[Therion] Transparent Labels and Hyperlinks in Labels

[Martin Budaj]

On Tue, Dec 15, 2009 at 5:21 AM, Carl Magnuson <magnu213 at umn.edu> wrote:
> These are two features that I would like to make use of and may already be possible, I just don't know how its done.  I have played around with custom metapost cide for making labels with a transparent background and can either make a therion label with a colored background or a label with a transparent background but none of the Therion text formatting.  Has anybody coded a transparent label for Therion?

Hi Carl,

if you mean something like on attached picture, I can give you some
hints how to modify the existing code until it would be implemented as
a regular feature:

therion provides a metapost macro def_transparent_rgb to define
transparent colors like

def_transparent_rgb(tr_blue, 0, 0, 1);

you apply it using 'withtransparentcolor <colorname>' operator.
Following code redefines p_continuation to use transparency:

def p_continuation(expr pos,theta,sc,al) =
  p_continuation_UIS(pos,theta,sc,al);
  if known(ATTR__text) and picture(ATTR__text):
    p_label.urt(ATTR__text,(.5u,-.25u) transformed T,0.0,8);   % last
argument (8) instructs therion to use filledlabel
  fi;
enddef;

def process_filledlabel(expr cent, rot) =
  begingroup;
    interim bboxmargin:=2.0bp;
    q:=((bbox lab) smoothed 2) rotatedaround (cent, rot);
    fill q withtransparentcolor tr_blue;      % transparency used
    draw lab rotatedaround (cent, rot);
    write_circ_bbox(q);  % without corners smoothing it was enough to use
                         % write_bbox(q);
  endgroup;
enddef;

All text formatting should be available as usual. Which problems did you have?

> My second thought is about hyperlinks from within a label.  For example one may want to label a significant feature and also include a link to a flickr photo or online video of the feature. This may already be possible by just inserting some Latex code, but I'm not sure what kind of processing Therion does on the label text.

Unfortunately it requires changes in the core, but it is so useful
that I will give it high priority.

Martin
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