Refactor zoom for Cesium and Leaflet maps.

CHANGES.md

@@ -2,6 +2,8 @@
 
 #### next release (8.3.4)
 
+- Refactor 3D & 2D zoom code path.
+- Improve zooming to clamped items in 3D.
 - [The next improvement]
 
 #### next release (8.3.3)

lib/Map/Cesium/Zooming.ts

@@ -0,0 +1,111 @@
+import BoundingSphere from "terriajs-cesium/Source/Core/BoundingSphere";
+import Cartesian3 from "terriajs-cesium/Source/Core/Cartesian3";
+import CameraView from "../../Models/CameraView";
+import Cesium from "../../Models/Cesium";
+import { ZoomTarget } from "../ZoomTarget";
+import compute3dZoomView from "./compute3dZoomView";
+
+/**
+ * Implements the zooming behaviour for Cesium viewer.
+ *
+ * @private
+ */
+export default class Zooming {
+  private currentZoomTarget?: ZoomTarget;
+
+  constructor(readonly cesium: Cesium) {}
+
+  private get scene() {
+    return this.cesium.scene;
+  }
+
+  /**
+   * Zoom Cesium map so that the given target is in view.
+   *
+   * @param target The target to zoom to
+   * @param flightDurationSeconds The length of the zoom animation in seconds
+   * @returns a promise that is fulfilled when the zoom animation is complete
+   */
+  async zoomTo(
+    target: ZoomTarget,
+    flightDurationSeconds: number
+  ): Promise<void> {
+    // Wake up renderer, this is required so that the map is updated and we can
+    // compute the most recent view
+    this.cesium.notifyRepaintRequired();
+    this.currentZoomTarget = target;
+    const view = await compute3dZoomView(target, this.cesium);
+    if (this.currentZoomTarget !== target || !view) {
+      return;
+    }
+    // Wake up renderer again, in case we `await`ed too long and it dozed
+    // again. Otherwise animations won't run.
+    this.cesium.notifyRepaintRequired();
+    if (view instanceof BoundingSphere) {
+      return this.zoomToBoundingSphere(view, flightDurationSeconds);
+    } else if (view instanceof Cartesian3) {
+      return this.zoomToPosition(view, flightDurationSeconds);
+    } else if (view instanceof CameraView) {
+      return this.zoomToCameraView(view, flightDurationSeconds);
+    }
+  }
+
+  /**
+   * Zoom to the given Cartesian position
+   */
+  private async zoomToPosition(
+    position: Cartesian3,
+    flightDurationSeconds: number
+  ): Promise<void> {
+    return new Promise((complete, cancel) => {
+      this.scene.camera.flyTo({
+        destination: position,
+        duration: flightDurationSeconds,
+        complete,
+        cancel
+      });
+    });
+  }
+
+  /**
+   * Zoom to the given camera view
+   */
+  private async zoomToCameraView(
+    cameraView: CameraView,
+    flightDurationSeconds: number
+  ): Promise<void> {
+    return new Promise((complete, cancel) => {
+      const destination = cameraView.position ?? cameraView.rectangle;
+      const orientation =
+        cameraView.direction || cameraView.up
+          ? {
+              direction: cameraView.direction,
+              up: cameraView.up
+            }
+          : undefined;
+      this.scene.camera.flyTo({
+        destination,
+        orientation,
+        duration: flightDurationSeconds,
+        complete,
+        cancel
+      });
+    });
+  }
+
+  /**
+   * Zoom to the given bounding sphere
+   */
+  private async zoomToBoundingSphere(
+    boundingSphere: BoundingSphere,
+    flightDurationSeconds: number
+  ): Promise<void> {
+    return new Promise((complete, cancel) => {
+      this.scene.camera.flyToBoundingSphere(boundingSphere, {
+        duration: flightDurationSeconds,
+        complete,
+        cancel
+      });
+    });
+  }
+}