Add existing to tracked

node_modules/@cesium/widgets/Source/Viewer/viewerPerformanceWatchdogMixin.js

@@ -0,0 +1,47 @@
+import { Frozen, defined, DeveloperError } from "@cesium/engine";
+import PerformanceWatchdog from "../PerformanceWatchdog/PerformanceWatchdog.js";
+
+/**
+ * A mixin which adds the {@link PerformanceWatchdog} widget to the {@link Viewer} widget.
+ * Rather than being called directly, this function is normally passed as
+ * a parameter to {@link Viewer#extend}, as shown in the example below.
+ * @function
+ *
+ * @param {Viewer} viewer The viewer instance.
+ * @param {object} [options] An object with properties.
+ * @param {string} [options.lowFrameRateMessage='This application appears to be performing poorly on your system.  Please try using a different web browser or updating your video drivers.'] The
+ *        message to display when a low frame rate is detected.  The message is interpeted as HTML, so make sure
+ *        it comes from a trusted source so that your application is not vulnerable to cross-site scripting attacks.
+ *
+ * @exception {DeveloperError} viewer is required.
+ *
+ * @example
+ * const viewer = new Cesium.Viewer('cesiumContainer');
+ * viewer.extend(Cesium.viewerPerformanceWatchdogMixin, {
+ *     lowFrameRateMessage : 'Why is this going so <em>slowly</em>?'
+ * });
+ */
+function viewerPerformanceWatchdogMixin(viewer, options) {
+  //>>includeStart('debug', pragmas.debug);
+  if (!defined(viewer)) {
+    throw new DeveloperError("viewer is required.");
+  }
+  //>>includeEnd('debug');
+
+  options = options ?? Frozen.EMPTY_OBJECT;
+
+  const performanceWatchdog = new PerformanceWatchdog({
+    scene: viewer.scene,
+    container: viewer.bottomContainer,
+    lowFrameRateMessage: options.lowFrameRateMessage,
+  });
+
+  Object.defineProperties(viewer, {
+    performanceWatchdog: {
+      get: function () {
+        return performanceWatchdog;
+      },
+    },
+  });
+}
+export default viewerPerformanceWatchdogMixin;