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.sample.showcase.client.content.panels; import com.google.gwt.core.client.GWT; import com.google.gwt.core.client.RunAsyncCallback; import com.google.gwt.core.client.Scheduler; import com.google.gwt.core.client.Scheduler.ScheduledCommand; import com.google.gwt.event.dom.client.ChangeEvent; import com.google.gwt.event.dom.client.ChangeHandler; import com.google.gwt.event.dom.client.KeyUpEvent; import com.google.gwt.event.dom.client.KeyUpHandler; import com.google.gwt.i18n.client.Constants; import com.google.gwt.sample.showcase.client.ContentWidget; import com.google.gwt.sample.showcase.client.Showcase; import com.google.gwt.sample.showcase.client.ShowcaseAnnotations.ShowcaseData; import com.google.gwt.sample.showcase.client.ShowcaseAnnotations.ShowcaseSource; import com.google.gwt.user.client.rpc.AsyncCallback; import com.google.gwt.user.client.ui.AbsolutePanel; import com.google.gwt.user.client.ui.Button; import com.google.gwt.user.client.ui.DecoratorPanel; import com.google.gwt.user.client.ui.FlexTable; import com.google.gwt.user.client.ui.Grid; import com.google.gwt.user.client.ui.HTML; import com.google.gwt.user.client.ui.HorizontalPanel; import com.google.gwt.user.client.ui.Image; import com.google.gwt.user.client.ui.ListBox; import com.google.gwt.user.client.ui.TextBox; import com.google.gwt.user.client.ui.Widget; import java.util.LinkedHashMap; import java.util.Map; /** * Example file. */ public class CwAbsolutePanel extends ContentWidget { /** * The constants used in this Content Widget. */ @ShowcaseSource public static interface CwConstants extends Constants { String cwAbsolutePanelClickMe(); String cwAbsolutePanelDescription(); String cwAbsolutePanelHelloWorld(); String cwAbsolutePanelItemsToMove(); String cwAbsolutePanelLeft(); String cwAbsolutePanelName(); String cwAbsolutePanelTop(); String[] cwAbsolutePanelWidgetNames(); } /** * The absolute panel used in the example. */ private AbsolutePanel absolutePanel = null; /** * An instance of the constants. */ @ShowcaseData private final CwConstants constants; /** * The input field used to set the left position of a {@link Widget}. */ @ShowcaseData private TextBox leftPosBox = null; /** * The list box of items that can be repositioned. */ @ShowcaseData private ListBox listBox = new ListBox(); /** * The input field used to set the top position of a {@link Widget}. */ @ShowcaseData private TextBox topPosBox = null; /** * A mapping between the name of a {@link Widget} and the widget in the * {@link AbsolutePanel}. */ @ShowcaseData private Map<String, Widget> widgetMap = null; /** * Constructor. * * @param constants the constants */ public CwAbsolutePanel(CwConstants constants) { super(constants.cwAbsolutePanelName(), constants.cwAbsolutePanelDescription(), false); this.constants = constants; } /** * Initialize this example. */ @ShowcaseSource @Override public Widget onInitialize() { // Create a new panel widgetMap = new LinkedHashMap<String, Widget>(); absolutePanel = new AbsolutePanel(); absolutePanel.setSize("250px", "250px"); absolutePanel.ensureDebugId("cwAbsolutePanel"); // Add an HTML widget to the panel String[] widgetNames = constants.cwAbsolutePanelWidgetNames(); HTML text = new HTML(constants.cwAbsolutePanelHelloWorld()); absolutePanel.add(text, 10, 20); widgetMap.put(widgetNames[0], text); // Add a Button to the panel Button button = new Button(constants.cwAbsolutePanelClickMe()); absolutePanel.add(button, 80, 45); widgetMap.put(widgetNames[1], button); // Add a Button to the panel Grid grid = new Grid(2, 3); grid.setBorderWidth(1); for (int i = 0; i < 3; i++) { grid.setHTML(0, i, i + ""); grid.setWidget(1, i, new Image(Showcase.images.gwtLogoThumb())); } absolutePanel.add(grid, 60, 100); widgetMap.put(widgetNames[2], grid); // Wrap the absolute panel in a DecoratorPanel DecoratorPanel absolutePanelWrapper = new DecoratorPanel(); absolutePanelWrapper.setWidget(absolutePanel); // Create the options bar DecoratorPanel optionsWrapper = new DecoratorPanel(); optionsWrapper.setWidget(createOptionsBar()); // Add the components to a panel and return it HorizontalPanel mainLayout = new HorizontalPanel(); mainLayout.setSpacing(10); mainLayout.add(optionsWrapper); mainLayout.add(absolutePanelWrapper); return mainLayout; } /** * Initialize the options panel after the {@link AbsolutePanel} has been * attached to the page. */ @ShowcaseSource @Override public void onInitializeComplete() { Scheduler.get().scheduleDeferred(new ScheduledCommand() { public void execute() { updateSelectedItem(); } }); } @Override protected void asyncOnInitialize(final AsyncCallback<Widget> callback) { GWT.runAsync(CwAbsolutePanel.class, new RunAsyncCallback() { public void onFailure(Throwable caught) { callback.onFailure(caught); } public void onSuccess() { callback.onSuccess(onInitialize()); } }); } /** * Create an options panel that allows users to select a widget and reposition * it. * * @return the new options panel */ @ShowcaseSource private Widget createOptionsBar() { // Create a panel to move components around FlexTable optionsBar = new FlexTable(); topPosBox = new TextBox(); topPosBox.setWidth("3em"); topPosBox.setText("100"); leftPosBox = new TextBox(); leftPosBox.setWidth("3em"); leftPosBox.setText("60"); listBox = new ListBox(); optionsBar.setHTML(0, 0, constants.cwAbsolutePanelItemsToMove()); optionsBar.setWidget(0, 1, listBox); optionsBar.setHTML(1, 0, constants.cwAbsolutePanelTop()); optionsBar.setWidget(1, 1, topPosBox); optionsBar.setHTML(2, 0, constants.cwAbsolutePanelLeft()); optionsBar.setWidget(2, 1, leftPosBox); // Add the widgets to the list box for (String name : widgetMap.keySet()) { listBox.addItem(name); } // Set the current item position when the user selects an item listBox.addChangeHandler(new ChangeHandler() { public void onChange(ChangeEvent event) { updateSelectedItem(); } }); // Move the item as the user changes the value in the left and top boxes KeyUpHandler repositionHandler = new KeyUpHandler() { public void onKeyUp(KeyUpEvent event) { repositionItem(); } }; topPosBox.addKeyUpHandler(repositionHandler); leftPosBox.addKeyUpHandler(repositionHandler); // Return the options bar return optionsBar; } /** * Reposition an item when the user changes the value in the top or left * position text boxes. */ @ShowcaseSource private void repositionItem() { // Get the selected item to move String name = listBox.getValue(listBox.getSelectedIndex()); Widget item = widgetMap.get(name); // Reposition the item try { int top = Integer.parseInt(topPosBox.getText()); int left = Integer.parseInt(leftPosBox.getText()); absolutePanel.setWidgetPosition(item, left, top); } catch (NumberFormatException e) { // Ignore invalid user input return; } } /** * Update the top and left position text fields when the user selects a new * item to move. */ @ShowcaseSource private void updateSelectedItem() { String name = listBox.getValue(listBox.getSelectedIndex()); Widget item = widgetMap.get(name); topPosBox.setText(absolutePanel.getWidgetTop(item) + ""); leftPosBox.setText(absolutePanel.getWidgetLeft(item) + ""); } }