//Compress aBitmap into byte array
public static byte[] Compress(AccessibleBitmap source)
{
//Initialize
List <int> distances = new List <int>(); //A list containing all the lenghts of same pixels
List <int> pixels = new List <int>(); //A list containing all the pixels that correspond to the lengths in 'distances' list
int tempDistance = -1; //The length of one run of bits with the same value, while it is not saved yet: -1 because it will be increased before the first check
byte[] lastPixel = source.GetPixel(0, 0); //The pixel of the last checked pixel, to compare with the current pixel: set value to the value of the first pixel so the first check will succeed
//Loop trough all lines of pixels
for (int y = 0; y < source.height; y++)
{
//Loop trough all pixels in this line
for (int x = 0; x < source.width; x++)
{
//Take value of the current pixel
byte[] currentPixel = source.GetPixel(x, y);
//If the value of the bit of this pixel matches the value of the bit of the previous pixel
if (currentPixel.SequenceEqual(lastPixel))
{
//Values are the same, so increase current run
tempDistance++;
}
else
{
//Values are not the same, so save the run
distances.Add(tempDistance);
pixels.AddRange(Array.ConvertAll(lastPixel, b => (int)b));
//Set the bit value for the next comparison to the bit value of this pixel
lastPixel = currentPixel;
//Reset the run length for the new run
tempDistance = 0;
}
}
}
//Save the last run becouse this never happens in the loop
distances.Add(tempDistance);
pixels.AddRange(Array.ConvertAll(lastPixel, b => (int)b));
//Compress the array of run lengths using different techniques
BitStreamFIFO pixelStream = VaryingIntArrayCompressor.Compress(pixels.ToArray());
//Compress the array of run lengths using different techniques
BitStreamFIFO lengthStream = VaryingIntArrayCompressor.Compress(distances.ToArray());
//Combine the compressed data of the runs with the compressed data of the pixel values, then return the BitStream
return(BitStreamFIFO.Merge(pixelStream, lengthStream).ToByteArray());
}
public static byte[] CompressVertical(AccessibleBitmap source)
{
byte[] lastpixel = null; // Create variable to store the last pixel
int colorCounter = 1; // Create counter for current color
BitStreamFIFO bs = new BitStreamFIFO(); // Create new bitstream for all the bits
int maxCount = 0; // Create variable to store the max bitcount
Queue<PixelArray> output = new Queue<PixelArray>(); // Create list to store all the pixelvalues in
// Write one bit to the bitstream, so the decompressor knows to decompress vertically
bs.Write(true);
// Iterate through every vertical row
for (int x = 0; x < source.width; x++)
{
// Iterate through every pixel in the vertical row
for (int y = 0; y < source.height; y++)
{
// Check if the variable lastpixel is empty
if (lastpixel == null)
{
// If lastpixel is empty, set last pixel to the first pixel
lastpixel = source.GetPixel(x, y);
}
else
{
// If lastpixel isn't empty, compare last pixel with new pixel
if (lastpixel.SequenceEqual(source.GetPixel(x, y)))
{
// Pixels matched, so increase the counter value
colorCounter++;
}
else
{
// If the pixels don't match, add the counter with the last pixel to the output queue
output.Enqueue(new PixelArray(colorCounter, lastpixel));
// Check if the new countervalue is higher then the last one, if so set maxBitCount to that
if (colorCounter > maxCount)
maxCount = colorCounter;
// Reset the colorCounter and set the last pixel to the new pixel
colorCounter = 1;
lastpixel = source.GetPixel(x, y);
}
}
}
}
// Add the remaining pixel(s) to the bitstream
output.Enqueue(new PixelArray(colorCounter, lastpixel));
// Check if the new countervalue is higher then the last one, if so set maxBitCount to that
if (colorCounter > maxCount)
maxCount = colorCounter;
// Write the maxCount to the bitstream
bs.Write((byte)Math.Ceiling(Math.Log(maxCount, 2)));
// Add all the pixels from the queue to the bitstream
while (output.Count > 0)
{
PixelArray pixel = output.Dequeue();
bs.Write(pixel.Count, (int)Math.Ceiling(Math.Log(maxCount, 2)));
bs.Write(pixel.Pixel);
}
// Return the bitsream as a byte[]
return bs.ToByteArray();
}
