public void NullPixels()
{
try
{
_e = new LzwEncoder( null );
}
catch( ArgumentNullException ex )
{
Assert.AreEqual( "pixels", ex.ParamName );
throw;
}
}
public void NullStream()
{
_e = new LzwEncoder( _ip );
try
{
_e.Encode( null );
}
catch( ArgumentNullException ex )
{
Assert.AreEqual( "outputStream", ex.ParamName );
throw;
}
}
/// <summary>
/// Encodes _ip and decodes the encoded data, then compares the decoded
/// data against the original.
/// Also calculates the compression rate.
/// </summary>
private void TestIt()
{
MemoryStream s = new MemoryStream();
_e = new LzwEncoder( _ip );
_e.Encode( s );
int encodedByteCount = (int) s.Position;
s.Seek( 0, SeekOrigin.Begin );
TableBasedImageData tbid = new TableBasedImageData( s, _ip.Count );
s.Seek( 0, SeekOrigin.Begin );
byte[] encodedBytes = new byte[encodedByteCount];
s.Read( encodedBytes, 0, encodedByteCount );
Assert.AreEqual( _ip.Count, tbid.Pixels.Count, "Pixel counts differ" );
for( int i = 0; i < _ip.Count; i++ )
{
Assert.AreEqual( _ip[i], tbid.Pixels[i], "pixel index " + i );
}
float compression = 100 - (100 * encodedByteCount / _ip.Count);
WriteMessage( "Original byte count: " + _ip.Count
+ ". Encoded byte count: " + encodedByteCount
+ ". Compression rate: " + compression + "%" );
}
/// <summary>
/// Encodes and writes pixel data to the supplied stream
/// </summary>
/// <param name="indexedPixels">
/// Collection of indices of the pixel colours within the active colour
/// table.
/// </param>
/// <param name="outputStream">
/// The stream to write to.
/// </param>
private static void WritePixels( IndexedPixels indexedPixels,
Stream outputStream )
{
LzwEncoder encoder = new LzwEncoder( indexedPixels );
encoder.Encode( outputStream );
}