Java tutorial
/* * Copyright 2008 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.user.client.ui; import com.google.gwt.core.client.GWT; import com.google.gwt.dom.client.Document; import com.google.gwt.dom.client.Element; import com.google.gwt.dom.client.FieldSetElement; import com.google.gwt.dom.client.LegendElement; import com.google.gwt.safehtml.shared.SafeHtml; import com.google.gwt.user.client.Command; import com.google.gwt.user.client.DeferredCommand; import java.util.Iterator; /** * A panel that wraps its contents in a border with a caption that appears in * the upper left corner of the border. This is an implementation of the * fieldset HTML element. */ public class CaptionPanel extends Composite implements HasWidgets.ForIsWidget { /** * Implementation class without browser-specific hacks. */ public static class CaptionPanelImpl { public void setCaption(FieldSetElement fieldset, Element legend, SafeHtml caption) { setCaption(fieldset, legend, caption.asString(), true); } public void setCaption(FieldSetElement fieldset, Element legend, String caption, boolean asHTML) { // TODO(bruce): rewrite to be inlinable assert (caption != null); if (asHTML) { legend.setInnerHTML(caption); } else { legend.setInnerText(caption); } if (!"".equals(caption)) { // This is formulated to become an append (if there's no widget), an // insertion at index 0 (if there is a widget but no legend already), or // a no-op (if the legend is already in place). fieldset.insertBefore(legend, fieldset.getFirstChild()); } else if (legend.getParentNode() != null) { // We remove the legend from the DOM because leaving it in with an empty // string renders as an ugly gap in the top border on some browsers. fieldset.removeChild(legend); } } } /** * Implementation class that handles Mozilla rendering issues. */ public static class CaptionPanelImplMozilla extends CaptionPanelImpl { @Override public void setCaption(final FieldSetElement fieldset, Element legend, SafeHtml caption) { setCaption(fieldset, legend, caption.asString(), true); } @Override public void setCaption(final FieldSetElement fieldset, Element legend, String caption, boolean asHTML) { fieldset.getStyle().setProperty("display", "none"); super.setCaption(fieldset, legend, caption, asHTML); fieldset.getStyle().setProperty("display", ""); } } /** * Implementation class that handles Safari rendering issues. */ public static class CaptionPanelImplSafari extends CaptionPanelImpl { @Override public void setCaption(final FieldSetElement fieldset, Element legend, SafeHtml caption) { setCaption(fieldset, legend, caption.asString(), true); } @Override public void setCaption(final FieldSetElement fieldset, Element legend, String caption, boolean asHTML) { fieldset.getStyle().setProperty("visibility", "hidden"); super.setCaption(fieldset, legend, caption, asHTML); DeferredCommand.addCommand(new Command() { public void execute() { fieldset.getStyle().setProperty("visibility", ""); } }); } } /** * The implementation instance. */ private static CaptionPanelImpl impl = (CaptionPanelImpl) GWT.create(CaptionPanelImpl.class); /** * The legend element used as the caption. */ private LegendElement legend; /** * Constructs a CaptionPanel with an empty caption. */ public CaptionPanel() { this("", false); } /** * Constructs a CaptionPanel with specified caption text. * * @param caption the text of the caption */ public CaptionPanel(SafeHtml caption) { this(caption.asString(), true); } /** * Constructs a CaptionPanel with specified caption text. * * @param captionText the text of the caption, which is automatically escaped */ public CaptionPanel(String captionText) { this(captionText, false); } /** * Constructs a CaptionPanel having the specified caption. * * @param caption the caption to display * @param asHTML if <code>true</code>, the <code>caption</code> param is * interpreted as HTML; otherwise, <code>caption</code> is * treated as text and automatically escaped */ public CaptionPanel(String caption, boolean asHTML) { FieldSetElement fieldSet = Document.get().createFieldSetElement(); initWidget(new SimplePanel(fieldSet)); legend = Document.get().createLegendElement(); fieldSet.appendChild(legend); if (asHTML) { setCaptionHTML(caption); } else { setCaptionText(caption); } } public void add(Widget w) { ((SimplePanel) getWidget()).add(w); } /** * Overloaded version for IsWidget. * * @see #add(Widget) */ public void add(IsWidget w) { this.add(asWidgetOrNull(w)); } /** * Removes the content widget. */ public void clear() { ((SimplePanel) getWidget()).clear(); } /** * Returns the caption as HTML; note that if the caption was previously set * using {@link #setCaptionText(String)}, the return value is undefined. */ public String getCaptionHTML() { String html = legend.getInnerHTML(); assert (html != null); return html; } /** * Returns the caption as text; note that if the caption was previously set * using {@link #setCaptionHTML(String)}, the return value is undefined. */ public String getCaptionText() { String text = legend.getInnerText(); assert (text != null); return text; } /** * Accesses the content widget, if present. * * @return the content widget specified previously in * {@link #setContentWidget(Widget)} */ public Widget getContentWidget() { return ((SimplePanel) getWidget()).getWidget(); } /** * Iterates over the singular content widget, if present. */ public Iterator<Widget> iterator() { return ((SimplePanel) getWidget()).iterator(); } /** * Removes the specified widget, although in practice the specified widget * must be the content widget. * * @param w the widget to remove; note that anything other than the Widget * returned by {@link #getContentWidget()} will have no effect */ public boolean remove(Widget w) { return ((SimplePanel) getWidget()).remove(w); } /** * Overloaded version for IsWidget. * * @see #remove(Widget) */ public boolean remove(IsWidget w) { return this.remove(asWidgetOrNull(w)); } /** * Sets the caption for the panel using an HTML fragment. Pass in empty string * to remove the caption completely, leaving just the unadorned panel. * * @param html HTML for the new caption; must not be <code>null</code> */ public void setCaptionHTML(String html) { assert (html != null); impl.setCaption(FieldSetElement.as(getElement()), legend, html, true); } /** * Sets the caption for the panel using a SafeHtml string. * * @param html HTML for the new caption; must not be <code>null</code> */ public void setCaptionHTML(SafeHtml html) { setCaptionHTML(html.asString()); } /** * Sets the caption for the panel using text that will be automatically * escaped. Pass in empty string to remove the caption completely, leaving * just the unadorned panel. * * @param text text for the new caption; must not be <code>null</code> */ public void setCaptionText(String text) { assert (text != null); impl.setCaption(FieldSetElement.as(getElement()), legend, text, false); } /** * Sets or replaces the content widget within the CaptionPanel. * * @param w the content widget to be set */ public void setContentWidget(Widget w) { ((SimplePanel) getWidget()).setWidget(w); } }