fix(grid): max zoom (#677)

Author: vicb

src/algorithms/core.ts

@@ -57,8 +57,10 @@ export interface Algorithm {
 }
 
 export interface AlgorithmOptions {
+  // Markers are not clustered at maxZoom and above.
   maxZoom?: number;
 }
+
 /**
  * @hidden
  */

src/algorithms/grid.test.ts

@@ -16,7 +16,6 @@
 
 import { GridAlgorithm } from "./grid";
 import { initialize, MapCanvasProjection } from "@googlemaps/jest-mocks";
-import { Marker } from "../marker-utils";
 
 initialize();
 const markers = [
@@ -35,7 +34,7 @@ describe.each(markers)(
 
     test("calculate should return changed: true for first call when zoom > max zoom", () => {
       const mapCanvasProjection = new MapCanvasProjection();
-      const markers: Marker[] = [marker];
+      const markers = [marker];
 
       const grid = new GridAlgorithm({ maxZoom: 16 });
       grid["noop"] = jest.fn();
@@ -60,10 +59,10 @@ describe.each(markers)(
       expect(changed).toBe(true);
     });
 
-    test("calculate should return changed: false for next calls above max zoom", () => {
+    test("calculate should return changed: false when zoom doesn't change", () => {
       const mapCanvasProjection =
         jest.fn() as unknown as google.maps.MapCanvasProjection;
-      const markers: Marker[] = [marker];
+      const markers = [marker];
 
       const grid = new GridAlgorithm({ maxZoom: 16 });
       grid["noop"] = jest.fn();
@@ -87,10 +86,10 @@ describe.each(markers)(
       expect(result.changed).toBe(false);
     });
 
-    test("calculate should return changed: false for next calls above max zoom, even if zoom changed", () => {
+    test("calculate should return changed: false for next calls at or above max zoom, even if zoom changed", () => {
       const mapCanvasProjection =
         jest.fn() as unknown as google.maps.MapCanvasProjection;
-      const markers: Marker[] = [marker];
+      const markers = [marker];
 
       const grid = new GridAlgorithm({ maxZoom: 16 });
       grid["noop"] = jest.fn();
@@ -114,6 +113,16 @@ describe.each(markers)(
       });
 
       expect(result.changed).toBe(false);
+
+      map.getZoom = jest.fn().mockReturnValue(16);
+
+      result = grid.calculate({
+        markers,
+        map,
+        mapCanvasProjection,
+      });
+
+      expect(result.changed).toBe(false);
     });
   }
 );

src/algorithms/grid.ts

@@ -50,14 +50,13 @@ export class GridAlgorithm extends AbstractViewportAlgorithm {
   protected gridSize: number;
   protected maxDistance: number;
   protected clusters: Cluster[] = [];
-  protected state: { zoom: number };
+  protected state = { zoom: -1 };
 
   constructor({ maxDistance = 40000, gridSize = 40, ...options }: GridOptions) {
     super(options);
 
     this.maxDistance = maxDistance;
     this.gridSize = gridSize;
-    this.state = { zoom: null };
   }
 
   public calculate({
@@ -67,8 +66,8 @@ export class GridAlgorithm extends AbstractViewportAlgorithm {
   }: AlgorithmInput): AlgorithmOutput {
     const state = { zoom: map.getZoom() };
     let changed = false;
-    if (this.state.zoom > this.maxZoom && state.zoom > this.maxZoom) {
-      // still beyond maxZoom, no change
+    if (this.state.zoom >= this.maxZoom && state.zoom >= this.maxZoom) {
+      // still at or beyond maxZoom, no change
     } else {
       changed = !equal(this.state, state);
     }

src/algorithms/supercluster.ts

@@ -36,7 +36,7 @@ export class SuperClusterAlgorithm extends AbstractAlgorithm {
   protected superCluster: SuperCluster;
   protected markers: Marker[];
   protected clusters: Cluster[];
-  protected state: { zoom: number | null };
+  protected state = { zoom: -1 };
 
   constructor({ maxZoom, radius = 60, ...options }: SuperClusterOptions) {
     super({ maxZoom });
@@ -46,8 +46,6 @@ export class SuperClusterAlgorithm extends AbstractAlgorithm {
       radius,
       ...options,
     });
-
-    this.state = { zoom: null };
   }
 
   public calculate(input: AlgorithmInput): AlgorithmOutput {