Adds support for -1 row index Escalator spacers (#16644)

Change-Id: Iced2f089785983ce2ef1d2225517156cec4a7db4

5 files changed, 32 insertions, 4 deletions

diff --git a/client/src/com/vaadin/client/widget/escalator/RowContainer.java b/client/src/com/vaadin/client/widget/escalator/RowContainer.java
index e2baf9a03b..b7aae1f4f3 100644
--- a/client/src/com/vaadin/client/widget/escalator/RowContainer.java
+++ b/client/src/com/vaadin/client/widget/escalator/RowContainer.java
@@ -57,7 +57,8 @@ public interface RowContainer {
          * 
          * @param rowIndex
          *            the row index for the spacer to modify. The affected
-         *            spacer is underneath the given index
+         *            spacer is underneath the given index. Use -1 to insert a
+         *            spacer before the first row
          * @param height
          *            the pixel height of the spacer. If {@code height} is
          *            negative, the affected spacer (if exists) will be removed
diff --git a/client/src/com/vaadin/client/widgets/Escalator.java b/client/src/com/vaadin/client/widgets/Escalator.java
index 1d7d9a9910..9b11e7aec1 100644
--- a/client/src/com/vaadin/client/widgets/Escalator.java
+++ b/client/src/com/vaadin/client/widgets/Escalator.java
@@ -4453,8 +4453,15 @@ public class Escalator extends Widget implements RequiresResize,
                             .getScrollSize() + heightDiff);
                 }
 
+                /*
+                 * Don't modify the scrollbars if we're expanding the -1 spacer
+                 * while we're scrolled to the top.
+                 */
+                boolean minusOneSpacerException = spacerIsGrowing
+                        && getRow() == -1 && body.getTopRowLogicalIndex() == 0;
+
                 boolean viewportNeedsScrolling = getRow() < body
-                        .getTopRowLogicalIndex();
+                        .getTopRowLogicalIndex() && !minusOneSpacerException;
                 if (viewportNeedsScrolling) {
 
                     /*
@@ -4570,7 +4577,7 @@ public class Escalator extends Widget implements RequiresResize,
         public void setSpacer(int rowIndex, double height)
                 throws IllegalArgumentException {
 
-            if (rowIndex < 0 || rowIndex >= getBody().getRowCount()) {
+            if (rowIndex < -1 || rowIndex >= getBody().getRowCount()) {
                 throw new IllegalArgumentException("invalid row index: "
                         + rowIndex + ", while the body only has "
                         + getBody().getRowCount() + " rows.");
diff --git a/uitest/src/com/vaadin/tests/components/grid/basicfeatures/EscalatorBasicClientFeaturesTest.java b/uitest/src/com/vaadin/tests/components/grid/basicfeatures/EscalatorBasicClientFeaturesTest.java
index 25c4c1ff67..853489746f 100644
--- a/uitest/src/com/vaadin/tests/components/grid/basicfeatures/EscalatorBasicClientFeaturesTest.java
+++ b/uitest/src/com/vaadin/tests/components/grid/basicfeatures/EscalatorBasicClientFeaturesTest.java
@@ -69,6 +69,7 @@ public abstract class EscalatorBasicClientFeaturesTest extends MultiBrowserTest
     protected static final String COLSPAN_NORMAL = "Apply normal colspan";
     protected static final String COLSPAN_NONE = "Apply no colspan";
     protected static final String SPACERS = "Spacers";
+    protected static final String ROW_MINUS1 = "Row -1";
     protected static final String ROW_1 = "Row 1";
     protected static final String ROW_99 = "Row 99";
     protected static final String SET_100PX = "Set 100px";
diff --git a/uitest/src/com/vaadin/tests/components/grid/basicfeatures/escalator/EscalatorSpacerTest.java b/uitest/src/com/vaadin/tests/components/grid/basicfeatures/escalator/EscalatorSpacerTest.java
index 5e56d9433a..da3472aebf 100644
--- a/uitest/src/com/vaadin/tests/components/grid/basicfeatures/escalator/EscalatorSpacerTest.java
+++ b/uitest/src/com/vaadin/tests/components/grid/basicfeatures/escalator/EscalatorSpacerTest.java
@@ -223,7 +223,7 @@ public class EscalatorSpacerTest extends EscalatorBasicClientFeaturesTest {
 
     }
 
-   @Test
+    @Test
     public void spacersAreFixedInViewport_firstFreezeThenScroll() {
         selectMenuPath(FEATURES, FROZEN_COLUMNS, FREEZE_1_COLUMN);
         selectMenuPath(FEATURES, SPACERS, ROW_1, SET_100PX);
@@ -249,6 +249,24 @@ public class EscalatorSpacerTest extends EscalatorBasicClientFeaturesTest {
                 getElementLeft(getSpacer(1)), WidgetUtil.PIXEL_EPSILON);
     }
 
+    @Test
+    public void addingMinusOneSpacerDoesNotScrollWhenScrolledAtTop() {
+        scrollVerticallyTo(5);
+        selectMenuPath(FEATURES, SPACERS, ROW_MINUS1, SET_100PX);
+        assertEquals(
+                "No scroll adjustment should've happened when adding the -1 spacer",
+                5, getScrollTop());
+    }
+
+    @Test
+    public void removingMinusOneSpacerScrolls() {
+        scrollVerticallyTo(5);
+        selectMenuPath(FEATURES, SPACERS, ROW_MINUS1, SET_100PX);
+        selectMenuPath(FEATURES, SPACERS, ROW_MINUS1, REMOVE);
+        assertEquals("Scroll adjustment should've happened when removing the "
+                + "-1 spacer", 0, getScrollTop());
+    }
+
     private static double[] getElementDimensions(WebElement element) {
         /*
          * we need to parse the style attribute, since using getCssValue gets a
diff --git a/uitest/src/com/vaadin/tests/widgetset/client/grid/EscalatorBasicClientFeaturesWidget.java b/uitest/src/com/vaadin/tests/widgetset/client/grid/EscalatorBasicClientFeaturesWidget.java
index 538f7a21a1..dc86b89167 100644
--- a/uitest/src/com/vaadin/tests/widgetset/client/grid/EscalatorBasicClientFeaturesWidget.java
+++ b/uitest/src/com/vaadin/tests/widgetset/client/grid/EscalatorBasicClientFeaturesWidget.java
@@ -645,6 +645,7 @@ public class EscalatorBasicClientFeaturesWidget extends
             }
         }, menupath);
 
+        createSpacersMenuForRow(-1, menupath);
         createSpacersMenuForRow(1, menupath);
         createSpacersMenuForRow(50, menupath);
         createSpacersMenuForRow(99, menupath);