ENH: Add vtkImageData example

.gitignore

@@ -18,6 +18,7 @@ js/package-lock.json
 005_32months_T2_RegT1_Reg2Atlas_ManualBrainMask_Stripped.nrrd
 examples/005_32months_T2_RegT1_Reg2Atlas_ManualBrainMask_Stripped.nrrd
 examples/cthead1.png
+examples/vase.vti
 
 js/lib/ZstdDecompress/web-build/
 .pytest_cache/

examples/vtkImageData.ipynb

@@ -0,0 +1,118 @@
+{
+ "cells": [
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# Install dependencies for this example\n",
+    "# Note: This does not include itk-jupyter-widgets, itself\n",
+    "import sys\n",
+    "!{sys.executable} -m pip install vtk requests"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import vtk\n",
+    "\n",
+    "import requests\n",
+    "import shutil\n",
+    "import os\n",
+    "\n",
+    "from itkwidgets import view"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# Download data\n",
+    "file_name = 'vase.vti'\n",
+    "if not os.path.exists(file_name):\n",
+    "    response = requests.get('https://data.kitware.com/api/v1/file/5a826bdc8d777f0685782960/download', stream=True)\n",
+    "    with open(file_name, 'wb') as fp:\n",
+    "        response.raw.decode_content = True\n",
+    "        shutil.copyfileobj(response.raw, fp)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "reader = vtk.vtkXMLImageDataReader()\n",
+    "reader.SetFileName(file_name)\n",
+    "reader.Update()\n",
+    "vtk_image = reader.GetOutput()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "application/vnd.jupyter.widget-view+json": {
+       "model_id": "a50c990db54a4d41b274aba2869e782d",
+       "version_major": 2,
+       "version_minor": 0
+      },
+      "text/html": [
+       "<p>Failed to display Jupyter Widget of type <code>Viewer</code>.</p>\n",
+       "<p>\n",
+       "  If you're reading this message in the Jupyter Notebook or JupyterLab Notebook, it may mean\n",
+       "  that the widgets JavaScript is still loading. If this message persists, it\n",
+       "  likely means that the widgets JavaScript library is either not installed or\n",
+       "  not enabled. See the <a href=\"https://ipywidgets.readthedocs.io/en/stable/user_install.html\">Jupyter\n",
+       "  Widgets Documentation</a> for setup instructions.\n",
+       "</p>\n",
+       "<p>\n",
+       "  If you're reading this message in another frontend (for example, a static\n",
+       "  rendering on GitHub or <a href=\"https://nbviewer.jupyter.org/\">NBViewer</a>),\n",
+       "  it may mean that your frontend doesn't currently support widgets.\n",
+       "</p>\n"
+      ],
+      "text/plain": [
+       "Viewer(image=<itkImagePython.itkImageUC3; proxy of <Swig Object of type 'itkImageUC3 *' at 0x7fc0d2764ba0> >)"
+      ]
+     },
+     "metadata": {},
+     "output_type": "display_data"
+    }
+   ],
+   "source": [
+    "view(vtk_image)"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.12"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 2
+}

itkwidgets/widget_viewer.py

@@ -10,6 +10,12 @@
 import numpy as np
 import itk
 from .trait_types import ITKImage, itkimage_serialization
+HAVE_VTK = False
+try:
+    import vtk
+    HAVE_VTK = True
+except ImportError:
+    pass
 
 @widgets.register
 class Viewer(widgets.DOMWidget):
@@ -26,6 +32,14 @@ def view(image):
     if isinstance(image, np.ndarray):
         image_from_array = itk.GetImageViewFromArray(image)
         viewer.image = image_from_array
+    elif HAVE_VTK and isinstance(image, vtk.vtkImageData):
+        from vtk.util import numpy_support as vtk_numpy_support
+        array = vtk_numpy_support.vtk_to_numpy(image.GetPointData().GetScalars())
+        array.shape = tuple(image.GetDimensions())[::-1]
+        image_from_array = itk.GetImageViewFromArray(array)
+        image_from_array.SetSpacing(image.GetSpacing())
+        image_from_array.SetOrigin(image.GetOrigin())
+        viewer.image = image_from_array
     else:
         viewer.image = image
     return viewer