Add an option for defining number of visible items in a NativeSelect (#9109)

client/src/main/java/com/vaadin/client/ui/VNativeSelect.java

@@ -110,4 +110,28 @@ public class VNativeSelect extends FocusableFlowPanelComposite
         }
         super.setHeight(height);
     }
+
+    /**
+     * Sets the number of items that are visible. If only one item is visible,
+     * then the box will be displayed as a drop-down list (the default).
+     *
+     * @since
+     * @param visibleItemCount
+     *            the visible item count
+     */
+    public void setVisibleItemCount(int visibleItemCount) {
+        getListBox().setVisibleItemCount(visibleItemCount);
+    }
+
+    /**
+     * Gets the number of items that are visible. If only one item is visible,
+     * then the box will be displayed as a drop-down list.
+     *
+     * @since
+     * @return the visible item count
+     */
+    public int getVisibleItemCount() {
+        return getListBox().getVisibleItemCount();
+    }
+
 }

server/src/main/java/com/vaadin/ui/NativeSelect.java

@@ -203,4 +203,33 @@ public class NativeSelect<T> extends AbstractSingleSelect<T>
         Objects.nonNull(caption);
         getState().emptySelectionCaption = caption;
     }
+
+    /**
+     * Sets the number of items that are visible. If only one item is visible,
+     * then the box will be displayed as a drop-down list (the default).
+     *
+     * @since
+     * @param visibleItemCount
+     *            the visible item count
+     * @throws IllegalArgumentException
+     *             if the value is smaller than one
+     */
+    public void setVisibleItemCount(int visibleItemCount) {
+        if (visibleItemCount < 1) {
+            throw new IllegalArgumentException(
+                    "There must be at least one item visible");
+        }
+        getState().visibleItemCount = visibleItemCount;
+    }
+
+    /**
+     * Gets the number of items that are visible. If only one item is visible,
+     * then the box will be displayed as a drop-down list.
+     *
+     * @since
+     * @return the visible item count
+     */
+    public int getVisibleItemCount() {
+        return getState(false).visibleItemCount;
+    }
 }

shared/src/main/java/com/vaadin/shared/ui/nativeselect/NativeSelectState.java

@@ -15,6 +15,7 @@
  */
 package com.vaadin.shared.ui.nativeselect;
 
+import com.vaadin.shared.annotations.DelegateToWidget;
 import com.vaadin.shared.ui.AbstractSingleSelectState;
 
 /**
@@ -43,6 +44,9 @@ public class NativeSelectState extends AbstractSingleSelectState {
      */
     public String emptySelectionCaption = "";
 
+    @DelegateToWidget
+    public int visibleItemCount = 1;
+
     {
         primaryStyleName = STYLE_NAME;
     }

uitest/src/main/java/com/vaadin/tests/components/nativeselect/NativeSelects.java

@@ -1,5 +1,7 @@
 package com.vaadin.tests.components.nativeselect;
 
+import java.util.LinkedHashMap;
+
 import com.vaadin.tests.components.abstractlisting.AbstractSingleSelectTestUI;
 import com.vaadin.ui.NativeSelect;
 
@@ -18,4 +20,21 @@ public class NativeSelects
         component.setEmptySelectionAllowed(false);
         return component;
     }
+
+    @Override
+    protected void createActions() {
+        super.createActions();
+        LinkedHashMap<String, Integer> options = new LinkedHashMap<>();
+        options.put("1", 1);
+        options.put("2", 2);
+        options.put("5", 5);
+        createSelectAction("Visible item count", CATEGORY_SIZE, options, "1",
+                new Command<NativeSelect<Object>, Integer>() {
+                    @Override
+                    public void execute(NativeSelect<Object> c, Integer value,
+                            Object data) {
+                        c.setVisibleItemCount(value);
+                    }
+                });
+    }
 }

uitest/src/test/java/com/vaadin/tests/components/nativeselect/NativeSelectVisibleItemCountTest.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2000-2016 Vaadin Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.vaadin.tests.components.nativeselect;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.openqa.selenium.WebElement;
+
+import com.vaadin.testbench.By;
+import com.vaadin.testbench.elements.NativeSelectElement;
+import com.vaadin.tests.tb3.SingleBrowserTest;
+
+public class NativeSelectVisibleItemCountTest extends SingleBrowserTest {
+
+    @Test
+    public void changeItemCount() {
+        openTestURL();
+        WebElement select = $(NativeSelectElement.class).first()
+                .findElement(By.xpath("select"));
+        Assert.assertEquals("1", select.getAttribute("size"));
+        selectMenuPath("Component", "Size", "Visible item count", "5");
+        Assert.assertEquals("5", select.getAttribute("size"));
+    }
+
+    @Override
+    protected Class<?> getUIClass() {
+        return NativeSelects.class;
+    }
+}