Question

i have big problem with explanation code under, meanwhile i made two loops function which does the same thing. I send my code to friend to tell me if it is possible to make is simplier 🙂 So i get something like that.

Array.Copy(
    myImageData
        .Select(
            (b, index) =>
                (
                    index > rooflimit && index < floorlimit && b == 252 &&
                    (myImageData[index + width] == 0 || (myImageData[index + width] > 168 && myImageData[index + width] < 173)) &&
                    myImageData[index - width] == 252 &&
                    myImageData[index - (2 * width)] == 159
                ) ? (byte)172 : b
        ).ToArray(),
    rooflimit + 1,
    myImageData,
    rooflimit + 1,
    floorlimit - rooflimit - 1
);

My loops was doing something like that (above do the same thing):

1. when you get all pixelse, copy them to array of bytes
2. find all pixels which have value 255, pixel under has 0 or it is from range 168-173
3. pixel above has value 255 and pixel 2 times above has value 159
4. if i found that pixel change that value to 172
5. * pixel checking starts from the second row [0][1][2], and finish before last row, to be able check pixels above and under of current pixel *

I get almost about that code above, however i don’t understand that part which starts with:

rooflimit + 1, 
myImageData, 
rooflimit + 1, 
floorlimit - rooflimit - 1);

So i ask you for a help, thanks!
PS. please change topic if it is not good specified.

Answer 1

The last four parameters are the last parameters to Array.Copy. Your code would be clearer if you split it up:

byte[] tmp = myImageData.Select([... big lambda expression ...])
                        .ToArray();

Array.Copy(tmp, rooflimit + 1, 
           myImageData, rooflimit + 1,
           floorlimit - rooflimit - 1);

I would also be very tempted to use a separate method instead of a lambda expression here – it’s too complicated to be readable, really.