fix(scrollpoint): calculate scroll on dragenter

Author: nivekcode

projects/ng-sortgrid/src/lib/ngsg-item.directive.spec.ts

@@ -221,4 +221,18 @@ describe('NgsgItemDirective', () => {
     sut.drop();
     expect(consoleWarnSpy).toHaveBeenCalledWith(expectedWarniningMessage);
   });
+
+  it('should call the scrollHelper once we drag', () => {
+    const event = {
+      target: 'Some target'
+    };
+    const scrollPointTop = 20;
+    const scrollSpeed = 50;
+    sut.scrollPointTop = scrollPointTop;
+    sut.scrollSpeed = scrollSpeed;
+    spyOn(scrollHelperService, 'scrollIfNecessary');
+
+    sut.drag(event);
+    expect(scrollHelperService.scrollIfNecessary).toHaveBeenCalledWith(event.target, {top: scrollPointTop}, scrollSpeed);
+  });
 });

projects/ng-sortgrid/src/lib/ngsg-item.directive.ts

@@ -88,17 +88,13 @@ export class NgsgItemDirective implements OnInit, OnChanges, AfterViewInit, OnDe
     this.sortService.sort(this.el.nativeElement);
   }
 
+  @HostListener('drag', ['$event'])
+  drag(event): void {
+    this.scrollHelperService.scrollIfNecessary(event.target, {top: this.scrollPointTop}, this.scrollSpeed);
+  }
+
   @HostListener('dragover', ['$event'])
   dragOver(event): boolean {
-
-    if (this.viewPortService.isOutOfViewport(event.target).top) {
-      window.scrollBy({top: -this.SCROLLSPEED, behavior: 'smooth'});
-    }
-
-    if (this.viewPortService.isOutOfViewport(event.target).bottom) {
-      window.scrollBy({top: this.SCROLLSPEED, behavior: 'smooth'});
-    }
-
     if (event.preventDefault) {
       // Necessary. Allows us to drop.
       event.preventDefault();