fix(ScrollCollapse): factor in element offsetTop when calculating min…

…imise mode

Minimise mode did not factor in offsetTop, it now does and both affix mode and minimise mode were
being triggered 1px too late

src/app/scroll-collapse/scroll-collapse.directive.spec.ts

@@ -100,6 +100,19 @@ describe('ScrollCollapseDirective', () => {
       directive.calculateMinimiseMode({ scrollX: 0, scrollY: 99, width: 1366, height: 768 });
       expect(directive.minimiseMode).toBeFalsy();
     });
+
+    it('should factor in element offsetTop when calculating minimise mode', () => {
+      directive.originalHeight = 100;
+      directive.originalTop = 100;
+      directive.calculateMinimiseMode({ scrollX: 0, scrollY: 0, width: 1366, height: 768 });
+      expect(directive.minimiseMode).toBeFalsy();
+
+      directive.calculateMinimiseMode({ scrollX: 0, scrollY: 200, width: 1366, height: 768 });
+      expect(directive.minimiseMode).toBeTruthy();
+
+      directive.calculateMinimiseMode({ scrollX: 0, scrollY: 199, width: 1366, height: 768 });
+      expect(directive.minimiseMode).toBeFalsy();
+    });
   });
 
   describe('affix mode', () => {

src/app/scroll-collapse/scroll-collapse.directive.ts

@@ -185,7 +185,7 @@ export class ScrollCollapseDirective implements AfterViewInit, OnDestroy {
    * @memberof ScrollCollapseDirective
    */
   public calculateMinimiseMode(viewport: Viewport): void {
-    this.minimiseMode = viewport.scrollY > this.originalHeight;
+    this.minimiseMode = viewport.scrollY >= (this.originalHeight + this.originalTop);
   }
   /**
    * Calculate if the user has scrolled pass the origin height of
@@ -194,7 +194,7 @@ export class ScrollCollapseDirective implements AfterViewInit, OnDestroy {
    * @memberof ScrollCollapseDirective
    */
   public calculateAffixMode(viewport: Viewport): void {
-    this.affixMode = viewport.scrollY > this.originalTop;
+    this.affixMode = viewport.scrollY >= this.originalTop;
   }
   /**
    * Return current viewport values