feat: add ability to delete workspace comments (google#8023)

core/comments/rendered_workspace_comment.ts

@@ -18,10 +18,16 @@ import {CommentDragStrategy} from '../dragging/comment_drag_strategy.js';
 import * as browserEvents from '../browser_events.js';
 import * as common from '../common.js';
 import {ISelectable} from '../interfaces/i_selectable.js';
+import {IDeletable} from '../interfaces/i_deletable.js';
 
 export class RenderedWorkspaceComment
   extends WorkspaceComment
-  implements IBoundedElement, IRenderedElement, IDraggable, ISelectable
+  implements
+    IBoundedElement,
+    IRenderedElement,
+    IDraggable,
+    ISelectable,
+    IDeletable
 {
   /** The class encompassing the svg elements making up the workspace comment. */
   private view: CommentView;
@@ -165,6 +171,20 @@ export class RenderedWorkspaceComment
     }
   }
 
+  /** Returns whether this comment is deletable or not. */
+  isDeletable(): boolean {
+    return !this.workspace.options.readOnly;
+  }
+
+  /** Visually indicates that this comment would be deleted if dropped. */
+  setDeleteStyle(wouldDelete: boolean): void {
+    if (wouldDelete) {
+      dom.addClass(this.getSvgRoot(), 'blocklyDraggingDelete');
+    } else {
+      dom.removeClass(this.getSvgRoot(), 'blocklyDraggingDelete');
+    }
+  }
+
   /** Returns whether this comment is movable or not. */
   isMovable(): boolean {
     return this.dragStrategy.isMovable();

core/shortcut_items.ts

@@ -16,6 +16,7 @@ import {KeyboardShortcut, ShortcutRegistry} from './shortcut_registry.js';
 import {KeyCodes} from './utils/keycodes.js';
 import type {WorkspaceSvg} from './workspace_svg.js';
 import {isDraggable} from './interfaces/i_draggable.js';
+import * as eventUtils from './events/utils.js';
 
 /**
  * Object holding the names of the default shortcut items.
@@ -75,7 +76,14 @@ export function registerDelete() {
       if (Gesture.inProgress()) {
         return false;
       }
-      (common.getSelected() as BlockSvg).checkAndDelete();
+      const selected = common.getSelected();
+      if (selected instanceof BlockSvg) {
+        selected.checkAndDelete();
+      } else if (isDeletable(selected) && selected.isDeletable()) {
+        eventUtils.setGroup(true);
+        selected.dispose();
+        eventUtils.setGroup(false);
+      }
       return true;
     },
     keyCodes: [KeyCodes.DELETE, KeyCodes.BACKSPACE],