Add existing to tracked

node_modules/@cesium/widgets/Source/HomeButton/HomeButtonViewModel.js

@@ -0,0 +1,86 @@
+import { defined, DeveloperError } from "@cesium/engine";
+import knockout from "../ThirdParty/knockout.js";
+import createCommand from "../createCommand.js";
+
+/**
+ * The view model for {@link HomeButton}.
+ * @alias HomeButtonViewModel
+ * @constructor
+ *
+ * @param {Scene} scene The scene instance to use.
+ * @param {number} [duration] The duration of the camera flight in seconds.
+ */
+function HomeButtonViewModel(scene, duration) {
+  //>>includeStart('debug', pragmas.debug);
+  if (!defined(scene)) {
+    throw new DeveloperError("scene is required.");
+  }
+  //>>includeEnd('debug');
+
+  this._scene = scene;
+  this._duration = duration;
+
+  const that = this;
+  this._command = createCommand(function () {
+    that._scene.camera.flyHome(that._duration);
+  });
+
+  /**
+   * Gets or sets the tooltip.  This property is observable.
+   *
+   * @type {string}
+   */
+  this.tooltip = "View Home";
+
+  knockout.track(this, ["tooltip"]);
+}
+
+Object.defineProperties(HomeButtonViewModel.prototype, {
+  /**
+   * Gets the scene to control.
+   * @memberof HomeButtonViewModel.prototype
+   *
+   * @type {Scene}
+   */
+  scene: {
+    get: function () {
+      return this._scene;
+    },
+  },
+
+  /**
+   * Gets the Command that is executed when the button is clicked.
+   * @memberof HomeButtonViewModel.prototype
+   *
+   * @type {Command}
+   */
+  command: {
+    get: function () {
+      return this._command;
+    },
+  },
+
+  /**
+   * Gets or sets the the duration of the camera flight in seconds.
+   * A value of zero causes the camera to instantly switch to home view.
+   * The duration will be computed based on the distance when undefined.
+   * @memberof HomeButtonViewModel.prototype
+   *
+   * @type {number|undefined}
+   */
+  duration: {
+    get: function () {
+      return this._duration;
+    },
+    set: function (value) {
+      //>>includeStart('debug', pragmas.debug);
+      if (defined(value) && value < 0) {
+        throw new DeveloperError("value must be positive.");
+      }
+      //>>includeEnd('debug');
+
+      this._duration = value;
+    },
+  },
+});
+export default HomeButtonViewModel;