Re: gEDA-user: PCB feature

[Karl Mowatt-Wilson <kmw1@xxxxxxxxxxx>]

On Thu, Aug 09, 2007 at 07:48:09PM +0100, Peter Clifton wrote:
> 
> On Thu, 2007-08-09 at 09:04 -0500, John Griessen wrote:
> > Karl. wrote:
> > > - left-to-right selects all elements completely contained within 
> > > the selection box (this seems to be the normal gschem behaviour)
> > > 
> > > - right-to-left selects as above plus anything that crosses the 
> > >   selection boundary.
>  
> What do other combinations do...
> 
> >From bottom left -> top right?
> >From top right -> bottom left?

As far as I can tell, it is only left-right vs right-left that makes a 
difference (I'm using an old version - AutoCAD LT98, but have done a web  
search and it appears they've not added any up/down behaviour in newer 
versions).

There are some pictures in this tutorial:
http://toi.bk.tudelft.nl/toi-pedia/index.php?title=AutoCAD_introduction#Selecting_objects

> Anyone _against_ this change?

Having researched the AutoCAD behaviour, it appears that some people 
*hate* it, apparently on the basis that they feel no distinction between 
left-right vs right-left drawing of the bounding box, and therefore feel 
that there should be no distinction in the behaviour.

It seems to me that the behaviour is potentially more useful than it is 
hindering.  I suspect that most people consistently draw selection boxes 
in the same direction without ever being aware of what they're doing, so 
they'll get consistent behaviour even if they don't know why.  That 
seems to me like a sufficient basis for acceptability, given that the 
directional behaviour is very useful for people who are aware of it.

I don't see any obvious use for up-down/down-up distinctions, but I 
would still consider allowing for it when coding for left/right 
distinctions.

Idle speculation based on whimsical ideas of the sourcecode:  I don't 
know how you would want to code the direction, but if it were a 2 char 
string, then first char could be 'L' or 'R' for left or right starting 
point, and second char could be 'T' or 'B' for top or bottom.  At the 
moment, anything looking at the direction of the selection could just 
look at the first char.  This is probably pure evil, from the standpoint  
of 'only write code now for what you need now'  :-)    I'm sure that it 
also fully demonstrates my lack of familiarity with the internals of the 
sourcecode.


Karl.
-- 
http://mowson.org/karl


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