Resolve constraints using anchor

Resolve constraints using anchor if view state is the result of cancelling an animation with anchor

src/ol/View.js

@@ -312,6 +312,12 @@ class View extends BaseObject {
      */
     this.targetRotation_;
 
+    /**
+     * @private
+     * @type {import("./coordinate.js").Coordinate|undefined}
+     */
+    this.cancelAnchor_ = undefined;
+
     if (options.center) {
       options.center = fromUserCoordinate(options.center, this.projection_);
     }
@@ -584,13 +590,19 @@ class View extends BaseObject {
    */
   cancelAnimations() {
     this.setHint(ViewHint.ANIMATING, -this.hints_[ViewHint.ANIMATING]);
+    let anchor;
     for (let i = 0, ii = this.animations_.length; i < ii; ++i) {
       const series = this.animations_[i];
       if (series[0].callback) {
         animationCallback(series[0].callback, false);
       }
+      anchor = anchor ||
+        series.filter(function(animation) {
+          return !animation.complete;
+        })[0].anchor;
     }
     this.animations_.length = 0;
+    this.cancelAnchor_ = anchor;
   }
 
   /**
@@ -1390,6 +1402,7 @@ class View extends BaseObject {
     if (this.getAnimating() && !opt_doNotCancelAnims) {
       this.cancelAnimations();
     }
+    this.cancelAnchor_ = undefined;
   }
 
   /**
@@ -1410,7 +1423,7 @@ class View extends BaseObject {
     const newResolution = this.constraints_.resolution(this.targetResolution_, direction, size);
     const newCenter = this.constraints_.center(this.targetCenter_, newResolution, size);
 
-    if (duration === 0) {
+    if (duration === 0 && !this.cancelAnchor_) {
       this.targetResolution_ = newResolution;
       this.targetRotation_ = newRotation;
       this.targetCenter_ = newCenter;
@@ -1418,6 +1431,9 @@ class View extends BaseObject {
       return;
     }
 
+    const anchor = opt_anchor || (duration === 0 ? this.cancelAnchor_ : undefined);
+    this.cancelAnchor_ = undefined;
+
     if (this.getResolution() !== newResolution ||
       this.getRotation() !== newRotation ||
       !this.getCenterInternal() ||
@@ -1433,7 +1449,7 @@ class View extends BaseObject {
         resolution: newResolution,
         duration: duration,
         easing: easeOut,
-        anchor: opt_anchor
+        anchor: anchor
       });
     }
   }