added ellipse compare script

svn path=/trunk/matplotlib/; revision=3941

Author: jdh2358

lib/matplotlib/backends/backend_agg.py

@@ -143,7 +143,7 @@ def draw_arc(self, gcEdge, rgbFace, x, y, width, height, angle1, angle2, rotatio
         """
         if __debug__: verbose.report('RendererAgg.draw_arc', 'debug-annoying')
         self._renderer.draw_ellipse(
-            gcEdge, rgbFace, x, y, width/2, height/2, rotation)  # ellipse takes radius
+            gcEdge, rgbFace, x, y, width/2., height/2., rotation)  # ellipse takes radius
 
 
     def draw_line(self, gc, x1, y1, x2, y2):

lib/matplotlib/backends/backend_ps.py

@@ -882,7 +882,7 @@ def _draw_ps(self, ps, gc, rgbFace, command=None):
         """
         # local variable eliminates all repeated attribute lookups
         write = self._pswriter.write
-
+        write('gsave\n')
         if debugPS and command:
             write("% "+command+"\n")
 
@@ -915,7 +915,7 @@ def _draw_ps(self, ps, gc, rgbFace, command=None):
             write("stroke\n")
         if cliprect:
             write("grestore\n")
-
+        write('grestore\n')            
     def push_gc(self, gc, store=1):
         """
         Push the current onto stack, with the exception of the clip box, which

unit/ellipse_compare.py

@@ -0,0 +1,53 @@
+"""
+Compare the ellipse generated with arcs versus a polygonal approximation 
+"""
+import numpy as npy
+from matplotlib import patches
+from pylab import figure, show
+
+xcenter, ycenter = 0.38, 0.52
+#xcenter, ycenter = 0., 0.
+width, height = 1e-1, 3e-1
+angle = -30
+
+theta = npy.arange(0.0, 360.0, 1.0)*npy.pi/180.0
+x = width/2. * npy.cos(theta)
+y = height/2. * npy.sin(theta)
+
+rtheta = angle*npy.pi/180.
+R = npy.array([
+    [npy.cos(rtheta),  -npy.sin(rtheta)],
+    [npy.sin(rtheta), npy.cos(rtheta)],
+    ])
+
+
+x, y = npy.dot(R, npy.array([x, y]))
+x += xcenter
+y += ycenter
+
+fig = figure()
+ax = fig.add_subplot(211, aspect='auto')
+ax.fill(x, y, alpha=0.2, facecolor='yellow')
+
+e1 = patches.Ellipse((xcenter, ycenter), width, height,
+             angle=angle, linewidth=2, fill=False)
+
+ax.add_artist(e1)
+
+ax = fig.add_subplot(212, aspect='equal')
+ax.fill(x, y, alpha=0.2, facecolor='yellow')
+e2 = patches.Ellipse((xcenter, ycenter), width, height,
+             angle=angle, linewidth=2, fill=False)
+
+
+ax.add_artist(e2)
+ax.autoscale_view()
+
+
+ax.set_xlim(0.2, .5)
+ax.set_ylim(0.3, 0.7)
+
+#fig.savefig('ellipse_compare.png')
+#fig.savefig('ellipse_compare.ps')
+
+show()