Allow maps to be configured with a promise for view props

src/ol/source/Source.js

@@ -90,6 +90,28 @@ class Source extends BaseObject {
      * @type {boolean}
      */
     this.wrapX_ = options.wrapX !== undefined ? options.wrapX : false;
+
+    /**
+     * @protected
+     * @type {function(import("../View.js").ViewOptions):void}
+     */
+    this.viewResolver = null;
+
+    /**
+     * @protected
+     * @type {function(Error):void}
+     */
+    this.viewRejector = null;
+
+    const self = this;
+    /**
+     * @private
+     * @type {Promise<import("../View.js").ViewOptions>}
+     */
+    this.viewPromise_ = new Promise(function (resolve, reject) {
+      self.viewResolver = resolve;
+      self.viewRejector = reject;
+    });
   }
 
   /**
@@ -126,6 +148,13 @@ class Source extends BaseObject {
     return abstract();
   }
 
+  /**
+   * @return {Promise<import("../View.js").ViewOptions>} A promise for view-related properties.
+   */
+  getView() {
+    return this.viewPromise_;
+  }
+
   /**
    * Get the state of the source, see {@link module:ol/source/State~State} for possible states.
    * @return {import("./State.js").default} State.