Support dynamic components

glue/core/data.py

@@ -1543,7 +1543,7 @@ def update_components(self, mapping):
 
         # alert hub of the change
         if self.hub is not None:
-            msg = NumericalDataChangedMessage(self)
+            msg = NumericalDataChangedMessage(self, components_changed=list(mapping.keys()))
             self.hub.broadcast(msg)
 
         for subset in self.subsets:

glue/core/layer_artist.py

@@ -228,6 +228,12 @@ def _check_subset_state_changed(self):
             self._changed = True
             self._state = state
 
+    def update_component_limits(self, components_changed):
+        """
+        Update component limits for this layer
+        """
+        pass
+
     def __str__(self):
         return "%s for %s" % (self.__class__.__name__, self.layer.label)
 

glue/core/message.py

@@ -182,7 +182,9 @@ def __init__(self, sender, attribute, tag=None):
 
 
 class NumericalDataChangedMessage(DataMessage):
-    pass
+    def __init__(self, sender, components_changed=None, tag=None):
+        super(NumericalDataChangedMessage, self).__init__(sender, tag=tag)
+        self.components_changed = components_changed
 
 
 class DataCollectionMessage(Message):

glue/core/tests/test_components_changed.py

@@ -0,0 +1,45 @@
+"""
+Test that data.update_components() sends a NumericalDataChangedMessage
+that conveys which components have been changed.
+"""
+from glue.core.data import Data
+from glue.core.hub import HubListener
+from glue.core.data_collection import DataCollection
+from glue.core.message import NumericalDataChangedMessage
+
+import numpy as np
+from numpy.testing import assert_array_equal
+
+
+def test_message_carries_components():
+
+    test_data = Data(x=np.array([1, 2, 3, 4, 5]), y=np.array([1, 2, 3, 4, 5]), label='test_data')
+    data_collection = DataCollection([test_data])
+
+    class CustomListener(HubListener):
+
+        def __init__(self, hub):
+            self.received = 0
+            self.components_changed = None
+            hub.subscribe(self, NumericalDataChangedMessage,
+                            handler=self.receive_message)
+
+        def receive_message(self, message):
+            self.received += 1
+            try:
+                self.components_changed = message.components_changed
+            except AttributeError:
+                self.components_changed = None
+
+    listener = CustomListener(data_collection.hub)
+    assert listener.received == 0
+    assert listener.components_changed is None
+
+    cid_to_change = test_data.id['x']
+    new_data = [5, 2, 6, 7, 10]
+    test_data.update_components({cid_to_change: new_data})
+
+    assert listener.received == 1
+    assert cid_to_change in listener.components_changed
+
+    assert_array_equal(test_data['x'], new_data)

glue/viewers/common/tests/test_viewer.py

@@ -3,6 +3,7 @@
 from glue.core import Data
 from glue.viewers.common.viewer import Viewer
 from glue.viewers.common.layer_artist import LayerArtist
+from glue.core.message import NumericalDataChangedMessage
 
 
 def test_custom_layer_artist_maker():
@@ -45,3 +46,60 @@ def custom_maker(viewer, data):
     viewer.add_data(data2)
     assert len(viewer.layers) == 2
     assert type(viewer.layers[1]) is CustomLayerArtist
+
+
+def test_viewer_update_data():
+    """
+    Test that we can have a LayerArtist that can respond
+    to a NumericalDataChangedMessage.
+    """
+
+    class CustomUpdateLayerArtist(LayerArtist):
+
+        def update_component_limits(self, components_changed):
+            self.called_component_limits = True
+            self.num_components_changed = len(components_changed)
+
+    class CustomApplication(Application):
+        def add_widget(self, *args, **kwargs):
+            pass
+
+    @layer_artist_maker('custom_maker_for_update')
+    def custom_maker_for_update(viewer, data):
+        if hasattr(data, 'custom_for_update'):
+            return CustomUpdateLayerArtist(viewer.state, layer=data)
+        if hasattr(data.data, 'custom_for_update'):
+            return CustomUpdateLayerArtist(viewer.state, layer=data)
+
+    app = CustomApplication()
+
+    data1 = Data(x=[1, 2, 3], label='test1')
+    data1.custom_for_update = True
+
+    app.data_collection.append(data1)
+
+    viewer = app.new_data_viewer(Viewer)
+
+    assert len(viewer.layers) == 0
+
+    # NOTE: Check exact type, not using isinstance
+    viewer.add_data(data1)
+    assert len(viewer.layers) == 1
+    assert type(viewer.layers[0]) is CustomUpdateLayerArtist
+
+    msg = NumericalDataChangedMessage(data1, components_changed=[data1.id['x']])
+
+    viewer._update_data(msg)
+    assert viewer.layers[0].called_component_limits
+    assert viewer.layers[0].num_components_changed == 1
+
+    subset = data1.new_subset()
+    subset.subset_state = data1.id['x'] > 2
+
+    assert len(viewer.layers) == 2
+    assert type(viewer.layers[1]) is CustomUpdateLayerArtist
+
+    msg = NumericalDataChangedMessage(data1, components_changed=[data1.id['x']])
+    viewer._update_data(msg)
+    assert viewer.layers[1].called_component_limits
+    assert viewer.layers[1].num_components_changed == 1

glue/viewers/common/viewer.py

@@ -288,9 +288,20 @@ def _update_data(self, message):
                 if isinstance(layer_artist.layer, Subset):
                     if layer_artist.layer.data is message.data:
                         layer_artist.update()
+                        try:
+                            components_changed = message.components_changed
+                            layer_artist.update_component_limits(components_changed)
+                        except AttributeError:
+                            pass
+
                 else:
                     if layer_artist.layer is message.data:
                         layer_artist.update()
+                        try:
+                            components_changed = message.components_changed
+                            layer_artist.update_component_limits(components_changed)
+                        except AttributeError:
+                            pass
 
     def _update_subset(self, message):
         if message.attribute == 'style':