feat(yOffset): remove yOffset logic from minimise mode calc

Author: jackhkmatthews

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

@@ -199,5 +199,42 @@ describe('ScrollCollapseDirective', () => {
       });
       expect(directive.affixMode).toBeFalsy();
     });
+
+    it('should factor in yOffset property when calculating affix mode', () => {
+      directive.originalHeight = 100;
+      directive.originalTop = 500;
+      directive.yOffset = 200;
+      directive.calculateAffixMode({
+        scrollX: 0,
+        scrollY: 0,
+        width: 1366,
+        height: 768
+      });
+      expect(directive.affixMode).toBeFalsy();
+
+      directive.calculateAffixMode({
+        scrollX: 0,
+        scrollY: 200,
+        width: 1366,
+        height: 768
+      });
+      expect(directive.affixMode).toBeFalsy();
+
+      directive.calculateAffixMode({
+        scrollX: 0,
+        scrollY: 300,
+        width: 1366,
+        height: 768
+      });
+      expect(directive.affixMode).toBeTruthy();
+
+      directive.calculateAffixMode({
+        scrollX: 0,
+        scrollY: 299,
+        width: 1366,
+        height: 768
+      });
+      expect(directive.affixMode).toBeFalsy();
+    });
   });
 });

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

@@ -76,7 +76,7 @@ export class ScrollCollapseDirective implements AfterViewInit, OnDestroy {
   @Input() public debounce = 0;
   /**
    * Number of pixels before the elements originalTop
-   * position is scroll to that the classes will be applied.
+   * position is scroll to that the sn-affix class will be applied.
    * This value will need to take into account elements which become
    * fixed above this element while scrolling as they reduce
    * the height of the document and the scrollY number.
@@ -201,7 +201,7 @@ export class ScrollCollapseDirective implements AfterViewInit, OnDestroy {
    */
   public calculateMinimiseMode(viewport: Viewport): void {
     this.minimiseMode =
-      viewport.scrollY >= this.originalHeight + this.originalTop - this.yOffset;
+      viewport.scrollY >= this.originalHeight + this.originalTop;
   }
   /**
    * Calculate if the user has scrolled pass the origin height of