com.google.gwt.cell.client.SelectionCell.java Source code

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Here is the source code for com.google.gwt.cell.client.SelectionCell.java

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/*
 * Copyright 2010 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.cell.client;

import com.google.gwt.core.client.GWT;
import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.NativeEvent;
import com.google.gwt.dom.client.SelectElement;
import com.google.gwt.safehtml.client.SafeHtmlTemplates;
import com.google.gwt.safehtml.shared.SafeHtml;
import com.google.gwt.safehtml.shared.SafeHtmlBuilder;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

/**
 * A {@link Cell} used to render a drop-down list.
 */
public class SelectionCell extends AbstractInputCell<String, String> {

    interface Template extends SafeHtmlTemplates {
        @Template("<option value=\"{0}\">{0}</option>")
        SafeHtml deselected(String option);

        @Template("<option value=\"{0}\" selected=\"selected\">{0}</option>")
        SafeHtml selected(String option);
    }

    private static Template template;

    private HashMap<String, Integer> indexForOption = new HashMap<String, Integer>();

    private final List<String> options;

    /**
     * Construct a new {@link SelectionCell} with the specified options.
     *
     * @param options the options in the cell
     */
    public SelectionCell(List<String> options) {
        super("change");
        if (template == null) {
            template = GWT.create(Template.class);
        }
        this.options = new ArrayList<String>(options);
        int index = 0;
        for (String option : options) {
            indexForOption.put(option, index++);
        }
    }

    @Override
    public void onBrowserEvent(Context context, Element parent, String value, NativeEvent event,
            ValueUpdater<String> valueUpdater) {
        super.onBrowserEvent(context, parent, value, event, valueUpdater);
        String type = event.getType();
        if ("change".equals(type)) {
            Object key = context.getKey();
            SelectElement select = parent.getFirstChild().cast();
            String newValue = options.get(select.getSelectedIndex());
            setViewData(key, newValue);
            finishEditing(parent, newValue, key, valueUpdater);
            if (valueUpdater != null) {
                valueUpdater.update(newValue);
            }
        }
    }

    @Override
    public void render(Context context, String value, SafeHtmlBuilder sb) {
        // Get the view data.
        Object key = context.getKey();
        String viewData = getViewData(key);
        if (viewData != null && viewData.equals(value)) {
            clearViewData(key);
            viewData = null;
        }

        int selectedIndex = getSelectedIndex(viewData == null ? value : viewData);
        sb.appendHtmlConstant("<select tabindex=\"-1\">");
        int index = 0;
        for (String option : options) {
            if (index++ == selectedIndex) {
                sb.append(template.selected(option));
            } else {
                sb.append(template.deselected(option));
            }
        }
        sb.appendHtmlConstant("</select>");
    }

    private int getSelectedIndex(String value) {
        Integer index = indexForOption.get(value);
        if (index == null) {
            return -1;
        }
        return index.intValue();
    }
}