| /* |
| * Copyright 2011 Google Inc. |
| * |
| * 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.google.gwt.uibinder.client; |
| |
| import com.google.gwt.dom.client.Document; |
| import com.google.gwt.dom.client.Element; |
| |
| /** |
| * Wraps a call to a DOM element. LazyDomElement can boost performance of html |
| * elements and delay calls to getElementById() to when the element is actually |
| * used. But note that it will throw a RuntimeException in case the element is |
| * accessed but not yet attached in the DOM tree. |
| * <p> |
| * Usage example: |
| * <p> |
| * <b>Template:</b> |
| * <pre> |
| * <gwt:HTMLPanel> |
| * <div ui:field="myDiv" /> |
| * </gwt:HTMLPanel> |
| * </pre> |
| * <p> |
| * <b>Class:</b> |
| * <pre> |
| * {@literal @}UiField LazyDomElement<DivElement> myDiv; |
| * |
| * public setText(String text) { |
| * myDiv.get().setInnerHtml(text); |
| * } |
| * </pre> |
| * |
| * @param <T> the Element type associated |
| */ |
| public class LazyDomElement<T extends Element> { |
| |
| private T element; |
| private final String domId; |
| |
| /** |
| * Creates an instance to fetch the element with the given id. |
| */ |
| public LazyDomElement(String domId) { |
| this.domId = domId; |
| } |
| |
| /** |
| * Returns the dom element. |
| * |
| * @return the dom element |
| * @throws RuntimeException if the element cannot be found |
| */ |
| public T get() { |
| if (element == null) { |
| element = Document.get().getElementById(domId).<T>cast(); |
| if (element == null) { |
| throw new RuntimeException("Cannot find element with id \"" + domId |
| + "\". Perhaps it is not attached to the document body."); |
| } |
| element.removeAttribute("id"); |
| } |
| return element; |
| } |
| } |