big cmap refactoring

static/cmap/cmap-view.js

@@ -1,3 +1,5 @@
+import { DiagramEngine } from "./cmap.js";
+
 /**
  * Present a CMap through the bundled drawing engine.
  *
@@ -6,11 +8,13 @@
  * rules; CmapEditor remains responsible for interpreting user interaction.
  */
 export class CmapView {
-  constructor(canvas, CmapFactory, onSelection, onActivation) {
+  constructor(canvas, onSelection, onActivation, createEngine = null) {
     if (!(canvas instanceof Object)) throw new TypeError("A CMap canvas is required");
-    if (typeof CmapFactory !== "function") throw new TypeError("A CMap factory is required");
+    if (createEngine !== null && typeof createEngine !== "function") {
+      throw new TypeError("A diagram-engine factory must be a function");
+    }
     this.canvas = canvas;
-    this.map = CmapFactory(canvas);
+    this.map = createEngine ? createEngine(canvas) : new DiagramEngine(canvas);
     this.map.onSelection(onSelection);
     this.map.onActivation(onActivation);
   }