From 82a001d2dc4e9e207e26107b6a31d6619ba6e7a4 Mon Sep 17 00:00:00 2001
From: Artur Signell <artur@vaadin.com>
Date: Wed, 19 Oct 2016 22:50:22 +0300
Subject: [PATCH] Make Grid isWorkPending wait for scroll events to complete
 (#20417)

Change-Id: I3cfdac539111ff2e88c7ff81e6d6b9a579160423
---
 .../client/widget/escalator/ScrollbarBundle.java   | 13 ++++++++++++-
 .../grid/basicfeatures/server/GridScrollTest.java  | 14 ++++++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/client/src/main/java/com/vaadin/client/widget/escalator/ScrollbarBundle.java b/client/src/main/java/com/vaadin/client/widget/escalator/ScrollbarBundle.java
index c8bc8462e9..6e2fb14f8f 100644
--- a/client/src/main/java/com/vaadin/client/widget/escalator/ScrollbarBundle.java
+++ b/client/src/main/java/com/vaadin/client/widget/escalator/ScrollbarBundle.java
@@ -368,6 +368,7 @@ public abstract class ScrollbarBundle implements DeferredWorker {
 
     private HandlerRegistration scrollSizeTemporaryScrollHandler;
     private HandlerRegistration offsetSizeTemporaryScrollHandler;
+    private HandlerRegistration scrollInProgress;
 
     private ScrollbarBundle() {
         root.appendChild(scrollSizeElement);
@@ -530,6 +531,16 @@ public abstract class ScrollbarBundle implements DeferredWorker {
         scrollPos = Math.max(0, Math.min(maxScrollPos, truncate(px)));
 
         if (!WidgetUtil.pixelValuesEqual(oldScrollPos, scrollPos)) {
+            if (scrollInProgress == null) {
+                // Only used for tracking that there is "workPending"
+                scrollInProgress = addScrollHandler(new ScrollHandler() {
+                    @Override
+                    public void onScroll(ScrollEvent event) {
+                        scrollInProgress.removeHandler();
+                        scrollInProgress = null;
+                    }
+                });
+            }
             if (isInvisibleScrollbar) {
                 invisibleScrollbarTemporaryResizer.show();
             }
@@ -919,6 +930,6 @@ public abstract class ScrollbarBundle implements DeferredWorker {
         // requestAnimationFrame - which is not automatically checked
         return scrollSizeTemporaryScrollHandler != null
                 || offsetSizeTemporaryScrollHandler != null
-                || scrollEventFirer.isBeingFired;
+                || scrollInProgress != null || scrollEventFirer.isBeingFired;
     }
 }
diff --git a/uitest/src/test/java/com/vaadin/tests/components/grid/basicfeatures/server/GridScrollTest.java b/uitest/src/test/java/com/vaadin/tests/components/grid/basicfeatures/server/GridScrollTest.java
index e394be36de..fbd36f87f9 100644
--- a/uitest/src/test/java/com/vaadin/tests/components/grid/basicfeatures/server/GridScrollTest.java
+++ b/uitest/src/test/java/com/vaadin/tests/components/grid/basicfeatures/server/GridScrollTest.java
@@ -54,4 +54,18 @@ public class GridScrollTest extends GridBasicFeaturesTest {
                 "0. Requested items 247 - 346", getLogRow(0));
         assertEquals("There should be only one log row", " ", getLogRow(1));
     }
+
+    @Test
+    public void workPendingWhileScrolling() {
+        openTestURL("theme=valo");
+        String script = "var c = window.vaadin.clients.runcomvaadintestscomponentsgridbasicfeaturesGridBasicFeatures;\n"
+                // Scroll down and cause lazy loading
+                + "c.getElementByPath(\"//Grid[0]#cell[21]\"); \n"
+                + "return c.isActive();";
+
+        Boolean active = (Boolean) executeScript(script);
+        assertTrue("Grid should be marked to have workPending while scrolling",
+                active);
+    }
+
 }
-- 
2.39.5