tweaked block highlights for fade-out

HISTORY.md

@@ -2,6 +2,9 @@
 
 ## in development:
 
+### 2020-07-21
+* blocks: tweaked block highlights for fade-out
+
 ### 2020-07-20
 * objects: fixed a list-watcher direct-editing offset bug
 * morphic: update the Hand's position on mouse-down - avoid triggering at the origin point

snap.html

@@ -7,7 +7,7 @@
         <script src="src/morphic.js?version=2020-07-20"></script>
         <script src="src/symbols.js?version=2020-07-20"></script>
         <script src="src/widgets.js?version=2020-07-13"></script>
-        <script src="src/blocks.js?version=2020-07-20"></script>
+        <script src="src/blocks.js?version=2020-07-21"></script>
         <script src="src/threads.js?version=2020-07-09"></script>
         <script src="src/objects.js?version=2020-07-20"></script>
         <script src="src/gui.js?version=2020-07-19"></script>

src/blocks.js

@@ -158,7 +158,7 @@ CustomCommandBlockMorph, SymbolMorph, ToggleButtonMorph, DialMorph*/
 
 // Global stuff ////////////////////////////////////////////////////////
 
-modules.blocks = '2020-July-20';
+modules.blocks = '2020-July-21';
 
 var SyntaxElementMorph;
 var BlockMorph;
@@ -785,6 +785,13 @@ SyntaxElementMorph.prototype.unflash = function () {
     }
 };
 
+SyntaxElementMorph.prototype.doWithAlpha = function (alpha, callback) {
+    var current = this.alpha;
+    SyntaxElementMorph.prototype.alpha = alpha;
+    callback();
+    SyntaxElementMorph.prototype.alpha = current;
+};
+
 // SyntaxElementMorph zebra coloring
 
 SyntaxElementMorph.prototype.fixBlockColor = function (
@@ -4198,7 +4205,7 @@ BlockMorph.prototype.highlight = function (color, blur, border) {
 BlockMorph.prototype.highlightImage = function (color, border) {
     var fb, img, hi, ctx, out;
     fb = this.fullBounds().extent();
-    img = this.fullImage();
+    this.doWithAlpha(1, () => img = this.fullImage());
 
     hi = newCanvas(fb.add(border * 2));
     ctx = hi.getContext('2d');
@@ -4228,7 +4235,7 @@ BlockMorph.prototype.highlightImage = function (color, border) {
 BlockMorph.prototype.highlightImageBlurred = function (color, blur) {
     var fb, img, hi, ctx;
     fb = this.fullBounds().extent();
-    img = this.fullImage();
+    this.doWithAlpha(1, () => img = this.fullImage());
 
     hi = newCanvas(fb.add(blur * 2));
     ctx = hi.getContext('2d');