added inheritance support for "balance"

HISTORY.md

@@ -63,6 +63,7 @@
 * moved "stage width" and "stage height" into attribute menu of the OF block for the stage
 * added 'volume' and 'balance' selectors to the OF block
 * Objects, Threads, Blocks: added inheritance support for "volume"
+* Objects, Threads, Blocks: added inheritance support for "balance"
 
 ### 2019-04-03
 * Objects, Threads: Safari compatibility tweaks (only use StereoPanner if available)

src/blocks.js

@@ -2668,7 +2668,8 @@ BlockMorph.prototype.userMenu = function () {
                     direction: 'direction',
                     getScale: 'size',
                     getCostumeIdx: 'costume #',
-                    getVolume: 'volume'
+                    getVolume: 'volume',
+                    getPan: 'balance'
                 }[this.selector];
                 if (field && rcvr && rcvr.exemplar) {
                     menu.addLine();

src/objects.js

@@ -126,6 +126,7 @@ SpriteMorph.prototype.attributes =
         'costumes',
         'costume #',
         'volume',
+        'balance',
         'sounds',
         'scripts'
     ];
@@ -2045,7 +2046,7 @@ SpriteMorph.prototype.blockTemplates = function (category) {
         blocks.push(block('changePan'));
         blocks.push(block('setPan'));
         blocks.push(watcherToggle('getPan'));
-        blocks.push(block('getPan'));
+        blocks.push(block('getPan', this.inheritsAttribute('balance')));
         blocks.push('-');
         blocks.push(block('playFreq'));
         blocks.push(block('stopFreq'));
@@ -3323,7 +3324,7 @@ SpriteMorph.prototype.playSound = function (name) {
         if (pan) {
             gain.connect(pan);
             pan.connect(ctx.destination); // perhaps redundant
-            this.setPan(this.pan); // yep, should be redundant, but still...
+            this.setPan(this.getPan()); // yep, should be redundant
         } else {
             gain.connect(ctx.destination);
         }
@@ -3388,7 +3389,7 @@ SpriteMorph.prototype.audioContext = function () {
 
 // SpriteMorph stero panning
 
-SpriteMorph.prototype.setPan = function (num) {
+SpriteMorph.prototype.setPan = function (num, noShadow) {
     var panner = this.getPannerNode();
     if (!panner) {return; }
     this.pan = Math.max(Math.min((+num || 0), 100), -100);
@@ -3396,13 +3397,27 @@ SpriteMorph.prototype.setPan = function (num) {
         this.pan / 100,
         this.audioContext().currentTime
     );
+    // propagate to children that inherit my balance
+    if (!noShadow) {
+        this.shadowAttribute('balance');
+    }
+    this.instances.forEach(function (instance) {
+        if (instance.cachedPropagation) {
+            if (instance.inheritsAttribute('balance')) {
+                instance.setPan(num, true);
+            }
+        }
+    });
 };
 
 SpriteMorph.prototype.changePan = function (delta) {
-    this.setPan(this.pan + (+delta || 0));
+    this.setPan(this.getPan() + (+delta || 0));
 };
 
 SpriteMorph.prototype.getPan = function () {
+    if (this.inheritsAttribute('balance')) {
+        return this.exemplar.getPan();
+    }
     return this.pan;
 };
 
@@ -5839,7 +5854,8 @@ SpriteMorph.prototype.updatePropagationCache = function () {
             'direction',
             'size',
             'costume #',
-            'volume'
+            'volume',
+            'balance'
         ],
         function (att) {
             return contains(myself.inheritedAttributes, att);
@@ -5963,6 +5979,10 @@ SpriteMorph.prototype.refreshInheritedAttribute = function (aName) {
         this.cachedPropagation = true;
         this.setVolume(this.getVolume(), true);
         break;
+    case 'balance':
+        this.cachedPropagation = true;
+        this.setPan(this.getPan(), true);
+        break;
     case 'costumes':
         idx = this.getCostumeIdx();
         this.costumes = this.exemplar.costumes;
@@ -10055,7 +10075,8 @@ WatcherMorph.prototype.update = function () {
                 direction: 'direction',
                 getCostumeIdx: 'costume #',
                 getScale: 'size',
-                getVolume: 'volume'
+                getVolume: 'volume',
+                getPan: 'balance'
             } [this.getter];
             isGhosted = att ? this.target.inheritsAttribute(att) : false;
         }

src/threads.js

@@ -4103,8 +4103,8 @@ Process.prototype.doPlayNoteForSecs = function (pitch, secs) {
     // interpolated
     var rcvr = this.blockReceiver();
     if (!this.context.startTime) {
-        rcvr.setVolume(rcvr.getVolume()); // b/c Chrome needs lazy initialization
-        rcvr.setPan(rcvr.pan); // b/c Chrome needs lazy initialization
+        rcvr.setVolume(rcvr.getVolume()); // b/c Chrome needs lazy init
+        rcvr.setPan(rcvr.getPan()); // b/c Chrome needs lazy initialization
         this.context.startTime = Date.now();
         this.context.activeNote = new Note(pitch);
         this.context.activeNote.play(