Fix grid and cursor coordinates and added reference image

wcsaxes/coordinate_helpers.py

@@ -179,16 +179,25 @@ def format_coord(self, value):
         Given the value of a coordinate, will format it according to the
         format of the formatter_locator.
         """
+
         if not hasattr(self, "_fl_spacing"):
             return ""  # _update_ticks has not been called yet
+
         fl = self._formatter_locator
         if isinstance(fl, AngleFormatterLocator):
+
+            # Convert to degrees if needed
+            if self._coord_unit_scale is not None:
+                value *= self._coord_unit_scale
+
             if self.coord_type == 'longitude':
                 value = wrap_angle_at(value, self.coord_wrap)
             value = value * u.degree
             value = value.to(fl._unit).value
+
         spacing = self._fl_spacing
         string = fl.formatter(values=[value] * fl._unit, spacing=spacing)
+
         return string[0]
 
     def set_separator(self, separator):
@@ -645,6 +654,11 @@ def _update_grid_lines(self):
         # single go rather than doing this in the gridline to path conversion
         # to fully benefit from vectorized coordinate transformations.
 
+        # Currently xy_world is in deg, but transform function needs it in
+        # native units
+        if self._coord_unit_scale is not None:
+            xy_world /= self._coord_unit_scale
+
         # Transform line to pixel coordinates
         pixel = self.transform.inverted().transform(xy_world)
 

wcsaxes/tests/test_images.py

@@ -364,7 +364,7 @@ def test_axislabels_regression(self):
 
     @pytest.mark.mpl_image_compare(savefig_kwargs={'bbox_inches': 'tight'},
                                    tolerance=1.5)
-    def test_noncelestial_angular(self):
+    def test_noncelestial_angular(self, tmpdir):
         # Regression test for a bug that meant that when passing a WCS that had
         # angular axes and using set_coord_type to set the coordinates to
         # longitude/latitude, but where the WCS wasn't recognized as celestial,
@@ -387,4 +387,12 @@ def test_noncelestial_angular(self):
         ax.coords[0].set_major_formatter('s.s')
         ax.coords[1].set_major_formatter('s.s')
 
+        ax.grid(color='white', ls='solid')
+
+        # Force drawing (needed for format_coord)
+        fig.savefig(tmpdir.join('nothing').strpath)
+
+        # TODO: the formatted string should show units
+        assert ax.format_coord(512, 512) == "513.0 513.0 (world)"
+
         return fig