Making a colorpicker

[cage]

On Mon, Aug 19, 2019 at 12:00:26AM +0200, Tom wrote:
> Hi,

Hello!

> I did some things, and now it's on Github. Feel free to look:
> https://github.com/Trashtalk217/ltk-colorpicker.

Congratulations! I hope you had fun with CL and LTK! :)

> Thanks for the advice I got. I now use two images for displaying the color
> wheel and the white-to-black gradient. While most of the code is still yanky
> as heck (just look at my installation instructions -_-).

That code looks clean and effective to me i think i can see you have a
good programming background (and,  for inesplicable reasons, i thought
you was a lisp newbie but seems i was wrong); I have anyway a couple of
humble considerations that i think are worth noting:

- FWIW the equivalent of '%' operation in  C99 is 'cl:rem', not 'cl:mod'
  (probably you are aware of that but, if not, this can save a few bug
  in the future :-) )

  http://clhs.lisp.se/Body/f_mod_r.htm

- likely  is better  to  replace 'cl:merge-pathnames'  with an  asdf
  function 'asdf:system-relative-pathname'

  https://common-lisp.net/project/asdf/asdf.html#Miscellaneous-Functions

  Maybe  (just guessing)  this could  solve your  installation problem
  (sorry i did not got your code running for lack of time :( ).

- some lisper  suggested (on IRC?)  to not to insert  empty lines in forms
  that are not toplevel so:

  (defun foo ()
   ....
   )

  (defun bar ()
   ...
   )

is ok but:

  (defun baz ()
   (form1)
   (form2)

   (form3))

not, instead:

  (defun baz ()
   (form1)
   (form2)
   (form3))

and i  followed this rule  more or less strictly  (but this is  just a
stylistic choice, of course)

- sometimes is better to reformat the math expressions for clarity, for example:

  https://github.com/Trashtalk217/ltk-colorpicker/blob/master/ltk-colorpicker.lisp#L48

  (+ (- (acos (/ x r))) (* 2 pi))

  to:

  (+ (- (acos (/ x r)))
     (* 2 pi))

this way i feel it is more clear the sum's operators but, again, YMMV.

I hope what i wrote do not annoyed you, all of above are just opinions
not law :)

Anyway, again: congratulation!

Bye!
C.