[Biojava-l] leader and trailer in Renderers

[Matthew Pocock]

The leading and trailing space is requested per renderer. This is 
because some glyphs (e.g. numbers) are scale-invarient and will be 
clipped off if the rendering is clipped exactly. I think the container 
of the sequence renderers loops over these and finds the maximum one. 
Then, it individualy translates each sequence renderer so that their 
sequence-based co-ordinates line up, but they are guaranteed a minimum 
of leader and trailer padding. Does that help?

M

David Huen wrote:
> I've been going thru' the SequencePanel code to document it a bit more and
> I am puzzled over the intent behind the leader and trailer allocations in
> this code.
> 
> If I understand the SequencePanel source correctly, each renderer tells
> SequencePanel thru' getMinimumLeader and getMinimumTrailer the number of
> pixels to set aside for these.  SequencePanel uses these on a per-renderer
> basis to append the number of pixels before and after the space required
> to render the sequence and aligns the left edge against the right edge of
> the leading Border allocation.
> 
> If this is the case, the moment we start allocating leaders and trailers
> (all renderers use sero so far), we might have sequence renderings out of
> kilter, wouldn't we?  Shouldn't the allocation be per-panel rather
> per-renderer?  If we use per-panel allocations, the renderers will need to
> recover from SequencePanel the actual leader/trailer allocations.  Have I
> understood the code correctly?
> 
> What was the original intent for these allocations?  Labels?
> 
> Thanks,
> David Huen
> 
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