From 70f7ec68ec489589524f497afbb307064a8788a5 Mon Sep 17 00:00:00 2001
From: Tomi Virkki <virkki@vaadin.com>
Date: Tue, 6 Feb 2018 12:15:02 +0200
Subject: [PATCH] Only scroll to index when necessary

---
 src/vaadin-grid-keyboard-navigation-mixin.html | 6 ++----
 test/keyboard-navigation.html                  | 8 ++++++++
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/vaadin-grid-keyboard-navigation-mixin.html b/src/vaadin-grid-keyboard-navigation-mixin.html
index c2ff3c88a..4c894b5b9 100644
--- a/src/vaadin-grid-keyboard-navigation-mixin.html
+++ b/src/vaadin-grid-keyboard-navigation-mixin.html
@@ -124,11 +124,9 @@
     }
 
     _ensureScrolledToIndex(index) {
-      const visibleItemsCount = this._lastVisibleIndex - this._firstVisibleIndex - 1;
-      if (index <= this._firstVisibleIndex) {
+      const targetRowInDom = Array.from(this.$.items.children).filter(child => child.index === index)[0];
+      if (!targetRowInDom) {
         this._scrollToIndex(index);
-      } else if (index >= this._firstVisibleIndex + visibleItemsCount) {
-        this._scrollToIndex(index - visibleItemsCount);
       }
     }
 
diff --git a/test/keyboard-navigation.html b/test/keyboard-navigation.html
index ce303c030..2bc992a45 100644
--- a/test/keyboard-navigation.html
+++ b/test/keyboard-navigation.html
@@ -1163,6 +1163,14 @@
             expect(grid.shadowRoot.activeElement).to.equal(getContainerCell(grid.$.header, 0, 0));
           });
 
+          it('should not scroll if the new focused item in viewport', () => {
+            focusItem(0);
+            ctrlEnd();
+            const scrollTop = grid.$.table.scrollTop;
+            up();
+            expect(grid.$.table.scrollTop).to.equal(scrollTop);
+          });
+
           describe('rotating focus indicator prevention', () => {
             it('should hide navigation mode when a focused row goes off screen', () => {
               focusItem(0);