ENH: Add vtkCamera support for the camera trait

Author: thewtex

examples/CameraParameters.ipynb

@@ -2,24 +2,14 @@
  "cells": [
   {
    "cell_type": "code",
-   "execution_count": 1,
+   "execution_count": null,
    "metadata": {},
-   "outputs": [
-    {
-     "name": "stdout",
-     "output_type": "stream",
-     "text": [
-      "Requirement already satisfied: itk-io in /home/matt/bin/miniconda3/envs/itkwidgets/lib/python3.7/site-packages (5.1.0.post3)\r\n",
-      "Requirement already satisfied: vtk in /home/matt/bin/miniconda3/envs/itkwidgets/lib/python3.7/site-packages (8.1.2)\r\n",
-      "Requirement already satisfied: itk-core==5.1.0.post3 in /home/matt/bin/miniconda3/envs/itkwidgets/lib/python3.7/site-packages (from itk-io) (5.1.0.post3)\r\n"
-     ]
-    }
-   ],
+   "outputs": [],
    "source": [
     "# Install dependencies for this example\n",
     "# Note: This does not include itkwidgets, itself\n",
     "import sys\n",
-    "!{sys.executable} -m pip install itk-io vtk"
+    "!{sys.executable} -m pip install itk vtk"
    ]
   },
   {
@@ -59,7 +49,7 @@
     {
      "data": {
       "application/vnd.jupyter.widget-view+json": {
-       "model_id": "6e4bf6b5d5524c27ab58325155a4b859",
+       "model_id": "4acaff0c96954105bd3a0264cfe837bf",
        "version_major": 2,
        "version_minor": 0
       },
@@ -123,15 +113,24 @@
     }
    ],
    "source": [
+    "# Get camera parameters\n",
     "viewer.camera"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 7,
    "metadata": {},
    "outputs": [],
-   "source": []
+   "source": [
+    "# Use a vtkCamera instance\n",
+    "vtk_camera = vtk.vtkCamera()\n",
+    "vtk_camera.SetPosition([3.6606824e+02,  1.4895028e+00,  1.0029479e+02])\n",
+    "vtk_camera.SetFocalPoint([ 1.5009012e+02,  1.2883676e+02, -1.1309737e+01])\n",
+    "vtk_camera.SetViewUp([-4.5256451e-01,  1.3861613e-02,  8.9162391e-01])\n",
+    "\n",
+    "viewer.camera = vtk_camera"
+   ]
   }
  ],
  "metadata": {

itkwidgets/trait_types.py

@@ -15,9 +15,15 @@
     from functools import reduce
 except ImportError:
     pass
+have_vtk = False
+try:
+    import vtk
+    have_vtk = True
+except ImportError:
+    pass
 
 from ._transform_types import to_itk_image, to_point_set, to_geometry
-from ipydatawidgets import array_serialization
+from ipydatawidgets import array_serialization, NDArray
 
 # from IPython.core.debugger import set_trace
 
@@ -721,3 +727,19 @@ def validate(self, obj, value):
                 'Custom'):
             raise self.error('Invalid lookup table')
         return super(LookupTable, self).validate(obj, value)
+
+class Camera(NDArray):
+    """A trait type holding visualization camera parameters."""
+
+    info_text = 'Camera parameters: [[position_x, position_y, position_z], '\
+                                    '[focal_point_x, focal_point_y, focal_point_z], '\
+                                    '[view_up_x, view_up_y, view_up_z]]'
+
+    def validate(self, obj, value):
+        result = value
+        if have_vtk and isinstance(value, vtk.vtkCamera):
+            result = np.zeros((3,3), dtype=np.float32)
+            result[0,:] = value.GetPosition()
+            result[1,:] = value.GetFocalPoint()
+            result[2,:] = value.GetViewUp()
+        return super(Camera, self).validate(obj, result)

itkwidgets/widget_viewer.py

@@ -16,7 +16,7 @@
 import ipywidgets as widgets
 from traitlets import CBool, CFloat, CInt, Unicode, CaselessStrEnum, List, validate, TraitError, Tuple
 from ipydatawidgets import NDArray, array_serialization, shape_constraints
-from .trait_types import ITKImage, ImagePointTrait, ImagePoint, PointSetList, PolyDataList, itkimage_serialization, image_point_serialization, polydata_list_serialization, Colormap, LookupTable
+from .trait_types import ITKImage, ImagePointTrait, ImagePoint, PointSetList, PolyDataList, itkimage_serialization, image_point_serialization, polydata_list_serialization, Colormap, LookupTable, Camera
 
 try:
     import ipywebrtc
@@ -313,7 +313,7 @@ class Viewer(ViewerParent):
         default_value='v',
         help="View mode: x: x plane, y: y plane, z: z plane, v: volume rendering").tag(
         sync=True)
-    camera = NDArray(dtype=np.float32, default_value=np.zeros((3, 3), dtype=np.float32),
+    camera = Camera(dtype=np.float32, default_value=np.zeros((3, 3), dtype=np.float32),
                      help="Camera parameters: [[position_x, position_y, position_z], "
                      "[focal_point_x, focal_point_y, focal_point_z], "
                      "[view_up_x, view_up_y, view_up_z]]")\
@@ -833,7 +833,7 @@ def view(image=None,  # noqa: C901
             'z': z-plane
             'v': volume rendering
 
-    camera: 3x3 numpy float32 array
+    camera: 3x3 numpy float32 array, or vtk.vtkCamera
         Camera parameters:
             [[position_x,    position_y,    position_z],
              [focal_point_x, focal_point_y, focal_point_z],