ENH: Add clicked_slice_point trait

Provides the index, position, value and label associated with the point
clicked on the image slice.

Author: thewtex

itkwidgets/trait_types.py

@@ -17,6 +17,7 @@
     pass
 
 from ._transform_types import to_itk_image, to_point_set, to_geometry
+from ipydatawidgets import array_serialization
 
 # from IPython.core.debugger import set_trace
 
@@ -252,12 +253,61 @@ def itkimage_from_json(js, manager=None):
                     row, col, directionJs[col + row * Dimension])
         return image
 
-
 itkimage_serialization = {
     'from_json': itkimage_from_json,
     'to_json': itkimage_to_json
 }
 
+class ImagePoint(object):
+    """Data from a picked point on an image slice."""
+
+    def __init__(self, index=None, position=None, value=None, label=None):
+        self.index = index
+        self.position = position
+        self.value = value
+        self.label = label
+
+    def __str__(self):
+        return 'index: {0}, position: {1}, value: {2}, label: {3}'.format(
+            self.index,
+            self.position,
+            self.value,
+            self.label)
+
+class ImagePointTrait(traitlets.Instance):
+    """A trait type holding an data from a picked point on an image slice."""
+
+    info_text = 'Data from a picked point on an image'
+
+    klass = ImagePoint
+
+def image_point_from_json(js, manager=None):
+    if js is None:
+        return None
+    else:
+        return ImagePoint(
+            index = array_serialization['from_json'](js['index'], manager),
+            position = array_serialization['from_json'](js['position'], manager),
+            value = array_serialization['from_json'](js['value'], manager),
+            label = int(js['label']),
+        )
+
+def image_point_to_json(image_point, manager=None):
+    if image_point is None:
+        return None
+    else:
+        return {
+            'index': array_serialization['to_json'](image_point.index, manager),
+            'position': array_serialization['to_json'](image_point.position,
+                manager),
+            'value': array_serialization['to_json'](image_point.value, manager),
+            'label': int(image_point.label, manager),
+        }
+
+image_point_serialization = {
+    'from_json': image_point_from_json,
+    'to_json': image_point_to_json
+}
 
 class PolyDataList(traitlets.TraitType):
     """A trait type holding a list of Python data structures compatible with vtk.js.

itkwidgets/widget_viewer.py

@@ -15,9 +15,9 @@
 import itk
 import numpy as np
 import ipywidgets as widgets
-from traitlets import CBool, CFloat, Unicode, CaselessStrEnum, List, validate
+from traitlets import CBool, CFloat, CInt, Unicode, CaselessStrEnum, List, validate
 from ipydatawidgets import NDArray, array_serialization, shape_constraints
-from .trait_types import ITKImage, PointSetList, PolyDataList, itkimage_serialization, polydata_list_serialization, Colormap
+from .trait_types import ITKImage, ImagePointTrait, ImagePoint, PointSetList, PolyDataList, itkimage_serialization, image_point_serialization, polydata_list_serialization, Colormap
 
 try:
     import ipywebrtc
@@ -170,6 +170,12 @@ class Viewer(ViewerParent):
         default_value=None,
         allow_none=True,
         help="World-space position of the Z slicing plane.").tag(sync=True)
+    clicked_slice_point = ImagePointTrait(
+        default_value=None,
+        allow_none=True,
+        help="Data for the point clicked on an image slice.").tag(
+            sync=True,
+            **image_point_serialization)
     gradient_opacity = CFloat(
         default_value=0.2,
         help="Volume rendering gradient opacity, from (0.0, 1.0]").tag(sync=True)
@@ -306,6 +312,9 @@ def __init__(self, **kwargs):  # noqa: C901
             opacities_array = self._validate_geometry_opacities(proposal)
             kwargs['geometry_opacities'] = opacities_array
         self.observe(self._on_geometries_changed, ['geometries'])
+        if 'label_map' in kwargs:
+            # Interpolation is not currently supported with label maps
+            kwargs['interpolation'] = False
 
         super(Viewer, self).__init__(**kwargs)
 
@@ -733,6 +742,7 @@ def view(image=None,  # noqa: C901
 
     interpolation: bool, optional, default: True
         Linear as opposed to nearest neighbor interpolation for image slices.
+        Note: Interpolation is not currently supported with label maps.
 
     gradient_opacity: float, optional, default: 0.22
         Gradient opacity for composite volume rendering, in the range (0.0, 1.0].