From 0538657164863c0811a50e590e3a7a923037e59f Mon Sep 17 00:00:00 2001
From: jbphet <jpblanco@yahoo.com>
Date: Thu, 16 Jan 2025 14:29:44 -0700
Subject: [PATCH] fix overzealous reset of data counts, see
 https://github.com/phetsims/quantum-measurement/issues/80

---
 js/bloch-sphere/model/BlochSphereModel.ts     | 20 ++++++++++---------
 .../view/BlochSphereMeasurementArea.ts        |  2 +-
 2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/js/bloch-sphere/model/BlochSphereModel.ts b/js/bloch-sphere/model/BlochSphereModel.ts
index 1bfcd29..b1e4702 100644
--- a/js/bloch-sphere/model/BlochSphereModel.ts
+++ b/js/bloch-sphere/model/BlochSphereModel.ts
@@ -162,33 +162,34 @@ class BlochSphereModel implements TModel {
     // measurement that is being made.
     this.timeToMeasurementProperty.link( () => this.resetCounts() );
 
-    // Clear accumulated counts, and potentially change the selected preset state direction to
-    // CUSTOM when the user changes the angles of the Bloch Sphere.
+    // Clear accumulated counts and potentially change the selected preset state direction to CUSTOM when the user
+    // changes the angles of the Bloch Sphere.
     Multilink.multilink(
-      [
-        this.preparationBlochSphere.polarAngleProperty,
-        this.preparationBlochSphere.azimuthalAngleProperty
-      ],
+      [ this.preparationBlochSphere.polarAngleProperty, this.preparationBlochSphere.azimuthalAngleProperty ],
       () => {
         // Clear the accumulated counts.
         this.resetCounts();
 
         if ( !selectingStateDirection ) {
+
           // Change the selected state to indicate that the user has moved away from the preset states.
           this.selectedStateDirectionProperty.value = StateDirection.CUSTOM;
         }
       }
     );
 
+    // Reset the counts when the user changes the magnetic field attributes.
+    Multilink.lazyMultilink(
+      [ this.magneticFieldStrengthProperty, this.magneticFieldEnabledProperty ],
+      () => this.resetCounts()
+    );
+
     // Set the precession rate of the Bloch sphere based on the state of the magnetic field, the selected scene, and the
     // measurement state.
     Multilink.lazyMultilink(
       [ this.magneticFieldStrengthProperty, this.magneticFieldEnabledProperty, this.measurementStateProperty ],
       ( magneticFieldStrength, showMagneticField, measurementState ) => {
 
-        // Changes to the field state should clear any accumulated counts.
-        this.resetCounts();
-
         // Set the precession rate of the Bloch sphere based on the measurement state and the state of the magnetic
         // field.
         const rotationRate = measurementState === 'timingObservation' && showMagneticField ? magneticFieldStrength : 0;
@@ -213,6 +214,7 @@ class BlochSphereModel implements TModel {
       } );
     } );
 
+    // Reset accumulated data when the user changes the measurement axis.
     this.measurementAxisProperty.link( () => {
       this.resetCounts();
     } );
diff --git a/js/bloch-sphere/view/BlochSphereMeasurementArea.ts b/js/bloch-sphere/view/BlochSphereMeasurementArea.ts
index 3fcfa4d..1eca0c4 100644
--- a/js/bloch-sphere/view/BlochSphereMeasurementArea.ts
+++ b/js/bloch-sphere/view/BlochSphereMeasurementArea.ts
@@ -242,7 +242,7 @@ export default class BlochSphereMeasurementArea extends Node {
 
     const magneticFieldCheckbox = new Checkbox(
       model.magneticFieldEnabledProperty,
-      // TODO: This text should be localized, see https://github.com/phetsims/quantum-measurement/issues/54
+      // TODO: This text should be localized, see https://github.com/phetsims/quantum-measurement/issues/80
       new Text( 'Enable Magnetic Field', { font: new PhetFont( { size: 16 } ) } ),
       {
         spacing: 10,