move common tangible code to tangible repo,

#249
phetsims/ratio-and-proportion#8

README.md

@@ -41,6 +41,7 @@ git clone https://github.com/phetsims/sherpa.git
 git clone https://github.com/phetsims/sun.git
 git clone https://github.com/phetsims/tambo.git
 git clone https://github.com/phetsims/tandem.git
+git clone https://github.com/phetsims/tangible.git
 git clone https://github.com/phetsims/utterance-queue.git
 ```
 (2) Start an http-server

gravity-force-lab_en.html

@@ -33,8 +33,12 @@
       },
       "phet": {
         "requirejsNamespace": "GRAVITY_FORCE_LAB",
+        "preload": [
+          "../tangible/js/preload/mechamarkers-21f16221e414ec2dca68bbfbb866369eea7abd70.js"
+        ],
         "phetLibs": [
-          "inverse-square-law-common"
+          "inverse-square-law-common",
+          "tangible"
         ],
         "runnable": true,
         "supportedBrands": [
@@ -103,7 +107,7 @@
     '../sherpa/lib/TextEncoderLite-3c9f6f0.js',
     '../tandem/js/PhetioIDUtils.js',
     '../chipper/js/SimVersion.js',
-    '../gravity-force-lab/js/view/mechamarkers-controller/mechamarkers-21f16221e414ec2dca68bbfbb866369eea7abd70.js'
+    '../tangible/js/preload/mechamarkers-21f16221e414ec2dca68bbfbb866369eea7abd70.js'
   ];
 
   if ( brand === 'phet-io' ) {

js/view/GravityForceLabScreenView.js

@@ -35,7 +35,7 @@ import GravityForceLabForceDescriber from './describers/GravityForceLabForceDesc
 import GravityForceLabPositionDescriber from './describers/GravityForceLabPositionDescriber.js';
 import GravityForceLabRulerDescriber from './describers/GravityForceLabRulerDescriber.js';
 import MassDescriber from './describers/MassDescriber.js';
-import MarkerInput from './mechamarkers-controller/MarkerInput.js';
+import GravityForceLabMarkerInput from './mechamarkers-controller/GravityForceLabMarkerInput.js';
 import GravityForceLabAlertManager from './GravityForceLabAlertManager.js';
 import GravityForceLabControlPanel from './GravityForceLabControlPanel.js';
 import GravityForceLabScreenSummaryNode from './GravityForceLabScreenSummaryNode.js';
@@ -80,7 +80,7 @@ function GravityForceLabScreenView( model, tandem ) {
   } );
 
   // wire up to marker input
-  MarkerInput.init( model );
+  GravityForceLabMarkerInput.init( model );
 
   const alertManager = new GravityForceLabAlertManager( model, massDescriber, forceDescriber );
 

js/view/mechamarkers-controller/GravityForceLabMarkerInput.js

@@ -0,0 +1,57 @@
+// Copyright 2020, University of Colorado Boulder
+
+/**
+ * This file is to prototype mechamarkers as an input controller to a phetsim, see https://github.com/phetsims/a11y-research/issues/153
+ * @author Michael Kauzmann (PhET Interactive Simulations)
+ */
+
+// modules
+import gravityForceLab from '../../gravityForceLab.js';
+import SliderGroupMarker from '../../../../tangible/js/SliderGroupMarker.js';
+import MarkerInput from '../../../../tangible/js/MarkerInput.js';
+
+// constants
+const CONSTANT_SIZE_MARKER = 18; // change this marker number to toggle constant radius
+
+class GravityForceLabMarkerInput extends MarkerInput {
+
+  /**
+   * @param {GravityForceLabModel} model
+   */
+  static init( model ) {
+
+    let previousButtonPresent = false;
+
+    const mass1PositionSlider = new SliderGroupMarker( 'mass1Position', 'slider',
+      model.object1.positionProperty, {
+        range: model.object1.enabledRangeProperty
+      } );
+    // const mass2PositionSlider = new SliderGroupMarker( 'mass1Position', 'slider',
+    //   model.object2.positionProperty, {
+    //     range: model.object2.enabledRangeProperty
+    //   } );
+    const mass1MassSlider = new SliderGroupMarker( 'mass1Position', 'slider',
+      model.object1.valueProperty );
+    const mass2MassSlider = new SliderGroupMarker( 'mass1Position', 'slider',
+      model.object2.valueProperty );
+
+    // initialize Mechamarkers with GFL specific update function.
+    super.init( Mechamarkers => {
+
+      mass1PositionSlider.update();
+
+      // This breaks right now because both positions will be set to the same value
+      // mass2PositionSlider.update();
+      mass1MassSlider.update();
+      mass2MassSlider.update();
+
+      if ( Mechamarkers.getMarker( CONSTANT_SIZE_MARKER ).present !== previousButtonPresent ) {
+        Mechamarkers.getMarker( CONSTANT_SIZE_MARKER ).present && model.constantRadiusProperty.toggle();
+        previousButtonPresent = Mechamarkers.getMarker( CONSTANT_SIZE_MARKER ).present;
+      }
+    } );
+  }
+}
+
+gravityForceLab.register( 'GravityForceLabMarkerInput', GravityForceLabMarkerInput );
+export default GravityForceLabMarkerInput;