[PyX-devel] [PATCH] deco.arrow: fix arrows at pos=0

[Michael J G. <mic...@us...>]

The arrowhead needs a piece of size "size" of the path for its
construction. Therefore, only (arclen-size) of the path is available as
positions for a head without extending the path.

So, change pos=0 to mean a position at arclenpos=size, and introduce the
necessary additional path exclusions for begin/end arrows.
---
Following up the pos/relarclen discussion, here's a patch within the
current design which prevents the necessity of extrapolating the path.

Also, in contrast to the other patches I sent a minute ago, I managed to set
my author field again...

Signed-off-by: Michael J Gruber <mic...@us...>
---
 pyx/deco.py | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/pyx/deco.py b/pyx/deco.py
index 193f566..e41e88e 100644
--- a/pyx/deco.py
+++ b/pyx/deco.py
@@ -472,7 +472,7 @@ class arrow(deco, attr.attr):
         dp.ensurenormpath()
         anormpath = dp.path
 
-        arclenfrombegin = (1-self.reversed)*self.constrictionlen + self.pos * (anormpath.arclen() - self.constrictionlen)
+        arclenfrombegin = (1-self.reversed)*self.size + self.pos * (anormpath.arclen() - self.size)
         direction = self.reversed and -1 or 1
         arrowhead = _arrowhead(anormpath, arclenfrombegin, direction, self.size, self.angle,
                                self.constriction is not None, self.constrictionlen)
@@ -481,10 +481,16 @@ class arrow(deco, attr.attr):
         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:
-            dp.excluderange(0, min(self.size, self.constrictionlen))
-        elif self.pos == 1 and not self.reversed:
-            dp.excluderange(anormpath.end() - min(self.size, self.constrictionlen), anormpath.end())
+        if self.pos == 0:
+            if self.reversed:
+                dp.excluderange(0, min(self.size, self.constrictionlen))
+            else:
+                dp.excluderange(0, min(self.size, self.size - self.constrictionlen))
+        elif self.pos == 1:
+            if self.reversed:
+                dp.excluderange(anormpath.end() - min(self.size, self.size - self.constrictionlen), anormpath.end())
+            else:
+                dp.excluderange(anormpath.end() - min(self.size, self.constrictionlen), anormpath.end())
 
 arrow.clear = attr.clearclass(arrow)
 
-- 
1.7.11.rc0.265.g7c5e375