Re: bounding points for boxes etc.

[Lars Clausen <lrclause cs uiuc edu>]

On 2 Sep 2003, avp@cad.ru wrote:
> Lars Clausen пишет:
>> On 2 Sep 2003, avp@cad.ru wrote:
>>
>>> Almost every shape in Dia has connection points that allow a user to
>>> bound these shapes to other ones via lines, curves etc. But there's a
>>> strict amount of such points. Is there an easy way to change this
>>> amount?
>> No.  We have discussed various solutions, but it's tricky.  It has to be
>> done in a way consistent with each object, and in such a way that saved
>> diagrams work correctly.  If we just added connection points at
>> user-defined places, they wouldn't move the right way when the object
>> changes shape.  There's some work on allowing a 'gap' at the start and
>> end of a line, which could allow the whole object to act as a
>> connectionpoint, but that's future music.
>
> What if connection points are added in user defined (and thus fixed)
> points, and Dia calculates percentage of each connection point's
> position and resizes sides keeping ratio taken from that percentage
> info?
>
> E.g.:
>
> 1      2     3   4        5
> *------*-----*---*--------*
> 0      30    50  60       100
>
> goes to... (by ratio ~1.5)
>
>
> 1         2        3     4            5
> *---------*--------*-----*------------*
> 0         30       50    60           100

That makes sense in most cases, but sometimes the object doesn't scale in a
linear fashion.  See for example the UML Component, the two extra block
don't change size when the whole thing is resized.

> Another way would be calculating equal distance between connection
> points after adding/removing a connection point.
>
> E.g.:
>
> *-------*-------*
>
> You add 1 connection point. Dia reaaranges distances and therre it goes:
>
> *----*----*-----*
>
> Add 1 more:
>
> *---*---*---*---*
>
> Of course here pops up the first problem: how to handle one side of a
> box apart of other ones.

Yes, that makes that solution difficult.  Most objects just have a
scattering of connectionpoints (not even always in order around the object)
rather than a distribution of them.

I'd much rather have a system where you can connect to the middle with a
gap, and then keep the old connection points as guides to where it'd be
pretty to have connections.

-Lars

-- 
Lars Clausen (http://shasta.cs.uiuc.edu/~lrclause)| Hårdgrim of Numenor
"I do not agree with a word that you say, but I   |----------------------------
will defend to the death your right to say it."   | Where are we going, and
    --Evelyn Beatrice Hall paraphrasing Voltaire  | what's with the handbasket?