com.googlecode.simplegwt.combobox.client.ui.ComboBox.java Source code

Introduction

Here is the source code for com.googlecode.simplegwt.combobox.client.ui.ComboBox.java

Source

/*
 * Copyright 2008 Isaac Truett.
 * 
 * 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.googlecode.simplegwt.combobox.client.ui;

import com.google.gwt.core.client.GWT;
import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.event.dom.client.KeyCodes;
import com.google.gwt.event.dom.client.KeyDownEvent;
import com.google.gwt.event.dom.client.KeyDownHandler;
import com.google.gwt.event.logical.shared.ValueChangeEvent;
import com.google.gwt.event.logical.shared.ValueChangeHandler;
import com.google.gwt.event.shared.HandlerRegistration;
import com.google.gwt.user.client.ui.AbstractImagePrototype;
import com.google.gwt.user.client.ui.Composite;
import com.google.gwt.user.client.ui.FocusPanel;
import com.google.gwt.user.client.ui.HasValue;
import com.google.gwt.user.client.ui.HorizontalPanel;
import com.google.gwt.user.client.ui.Image;
import com.google.gwt.user.client.ui.ImageBundle;
import com.google.gwt.user.client.ui.SimpleGwtSuggestBox;
import com.google.gwt.user.client.ui.SuggestBox;
import com.googlecode.simplegwt.command.client.ui.CommandIcon;
import com.googlecode.simplegwt.style.client.ui.HoverStyler;

/**
 * An enhanced {@link SuggestBox} that adds a {@link CommandIcon} which allows the user to display
 * the suggestion list without typing anything.
 * 
 * @param <T>
 */
public class ComboBox<T> extends Composite implements HasValue<T> {
    /**
     * An {@link ImageBundle} that defines images used by a <code>ComboBox</code>.
     */
    public interface ComboBoxImageBundle extends ImageBundle {
        /**
         * The icon for opening the suggestion list.
         * 
         * @return the image
         */
        @Resource("openIcon.png")
        AbstractImagePrototype getOpenIcon();
    }

    private static Image getDefaultOpenIcon() {
        return ((ComboBoxImageBundle) GWT.create(ComboBoxImageBundle.class)).getOpenIcon().createImage();
    }

    private final SimpleGwtSuggestBox suggestBox;

    private final CommandIcon openIcon;

    private final ComboBoxOracle<T> oracle;

    private int selectedIndex = -1;

    /**
     * Creates a new <code>ComboBox</code>.
     * 
     * @param oracle
     */
    public ComboBox(final ComboBoxOracle<T> oracle) {
        this(getDefaultOpenIcon(), oracle);
    }

    /**
     * Creates a new <code>ComboBox</code>.
     * 
     * @param openIconImage
     * @param oracle
     */
    public ComboBox(final Image openIconImage, final ComboBoxOracle<T> oracle) {
        this.oracle = oracle;
        suggestBox = new SimpleGwtSuggestBox(oracle.getSuggestOracle());

        final ShowSuggestionsCommand command = new ShowSuggestionsCommand(suggestBox);

        openIcon = new CommandIcon(openIconImage, command);

        final HorizontalPanel layout = new HorizontalPanel();
        final FocusPanel iconWrapper = new FocusPanel();
        iconWrapper.setStylePrimaryName("openIconWrapper");
        iconWrapper.add(openIcon);
        iconWrapper.addClickHandler(new ClickHandler() {
            public void onClick(ClickEvent event) {
                selectedIndex = -1;
                iconWrapper.setFocus(true);
                command.execute();
            }
        });

        KeyDownHandler keyDownHandler = new KeyDownHandler() {
            public void onKeyDown(KeyDownEvent event) {
                boolean navKey = false;

                if (!suggestBox.isSuggestionListShowing()) {
                    selectedIndex = -1;
                }

                switch (event.getNativeKeyCode()) {
                case KeyCodes.KEY_UP:
                    selectedIndex--;
                    navKey = true;
                    break;
                case KeyCodes.KEY_DOWN:
                    selectedIndex++;
                    navKey = true;
                    break;
                case KeyCodes.KEY_ESCAPE:
                    suggestBox.hideSuggestionList();
                    break;
                case KeyCodes.KEY_ENTER:
                case KeyCodes.KEY_TAB:
                    if (suggestBox.getSuggestionMenuSelectedItemIndex() < 0) {
                        suggestBox.hideSuggestionList();
                    } else if (suggestBox.isSuggestionListShowing()) {
                        suggestBox.doSelectedItemAction();
                    }
                    break;
                }

                if (navKey) {
                    if (selectedIndex > -1) {
                        if (!suggestBox.isSuggestionListShowing()) {
                            command.execute();
                        }

                        suggestBox.selectItem(selectedIndex);
                    } else if (selectedIndex < -1) {
                        selectedIndex = -1;
                    }

                    event.stopPropagation();
                    event.preventDefault();
                }
            }
        };

        suggestBox.addKeyDownHandler(keyDownHandler);
        iconWrapper.addKeyDownHandler(keyDownHandler);

        layout.add(suggestBox);
        layout.add(iconWrapper);

        initWidget(layout);

        setStylePrimaryName("simpleGwt-ComboBox");

        new HoverStyler().registerOn(iconWrapper);
    }

    /**
     * @see com.google.gwt.event.logical.shared.HasValueChangeHandlers#addValueChangeHandler(com.google.gwt.event.logical.shared.ValueChangeHandler)
     */
    public HandlerRegistration addValueChangeHandler(final ValueChangeHandler<T> handler) {
        return addHandler(handler, ValueChangeEvent.getType());
    }

    /**
     * @see com.google.gwt.user.client.ui.HasValue#getValue()
     */
    public T getValue() {
        return oracle.getValue(suggestBox.getText());
    }

    /**
     * @see com.google.gwt.user.client.ui.HasValue#setValue(java.lang.Object)
     */
    public void setValue(final T value) {
        setValue(value, false);
    }

    /**
     * @see com.google.gwt.user.client.ui.HasValue#setValue(java.lang.Object, boolean)
     */
    public void setValue(final T value, final boolean fireEvents) {
        final T oldValue = getValue();

        suggestBox.setText(oracle.getDisplayText(value));

        if (fireEvents) {
            ValueChangeEvent.fireIfNotEqual(this, oldValue, value);
        }
    }
}