ENH: Simplify EndoscopyLogic API to set and get input curve CameraOri…

…entations

This allows to set and get the input curve CameraOrientations independently
of the EndoscopyWidget.

To support this it also updates the `interpolateOrientations` to require
a cameraOrientations parameter. This allows to remove the need for maintaining
a dedicated "cameraOrientations" instance variable.

It also renames the functions:
* `loadCameraOrientations` to `getCameraOrientationsFromInputCurve`
* `saveCameraOrientations` to `setInputCurveCameraOrientations`

Modules/Scripted/Endoscopy/Endoscopy.py

@@ -318,8 +318,8 @@ def setInputCurve(self, newInputCurve):
         if self.logic is not None:
             self.logic.cleanup()
             self.logic = None
-        cameraOrientations = self.loadCameraOrientations()
-        self.logic = EndoscopyLogic(self.inputCurve, cameraOrientations)
+
+        self.logic = EndoscopyLogic(self.inputCurve)
 
         # Update UI
         self.updateWidgetFromMRML()
@@ -441,11 +441,14 @@ def onSaveOrientationButtonClicked(self):
         worldOrientation = EndoscopyLogic.matrix3x3ToOrientation(worldMatrix3x3)
 
         # Add new dictionary key-value pair
-        cameraOrientations = self.loadCameraOrientations()
+        cameraOrientations = EndoscopyLogic.getCameraOrientationsFromInputCurve(self.inputCurve)
         cameraOrientations[distanceAlongResampledCurve] = worldOrientation
-        self.saveCameraOrientations(cameraOrientations)
 
-        self.logic.interpolateOrientations()
+        self.ignoreInputCurveModified += 1
+        EndoscopyLogic.setInputCurveCameraOrientations(self.inputCurve, cameraOrientations)
+        self.ignoreInputCurveModified -= 1
+
+        self.logic.interpolateOrientations(cameraOrientations)
 
         self.flyTo(resampledCurvePointIndex)
 
@@ -456,7 +459,7 @@ def onDeleteOrientationButtonClicked(self):
         # meaning that computing a distance from an index may not now give the same distance value.  However, we can
         # delete the entries associated with this resampledCurvePointIndexToDelete even in the case that its
         # distance has changed.
-        cameraOrientations = self.loadCameraOrientations()
+        cameraOrientations = EndoscopyLogic.getCameraOrientationsFromInputCurve(self.inputCurve)
         # We must freeze the cameraOrientations.keys() generator at the start (by converting it to a list) because we
         # delete from the cameraOrientations Python dict in this loop.
         for distanceAlongResampledCurve in list(cameraOrientations.keys()):
@@ -465,9 +468,12 @@ def onDeleteOrientationButtonClicked(self):
             )
             if resampledCurvePointIndex == resampledCurvePointIndexToDelete:
                 del cameraOrientations[distanceAlongResampledCurve]
-        self.saveCameraOrientations(cameraOrientations)
 
-        self.logic.interpolateOrientations()
+        self.ignoreInputCurveModified += 1
+        EndoscopyLogic.setInputCurveCameraOrientations(self.inputCurve, cameraOrientations)
+        self.ignoreInputCurveModified -= 1
+
+        self.logic.interpolateOrientations(cameraOrientations)
 
         self.flyTo(resampledCurvePointIndex)
 
@@ -513,61 +519,6 @@ def onSaveExportModelButtonClicked(self):
         )
         logging.debug("-> Model created")
 
-    def loadCameraOrientations(self):
-        cameraOrientationsString = self.inputCurve.GetAttribute(
-            EndoscopyLogic.NODE_PATH_CAMERA_ORIENTATIONS_ATTRIBUTE_NAME,
-        )
-        convertedCameraOrientations = (
-            dict() if cameraOrientationsString is None else json.loads(cameraOrientationsString)
-        )
-        if not self.cameraOrientationsIsCorrectType(convertedCameraOrientations):
-            raise ValueError(
-                "EndoscopyWidget.loadCameraOrientations:"
-                " Retrieved cameraOrientations is not of the correct type.",
-            )
-        # JSON turns the `keys` into strings and cannot handle `values` that are numpy arrays.
-        # So, let's convert back.
-        cameraOrientations = {float(k): np.array(v) for k, v in convertedCameraOrientations.items()}
-        if self.logic:
-            self.logic.cameraOrientations = cameraOrientations
-
-        return cameraOrientations
-
-    def saveCameraOrientations(self, cameraOrientations):
-        if cameraOrientations:
-            # JSON turns float `keys` into strings and cannot handle `values` that are numpy arrays.
-            # So, let's convert.
-            convertedCameraOrientations = {str(k): list(v) for k, v in cameraOrientations.items()}
-            if not self.cameraOrientationsIsCorrectType(convertedCameraOrientations):
-                raise ValueError(
-                    "EndoscopyWidget.saveCameraOrientations:"
-                    " supplied cameraOrientations is not of the correct type",
-                )
-            cameraOrientationsString = json.dumps(convertedCameraOrientations)
-        else:
-            # Rather than a length-zero or length-two string representing an empty dictionary, clear the string.
-            cameraOrientationsString = None
-
-        self.ignoreInputCurveModified += 1
-        self.inputCurve.SetAttribute(
-            EndoscopyLogic.NODE_PATH_CAMERA_ORIENTATIONS_ATTRIBUTE_NAME, cameraOrientationsString,
-        )
-        self.ignoreInputCurveModified -= 1
-        if self.logic:
-            self.logic.cameraOrientations = cameraOrientations
-
-    def cameraOrientationsIsCorrectType(self, convertedCameraOrientations):
-        return (
-            isinstance(convertedCameraOrientations, dict)
-            and all([isinstance(k, (int, float, str)) for k in convertedCameraOrientations.keys()])
-            and all(
-                [
-                    isinstance(v, list) and len(v) == 4 and all([isinstance(e, (int, float)) for e in v])
-                    for v in convertedCameraOrientations.values()
-                ],
-            )
-        )
-
     def flyToNext(self):
         currentStep = int(self.frameSlider.value)
         nextStep = currentStep + self.skip + 1
@@ -707,9 +658,8 @@ class EndoscopyLogic:
 
     NODE_PATH_CAMERA_ORIENTATIONS_ATTRIBUTE_NAME = "Endoscopy.Path.CameraOrientations"
 
-    def __init__(self, inputCurve, cameraOrientations, dl=0.5):
+    def __init__(self, inputCurve, dl=0.5):
         self.cleanup()
-        self.cameraOrientations = cameraOrientations
         self.dl = dl  # desired world space step size (in mm)
         self.setControlPoints(inputCurve)
 
@@ -719,7 +669,6 @@ def cleanup(self):
         self.inputCurve = None
         self.resampledCurve = None
         self.planeNormal = None
-        self.cameraOrientations = None
         self.cameraOrientationResampledCurveIndices = None
 
     def setControlPoints(self, inputCurve: slicer.vtkMRMLMarkupsCurveNode) -> None:
@@ -781,19 +730,15 @@ def setControlPoints(self, inputCurve: slicer.vtkMRMLMarkupsCurveNode) -> None:
         # nonsensical if self.resampledCurve.GetNumberOfControlPoints() < 3, but proceed anyway.
         _, self.planeNormal = EndoscopyLogic.planeFit(points.T)
 
-        # Interpolate the user-supplied orientations to compute (and assign) an orientation to every control point of
-        # the resampledCurve.
-        self.interpolateOrientations()
+        cameraOrientations = EndoscopyLogic.getCameraOrientationsFromInputCurve(inputCurve)
+
+        self.interpolateOrientations(cameraOrientations)
 
-    def interpolateOrientations(self):
+    def interpolateOrientations(self, cameraOrientations):
 
         # Configure a vtkQuaternionInterpolator using the user's supplied orientations.
         # Note that all distances are as measured along resampledCurve rather than along inputCurve.
 
-        cameraOrientations = self.cameraOrientations
-        if not cameraOrientations:
-            # None supplied
-            cameraOrientations = dict()
         quaternionInterpolator = vtk.vtkQuaternionInterpolator()
         quaternionInterpolator.SetSearchMethod(0)  # binary search
 
@@ -989,6 +934,51 @@ def buildCameraMatrix4x4(cameraPosition, inputMatrix3x3):
             outputMatrix4x4.SetElement(col, 3, cameraPosition[col])
         return outputMatrix4x4
 
+    @staticmethod
+    def getCameraOrientationsFromInputCurve(inputCurve):
+        cameraOrientationsString = inputCurve.GetAttribute(
+            EndoscopyLogic.NODE_PATH_CAMERA_ORIENTATIONS_ATTRIBUTE_NAME,
+        )
+        convertedCameraOrientations = (
+            dict() if cameraOrientationsString is None else json.loads(cameraOrientationsString)
+        )
+        if not EndoscopyLogic.cameraOrientationsIsCorrectType(convertedCameraOrientations):
+            raise ValueError(f"cameraOrientations for curve {inputCurve.GetID()} is not of the correct type.")
+        # JSON turns the `keys` into strings and cannot handle `values` that are numpy arrays.
+        # So, let's convert back.
+        cameraOrientations = {float(k): np.array(v) for k, v in convertedCameraOrientations.items()}
+
+        return cameraOrientations
+
+    @staticmethod
+    def setInputCurveCameraOrientations(inputCurve, cameraOrientations):
+        if cameraOrientations:
+            # JSON turns float `keys` into strings and cannot handle `values` that are numpy arrays.
+            # So, let's convert.
+            convertedCameraOrientations = {str(k): list(v) for k, v in cameraOrientations.items()}
+            if not EndoscopyLogic.cameraOrientationsIsCorrectType(convertedCameraOrientations):
+                raise ValueError("cameraOrientations is not of the correct type")
+            cameraOrientationsString = json.dumps(convertedCameraOrientations)
+        else:
+            # Rather than a length-zero or length-two string representing an empty dictionary, clear the string.
+            cameraOrientationsString = None
+        inputCurve.SetAttribute(
+            EndoscopyLogic.NODE_PATH_CAMERA_ORIENTATIONS_ATTRIBUTE_NAME, cameraOrientationsString,
+        )
+
+    @staticmethod
+    def cameraOrientationsIsCorrectType(convertedCameraOrientations):
+        return (
+            isinstance(convertedCameraOrientations, dict)
+            and all([isinstance(k, (int, float, str)) for k in convertedCameraOrientations.keys()])
+            and all(
+                [
+                    isinstance(v, list) and len(v) == 4 and all([isinstance(e, (int, float)) for e in v])
+                    for v in convertedCameraOrientations.values()
+                ],
+            )
+        )
+
 
 class EndoscopyPathModel:
     """Create a vtkPolyData for a polyline: