Michael J Gruber wrote:
Gary venit, vidit, dixit 03/13/06 16:33:
Alan G Isaac wrote:
What's the preferred way to put an arrowhead at the midpoint
of a line segment? (Like this:
http://en.wikipedia.org/wiki/Cobweb_Cycle )
Drawing it in two pieces seems the obvious choice right now,
but it seems like there was talk of a decoration for this?
Thank you,
Alan Isaac
Similar newbie question: How to make a double-ended arrow?
( <--------------------> )
For that you don't need the SVN version of PyX, that's in the release
code already. The deco module defines the special decorators deco.barrow
and deco.earrow for arrows at the begin and end of the path. So, if you
want a straight line with double arrows:
from pyx import *
c = canvas.canvas()
c.stroke(path.line(0,0,3,2),[deco.barrow,deco.earrow])
c.writeEPSfile("darrow")
The beauty of the underlying concept (decorators) is that you can do
this with any paths, not just lines; and that you can add other
decorators. You can add text labels simply by adding something like
deco.text("label") to the list of decorations.
Thanks for the reply. BTW, this is my second time around trying to learn
PyX. The first time I tried something too ambitious, and got very
confused. Learning PyX seems to require a slow period of osmosis.
But consider this:
from pyx import *
c = canvas.canvas()
c.stroke(path.line(0,0,3,2),[deco.barrow,deco.earrow, deco.text("hello")])
c.writeEPSfile("darrow")
Traceback (most recent call last):
File "<stdin>", line 3, in ?
AttributeError: 'module' object has no attribute 'text'
deco does not have a method or attribute called "text". Did you have
something different in mind?
-gary
In the current
development version you can have multiple arrows at arbitrary positions:
[deco.barrow,deco.arrow(0.2),deco.earrow] etc.
Cheers,
Michael
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