org.opendatakit.common.web.client.UIEnabledValidatingSelectionCell.java Source code

Introduction

Here is the source code for org.opendatakit.common.web.client.UIEnabledValidatingSelectionCell.java

Source

/*
 * Copyright 2010 Google Inc.
 * Copyright (C) 2011 University of Washington
 *
 * 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 org.opendatakit.common.web.client;

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

import com.google.gwt.cell.client.AbstractInputCell;
import com.google.gwt.cell.client.SelectionCell;
import com.google.gwt.cell.client.ValueUpdater;
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;

/**
 * This is a SelectionCell (code copied from 2.3.0) modified
 * to perform validation checking before allowing a selection
 * and to support disabling of the drop-down.  If you don't
 * supply any validation, visibility or enablement predicates,
 * this behaves the same as the SelectionCell.
 *
 * @author mitchellsundt@gmail.com
 *
 * @param <T>
 */
public class UIEnabledValidatingSelectionCell<T> extends /* SelectionCell */
        AbstractInputCell<String, String> {

    interface OptionsTemplate 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 OptionsTemplate template;

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

    private final ArrayList<String> options;

    final StringValidationPredicate<T> validationPredicate;
    final UIEnabledPredicate<T> isEnabledPredicate;
    private final UIVisiblePredicate<T> isVisiblePredicate;

    public UIEnabledValidatingSelectionCell(StringValidationPredicate<T> validationPredicate,
            UIEnabledPredicate<T> isEnabledPredicate, ArrayList<String> options) {
        this(validationPredicate, null, isEnabledPredicate, options);
    }

    public UIEnabledValidatingSelectionCell(StringValidationPredicate<T> validationPredicate,
            UIVisiblePredicate<T> isVisiblePredicate, ArrayList<String> options) {
        this(validationPredicate, isVisiblePredicate, null, options);
    }

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

    @SuppressWarnings("unchecked")
    @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());

            // Get the prior value of the view data.
            String lastValue = getViewData(key);
            boolean changed = true;
            if (lastValue != null && newValue != null && lastValue.equals(newValue)) {
                changed = false;
            }

            if (validationPredicate != null && !validationPredicate.isValid(newValue, (T) key)) {
                // either there is no change in value
                // or the validation failed.
                // restore drop-down to prior value...
                newValue = lastValue;
                changed = false;
            }

            // update backing map with whatever we ended up with...
            setViewData(key, newValue);

            // redraw our parent with the value we ended up with...
            SafeHtmlBuilder sb = new SafeHtmlBuilder();
            render(context, newValue, sb);
            parent.setInnerHTML(sb.toSafeHtml().asString());
            // remove keyboard focus on this element...
            finishEditing(parent, newValue, key, valueUpdater);

            if (changed) {
                // do value-change action...
                if (valueUpdater != null) {
                    valueUpdater.update(newValue);
                }
            }
        }
    }

    @SuppressWarnings("unchecked")
    @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;
        }

        if (isVisiblePredicate == null || isVisiblePredicate.isVisible((T) key)) {
            int selectedIndex = getSelectedIndex(viewData == null ? value : viewData);
            if (isEnabledPredicate == null || isEnabledPredicate.isEnabled((T) key)) {
                sb.appendHtmlConstant("<select tabindex=\"-1\">");
            } else {
                sb.appendHtmlConstant("<select tabindex=\"-1\" disabled>");
            }
            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();
    }
}