fix(reslicecursorwidget): fix camera reset on rotation after a camera…

… translation

When the user translates a camera (shift+left drag), and then rotate the reslice cursor widget in
another view, the camera was reset. This is because the focal point offsets were not "stored" after
the camera translation. The rotation was therefore resetting the camera translation. A solution
would have been to observe the interactor style each time the camera is manipulated. Instead, we
prefer to save the focal point offsets before any reslice cursor widget interaction happens, namely
when startInteraction is triggered. This makes computeFocalPointOffset parameter in the reslice
cursor widget interactionEvent obsolete. It has therefore been removed along with the associated
canUpdateFocalPoint. This is not the behavior's responsibility to tell the event consumers what they
must do.

BREAKING CHANGE: ResliceCursorWidget.interactionEvent has been modified

BREAKING_CHANGES.md

@@ -1,3 +1,8 @@
+## From 29.x to 30
+
+- **ResliceCursorWidget.interactionEvent**: no longer pass an object of computeFocalPointOffset, canUpdateFocalPoint but simply the type of the handle that triggers the event. Those values can easily be recomputed by the consumers of the event. Regarding `computeFocalPointOffset`, it is no longer adviced to compute focal point offset for each interaction, instead observing `startInteraction()` should be considered (see ResliceCursorWidget example).
+  - **ResliceCursorWidget.invokeInternalInteractionEvent(methodName)**: has been removed and should be replaced by `ResliceCursorWidget.invokeInteractionEvent(methodName)`.
+
 ## From 28.x to 29
 
 - **getOpenGLRenderWindow**: `getOpenGLRenderWindow` has been renamed to `getApiSpecificRenderWindow` in `vtkFullScreenRenderWindow`, `vtkGenericRenderWindow` and `vtkViewProxy` to support WebGL and WebGPU backend. ([#2816](https://github.com/Kitware/vtk-js/pull/2816))

Sources/Widgets/Widgets3D/ResliceCursorWidget/behavior.d.ts

@@ -1,5 +1,4 @@
 import vtkAbstractWidget from "../../Core/AbstractWidget";
 
 export default interface vtkResliceCursorWidgetDefaultInstance extends vtkAbstractWidget {
-    invokeInternalInteractionEvent: () => void;
 }

Sources/Widgets/Widgets3D/ResliceCursorWidget/behavior.js

@@ -185,7 +185,7 @@ export default function widgetBehavior(publicAPI, model) {
         publicAPI.translateCenterOnPlaneDirection(step);
         previousPosition = callData.position;
 
-        publicAPI.invokeInternalInteractionEvent();
+        publicAPI.invokeInteractionEvent(publicAPI.getActiveInteraction());
       }
     }
     return macro.VOID;
@@ -226,7 +226,7 @@ export default function widgetBehavior(publicAPI, model) {
     isScrolling = true;
     publicAPI.translateCenterOnPlaneDirection(step);
 
-    publicAPI.invokeInternalInteractionEvent(
+    publicAPI.invokeInteractionEvent(
       // Force interaction mode because mouse cursor could be above rotation handle
       InteractionMethodsName.TranslateCenter
     );
@@ -261,25 +261,12 @@ export default function widgetBehavior(publicAPI, model) {
     if (model.activeState.getActive()) {
       const methodName = publicAPI.getActiveInteraction();
       publicAPI[methodName](callData);
-      publicAPI.invokeInternalInteractionEvent(methodName);
+      publicAPI.invokeInteractionEvent(methodName);
       return macro.EVENT_ABORT;
     }
     return macro.VOID;
   };
 
-  publicAPI.invokeInternalInteractionEvent = (
-    methodName = publicAPI.getActiveInteraction()
-  ) => {
-    const computeFocalPointOffset =
-      methodName !== InteractionMethodsName.RotateLine;
-    const canUpdateFocalPoint =
-      methodName === InteractionMethodsName.RotateLine;
-    publicAPI.invokeInteractionEvent({
-      computeFocalPointOffset,
-      canUpdateFocalPoint,
-    });
-  };
-
   publicAPI.startInteraction = () => {
     publicAPI.invokeStartInteractionEvent();
     // When interacting, plane actor and lines must be re-rendered on other views

Sources/Widgets/Widgets3D/ResliceCursorWidget/example/index.js

@@ -27,7 +27,10 @@ import { CaptureOn } from '@kitware/vtk.js/Widgets/Core/WidgetManager/Constants'
 import { vec3 } from 'gl-matrix';
 import { SlabMode } from '@kitware/vtk.js/Imaging/Core/ImageReslice/Constants';
 
-import { xyzToViewType } from '@kitware/vtk.js/Widgets/Widgets3D/ResliceCursorWidget/Constants';
+import {
+  xyzToViewType,
+  InteractionMethodsName,
+} from '@kitware/vtk.js/Widgets/Widgets3D/ResliceCursorWidget/Constants';
 import controlPanel from './controlPanel.html';
 
 // Force the loading of HttpDataAccessHelper to support gzip decompression
@@ -45,7 +48,10 @@ const viewColors = [
 ];
 
 const viewAttributes = [];
+window.va = viewAttributes;
 const widget = vtkResliceCursorWidget.newInstance();
+window.widget = widget;
+window.splineWidget = vtkSplineWidget.newInstance();
 const widgetState = widget.getWidgetState();
 // Set size in CSS pixel space because scaleInPixels defaults to true
 widgetState
@@ -285,7 +291,9 @@ for (let i = 0; i < 4; i++) {
         []
       );
       widget.setCenter(newCenter);
-      obj.widgetInstance.invokeInternalInteractionEvent();
+      obj.widgetInstance.invokeInteractionEvent(
+        obj.widgetInstance.getActiveInteraction()
+      );
       viewAttributes.forEach((obj2) => {
         obj2.interactor.render();
       });
@@ -386,13 +394,30 @@ reader.setUrl(`${__BASE_PATH__}/data/volume/LIDC2.vti`).then(() => {
         // Note: Need to refresh also the current view because of adding the mouse wheel
         // to change slicer
         .forEach((v) => {
+          // Store the FocalPoint offset before "interacting".
+          // The offset may have been changed externally when manipulating the camera
+          // or interactorstyle.
+          v.widgetInstance.onStartInteractionEvent(() => {
+            updateReslice({
+              viewType,
+              reslice,
+              actor: obj.resliceActor,
+              renderer: obj.renderer,
+              resetFocalPoint: false,
+              keepFocalPointPosition: false,
+              computeFocalPointOffset: true,
+              sphereSources: obj.sphereSources,
+              slider: obj.slider,
+            });
+          });
+
           // Interactions in other views may change current plane
           v.widgetInstance.onInteractionEvent(
-            // computeFocalPointOffset: Boolean which defines if the offset between focal point and
-            // reslice cursor display center has to be recomputed (while translation is applied)
             // canUpdateFocalPoint: Boolean which defines if the focal point can be updated because
             // the current interaction is a rotation
-            ({ computeFocalPointOffset, canUpdateFocalPoint }) => {
+            (interactionMethodName) => {
+              const canUpdateFocalPoint =
+                interactionMethodName === InteractionMethodsName.RotateLine;
               const activeViewType = widget
                 .getWidgetState()
                 .getActiveViewType();
@@ -405,7 +430,7 @@ reader.setUrl(`${__BASE_PATH__}/data/volume/LIDC2.vti`).then(() => {
                 renderer: obj.renderer,
                 resetFocalPoint: false,
                 keepFocalPointPosition,
-                computeFocalPointOffset,
+                computeFocalPointOffset: !keepFocalPointPosition,
                 sphereSources: obj.sphereSources,
                 slider: obj.slider,
               });