Grow cache size dynamically

src/ol/source/VectorTile.js

@@ -27,7 +27,7 @@ import {toSize} from '../size.js';
  * @typedef {Object} Options
  * @property {import("./Source.js").AttributionLike} [attributions] Attributions.
  * @property {boolean} [attributionsCollapsible=true] Attributions are collapsible.
- * @property {number} [cacheSize=128] Cache size.
+ * @property {number} [cacheSize] Initial tile cache size. Will auto-grow to hold at least twice the number of tiles in the viewport.
  * @property {import("../extent.js").Extent} [extent]
  * @property {import("../format/Feature.js").default} [format] Feature format for tiles. Used and required by the default.
  * @property {boolean} [overlaps=true] This source may have overlapping geometries. Setting this
@@ -509,6 +509,15 @@ class VectorTile extends UrlTile {
       Math.round(tileSize[1] * pixelRatio),
     ];
   }
+
+  /**
+   * Increases the cache size if needed
+   * @param {number} tileCount Minimum number of tiles needed.
+   * @param {import("../proj/Projection.js").default} projection Projection.
+   */
+  updateCacheSize(tileCount, projection) {
+    super.updateCacheSize(tileCount * 2, projection);
+  }
 }
 
 export default VectorTile;