Make it easy to disable unconnected blocks.

core/events.js

@@ -784,3 +784,34 @@ Blockly.Events.Ui.prototype.fromJson = function(json) {
   this.element = json['element'];
   this.newValue = json['newValue'];
 };
+
+/**
+ * Enable/disable a block depending on whether it is properly connected.
+ * Use this on applications where all blocks should be connected to a top block.
+ * Recommend setting the 'disable' option to 'false' in the config so that
+ * users don't try to reenable disabled orphan blocks.
+ * @param {!Blockly.Events.Abstract} event Custom data for event.
+ */
+Blockly.Events.disableOrphans = function(event) {
+  if (event.type == Blockly.Events.MOVE ||
+      event.type == Blockly.Events.CREATE) {
+    Blockly.Events.disable();
+    var workspace = Blockly.Workspace.getById(event.workspaceId);
+    var block = workspace.getBlockById(event.blockId);
+    if (block) {
+      if (block.getParent() && !block.getParent().disabled) {
+        do {
+          block.setDisabled(false);
+          block = block.getNextBlock();
+        } while (block);
+      } else if ((block.outputConnection || block.previousConnection) &&
+                 Blockly.dragMode_ == Blockly.DRAG_NONE) {
+        do {
+          block.setDisabled(true);
+          block = block.getNextBlock();
+        } while (block);
+      }
+    }
+    Blockly.Events.enable();
+  }
+};

demos/blockfactory/factory.js

@@ -790,6 +790,7 @@ function init() {
   }
   mainWorkspace.clearUndo();
 
+  mainWorkspace.addChangeListener(Blockly.Events.disableOrphans);
   mainWorkspace.addChangeListener(updateLanguage);
   document.getElementById('direction')
       .addEventListener('change', updatePreview);

demos/graph/index.html

@@ -337,6 +337,7 @@ Graph.resize = function() {
 Graph.init = function() {
   Graph.workspace = Blockly.inject('blocklyDiv',
       {collapse: false,
+       disable: false,
        media: '../../media/',
        toolbox: document.getElementById('toolbox')});
   Blockly.Xml.domToWorkspace(document.getElementById('startBlocks'),
@@ -345,6 +346,7 @@ Graph.init = function() {
 
   // When Blockly changes, update the graph.
   Graph.workspace.addChangeListener(Graph.drawVisualization);
+  Graph.workspace.addChangeListener(Blockly.Events.disableOrphans);
   Graph.resize();
 };
 

demos/plane/plane.js

@@ -276,6 +276,7 @@ Plane.init = function() {
   Plane.loadBlocks(defaultXml);
 
   Plane.workspace.addChangeListener(Plane.recalculate);
+  Plane.workspace.addChangeListener(Blockly.Events.disableOrphans);
 
   // Initialize the slider.
   var svg = document.getElementById('plane');