionary
int currentCodeSize;
int in_code;
int previousCode;
int code;
int datum = 0; // temporary storage for codes read from the input stream
int meaningfulBitsInDatum = 0; // number of bits of useful information held in the datum variable
int firstCode = 0; // first code read from the stream since last clear code
int indexInDataBlock = 0;
int pixelIndex = 0;
// number of bytes still to be extracted from the current data block
int bytesToExtract = 0;
short[] prefix = new short[_maxStackSize];
byte[] suffix = new byte[_maxStackSize];
Stack<byte> pixelStack = new Stack<byte>();
#endregion
// Initialize GIF data stream decoder.
_lzwMinimumCodeSize = Read( inputStream ); // number of bits initially used for LZW codes in image data
WriteDebugXmlElement( "LzwMinimumCodeSize", _lzwMinimumCodeSize );
nextAvailableCode = ClearCode + 2;
previousCode = _nullCode;
currentCodeSize = InitialCodeSize;
#region guard against LZW code size being too large
if( ClearCode >= _maxStackSize )
{
string message
= "LZW minimum code size: " + _lzwMinimumCodeSize
+ ". Clear code: " + ClearCode
+ ". Max stack size: " + _maxStackSize;
SetStatus( ErrorState.LzwMinimumCodeSizeTooLarge, message );
WriteDebugXmlFinish();
return;
}
#endregion
// TODO: what are prefix and suffix and why are we initialising them like this?
for( code = 0; code < ClearCode; code++ )
{
prefix[code] = 0;
suffix[code] = (byte) code;
}
WriteDebugXmlStartElement( "DataBlocks" );
#region decode LZW image data
// Initialise block to an empty data block. This will be overwritten
// first time through the loop with a data block read from the input
// stream.
DataBlock block = new DataBlock( 0, new byte[0] );
for( pixelIndex = 0; pixelIndex < pixelCount; )
{
if( pixelStack.Count == 0 )
{
// There are no pixels in the stack at the moment, so...
#region get some pixels and put them on the stack
if( meaningfulBitsInDatum < currentCodeSize )
{
// Then we don't have enough bits in the datum to make
// a code; we need to get some more from the current
// data block, or we may need to read another data
// block from the input stream
#region get another byte from the current data block
if( bytesToExtract == 0 )
{
// Then we've extracted all the bytes from the
// current data block, so...
#region read the next data block from the stream
block = ReadDataBlock( inputStream );
bytesToExtract = block.ActualBlockSize;
// Point to the first byte in the new data block
indexInDataBlock = 0;
if( block.TestState( ErrorState.DataBlockTooShort ) )
{
// then we've reached the end of the stream
// prematurely
break;
}
if( bytesToExtract == 0 )
{
// then it's a block terminator, end of the
// image data (this is a data block other than
// the first one)
break;
}
#endregion
}
// Append the contents of the current byte in the data
// block to the beginning of the datum
int newDatum = block[indexInDataBlock] << meaningfulBitsInDatum;
datum += newDatum;
// so we've now got 8 more bits of information in the
// datum.
meaningfulBitsInDatum += 8;
// Point to the next byte in the data block
indexInDataBlock++;
// We've one less byte still to read from the data block
// now.
bytesToExtract--;
// and carry on reading through the data block
continue;
#endregion
}
#region get the next code from the datum
// Get the least significant bits from the read datum, up
// to the maximum allowed by the current code size.
code = datum & GetMaximumPossibleCode( currentCodeSize );
// Drop the bits we've just extracted from the datum.
datum >>= currentCodeSize;
// Reduce the count of meaningful bits held in the datum
meaningfulBitsInDatum -= currentCodeSize;
#endregion
#region interpret the code
#region end of information?
if( code == EndOfInformation )
{
// We've reached an explicit marker for the end of the
// image data.
break;
}
#endregion
#region code not in dictionary?
if( code > nextAvailableCode )
{
// We expect the code to be either one which is already
// in the dictionary, or the next available one to be
// added. If it's neither of these then abandon
// processing of the image data.
string message
= "Next available code: " + nextAvailableCode
+ ". Last code read from input stream: " + code;
SetStatus( ErrorState.CodeNotInDictionary, message );
break;
}
#endregion
#region clear code?
if( code == ClearCode )
{
// We can get a clear code at any point in the image
// data, this is an instruction to reset the decoder
// and empty the dictionary of codes.
currentCodeSize = InitialCodeSize;
nextAvailableCode = ClearCode + 2;
previousCode = _nullCode;
// Carry on reading from the input stream.
continue;
}
#endregion
#region first code since last clear code?
if( previousCode == _nullCode )
{
// This is the first code read since the start of the
// image data or the most recent clear code.
// There's no previously read code in memory yet, so
// get the pixel index for the current code and add it
// to the stack.
pixelStack.Push( suffix[code] );
previousCode = code;
firstCode = code;
// and carry on to the next pixel
continue;
}
#endregion
in_code = code;
if( code == nextAvailableCode )
{
pixelStack.Push( (byte) firstCode );
code = previousCode;
}
while( code > ClearCode )
{
pixelStack.Push( suffix[code] );
code = prefix[code];
}
#endregion
firstCode = ((int) suffix[code]) & 0xff;
#region add a new string to the string table
if( nextAvailableCode >= _maxStackSize )
{
// TESTME: constructor - next available code >- _maxStackSize
break;
}
pixelStack.Push( (byte) firstCode );
prefix[nextAvailableCode] = (short) previousCode;
suffix[nextAvailableCode] = (byte) firstCode;
nextAvailableCode++;
#endregion
#region do we need to increase the code size?
if( ( nextAvailableCode & GetMaximumPossibleCode( currentCodeSize ) ) == 0 )
{
// We've reached the largest code possible for this size
if( nextAvailableCode < _maxStackSize )
{
// so increase the code size by 1
currentCodeSize++;
}
}
#endregion
previousCode = in_code;
#endregion
}
// Pop all the pixels currently on the stack off, and add them
// to the return value.
_pixels[pixelIndex] = pixelStack.Pop();
pixelIndex++;
}
#endregion
#region check input stream contains enough data to fill the image
if( pixelIndex < pixelCount )
{
string message
= "Expected pixel count: " + pixelCount
+ ". Actual pixel count: " + pixelIndex;
SetStatus( ErrorState.TooFewPixelsInImageData, message );
}
#endregion
if( XmlDebugging )
{
WriteDebugXmlEndElement();
byte[] bytes = new byte[_pixels.Count];
_pixels.CopyTo( bytes, 0 );
WriteDebugXmlByteValues( "IndexedPixels", bytes );
WriteDebugXmlFinish();
}
}
private DataBlock ReadDataBlock( Stream inputStream )
{
DataBlock block = new DataBlock( inputStream, XmlDebugging );
_dataBlocks.Add( block );
WriteDebugXmlNode( block.DebugXmlReader );
return block;
}
private static Collection<DataBlock> GetApplicationData( int repeatCount )
{
MemoryStream s = new MemoryStream();
WriteByte( 1, s );
WriteShort( repeatCount, s );
s.Seek( 0, SeekOrigin.Begin );
byte[] repeatData = new byte[3];
s.Read( repeatData, 0, 3 );
DataBlock repeatBlock = new DataBlock( 3, repeatData );
byte[] terminatorData = new byte[0];
DataBlock terminatorBlock = new DataBlock( 0, terminatorData );
Collection<DataBlock> appData = new Collection<DataBlock>();
appData.Add( repeatBlock );
appData.Add( terminatorBlock );
return appData;
}
private static DataBlock GetIdentificationBlock()
{
MemoryStream s = new MemoryStream();
WriteString( "NETSCAPE2.0", s );
s.Seek( 0, SeekOrigin.Begin );
byte[] identificationData = new byte[11];
s.Read( identificationData, 0, 11 );
DataBlock identificationBlock = new DataBlock( 11, identificationData );
return identificationBlock;
}
/// <summary>
/// Reads and returns an application extension from the supplied input
/// stream.
/// </summary>
/// <param name="inputStream">
/// The input stream to read.
/// </param>
/// <param name="xmlDebugging">Whether or not to create debug XML</param>
public ApplicationExtension( Stream inputStream, bool xmlDebugging )
: base( xmlDebugging )
{
DataBlock identificationBlock = new DataBlock( inputStream,
XmlDebugging );
Collection<DataBlock> applicationData = new Collection<DataBlock>();
if( !identificationBlock.TestState( ErrorState.EndOfInputStream ) )
{
// Read application specific data
DataBlock thisBlock;
do
{
thisBlock = new DataBlock( inputStream, XmlDebugging );
applicationData.Add( thisBlock );
}
// A zero-length block indicates the end of the data blocks
while( thisBlock.DeclaredBlockSize != 0
&& !thisBlock.TestState( ErrorState.EndOfInputStream )
);
}
SaveData( identificationBlock, applicationData );
}
public void ConstructorTest()
{
ReportStart();
_block = new DataBlock( 4, _data );
Assert.AreEqual( 4, _block.ActualBlockSize );
Assert.AreEqual( 4, _block.DeclaredBlockSize );
Assert.AreEqual( ErrorState.Ok, _block.ConsolidatedState );
Assert.AreEqual( _data.Length, _block.Data.Length );
for( int i = 0; i < _data.Length; i++ )
{
Assert.AreEqual( _data[i], _block.Data[i], i );
Assert.AreEqual( _data[i], _block[i], i );
}
ReportEnd();
}
public void ConstructorTestNot2Point0()
{
byte[] idData = new byte[]
{
(byte) 'N',
(byte) 'E',
(byte) 'T',
(byte) 'S',
(byte) 'C',
(byte) 'A',
(byte) 'P',
(byte) 'E',
(byte) '3',
(byte) '.',
(byte) '0',
};
DataBlock idBlock = new DataBlock( 11, idData );
ApplicationExtension appExt
= new ApplicationExtension( idBlock, new Collection<DataBlock>() );
try
{
_ne = new NetscapeExtension( appExt );
}
catch( ArgumentException ex )
{
string message
= "The application authentication code is not '2.0' "
+ "therefore this application extension is not a "
+ "Netscape extension. Application authentication code: 3.0";
StringAssert.Contains( message, ex.Message );
Assert.AreEqual( "applicationExtension", ex.ParamName );
throw;
}
}
public void ConstructorTestBlockSizeTooSmall()
{
ReportStart();
_block = new DataBlock( 5, _data );
Assert.AreEqual( 4, _block.ActualBlockSize );
Assert.AreEqual( 5, _block.DeclaredBlockSize );
Assert.AreEqual( ErrorState.DataBlockTooShort, _block.ErrorState );
Assert.AreEqual( _data.Length, _block.Data.Length );
for( int i = 0; i < _data.Length; i++ )
{
Assert.AreEqual( _data[i], _block.Data[i], i );
}
ReportEnd();
}
public void ConstructorTestNotNetscape()
{
byte[] idData = new byte[]
{
(byte) 'B',
(byte) 'I',
(byte) 'G',
(byte) 'P',
(byte) 'A',
(byte) 'N',
(byte) 'T',
(byte) 'S',
(byte) '2',
(byte) '.',
(byte) '0',
};
DataBlock idBlock = new DataBlock( 11, idData );
ApplicationExtension appExt
= new ApplicationExtension( idBlock, new Collection<DataBlock>() );
try
{
_ne = new NetscapeExtension( appExt );
}
catch( ArgumentException ex )
{
string message
= "The application identifier is not 'NETSCAPE' "
+ "therefore this application extension is not a "
+ "Netscape extension. Application identifier: BIGPANTS";
StringAssert.Contains( message, ex.Message );
Assert.AreEqual( "applicationExtension", ex.ParamName );
throw;
}
}
public void IndexerTestArgumentOutOfRange()
{
ReportStart();
_block = new DataBlock( 4, _data );
try
{
byte b = _block[4];
}
catch( ArgumentOutOfRangeException ex )
{
string message
= "Supplied index: 4. Array length: 4";
StringAssert.Contains( message, ex.Message );
Assert.AreEqual( "index", ex.ParamName );
ReportEnd();
throw;
}
}
public void ConstructorTest()
{
byte[] idData = new byte[]
{
(byte) 'N',
(byte) 'E',
(byte) 'T',
(byte) 'S',
(byte) 'C',
(byte) 'A',
(byte) 'P',
(byte) 'E',
(byte) '2',
(byte) '.',
(byte) '0',
};
DataBlock idBlock = new DataBlock( 11, idData );
Collection<DataBlock> appData = new Collection<DataBlock>();
// First byte in the data block is always 1 for a netscape extension
// Second and third bytes are the loop count, lsb first
byte[] loopCount = new byte[] { 1, 4, 0 };
appData.Add( new DataBlock( 3, loopCount ) );
// Add the block terminator
appData.Add( new DataBlock( 0, new byte[0] ) );
ApplicationExtension appExt
= new ApplicationExtension( idBlock, appData );
_ne = new NetscapeExtension( appExt );
Assert.AreEqual( 4, _ne.LoopCount );
Assert.AreEqual( "NETSCAPE", _ne.ApplicationIdentifier );
Assert.AreEqual( "2.0", _ne.ApplicationAuthenticationCode );
Assert.AreEqual( ErrorState.Ok, _ne.ConsolidatedState );
}
private void ConstructorStreamTestBlockSizeTooLarge( bool xmlDebugging )
{
Stream s = new MemoryStream();
s.WriteByte( 5 ); // write block size
s.Write( _data, 0, _data.Length ); // write data block
s.Seek( 0, SeekOrigin.Begin ); // go to start of stream
_block = new DataBlock( s, xmlDebugging );
Assert.AreEqual( 5, _block.ActualBlockSize );
Assert.AreEqual( 5, _block.DeclaredBlockSize );
Assert.AreEqual( ErrorState.DataBlockTooShort, _block.ErrorState );
Assert.AreEqual( 5, _block.Data.Length );
for( int i = 0; i < _data.Length; i++ )
{
Assert.AreEqual( _data[i], _block.Data[i], i );
}
if( xmlDebugging )
{
Assert.AreEqual( ExpectedDebugXml, _block.DebugXml );
}
}
/// <summary>
/// Constructor.
/// </summary>
/// <param name="inputStream">
/// The stream from which the image data is to be read, starting with
/// the LZW minimum code size, and ending with a block terminator.
/// </param>
/// <param name="pixelCount">
/// Number of pixels in the image.
/// </param>
/// <param name="xmlDebugging">Whether or not to create debug XML</param>
/// <remarks>
/// The input stream is read, first into the LZW minimum code size, then
/// into data blocks. Bytes are extracted from the data blocks into a
/// datum until the datum contains enough bits to form a code; this code
/// is then extracted from the datum and decoded into a pixel index.
/// Once all data has been read, or a block terminator,
/// end-of-information code or error condition is encountered, any
/// remaining pixel indices not already populated default to zero.
/// </remarks>
public TableBasedImageData(Stream inputStream,
int pixelCount,
bool xmlDebugging)
: base(xmlDebugging)
{
#region guard against silly image sizes
if (pixelCount < 1)
{
string message
= "The pixel count must be greater than zero. "
+ "Supplied value was " + pixelCount;
throw new ArgumentOutOfRangeException("pixelCount", message);
}
#endregion
#region declare / initialise local variables
_pixels = new IndexedPixels(pixelCount);
_dataBlocks = new Collection <DataBlock>();
int nextAvailableCode; // the next code to be added to the dictionary
int currentCodeSize;
int in_code;
int previousCode;
int code;
int datum = 0; // temporary storage for codes read from the input stream
int meaningfulBitsInDatum = 0; // number of bits of useful information held in the datum variable
int firstCode = 0; // first code read from the stream since last clear code
int indexInDataBlock = 0;
int pixelIndex = 0;
// number of bytes still to be extracted from the current data block
int bytesToExtract = 0;
short[] prefix = new short[_maxStackSize];
byte[] suffix = new byte[_maxStackSize];
Stack <byte> pixelStack = new Stack <byte>();
#endregion
// Initialize GIF data stream decoder.
_lzwMinimumCodeSize = Read(inputStream); // number of bits initially used for LZW codes in image data
WriteDebugXmlElement("LzwMinimumCodeSize", _lzwMinimumCodeSize);
nextAvailableCode = ClearCode + 2;
previousCode = _nullCode;
currentCodeSize = InitialCodeSize;
#region guard against LZW code size being too large
if (ClearCode >= _maxStackSize)
{
string message
= "LZW minimum code size: " + _lzwMinimumCodeSize
+ ". Clear code: " + ClearCode
+ ". Max stack size: " + _maxStackSize;
SetStatus(ErrorState.LzwMinimumCodeSizeTooLarge, message);
WriteDebugXmlFinish();
return;
}
#endregion
// TODO: what are prefix and suffix and why are we initialising them like this?
for (code = 0; code < ClearCode; code++)
{
prefix[code] = 0;
suffix[code] = (byte)code;
}
WriteDebugXmlStartElement("DataBlocks");
#region decode LZW image data
// Initialise block to an empty data block. This will be overwritten
// first time through the loop with a data block read from the input
// stream.
DataBlock block = new DataBlock(0, new byte[0]);
for (pixelIndex = 0; pixelIndex < pixelCount;)
{
if (pixelStack.Count == 0)
{
// There are no pixels in the stack at the moment, so...
#region get some pixels and put them on the stack
if (meaningfulBitsInDatum < currentCodeSize)
{
// Then we don't have enough bits in the datum to make
// a code; we need to get some more from the current
// data block, or we may need to read another data
// block from the input stream
#region get another byte from the current data block
if (bytesToExtract == 0)
{
// Then we've extracted all the bytes from the
// current data block, so...
#region read the next data block from the stream
block = ReadDataBlock(inputStream);
bytesToExtract = block.ActualBlockSize;
// Point to the first byte in the new data block
indexInDataBlock = 0;
if (block.TestState(ErrorState.DataBlockTooShort))
{
// then we've reached the end of the stream
// prematurely
break;
}
if (bytesToExtract == 0)
{
// then it's a block terminator, end of the
// image data (this is a data block other than
// the first one)
break;
}
#endregion
}
// Append the contents of the current byte in the data
// block to the beginning of the datum
int newDatum = block[indexInDataBlock] << meaningfulBitsInDatum;
datum += newDatum;
// so we've now got 8 more bits of information in the
// datum.
meaningfulBitsInDatum += 8;
// Point to the next byte in the data block
indexInDataBlock++;
// We've one less byte still to read from the data block
// now.
bytesToExtract--;
// and carry on reading through the data block
continue;
#endregion
}
#region get the next code from the datum
// Get the least significant bits from the read datum, up
// to the maximum allowed by the current code size.
code = datum & GetMaximumPossibleCode(currentCodeSize);
// Drop the bits we've just extracted from the datum.
datum >>= currentCodeSize;
// Reduce the count of meaningful bits held in the datum
meaningfulBitsInDatum -= currentCodeSize;
#endregion
#region interpret the code
#region end of information?
if (code == EndOfInformation)
{
// We've reached an explicit marker for the end of the
// image data.
break;
}
#endregion
#region code not in dictionary?
if (code > nextAvailableCode)
{
// We expect the code to be either one which is already
// in the dictionary, or the next available one to be
// added. If it's neither of these then abandon
// processing of the image data.
string message
= "Next available code: " + nextAvailableCode
+ ". Last code read from input stream: " + code;
SetStatus(ErrorState.CodeNotInDictionary, message);
break;
}
#endregion
#region clear code?
if (code == ClearCode)
{
// We can get a clear code at any point in the image
// data, this is an instruction to reset the decoder
// and empty the dictionary of codes.
currentCodeSize = InitialCodeSize;
nextAvailableCode = ClearCode + 2;
previousCode = _nullCode;
// Carry on reading from the input stream.
continue;
}
#endregion
#region first code since last clear code?
if (previousCode == _nullCode)
{
// This is the first code read since the start of the
// image data or the most recent clear code.
// There's no previously read code in memory yet, so
// get the pixel index for the current code and add it
// to the stack.
pixelStack.Push(suffix[code]);
previousCode = code;
firstCode = code;
// and carry on to the next pixel
continue;
}
#endregion
in_code = code;
if (code == nextAvailableCode)
{
pixelStack.Push((byte)firstCode);
code = previousCode;
}
while (code > ClearCode)
{
pixelStack.Push(suffix[code]);
code = prefix[code];
}
#endregion
firstCode = ((int)suffix[code]) & 0xff;
#region add a new string to the string table
if (nextAvailableCode >= _maxStackSize)
{
// TESTME: constructor - next available code >- _maxStackSize
break;
}
pixelStack.Push((byte)firstCode);
prefix[nextAvailableCode] = (short)previousCode;
suffix[nextAvailableCode] = (byte)firstCode;
nextAvailableCode++;
#endregion
#region do we need to increase the code size?
if ((nextAvailableCode & GetMaximumPossibleCode(currentCodeSize)) == 0)
{
// We've reached the largest code possible for this size
if (nextAvailableCode < _maxStackSize)
{
// so increase the code size by 1
currentCodeSize++;
}
}
#endregion
previousCode = in_code;
#endregion
}
// Pop all the pixels currently on the stack off, and add them
// to the return value.
_pixels[pixelIndex] = pixelStack.Pop();
pixelIndex++;
}
#endregion
#region check input stream contains enough data to fill the image
if (pixelIndex < pixelCount)
{
string message
= "Expected pixel count: " + pixelCount
+ ". Actual pixel count: " + pixelIndex;
SetStatus(ErrorState.TooFewPixelsInImageData, message);
}
#endregion
if (XmlDebugging)
{
WriteDebugXmlEndElement();
byte[] bytes = new byte[_pixels.Count];
_pixels.CopyTo(bytes, 0);
WriteDebugXmlByteValues("IndexedPixels", bytes);
WriteDebugXmlFinish();
}
}
private void ConstructorStreamTestEndOfStream( bool xmlDebugging )
{
Stream s = new MemoryStream();
s.Seek( 0, SeekOrigin.Begin );
_block = new DataBlock( s, xmlDebugging );
Assert.AreEqual( ErrorState.EndOfInputStream, _block.ErrorState );
if( xmlDebugging )
{
Assert.AreEqual( ExpectedDebugXml, _block.DebugXml );
}
}
private void SaveData( DataBlock identificationBlock,
Collection<DataBlock> applicationData )
{
_identificationBlock = identificationBlock;
StringBuilder sb;
if( _identificationBlock.Data.Length < 11 )
{
string message
= "The identification block should be 11 bytes long but "
+ "is only " + _identificationBlock.Data.Length + " bytes.";
throw new ArgumentException( message, "identificationBlock" );
}
if( _identificationBlock.Data.Length > 11 )
{
string message
= "The identification block should be 11 bytes long but "
+ "is " + _identificationBlock.Data.Length + " bytes long. "
+ "Additional bytes are ignored.";
SetStatus( ErrorState.IdentificationBlockTooLong, message );
}
// Read application identifer
sb = new StringBuilder();
for( int i = 0; i < 8; i++ )
{
sb.Append( (char) _identificationBlock[i] );
}
_applicationIdentifier = sb.ToString();
// Read application authentication code
sb = new StringBuilder();
for( int i = 8; i < 11; i++ )
{
sb.Append( (char) _identificationBlock[i] );
}
_applicationAuthenticationCode = sb.ToString();
_applicationData = applicationData;
if( XmlDebugging )
{
WriteDebugXmlStartElement( "IdentificationData" );
WriteDebugXmlNode( identificationBlock.DebugXmlReader );
WriteDebugXmlElement( "ApplicationIdentifier",
_applicationIdentifier );
WriteDebugXmlElement( "ApplicationAuthenticationCode",
_applicationAuthenticationCode );
WriteDebugXmlEndElement();
WriteDebugXmlStartElement( "ApplicationData" );
foreach( DataBlock db in applicationData )
{
WriteDebugXmlNode( db.DebugXmlReader );
}
WriteDebugXmlEndElement();
WriteDebugXmlFinish();
}
}
