Add slices callback from self.viewer_state; check for "Custom" perc…

…entile

glue/core/state_objects.py

@@ -324,7 +324,7 @@ def update_values(self, force=False, use_default_modifiers=False, **properties):
             percentile = getattr(self, 'percentile', None) or 100
             log = getattr(self, 'log', None) or False
 
-        if not force and (percentile == 'Custom' or not hasattr(self, 'data') or self.data is None):
+        if percentile == 'Custom' or (not force and getattr(self, 'data', None) is None):
             self.set(percentile=percentile, log=log)
         else:
             # Shortcut if the component ID is a pixel component ID
@@ -377,8 +377,12 @@ def flip_limits(self):
         self.set(lower=self.upper, upper=self.lower)
 
     def set_slice(self, slices):
+        """Set subset for compute_statistic to current slice or global"""
+
         self.set(subset_state=None if slices is None else SliceSubsetState(self.data, slices))
-        self.update_values(force=True)
+        # Force update if percentile not set to 'Custom'.
+        if isinstance(self.percentile, (int, float)):
+            self.update_values(force=True)
 
 
 class StateAttributeSingleValueHelper(StateAttributeCacheHelper):

glue/viewers/image/state.py

@@ -9,7 +9,7 @@
                                            DeferredDrawSelectionCallbackProperty as DDSCProperty)
 from glue.core.state_objects import StateAttributeLimitsHelper
 from glue.utils import defer_draw, view_shape
-from echo import callback_property, delay_callback
+from echo import delay_callback
 from glue.core.data_combo_helper import ManualDataComboHelper, ComponentIDComboHelper
 from glue.core.exceptions import IncompatibleDataException
 from glue.viewers.common.stretch_state_mixin import StretchStateMixin
@@ -572,49 +572,25 @@ def _get_image(self, view=None):
 
     def _set_global_limits(self, global_limits=True):
         if global_limits:
-            self.remove_callback('slice_subset_state', self._update_slice_subset)
+            self.viewer_state.remove_callback('slices', self._update_slice_subset)
             self.attribute_lim_helper.set_slice(None)
         else:
-            self.add_callback('slice_subset_state', self._update_slice_subset)
-            slices = [slice(s) if s is None else s for s in self.slice_subset_state]
-            self.attribute_lim_helper.set_slice(slices)
+            self.viewer_state.add_callback('slices', self._update_slice_subset)
+            self.attribute_lim_helper.set_slice(self.viewer_state.numpy_slice_aggregation_transpose[0])
 
-    def _update_slice_subset(self, slice_subset_state):
+    def _update_slice_subset(self, slices):
         """
         Select a subset slice for determining image levels.
 
         Parameters
         ----------
-        slice_subset_state : iterable of :class:`slice` or `None`
+        slices : iterable of :class:`slice` or `None`
             An iterable containing :class:`slice` objects that can instantiate
             a :class:`~glue.core.subset.SliceSubsetState` and has to be consistent
-            with the shape of `self.data`; `None` to unslice.
+            with the shape of `self.data`; `None` to unslice
+            - will be used via helper property.
         """
-        slices = [slice(s) if s is None else s for s in slice_subset_state]
-        self.attribute_lim_helper.set_slice(slices)
-
-    @callback_property
-    def slice_subset_state(self):
-        """
-        Returns slicing information usable by :class:`~glue.core.subset.SliceSubsetState`.
-
-        slice_subset_state = DDCProperty(docstring='Slices iterable describing the current '
-                                               'slice along all dimensions as subset')
-        """
-        # Need a safety check here if self.viewer_state is already fully initialised.
-        if self.viewer_state.reference_data is None or self.viewer_state.x_att is None:
-            return None
-        else:
-            slices = []
-            for i in range(self.viewer_state.reference_data.ndim):
-                if i == self.viewer_state.x_att.axis or i == self.viewer_state.y_att.axis:
-                    slices.append(None)
-                else:
-                    if isinstance(self.viewer_state.slices[i], AggregateSlice):
-                        slices.append(self.viewer_state.slices[i].slice)
-                    else:
-                        slices.append(self.viewer_state.slices[i])
-            return slices  # self.viewer_state.numpy_slice_aggregation_transpose[0]
+        self.attribute_lim_helper.set_slice(self.viewer_state.numpy_slice_aggregation_transpose[0])
 
     def flip_limits(self):
         """