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Commit7a82ea8

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committed
Added (experimental) support for large arcs
svn path=/branches/transforms/; revision=4700
1 parent12cc2fc commit7a82ea8

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5 files changed

+191
-18
lines changed

5 files changed

+191
-18
lines changed

‎lib/matplotlib/patches.py

Lines changed: 175 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -839,6 +839,7 @@ def __init__(self, xy, width, height, angle=0.0, **kwargs):
839839
self._width,self._height=width,height
840840
self._angle=angle
841841
self._recompute_transform()
842+
self._path=Path.unit_circle()
842843

843844
def_recompute_transform(self):
844845
self._patch_transform=transforms.Affine2D() \
@@ -850,7 +851,7 @@ def get_path(self):
850851
"""
851852
Return the vertices of the rectangle
852853
"""
853-
returnPath.unit_circle()
854+
returnself._path
854855

855856
defget_patch_transform(self):
856857
returnself._patch_transform
@@ -881,7 +882,6 @@ def _set_angle(self, angle):
881882
self._recompute_transform()
882883
angle=property(_get_angle,_set_angle)
883884

884-
885885
classCircle(Ellipse):
886886
"""
887887
A circle patch
@@ -908,6 +908,179 @@ def __init__(self, xy, radius=5, **kwargs):
908908
Ellipse.__init__(self,xy,radius*2,radius*2,**kwargs)
909909
__init__.__doc__=cbook.dedent(__init__.__doc__)%artist.kwdocd
910910

911+
classArc(Ellipse):
912+
"""
913+
An elliptical arc. Because it performs various optimizations, it may not be
914+
filled.
915+
"""
916+
def__str__(self):
917+
return"Arc(%d,%d;%dx%d)"%(self.center[0],self.center[1],self.width,self.height)
918+
919+
def__init__(self,xy,width,height,angle=0.0,theta1=0.0,theta2=360.0,**kwargs):
920+
"""
921+
xy - center of ellipse
922+
width - length of horizontal axis
923+
height - length of vertical axis
924+
angle - rotation in degrees (anti-clockwise)
925+
theta1 - starting angle of the arc in degrees
926+
theta2 - ending angle of the arc in degrees
927+
928+
If theta1 and theta2 are not provided, the arc will form a
929+
complete ellipse.
930+
931+
Valid kwargs are:
932+
%(Patch)s
933+
"""
934+
fill=kwargs.pop('fill')
935+
iffill:
936+
raiseValueError("Arc objects can not be filled")
937+
kwargs['fill']=False
938+
939+
Ellipse.__init__(self,xy,width,height,angle,**kwargs)
940+
941+
self._theta1=theta1
942+
self._theta2=theta2
943+
944+
defdraw(self,renderer):
945+
"""
946+
Ellipses are normally drawn using an approximation that uses
947+
eight cubic bezier splines. The error of this approximation
948+
is 1.89818e-6, according to this unverified source:
949+
950+
Lancaster, Don. Approximating a Circle or an Ellipse Using
951+
Four Bezier Cubic Splines.
952+
953+
http://www.tinaja.com/glib/ellipse4.pdf
954+
955+
There is a use case where very large ellipses must be drawn
956+
with very high accuracy, and it is too expensive to render the
957+
entire ellipse with enough segments (either splines or line
958+
segments). Therefore, in the case where either radius of the
959+
ellipse is large enough that the error of the spline
960+
approximation will be visible (greater than one pixel offset
961+
from the ideal), a different technique is used.
962+
963+
In that case, only the visible parts of the ellipse are drawn,
964+
with each visible arc using a fixed number of spline segments
965+
(8). The algorithm proceeds as follows:
966+
967+
1. The points where the ellipse intersects the axes bounding
968+
box are located. (This is done be performing an inverse
969+
transformation on the axes bbox such that it is relative to
970+
the unit circle -- this makes the intersection calculation
971+
much easier than doing rotated ellipse intersection
972+
directly).
973+
974+
This uses the "line intersecting a circle" algorithm from:
975+
976+
Vince, John. Geometry for Computer Graphics: Formulae,
977+
Examples & Proofs. London: Springer-Verlag, 2005.
978+
979+
2. The angles of each of the intersection points are
980+
calculated.
981+
982+
3. Proceeding counterclockwise starting in the positive
983+
x-direction, each of the visible arc-segments between the
984+
pairs of vertices are drawn using the bezier arc
985+
approximation technique implemented in Path.arc().
986+
"""
987+
# Get the width and height in pixels
988+
width,height=self.get_transform().transform_point(
989+
(self._width,self._height))
990+
inv_error= (1.0/1.89818e-6)
991+
992+
ifwidth<inv_errorandheight<inv_errorandFalse:
993+
self._path=Path.arc(self._theta1,self._theta2)
994+
returnPatch.draw(self,renderer)
995+
996+
# Transforms the axes box_path so that it is relative to the unit
997+
# circle in the same way that it is relative to the desired
998+
# ellipse.
999+
box_path=Path.unit_rectangle()
1000+
box_path_transform=transforms.BboxTransformTo(self.axes.bbox)+ \
1001+
self.get_transform().inverted()
1002+
box_path=box_path.transformed(box_path_transform)
1003+
vertices= []
1004+
1005+
defiter_circle_intersect_on_line(x0,y0,x1,y1):
1006+
dx=x1-x0
1007+
dy=y1-y0
1008+
dr2=dx*dx+dy*dy
1009+
dr=npy.sqrt(dr2)
1010+
D=x0*y1-x1*y0
1011+
D2=D*D
1012+
discrim=dr2-D2
1013+
1014+
# Single (tangential) intersection
1015+
ifdiscrim==0.0:
1016+
x= (D*dy)/dr2
1017+
y= (-D*dx)/dr2
1018+
yieldx,y
1019+
elifdiscrim>0.0:
1020+
ifdy<0:
1021+
sign_dy=-1.0
1022+
else:
1023+
sign_dy=1.0
1024+
sqrt_discrim=npy.sqrt(discrim)
1025+
forsignin (1.,-1.):
1026+
x= (D*dy+sign*sign_dy*dx*sqrt_discrim)/dr2
1027+
y= (-D*dx+sign*npy.abs(dy)*sqrt_discrim)/dr2
1028+
yieldx,y
1029+
1030+
defiter_circle_intersect_on_line_seg(x0,y0,x1,y1):
1031+
epsilon=1e-9
1032+
ifx1<x0:
1033+
x0e,x1e=x1,x0
1034+
else:
1035+
x0e,x1e=x0,x1
1036+
ify1<y0:
1037+
y0e,y1e=y1,y0
1038+
else:
1039+
y0e,y1e=y0,y1
1040+
x0e-=epsilon
1041+
y0e-=epsilon
1042+
x1e+=epsilon
1043+
y1e+=epsilon
1044+
forx,yiniter_circle_intersect_on_line(x0,y0,x1,y1):
1045+
ifx>=x0eandx<=x1eandy>=y0eandy<=y1e:
1046+
yieldx,y
1047+
1048+
PI=npy.pi
1049+
TWOPI=PI*2.0
1050+
RAD2DEG=180.0/PI
1051+
DEG2RAD=PI/180.0
1052+
theta1=self._theta1
1053+
theta2=self._theta2
1054+
thetas= {}
1055+
# For each of the point pairs, there is a line segment
1056+
forp0,p1inzip(box_path.vertices[:-1],box_path.vertices[1:]):
1057+
x0,y0=p0
1058+
x1,y1=p1
1059+
forx,yiniter_circle_intersect_on_line_seg(x0,y0,x1,y1):
1060+
# Convert radians to angles
1061+
theta=npy.arccos(x)
1062+
ify<0:
1063+
theta=TWOPI-theta
1064+
theta*=RAD2DEG
1065+
iftheta>theta1andtheta<theta2:
1066+
thetas[theta]=None
1067+
1068+
thetas=thetas.keys()
1069+
thetas.sort()
1070+
thetas.append(theta2)
1071+
1072+
last_theta=theta1
1073+
theta1_rad=theta1*DEG2RAD
1074+
inside=box_path.contains_point((npy.cos(theta1_rad),npy.sin(theta1_rad)))
1075+
1076+
forthetainthetas:
1077+
ifinside:
1078+
self._path=Path.arc(last_theta,theta,8)
1079+
Patch.draw(self,renderer)
1080+
inside=False
1081+
else:
1082+
inside=True
1083+
last_theta=theta
9111084

9121085
defbbox_artist(artist,renderer,props=None,fill=True):
9131086
"""

‎lib/matplotlib/path.py

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -408,7 +408,7 @@ def unit_circle(cls):
408408
unit_circle=classmethod(unit_circle)
409409

410410
#@classmethod
411-
defarc(cls,theta1,theta2,is_wedge=False,n=None):
411+
defarc(cls,theta1,theta2,n=None,is_wedge=False):
412412
"""
413413
Returns an arc on the unit circle from angle theta1 to angle
414414
theta2 (in degrees).
@@ -486,12 +486,12 @@ def arc(cls, theta1, theta2, is_wedge=False, n=None):
486486
arc=classmethod(arc)
487487

488488
#@classmethod
489-
defwedge(cls,theta1,theta2):
489+
defwedge(cls,theta1,theta2,n=None):
490490
"""
491491
Returns a wedge of the unit circle from angle theta1 to angle
492492
theta2 (in degrees).
493493
"""
494-
returncls.arc(theta1,theta2,True)
494+
returncls.arc(theta1,theta2,True,n)
495495
wedge=classmethod(wedge)
496496

497497
_get_path_collection_extents=get_path_collection_extents

‎src/_path.cpp

Lines changed: 5 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -109,7 +109,7 @@ class _path_module : public Py::ExtensionModule<_path_module>
109109
// Input 2D polygon _pgon_ with _numverts_ number of vertices and test point
110110
// _point_, returns 1 if inside, 0 if outside.
111111
template<classT>
112-
boolpoint_in_path_impl(double tx,double ty, T& path)
112+
boolpoint_in_path_impl(constdouble tx,constdouble ty, T& path)
113113
{
114114
int yflag0, yflag1, inside_flag;
115115
double vtx0, vty0, vtx1, vty1, sx, sy;
@@ -132,7 +132,7 @@ bool point_in_path_impl(double tx, double ty, T& path)
132132
yflag0 = (vty0 >= ty);
133133

134134
vtx1 = x;
135-
vty1 =x;
135+
vty1 =y;
136136

137137
inside_flag =0;
138138
do
@@ -141,7 +141,7 @@ bool point_in_path_impl(double tx, double ty, T& path)
141141

142142
// The following cases denote the beginning on a new subpath
143143
if (code == agg::path_cmd_stop ||
144-
(code & agg::path_cmd_end_poly) == agg::path_cmd_end_poly)
144+
(code & agg::path_cmd_end_poly) == agg::path_cmd_end_poly)
145145
{
146146
x = sx;
147147
y = sy;
@@ -169,7 +169,7 @@ bool point_in_path_impl(double tx, double ty, T& path)
169169
// by Joseph Samosky's and Mark Haigh-Hutchinson's different
170170
// polygon inclusion tests.
171171
if ( ((vty1-ty) * (vtx0-vtx1) >=
172-
(vtx1-tx) * (vty0-vty1)) == yflag1 )
172+
(vtx1-tx) * (vty0-vty1)) == yflag1 )
173173
{
174174
inside_flag ^=1;
175175
}
@@ -184,7 +184,7 @@ bool point_in_path_impl(double tx, double ty, T& path)
184184
vty1 = y;
185185
}
186186
while (code != agg::path_cmd_stop &&
187-
(code & agg::path_cmd_end_poly) != agg::path_cmd_end_poly);
187+
(code & agg::path_cmd_end_poly) != agg::path_cmd_end_poly);
188188

189189
yflag1 = (vty1 >= ty);
190190
if (yflag0 != yflag1)

‎unit/ellipse_compare.py

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
"""
2-
Compare the ellipse generated with arcs versus a polygonal approximation
2+
Compare the ellipse generated with arcs versus a polygonal approximation
33
"""
44
importnumpyasnpy
55
frommatplotlibimportpatches
@@ -29,7 +29,7 @@
2929
ax=fig.add_subplot(211,aspect='auto')
3030
ax.fill(x,y,alpha=0.2,facecolor='yellow',edgecolor='yellow',linewidth=1,zorder=1)
3131

32-
e1=patches.Ellipse((xcenter,ycenter),width,height,
32+
e1=patches.Arc((xcenter,ycenter),width,height,
3333
angle=angle,linewidth=2,fill=False,zorder=2)
3434

3535
ax.add_patch(e1)

‎unit/ellipse_large.py

Lines changed: 6 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66

77
importmath
88
frompylabimport*
9-
frommatplotlib.patchesimportEllipse
9+
frommatplotlib.patchesimportArc
1010

1111
# given a point x, y
1212
x=2692.440
@@ -54,22 +54,22 @@ def custom_ellipse( ax, x, y, major, minor, theta, numpoints = 750, **kwargs ):
5454

5555
# make the lower-bound ellipse
5656
diam= (r-delta)*2.0
57-
lower_ellipse=Ellipse( (0.0,0.0),diam,diam,0.0,fill=False,edgecolor="darkgreen" )
57+
lower_ellipse=Arc( (0.0,0.0),diam,diam,0.0,fill=False,edgecolor="darkgreen" )
5858
ax.add_patch(lower_ellipse )
5959

6060
# make the target ellipse
6161
diam=r*2.0
62-
target_ellipse=Ellipse( (0.0,0.0),diam,diam,0.0,fill=False,edgecolor="darkred" )
62+
target_ellipse=Arc( (0.0,0.0),diam,diam,0.0,fill=False,edgecolor="darkred" )
6363
ax.add_patch(target_ellipse )
6464

6565
# make the upper-bound ellipse
6666
diam= (r+delta)*2.0
67-
upper_ellipse=Ellipse( (0.0,0.0),diam,diam,0.0,fill=False,edgecolor="darkblue" )
67+
upper_ellipse=Arc( (0.0,0.0),diam,diam,0.0,fill=False,edgecolor="darkblue" )
6868
ax.add_patch(upper_ellipse )
6969

7070
# make the target
7171
diam=delta*2.0
72-
target=Ellipse( (x,y),diam,diam,0.0,fill=False,edgecolor="#DD1208" )
72+
target=Arc( (x,y),diam,diam,0.0,fill=False,edgecolor="#DD1208" )
7373
ax.add_patch(target )
7474

7575
# give it a big marker
@@ -104,4 +104,4 @@ def custom_ellipse( ax, x, y, major, minor, theta, numpoints = 750, **kwargs ):
104104
ax.set_ylim(6705,6735)
105105
show()
106106

107-
savefig("ellipse")
107+
#savefig("ellipse")

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