added new change-of-scene event

still very experimental

HISTORY.md

@@ -33,6 +33,9 @@
     * German
     * Chinese, thanks, Simon!
 
+### 2021-09-07
+* blocks, objects, threads: new change-of-scene event 
+
 ### 2021-09-06
 * blocks: fixed exporting comment pics from inside the block editor, thanks, Jadga, for the report!
 * gui: fixed copying unattached comments among sprites, thanks, Jadga, for the report!

snap.html

@@ -16,9 +16,9 @@
         <script src="src/morphic.js?version=2021-07-09"></script>
         <script src="src/symbols.js?version=2021-03-03"></script>
         <script src="src/widgets.js?version=2021-07-21"></script>
-        <script src="src/blocks.js?version=2021-09-06"></script>
-        <script src="src/threads.js?version=2021-07-20"></script>
-        <script src="src/objects.js?version=2021-07-23"></script>
+        <script src="src/blocks.js?version=2021-09-07"></script>
+        <script src="src/threads.js?version=2021-09-07"></script>
+        <script src="src/objects.js?version=2021-09-07"></script>
         <script src="src/scenes.js?version=2021-07-21"></script>
         <script src="src/gui.js?version=2021-09-06"></script>
         <script src="src/paint.js?version=2021-07-05"></script>

src/blocks.js

@@ -160,7 +160,7 @@ CustomCommandBlockMorph, ToggleButtonMorph, DialMorph, SnapExtensions*/
 
 // Global stuff ////////////////////////////////////////////////////////
 
-modules.blocks = '2021-September-06';
+modules.blocks = '2021-September-07';
 
 var SyntaxElementMorph;
 var BlockMorph;
@@ -416,7 +416,8 @@ SyntaxElementMorph.prototype.labelParts = {
             'mouse-departed' : ['mouse-departed'],
             'scrolled-up' : ['scrolled-up'],
             'scrolled-down' : ['scrolled-down'],
-            'stopped' : ['stopped'] // experimental
+            'stopped' : ['stopped'], // experimental
+            'entering a scene' : ['entering a scene'] // experimental
         }
     },
     '%dates': {

src/objects.js

@@ -86,7 +86,7 @@ AlignmentMorph, Process, WorldMap, copyCanvas, useBlurredShadows*/
 
 /*jshint esversion: 6*/
 
-modules.objects = '2021-July-23';
+modules.objects = '2021-September-07';
 
 var SpriteMorph;
 var StageMorph;
@@ -8431,6 +8431,25 @@ StageMorph.prototype.processKeyPress = function (event) {
 StageMorph.prototype.inspectKeyEvent
     = CursorMorph.prototype.inspectKeyEvent;
 
+StageMorph.prototype.fireChangeOfSceneEvent = function () {
+    var procs = [];
+
+    this.children.concat(this).forEach(morph => {
+        if (isSnapObject(morph)) {
+            morph.allHatBlocksForInteraction(
+                'entering a scene'
+            ).forEach(block =>
+                procs.push(this.threads.startProcess(
+                    block,
+                    morph,
+                    this.isThreadSafe
+                ))
+            );
+        }
+    });
+    return procs;
+};
+
 StageMorph.prototype.fireGreenFlagEvent = function () {
     var procs = [],
         ide = this.parentThatIsA(IDE_Morph);

src/threads.js

@@ -60,11 +60,11 @@ IDE_Morph, ArgLabelMorph, localize, XML_Element, hex_sha512, TableDialogMorph,
 StageMorph, SpriteMorph, StagePrompterMorph, Note, modules, isString, copy, Map,
 isNil, WatcherMorph, List, ListWatcherMorph, alert, console, TableMorph, BLACK,
 TableFrameMorph, ColorSlotMorph, isSnapObject, newCanvas, Symbol, SVG_Costume,
-SnapExtensions, AlignmentMorph, TextMorph*/
+SnapExtensions, AlignmentMorph, TextMorph, Cloud*/
 
 /*jshint esversion: 6*/
 
-modules.threads = '2021-July-20';
+modules.threads = '2021-September-07';
 
 var ThreadManager;
 var Process;
@@ -3675,7 +3675,7 @@ Process.prototype.checkURLAllowed = function (url) {
                     // Check only against the host -not the protocol, path or
                     // port- of the domain
                     new RegExp(`${(new URL(domain)).host}.*${pathPart}`, 'i'))
-            )
+            );
         }
     )) {
         throw new Error('Request blocked');
@@ -4735,6 +4735,7 @@ Process.prototype.doSwitchToScene = function (id) {
             break;
         }
         ide.switchToScene(scenes.at(idx));
+        ide.stage.fireChangeOfSceneEvent();
         return;
     }
 
@@ -4748,6 +4749,7 @@ Process.prototype.doSwitchToScene = function (id) {
     }
 
     ide.switchToScene(scene);
+    ide.stage.fireChangeOfSceneEvent();
 };