Re: Dynamic Arrows

[Richard Rowell <rwrowell bellsouth net>]

On Friday 01 February 2002 20:43, you wrote:
> Then strike that <stroke> section and grab (share) the SVG-reading code
> from the Shapes support. This'll save you a lot of time and make the
> overall system more consistent. SVG is the standard for describing this
> kind of geometry in XMLish way (at least, that's the standard dia uses in
> addition to its own format).
I will take a look at the shape stuff before I start on anything else, I 
promise.

> What information was this <type> tag supposed to carry ?
The arrow type I thought might be usefull to categorize the various arrows as 
there are already enough that the arrow menu spans my entire screen.  I 
hadn't planned on hacking the interface stuff in right away, but perhaps this 
might be a good idea for the future?  (especially since users may/will be 
hacking in their own "arrows", no telling how many there may be a year from 
now).

> > I was thinking of a coordinate system where the origin is "on the
> > line" 1/2 of the "length" of the arrow away from "to".  The coordinates
> > would be such that 100,0 would be "to".
>
> So, basically, the exact shape of the arrow depends on the size of the line
> which holds the arrow ? Uuuuh. Why not take the existing "width" and
> "length" and use these as a scaling factor (and define the arrow as in a
> 1x1 or 10x10 or 100x100 box, you choose the scale) ?

No, the arrow's size depends only upon "length" and "width".  The way it is 
coded now, there is a 200x200 unit box the arrow can be drawn in.  0,0 is 1/2 
the "length" away from "to" and is "on the line".  100,0 is "to" .  100,100 
would be a point tangent to the "to,from" line 1/2 "width" away from "to", 
and so is 100,-100.  

To make a long story short the code already scales on width/length, and the 
units are arbitrary. I could just as easily make the origin "to" and make the 
"unit" length/width 1 instead of 100.
_________________________
Richard Rowell
rwrowell@bellsouth.net