Article: Functional image processing in D

[Jakob Ovrum]

On Friday, 21 March 2014 at 11:04:58 UTC, Vladimir Panteleev 
wrote:
> http://blog.thecybershadow.net/2014/03/21/functional-image-processing-in-d/
>
> Some highlights from a recent overhaul of the graphics package 
> from my D library. It makes use of a number of D-specific 
> language features, so I've tried to make the article accessible 
> to people new to D as well.

That's really cool. I have some notes though:

  * All the function templates separate the template declaration 
from the function declaration, when they can just use the 
function template syntax.

  * Any type is accepted for the colour type, even though certain 
basic assumptions are made, such as the colour type being 
assignable to itself.

  * Image.w/h/pixels should probably be read-only properties in 
the public interface.

  * Any particular reason that coordinate integers are signed? 
`isView` seems to prefer `size_t`.

  * `Warp` should probably have a `if (isView!V)` constraint.

  * `warp` exclusively uses string expression arguments...

  * I'd recommend sticking to structs (often with AliasThis) over 
mixins for as far as it goes, as it's much more structured, thus 
easier to read and reason with.

  * The most common style for template parameter names (Phobos 
uses it, too) is just `Color`, not `COLOR`.

  * I know "w" and "h" are common abbreviations used in C, but 
they seem unnecessary in D - detrimental rather - if your code 
examples are anything to go by.

It's always nice to know examples of high performance range-based 
code. I noticed that the `View` concept does not have the concept 
of stride or access to pixels using a single absolute coordinate; 
maybe if that was the case, the `blitTo` algorithm could be 
optimized to its conclusion, instead of copying scanlines one by 
one.