Re: gEDA-user: next PCB release - 1.99za vs 4.0

[Peter Clifton <pcjc2@xxxxxxxxx>]

On Wed, 2010-09-08 at 17:46 -0700, Andrew Poelstra wrote:

> Well, I am converting the top-level window to its own widget, rather than
> using a stock GtkWindow and tacking stuff onto it. That way I can migrate
> a lot of the global variables to member variables, pass more things as
> parameters, and use the 'const' keyword a lot more.

I'm not sure I see the point of making the whole top-level window a
dedicated widget per-se, although the goal to encapsulate various state
variables sounds excellent.

I was never really sure what point to start sub-classing to make a new
widget. My acid test was usually whether that widget had useful
self-contained functionality which could be re-used in other places.

For example, I've got a moderately large refactor queued which removes
most of the drawing back-end specific code from the GTK hid, splitting
all the GDK specific rendering details into a separate file. With GL
enabled, it removes that file from the build and swaps in an equivalent
which uses OpenGL. All render-specific member variables are defined
locally to those files, avoiding the GDK/GL choice cluttering up more
global structures.

When devising this split, I was very tempted to turn the PCB drawing
area into its own widget, and teach that to draw (and potentially have
two implementations / sub-classes), but so far I didn't take that route.
There is code in PCB which depends GDK / GL rendering, but does not
renders not to a widget, rather to a GdkPixbuf.


I think making the whole main window a dedicated widget is perhaps a
step to far (or too early). There are probably other more useful
refactors, such as making a layer-selector widget, route-style selector
widget etc., and defining clean interfaces with those.



Peter Clifton

Electrical Engineering Division,
Engineering Department,
University of Cambridge,
9, JJ Thomson Avenue,
Cambridge
CB3 0FA

Tel: +44 (0)7729 980173 - (No signal in the lab!)
Tel: +44 (0)1223 748328 - (Shared lab phone, ask for me)



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