Re: [Gmod-ajax] interesting arrowhead question

[Mitch S. <mit...@be...>]

On 03/17/2010 08:34 PM, Scott Cain wrote:
> Without double checking, I'd say I'm reasonably sure that the
> arrowheads are drawn inside the feature, such that the very point of
> the arrowhead is at the edge of the feature.
>    

I did some looking, and my current understanding is that in GBrowse it 
depends on the glyph.  For example, it looks like the transcript glyph 
draws them outside the feature (is this the latest code?  It's the 
Bio::Graphics SVN HEAD):

http://gmod.svn.sourceforge.net/viewvc/gmod/Bio-Graphics/trunk/lib/Bio/Graphics/Glyph/transcript.pm?view=markup#l_38

It looks to me like the $self->arrow calls are drawing outside the glyph 
bounds; also, the pad_left and pad_right subs take into account the 
arrow length.  It's a little complicated to follow because of the "flip" 
logic, though.

For the transcript2 glyph, it looks like it draws the arrowhead inside 
the feature unless the feature is too small for the arrowhead, in which 
case it draws it outside.

http://gmod.svn.sourceforge.net/viewvc/gmod/Bio-Graphics/trunk/lib/Bio/Graphics/Glyph/transcript2.pm?view=markup

Mitch