Merge a308597 into fb7e8d2

docs/custom_frames.rst

@@ -33,6 +33,38 @@ following example shows how to use the built-in
     # Clip the image to the frame
     im.set_clip_path(ax.coords.frame.patch)
 
+The :class:`~wcsaxes.frame.EllipticalFrame` class is especially useful for
+all-sky plots such as Aitoff projections:
+
+.. plot::
+   :context: reset
+   :include-source:
+   :align: center
+
+    from astropy.wcs import WCS
+    from wcsaxes import datasets
+    from wcsaxes.frame import EllipticalFrame
+    from matplotlib import patheffects
+
+    hdu = datasets.fetch_rosat_hdu()
+    wcs = WCS(hdu.header)
+
+    import matplotlib.pyplot as plt
+
+    fig = plt.figure(figsize=(7, 4))
+    ax = fig.add_axes([0.05, 0.05, 0.9, 0.9], projection=wcs,
+                      frame_class=EllipticalFrame)
+
+    path_effects=[patheffects.withStroke(linewidth=3, foreground='black')]
+    ax.coords.grid(color='white')
+    ax.coords['glon'].set_ticklabel(color='white', path_effects=path_effects)
+
+    im = ax.imshow(hdu.data, vmin=0., vmax=300.,
+              cmap=plt.cm.inferno, origin='lower')
+
+    # Clip the image to the frame
+    im.set_clip_path(ax.coords.frame.patch)
+
 However, you can also write your own frame class. The idea is to set up any
 number of connecting spines that define the frame. You can define a frame as a
 spine, but if you define it as multiple spines you will be able to control on

docs/ticks_labels_grid.rst

@@ -258,6 +258,11 @@ We can set the defaults back using:
     lat.set_ticklabel_position('l')
     lat.set_axislabel_position('l')
 
+On plots with elliptical frames, three alternate tick positions are supported:
+``c`` for the outer circular or elliptical border, ``h`` for the horizontal
+axis (which is usually the major axis of the ellipse), and ``v`` for the
+vertical axis (which is usually the minor axis of the ellipse).
+
 
 Hiding ticks and tick labels
 ============================

wcsaxes/core.py

@@ -11,7 +11,7 @@
                          CoordinateTransform)
 from .coordinates_map import CoordinatesMap
 from .utils import get_coord_meta
-from .frame import RectangularFrame
+from .frame import EllipticalFrame, RectangularFrame
 import numpy as np
 
 __all__ = ['WCSAxes', 'WCSAxesSubplot']
@@ -185,6 +185,22 @@ def reset_wcs(self, wcs=None, slices=None, transform=None, coord_meta=None):
                     self.coords[coord_index].set_axislabel_position('')
                     self.coords[coord_index].set_ticklabel_position('')
                     self.coords[coord_index].set_ticks_position('')
+        # Common default settings for Elliptical Frame
+        elif self.frame_class is EllipticalFrame:
+            for coord_index in range(len(self.slices)):
+                if self.slices[coord_index] == 'x':
+                    self.coords[coord_index].set_axislabel_position('h')
+                    self.coords[coord_index].set_ticklabel_position('h')
+                    self.coords[coord_index].set_ticks_position('h')
+                elif self.slices[coord_index] == 'y':
+                    self.coords[coord_index].set_ticks_position('c')
+                    self.coords[coord_index].set_axislabel_position('c')
+                    self.coords[coord_index].set_ticklabel_position('c')
+                else:
+                    self.coords[coord_index].set_axislabel_position('')
+                    self.coords[coord_index].set_ticklabel_position('')
+                    self.coords[coord_index].set_ticks_position('')
+
 
     def draw(self, renderer, inframe=False):
 

wcsaxes/frame.py

@@ -202,7 +202,7 @@ def update_spines(self):
 
 class EllipticalFrame(BaseFrame):
 
-    spine_names = 'c'
+    spine_names = 'chv'
 
     def update_spines(self):
 
@@ -218,3 +218,30 @@ def update_spines(self):
         theta = np.linspace(0., 2 * np.pi, 1000)
         self['c'].data = np.array([xmid + dx * np.cos(theta),
                                    ymid + dy * np.sin(theta)]).transpose()
+        self['h'].data = np.array([np.linspace(xmin, xmax, 1000),
+                                   np.repeat(ymid, 1000)]).transpose()
+        self['v'].data = np.array([np.repeat(xmid, 1000),
+                                   np.linspace(ymin, ymax, 1000)]).transpose()
+
+    def _update_patch_path(self):
+        """Override path patch to include only the outer ellipse,
+        not the major and minor axes in the middle."""
+
+        self.update_spines()
+        vertices = self['c'].data
+
+        if self._path is None:
+            self._path = Path(vertices)
+        else:
+            self._path.vertices = vertices
+
+    def draw(self, renderer):
+        """Override to draw only the outer ellipse,
+        not the major and minor axes in the middle.
+
+        FIXME: we may want to add a general method to give the user control
+        over which spines are drawn."""
+        axis = 'c'
+        x, y = self[axis].pixel[:, 0], self[axis].pixel[:, 1]
+        line = Line2D(x, y, linewidth=self._linewidth, color=self._color, zorder=1000)
+        line.draw(renderer)