[Gimp-developer] RFC and some doubts about crop guide overlays

[Nelson A. de Oliveira]

Hi!

I would like to have some comments/suggestions/criticisms/etc about
the quality and the implementation of the following crop guide
overlays.
This is related with http://bugzilla.gnome.org/show_bug.cgi?id=575911

Please, consider them as proof of concept; also, I am only including
the relevant part of the code.

First the easy one: a rule of fifths (more info about the rule of
fifths at http://markhancock.blogspot.com/2006/03/address-basic-composition.html)

Code is available at http://naoliv.googlepages.com/gimp-fifhts.txt

Can it be implemented in a better way, optimized, etc?

Now about the other overlays, like this golden triangle overlay:
http://naoliv.googlepages.com/gimp-triangle.txt

This is the code to represent
http://pendery.org/files/other%20images/Techniques%20-%20Lightroom/Triangle.png
(that is the pink lines from
http://www.corel.com/img/content/community/tips/px/2007-03d/Divine_Proportion_Final_1.jpg).

Can I use "phi" as I am using now or can I define it like SQRT5 is
already defined?

Also, it will be necessary to flip it vertically and horizontally
(like it's possible to see at
http://www.corel.com/img/content/community/tips/px/2007-03d/Divine_Proportion_Final_0.jpg).
Any hints how can I do this, please?

Is it possible to draw lines with different colors? (like
http://www.corel.com/img/content/community/tips/px/2007-03d/Divine_Proportion_Final_1.jpg)

Thank you very much!

Best regards,
Nelson