//Compress aBitmap into byte array
public static byte[] Compress(AccessibleBitmapBytewise source, int byteLayer)
{
//Loop trough all layers of bits, where possible at the same time
AccessibleBitmapBitwise aBitmap = new AccessibleBitmapBitwise(source);
BitStreamFIFO[] byteLayers = new BitStreamFIFO[8];
Parallel.For(byteLayer * 8, byteLayer * 8 + 8, (z, state) => //for(int z = byteLayer * 8; z < byteLayer * 8 + 8; z++)
{
//Compress image using all different compression techniques, where possible at the same time
BitStreamFIFO[] compressionTechniques = new BitStreamFIFO[4];
Parallel.For(0, compressionTechniques.Length, (i, state2) =>
{
switch (i)
{
//Uncompressed (only used if no compression technique is smaller)
case 0:
compressionTechniques[i] = UncompressedBitmapCompressorBitwise.Compress(aBitmap, z);
break;
//Compress bit channel as an integer array using several techniques, using 8-bit integers
case 1:
compressionTechniques[i] = ByteArrayCompressorBitwise.Compress(aBitmap, z);
break;
//Run length compression: save the length of a sequence of bit values instead of saving them seperately
case 2:
compressionTechniques[i] = RunLengthEncodingCompressorBitwise.Compress(aBitmap, z);
break;
//Run length compression vertical: run length compression, but scan the pixels horizontally, becouse with some images this yields better results
case 3:
compressionTechniques[i] = RunLengthEncodingCompressorVerticalBitwise.Compress(aBitmap, z);
break;
//To add a compression technique, add a new case like the existing ones and increase the length of new byte[??][]
}
});
//Choose the smallest compression type
//Initialize
int smallestID = 0; //The ID of the smallest compression type
int smallestSize = int.MaxValue; //The size ofthe smallest compression type: int.MaxValue is assigned to make sure that the first compression to be checked will be smaaller than this value
//Loop trough all saved compression techniques
for (int i = 0; i < compressionTechniques.Length; i++)
{
//If the current technique is smaller than the smallest technique which has been checked
if (compressionTechniques[i].Length < smallestSize)
{
//Mark this technique as smallest
smallestSize = compressionTechniques[i].Length;
smallestID = i;
}
}
//Merge the number of the compression type of this layer with corresponding bitStream
BitStreamFIFO tmpStream = new BitStreamFIFO();
tmpStream.Write(smallestID, 3); //This 3-bit integer indicates which technique the decompressor should use, and should be before the image data
byteLayers[z % 8] = BitStreamFIFO.Merge(tmpStream, compressionTechniques[smallestID]);
});
//Combine all bitstreams & convert the result to a byte array
byte[] outputStream = BitStreamFIFO.Merge(byteLayers).ToByteArray();
//Return the data of all the bit channels combined
return(outputStream);
}
