Frank Buss wrote:
I've created a small program to compose images with combinators:
http://www.frank-buss.de/haskell/OlympicRings.hs.txt
Finally, what do you think about using this concept for generating images? It has some advantages, e.g. it is possible to scale the image without quality loss. But it needs some improvement, e.g. the anti-aliasing doesn't look very smooth. And it is very slow, it needs about 40 seconds on my computer to calculate the image.
The idea of representing images simply by a function Int -> Int -> RGB is great :) You may want to look at Pan and its various offsprings, in particular Pancito http://www.haskell.org/haskellwiki/Applications_and_libraries/Graphics#Pan Unfortunately, there's not much you can do about the speed. Pan is faster, but it creates the illusion that you're programming in Haskell while internally, it compiles the image generation code to C++. Very clever, but hard to maintain and one of the reasons why it only works on Windows.
There are many functions like circle1Center, circle2Center, ... Is it possible to rewrite the program that it will be shorter, maybe using lists or an interpreter for a language for this kind of combinator programming style?
Well, you have lists for that type Point = (Int,Int) positions :: [Point] positions = zip [0.5 + fromIntegral n * dx | n <- [-2..2]] (cycle [y1,y2]) where dx = 0.125 y1 = 0.15 y2 = 0.25 colors :: [RGB] colors = [blue, yellow, black, green, red] type Image = Point -> RGB circles :: RGB -> [Image] circles background = map circle (zip positions colors) where circle (p,c) = fillMask (translate p ringCenter) c $ fillMask (translate p ringOutline) white background
Is it possible to write functions with an arbitrary number of arguments? Would be nice if the average function would accept any number of pixel values.
Lists are the natural choice here.
Is there a PNG writer library for Haskell? I've seen a zlib interface, should be not too difficult to implement it in Haskell itself.
Not that I know of. But gtk2hs has a Cairo-binding and I guess this one supports PNG. Note that this is vector graphics though, your approach is more general. Regards, apfelmus