Adam Bloom wrote:

> I'm new to Squeak so this may sound like a stupid question, what does this
> program do?

Dan's fix #2756 changes the arrowhead drawing behavior of open PolygonMorph's.
I'd done an earlier fix for some of the geometry, then Dan released a
change set (fix) that really fixed the arrowhead drawing.

Then I asked for having arrowheads that weren't filled with the border
color (for various kinds of diagramming). So Dan started on this but
had to put it down because he got (more) busy.

But he posted his current work to the list so someone could grab it
and make it work.

It's tricky for the reasons Dan described: drawing a line leaves
square ends, and you really want nice sharp points where they meet
(there is no logic yet for fillets). So you have to draw
a little filled polygon or something to fix it up.
Further, the line itself has
to stop right at the base of the arrowhead (the current version
goes up to 3 borderWidths away from the tip of the arrow, which is
usually too far for an un-filled arrowhead).

At a higher level, the method PolygonMorph>>drawArrowOn:at:from:
is called from PolygonMorph>>drawOn: when arrowheads are needed.

Each Morph class defines drawOn: so that when a redraw is needed,
some owner (like a PasteUpMorph) can ask it to draw itself on a
Canvas.

-- 
Ned Konz
currently: Stanwood, WA
email:     ned at bike-nomad.com
homepage:  http://bike-nomad.com