Sum vector not counted when describing how many vectors there are

[KatieWoe]

Device
Samung Laptop
OS
Win 11
Browser
Chrome + Jaws
Problem Description
For phetsims/qa#1335
In both the scene summary and the graph area descriptions, it will not count the sum vector in the number of vectors in the graph area.
Visuals

[pixelzoom]

Thanks @KatieWoe. Reproduced in master.

In VectorSet.ts, numberOfVectorsOnGraphProperty is derived from allVectors, which does not include the resultant vector:

    this.numberOfVectorsOnGraphProperty = DerivedProperty.deriveAny( this.allVectors.map( vector => vector.isOnGraphProperty ),
      () => this.allVectors.filter( vector => vector.isOnGraphProperty.value ).length );

Unfortunately we can't just add 1 here for the sum vector, because it may or may not be visible depending on whether the Sum checkbox is checked. And here in the model, we do not know whether the resultant vector is visible. And the sum vector also must be defined -- an undefined sum is not visible.

I will ruminate on a solution for this.

[pixelzoom]

The number of vectors needs to be increased by 1 if the resultant vector is visible and defined.

Below are the sites that are incorrect. They occur in screen summaries and in accessibleParagraphs for the graph areas.

// Explore1DScreenSummaryContent
    const numberOfVectorsProperty = new DynamicProperty( sceneProperty, {
      derive: scene => scene.vectorSet.numberOfVectorsOnGraphProperty
    } );

// Explore1DScreenView
      accessibleParagraph: new PatternStringProperty( VectorAdditionStrings.a11y.graphArea.accessibleParagraphExploreStringProperty, {
        numberOfVectors: model.horizontalScene.vectorSet.numberOfVectorsOnGraphProperty
      } )
...
      accessibleParagraph: new PatternStringProperty( VectorAdditionStrings.a11y.graphArea.accessibleParagraphExploreStringProperty, {
        numberOfVectors: model.verticalScene.vectorSet.numberOfVectorsOnGraphProperty
      } )

// Explore2DScreenSummaryContent
    const numberOfVectorsProperty = new DynamicProperty( sceneProperty, {
      derive: scene => scene.vectorSet.numberOfVectorsOnGraphProperty
    } );

// Explore2DScreenView
      accessibleParagraph: new PatternStringProperty( VectorAdditionStrings.a11y.graphArea.accessibleParagraphExploreStringProperty, {
        numberOfVectors: model.cartesianScene.vectorSet.numberOfVectorsOnGraphProperty
      } )
...
      accessibleParagraph: new PatternStringProperty( VectorAdditionStrings.a11y.graphArea.accessibleParagraphExploreStringProperty, {
        numberOfVectors: model.cartesianScene.vectorSet.numberOfVectorsOnGraphProperty
      } )

// LabScreenSummaryContent
    const vectorSet2SizeProperty = new DynamicProperty( sceneProperty, {
      derive: scene => scene.vectorSet2.numberOfVectorsOnGraphProperty
    } );
...
    const vectorSet1SizeProperty = new DynamicProperty( sceneProperty, {
      derive: scene => scene.vectorSet1.numberOfVectorsOnGraphProperty
    } );

// LabScreenView
      accessibleParagraph: new PatternStringProperty( VectorAdditionStrings.a11y.graphArea.accessibleParagraphLabStringProperty, {
        vectorSet1Size: model.cartesianScene.vectorSet1.numberOfVectorsOnGraphProperty,
        vectorSet1Symbol: model.cartesianScene.vectorSet1.accessibleSymbolProperty,
        vectorSet2Size: model.cartesianScene.vectorSet2.numberOfVectorsOnGraphProperty,
        vectorSet2Symbol: model.cartesianScene.vectorSet2.accessibleSymbolProperty
      } )
...
      accessibleParagraph: new PatternStringProperty( VectorAdditionStrings.a11y.graphArea.accessibleParagraphLabStringProperty, {
        vectorSet1Size: model.polarScene.vectorSet1.numberOfVectorsOnGraphProperty,
        vectorSet1Symbol: model.polarScene.vectorSet1.accessibleSymbolProperty,
        vectorSet2Size: model.polarScene.vectorSet2.numberOfVectorsOnGraphProperty,
        vectorSet2Symbol: model.polarScene.vectorSet2.accessibleSymbolProperty
      } )

[pixelzoom]

I took a stab at adding viewProperty.sumVisibleProperty and resultantVector.isDefinedProperty to the derivations. It was quite a mess, with duplicated code. So I did not commit. Now I'm considering getting this information from the view based on how many vector Nodes exist and are visible. I'll think about this some more.

[pixelzoom]

In addition to fixing the problem reported, I added an accessibleParagraph for the "Graph Area" in the Equations screen. This originally seemed unnecessary because there is no toolbox in the Equations screen. But the resultant vector (c, f) can be hidden, so the number of vectors is indeed still dymanic.

Patched into 1.2 branches using the following process:

shas:
fc40ee1

steps:

% cd vector-addition 
% git checkout 1.2
% git cherry-pick fc40ee1418581e4dac0f56a0f7d04ae6eeac9c1e
% git push origin 1.2
% git checkout main

% cd perennial
% grunt maintenance
maintenance> Maintenance.reset()
maintenance> Maintenance.createPatch( 'vector-addition', 'https://github.com/phetsims/vector-addition/issues/441' );
maintenance> Maintenance.addNeededPatch( 'vector-addition-equations', '1.2', 'vector-addition' );
maintenance> Maintenance.addPatchSHA( 'vector-addition', 'fc40ee1418581e4dac0f56a0f7d04ae6eeac9c1e' );
maintenance> Maintenance.applyPatches();
maintenance> Maintenance.updateDependencies();

[pixelzoom]

@KatieWoe please verify in master. Be sure to check all 4 screens, including the Equations screen which now has an accessibleParagraph for the "Graph Area" section. Verify that the number of vectors reported in A11y View changes when dragging vectors to/from the toolbox, and when toggling the "Sum" checkboxes (or "c" and "f" checkboxes in the Equations screen).

Assign back to me when you're done.