fix(Map): use same size calculation in updateSize and updateViewportSize_

src/ol/Map.js

@@ -1367,7 +1367,7 @@ class Map extends BaseObject {
     }
     const view = this.getView();
     if (view) {
-      this.updateViewportSize_();
+      this.updateViewportSize_(this.getSize());
 
       this.viewPropertyListenerKey_ = listen(
         view,
@@ -1738,25 +1738,18 @@ class Map extends BaseObject {
     const oldSize = this.getSize();
     if (size && (!oldSize || !equals(size, oldSize))) {
       this.setSize(size);
-      this.updateViewportSize_();
+      this.updateViewportSize_(size);
     }
   }
 
   /**
    * Recomputes the viewport size and save it on the view object (if any)
+   * @param {import("./size.js").Size|undefined} size The size.
    * @private
    */
-  updateViewportSize_() {
+  updateViewportSize_(size) {
     const view = this.getView();
     if (view) {
-      let size = undefined;
-      const computedStyle = getComputedStyle(this.viewport_);
-      if (computedStyle.width && computedStyle.height) {
-        size = [
-          parseInt(computedStyle.width, 10),
-          parseInt(computedStyle.height, 10),
-        ];
-      }
       view.setViewportSize(size);
     }
   }

src/ol/View.js

@@ -74,9 +74,11 @@ import {fromExtent as polygonFromExtent} from './geom/Polygon.js';
 
 /**
  * @typedef {Object} FitOptions
- * @property {import("./size.js").Size} [size] The size in pixels of the box to fit
- * the extent into. Default is the current size of the first map in the DOM that
- * uses this view, or `[100, 100]` if no such map is found.
+ * @property {import("./size.js").Size} [size] The size in pixels of the box to
+ * fit the extent into. If the view is associated with one map, it defaults to
+ * the size of the map. If it is associated with multiple maps, the size can be
+ * of any one of the maps, so the desired size should be specified. If no map
+ * is associated it uses `[100, 100]` as the size.
  * @property {!Array<number>} [padding=[0, 0, 0, 0]] Padding (in pixels) to be
  * cleared inside the view. Values in the array are top, right, bottom and left
  * padding.