Currently, the pos parameter gives the position of the head of tip of
the arrow. This is problematic when one wants to position the arrow in
the middle of a line or arc: pos=0.5 gives an arrow which is visually
off the middle (it is visually to the left of it).
Introduce a parameter poscorr which shifts the arrow by an amount which
is relative to the size of the arrowhead (and the constriction).
poscorr=0 is the default (tip at pos)
poscorr=1 puts the constriction center at pos
---
pyx/deco.py | 21 +++++++++++++++------
1 files changed, 15 insertions(+), 6 deletions(-)
diff --git a/pyx/deco.py b/pyx/deco.py
index 3206627..41848db 100644
--- a/pyx/deco.py
+++ b/pyx/deco.py
@@ -431,20 +431,23 @@ class arrow(deco, attr.attr):
"""arrow is a decorator which adds an arrow to either side of the path"""
- def __init__(self, attrs=[], pos=1, reversed=0, size=_base, angle=45,
constriction=0.8):
+ def __init__(self, attrs=[], pos=1, poscorr=0, reversed=0, size=_base,
angle=45, constriction=0.8):
self.attrs = attr.mergeattrs([style.linestyle.solid, filled] + attrs)
attr.checkattrs(self.attrs, [deco, style.fillstyle, style.strokestyle])
self.pos = pos
+ self.poscorr = poscorr
self.reversed = reversed
self.size = size
self.angle = angle
self.constriction = constriction
- def __call__(self, attrs=None, pos=None, reversed=None, size=None,
angle=None, constriction=_marker):
+ def __call__(self, attrs=None, pos=None, poscorr=None, reversed=None,
size=None, angle=None, constriction=_marker):
if attrs is None:
attrs = self.attrs
if pos is None:
pos = self.pos
+ if poscorr is None:
+ poscorr = self.poscorr
if reversed is None:
reversed = self.reversed
if size is None:
@@ -453,11 +456,12 @@ class arrow(deco, attr.attr):
angle = self.angle
if constriction is _marker:
constriction = self.constriction
- return arrow(attrs=attrs, pos=pos, reversed=reversed, size=size,
angle=angle, constriction=constriction)
+ return arrow(attrs=attrs, pos=pos, poscorr=poscorr, reversed=reversed,
size=size, angle=angle, constriction=constriction)
def decorate(self, dp, texrunner):
dp.ensurenormpath()
anormpath = dp.path
+ arclen = anormpath.arclen()
# calculate absolute arc length of constricition
# Note that we have to correct this length because the arrowtemplates
are rotated
@@ -472,17 +476,22 @@ class arrow(deco, attr.attr):
constrictionlen = self.size * 1 *
math.cos(math.radians(self.angle/2.0))
arrowheadconstrictionlen = None
- arclenfrombegin = self.pos * anormpath.arclen()
direction = self.reversed and -1 or 1
+ selfpos = self.pos
+ if self.poscorr:
+ selfpos += direction * self.poscorr * constrictionlen / arclen
+ selfpos = max(0, min(1, selfpos))
+
+ arclenfrombegin = selfpos * arclen
arrowhead = _arrowhead(anormpath, arclenfrombegin, direction,
self.size, self.angle, arrowheadconstrictionlen)
# add arrowhead to decoratedpath
dp.ornaments.draw(arrowhead, self.attrs)
# exlude part of the path from stroking when the arrow is strictly at
the begin or the end
- if self.pos == 0 and self.reversed:
+ if selfpos == 0 and self.reversed:
dp.excluderange(0, min(self.size, constrictionlen))
- elif self.pos == 1 and not self.reversed:
+ elif selfpos == 1 and not self.reversed:
dp.excluderange(anormpath.end() - min(self.size, constrictionlen),
anormpath.end())
arrow.clear = attr.clearclass(arrow)
--
1.7.5.1.445.gf3e03
------------------------------------------------------------------------------
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