Scroll selected tab into view (#3899)

Change-Id: I4e86caa4ad02dfc5d0eaa33b85f67da3837fcea0

3 files changed, 44 insertions, 1 deletions

diff --git a/client/src/main/java/com/vaadin/client/ui/VTabsheet.java b/client/src/main/java/com/vaadin/client/ui/VTabsheet.java
index e196870348..1ea41f634d 100644
--- a/client/src/main/java/com/vaadin/client/ui/VTabsheet.java
+++ b/client/src/main/java/com/vaadin/client/ui/VTabsheet.java
@@ -531,6 +531,9 @@ public class VTabsheet extends VTabsheetBase implements Focusable, SubPartAware
         public void selectTab(int index) {
             final Tab newSelected = getTab(index);
             final Tab oldSelected = selected;
+            if (oldSelected == newSelected) {
+                return;
+            }
 
             newSelected.setStyleNames(true, isFirstVisibleTab(index), true);
             newSelected.setTabulatorIndex(getTabsheet().tabulatorIndex);
@@ -552,6 +555,10 @@ public class VTabsheet extends VTabsheetBase implements Focusable, SubPartAware
             // The selected tab might need more (or less) space
             newSelected.recalculateCaptionWidth();
             getTab(tabsheet.activeTabIndex).recalculateCaptionWidth();
+
+            // Scroll the tab into view if it is not already
+            getTabsheet().scrollIntoView(getTab(tabsheet.activeTabIndex));
+
         }
 
         public Tab navigateTab(int fromIndex, int toIndex) {
diff --git a/uitest/src/main/java/com/vaadin/tests/components/tabsheet/TabsheetScrolling.java b/uitest/src/main/java/com/vaadin/tests/components/tabsheet/TabsheetScrolling.java
index da449a2461..fe1bcd0a1a 100644
--- a/uitest/src/main/java/com/vaadin/tests/components/tabsheet/TabsheetScrolling.java
+++ b/uitest/src/main/java/com/vaadin/tests/components/tabsheet/TabsheetScrolling.java
@@ -9,6 +9,8 @@ import com.vaadin.ui.TabSheet.Tab;
 
 public class TabsheetScrolling extends TestBase {
 
+    public static final String SELECT_FIRST = "selFirst";
+    public static final String SELECT_LAST = "selLast";
     private TabSheet fixedSizeTabSheet;
     private TabSheet autoWideTabSheet;
 
@@ -60,7 +62,28 @@ public class TabsheetScrolling extends TestBase {
         }
 
         addComponent(autoWideTabSheet);
-
+        Button selectFirst = new Button("Select first tab in both tabsheets",
+                new ClickListener() {
+                    @Override
+                    public void buttonClick(ClickEvent event) {
+                        fixedSizeTabSheet.setSelectedTab(0);
+                        autoWideTabSheet.setSelectedTab(0);
+                    }
+                });
+        selectFirst.setId(SELECT_FIRST);
+        addComponent(selectFirst);
+        Button selectLast = new Button("Select last tab in both tabsheets",
+                new ClickListener() {
+                    @Override
+                    public void buttonClick(ClickEvent event) {
+                        int lastFixed = fixedSizeTabSheet.getComponentCount() - 1;
+                        fixedSizeTabSheet.setSelectedTab(lastFixed);
+                        int lastAuto = autoWideTabSheet.getComponentCount() - 1;
+                        autoWideTabSheet.setSelectedTab(lastAuto);
+                    }
+                });
+        selectLast.setId(SELECT_LAST);
+        addComponent(selectLast);
     }
 
     @Override
diff --git a/uitest/src/test/java/com/vaadin/tests/components/tabsheet/TabsheetScrollingTest.java b/uitest/src/test/java/com/vaadin/tests/components/tabsheet/TabsheetScrollingTest.java
index 1da42bb1ce..47753e09d3 100644
--- a/uitest/src/test/java/com/vaadin/tests/components/tabsheet/TabsheetScrollingTest.java
+++ b/uitest/src/test/java/com/vaadin/tests/components/tabsheet/TabsheetScrollingTest.java
@@ -23,6 +23,7 @@ import org.openqa.selenium.interactions.Actions;
 
 import com.vaadin.testbench.By;
 import com.vaadin.testbench.elements.ButtonElement;
+import com.vaadin.testbench.elements.TabSheetElement;
 import com.vaadin.tests.tb3.MultiBrowserTest;
 
 public class TabsheetScrollingTest extends MultiBrowserTest {
@@ -51,4 +52,16 @@ public class TabsheetScrollingTest extends MultiBrowserTest {
         new Actions(getDriver()).sendKeys(key).perform();
     }
 
+    @Test
+    public void serverChangeShouldShowTab() {
+        openTestURL();
+        $(ButtonElement.class).id(TabsheetScrolling.SELECT_LAST).click();
+        TabSheetElement tabsheetFixed = $(TabSheetElement.class).first();
+        Assert.assertTrue("Select last should scroll last tab into view",
+                tabsheetFixed.getTabCaptions().contains("Tab 99"));
+        $(ButtonElement.class).id(TabsheetScrolling.SELECT_FIRST).click();
+        Assert.assertTrue("Select first should scroll first tab into view",
+                tabsheetFixed.getTabCaptions().contains("Tab 1"));
+
+    }
 }