From b1355c6b0b6ac4c9ade1a9fc547eb42740fb18a2 Mon Sep 17 00:00:00 2001
From: DD Liu <liudi@media.mit.edu>
Date: Wed, 10 May 2017 15:47:06 -0400
Subject: [PATCH] Fire remove monitors VM event

---
 src/engine/blocks.js   |  9 +++++++--
 src/engine/runtime.js  | 18 +++++++++++++++++-
 src/virtual-machine.js |  7 +++++--
 3 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/src/engine/blocks.js b/src/engine/blocks.js
index fb6634838..d0d2f82d0 100644
--- a/src/engine/blocks.js
+++ b/src/engine/blocks.js
@@ -215,7 +215,7 @@ class Blocks {
                 element: e.element,
                 name: e.name,
                 value: e.newValue
-            });
+            }, optRuntime);
             break;
         case 'move':
             this.moveBlock({
@@ -270,11 +270,13 @@ class Blocks {
     /**
      * Block management: change block field values
      * @param {!object} args Blockly change event to be processed
+     * @param {?Runtime} optRuntime Optional runtime to allow changeBlock to emit actions.
      */
-    changeBlock (args) {
+    changeBlock (args, optRuntime) {
         // Validate
         if (['field', 'mutation', 'checkbox'].indexOf(args.element) === -1) return;
         const block = this._blocks[args.id];
+        let wasMonitored = block.isMonitored;
         if (typeof block === 'undefined') return;
 
         switch (args.element) {
@@ -288,6 +290,9 @@ class Blocks {
             break;
         case 'checkbox':
             block.isMonitored = args.value;
+            if (optRuntime && wasMonitored && !block.isMonitored) {
+                optRuntime.removeMonitors([{id: block.id}]);
+            }
             break;
         }
     }
diff --git a/src/engine/runtime.js b/src/engine/runtime.js
index 17690ee7f..d94b53c0f 100644
--- a/src/engine/runtime.js
+++ b/src/engine/runtime.js
@@ -241,6 +241,14 @@ class Runtime extends EventEmitter {
         return 'MONITORS_UPDATE';
     }
 
+    /**
+     * Event name for monitors removed.
+     * @const {string}
+     */
+    static get MONITORS_REMOVED () {
+        return 'MONITORS_REMOVED';
+    }
+
     /**
      * How rapidly we try to step threads by default, in ms.
      */
@@ -859,12 +867,20 @@ class Runtime extends EventEmitter {
 
     /**
      * Emit a monitor update which adds or updates if exists the given monitors.
-     * @param {!Array} monitors Array of all monitors
+     * @param {!Array} monitors Array of monitors to update.
      */
     updateMonitors (monitors) {
         this.emit(Runtime.MONITORS_UPDATE, monitors);
     }
 
+    /**
+     * Emit a monitor update which removes if exists the given monitors.
+     * @param {!Array} monitors Array of monitors to remove.
+     */
+    removeMonitors (monitors) {
+        this.emit(Runtime.MONITORS_REMOVED, monitors);
+    }
+
     /**
      * Get a target by its id.
      * @param {string} targetId Id of target to find.
diff --git a/src/virtual-machine.js b/src/virtual-machine.js
index 0e5048f52..953336d84 100644
--- a/src/virtual-machine.js
+++ b/src/virtual-machine.js
@@ -55,8 +55,11 @@ class VirtualMachine extends EventEmitter {
         instance.runtime.on(Runtime.SPRITE_INFO_REPORT, spriteInfo => {
             instance.emit(Runtime.SPRITE_INFO_REPORT, spriteInfo);
         });
-        instance.runtime.on(Runtime.MONITORS_UPDATE, data => {
-            instance.emit(Runtime.MONITORS_UPDATE, data);
+        instance.runtime.on(Runtime.MONITORS_UPDATE, monitorList => {
+            instance.emit(Runtime.MONITORS_UPDATE, monitorList);
+        });
+        instance.runtime.on(Runtime.MONITORS_REMOVED, monitorList => {
+            instance.emit(Runtime.MONITORS_REMOVED, monitorList);
         });
 
         this.blockListener = this.blockListener.bind(this);