scrollPosition - baScrollPosition

src/app/theme/directives/baScrollPosition/baScrollPosition.directive.ts

@@ -0,0 +1,25 @@
+import {Directive, Input, Output, EventEmitter, HostListener} from '@angular/core';
+
+@Directive({
+  selector: '[baScrollPosition]'
+})
+export class BaScrollPosition {
+
+  @Input() public maxHeight:number;
+  @Output() public scrollChange:EventEmitter<boolean> = new EventEmitter<boolean>();
+
+  private _isScrolled:boolean;
+
+  public ngOnInit():void {
+    this.onWindowScroll();
+  }
+
+  @HostListener('window:scroll')
+  onWindowScroll():void {
+    let isScrolled = window.scrollY > this.maxHeight;
+    if (isScrolled !== this._isScrolled) {
+      this._isScrolled = isScrolled;
+      this.scrollChange.emit(isScrolled);
+    }
+  }
+}