Adds SpacerUpdater support for Escalator (#16644)

Change-Id: I9d73a3fc36e94e36c35859a4ae456002c75df2f5

client/src/com/vaadin/client/widget/escalator/EscalatorUpdater.java

@@ -16,8 +16,6 @@
 
 package com.vaadin.client.widget.escalator;
 
-import com.vaadin.client.widgets.Escalator;
-
 /**
  * An interface that allows client code to define how a certain row in Escalator
  * will be displayed. The contents of an escalator's header, body and footer are

client/src/com/vaadin/client/widget/escalator/Row.java

@@ -17,7 +17,6 @@
 package com.vaadin.client.widget.escalator;
 
 import com.google.gwt.dom.client.TableRowElement;
-import com.vaadin.client.widgets.Escalator;
 
 /**
  * A representation of a row in an {@link Escalator}.

client/src/com/vaadin/client/widget/escalator/RowContainer.java

@@ -44,6 +44,7 @@ public interface RowContainer {
      * @see com.vaadin.client.widgets.Escalator#getBody()
      */
     public interface BodyRowContainer extends RowContainer {
+
         /**
          * Marks a spacer and its height.
          * <p>
@@ -61,6 +62,32 @@ public interface BodyRowContainer extends RowContainer {
          */
         void setSpacer(int rowIndex, double height)
                 throws IllegalArgumentException;
+
+        /**
+         * Sets a new spacer updater.
+         * <p>
+         * Spacers that are currently visible will be updated, i.e.
+         * {@link SpacerUpdater#destroy(Spacer) destroyed} with the previous
+         * one, and {@link SpacerUpdater#init(Spacer) initialized} with the new
+         * one.
+         * 
+         * @param spacerUpdater
+         *            the new spacer updater
+         * @throws IllegalArgumentException
+         *             if {@code spacerUpdater} is {@code null}
+         */
+        void setSpacerUpdater(SpacerUpdater spacerUpdater)
+                throws IllegalArgumentException;
+
+        /**
+         * Gets the spacer updater currently in use.
+         * <p>
+         * {@link SpacerUpdater#NULL} is the default.
+         * 
+         * @return the spacer updater currently in use. Never <code>null</code>
+         */
+        SpacerUpdater getSpacerUpdater();
+
     }
 
     /**

client/src/com/vaadin/client/widget/escalator/Spacer.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2000-2014 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.client.widget.escalator;
+
+import com.google.gwt.dom.client.Element;
+
+/**
+ * A representation of a spacer element in a {@link SpacerContainer}.
+ * 
+ * @since
+ * @author Vaadin Ltd
+ */
+public interface Spacer {
+
+    /**
+     * Gets the root element for the spacer content.
+     * 
+     * @return the root element for the spacer content
+     */
+    Element getElement();
+
+    /**
+     * Gets the row index.
+     * 
+     * @return the row index.
+     */
+    int getRow();
+}

client/src/com/vaadin/client/widget/escalator/SpacerUpdater.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright 2000-2014 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.client.widget.escalator;
+
+/**
+ * An interface that handles the display of content for spacers.
+ * <p>
+ * The updater is responsible for making sure all elements are properly
+ * constructed and cleaned up.
+ * 
+ * @since
+ * @author Vaadin Ltd
+ * @see Spacer
+ * @see SpacerContainer
+ */
+public interface SpacerUpdater {
+
+    /** A spacer updater that does nothing. */
+    public static final SpacerUpdater NULL = new SpacerUpdater() {
+        @Override
+        public void init(Spacer spacer) {
+            // NOOP
+        }
+
+        @Override
+        public void destroy(Spacer spacer) {
+            // NOOP
+        }
+    };
+
+    /**
+     * Called whenever a spacer should be initialized with content.
+     * 
+     * @param spacer
+     *            the spacer reference that should be initialized
+     */
+    void init(Spacer spacer);
+
+    /**
+     * Called whenever a spacer should be cleaned.
+     * <p>
+     * The structure to clean up is the same that has been constructed by
+     * {@link #init(Spacer)}.
+     * 
+     * @param spacer
+     *            the spacer reference that should be destroyed
+     */
+    void destroy(Spacer spacer);
+}