JustifyPlugin.java

/*
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.xwiki.gwt.wysiwyg.client.plugin.justify;

import java.util.HashMap;
import java.util.Map;

import org.xwiki.gwt.dom.client.Style;
import org.xwiki.gwt.user.client.Config;
import org.xwiki.gwt.user.client.ui.rta.RichTextArea;
import org.xwiki.gwt.user.client.ui.rta.cmd.Command;
import org.xwiki.gwt.user.client.ui.rta.cmd.internal.BlockStyleExecutable;
import org.xwiki.gwt.user.client.ui.rta.cmd.internal.ToggleExecutable;
import org.xwiki.gwt.wysiwyg.client.Images;
import org.xwiki.gwt.wysiwyg.client.Strings;
import org.xwiki.gwt.wysiwyg.client.plugin.internal.AbstractStatefulPlugin;
import org.xwiki.gwt.wysiwyg.client.plugin.internal.FocusWidgetUIExtension;

import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.resources.client.ImageResource;
import com.google.gwt.user.client.ui.FocusWidget;
import com.google.gwt.user.client.ui.Image;
import com.google.gwt.user.client.ui.ToggleButton;

/**
 * Plug-in for justifying text. It can be used to align text to the left, to the right, in center or to make it expand
 * to fill the entire line. It installs four toggle buttons on the tool bar and updates their status depending on the
 * current cursor position.
 * 
 * @version $Id: 32c4c582576664946f3bd7bccaad2a39ba0a455d $
 */
public class JustifyPlugin extends AbstractStatefulPlugin implements ClickHandler
{
    /**
     * The association between tool bar buttons and the commands that are executed when these buttons are clicked.
     */
    private final Map<ToggleButton, Command> buttons = new HashMap<ToggleButton, Command>();

    /**
     * User interface extension for the editor tool bar.
     */
    private final FocusWidgetUIExtension toolBarExtension = new FocusWidgetUIExtension("toolbar");

    @Override
    public void init(RichTextArea textArea, Config config)
    {
        super.init(textArea, config);

        registerCustomExecutable(Command.JUSTIFY_LEFT, Style.TextAlign.LEFT);
        registerCustomExecutable(Command.JUSTIFY_CENTER, Style.TextAlign.CENTER);
        registerCustomExecutable(Command.JUSTIFY_RIGHT, Style.TextAlign.RIGHT);
        registerCustomExecutable(Command.JUSTIFY_FULL, Style.TextAlign.JUSTIFY);

        addFeature("justifyleft", Command.JUSTIFY_LEFT, Images.INSTANCE.justifyLeft(), Strings.INSTANCE.justifyLeft());
        addFeature("justifycenter", Command.JUSTIFY_CENTER, Images.INSTANCE.justifyCenter(), Strings.INSTANCE
            .justifyCenter());
        addFeature("justifyright", Command.JUSTIFY_RIGHT, Images.INSTANCE.justifyRight(), Strings.INSTANCE
            .justifyRight());
        addFeature("justifyfull", Command.JUSTIFY_FULL, Images.INSTANCE.justifyFull(), Strings.INSTANCE.justifyFull());

        if (toolBarExtension.getFeatures().length > 0) {
            registerTextAreaHandlers();
            getUIExtensionList().add(toolBarExtension);
        }
    }

    /**
     * Registers a custom executable for the given command that toggles the specified alignment.
     * 
     * @param command the command whose executable is overwritten
     * @param alignment the alignment toggled by the custom executable
     */
    private void registerCustomExecutable(Command command, String alignment)
    {
        getTextArea().getCommandManager().registerCommand(
            command,
            new ToggleExecutable(new BlockStyleExecutable(getTextArea(), Style.TEXT_ALIGN), alignment, Style.TEXT_ALIGN
                .getDefaultValue()));
    }

    /**
     * Creates a tool bar feature and adds it to the tool bar.
     * 
     * @param name the feature name
     * @param command the rich text area command that is executed by this feature
     * @param imageResource the image displayed on the tool bar
     * @param title the tool tip used on the tool bar button
     * @return the tool bar button that exposes this feature
     */
    private ToggleButton addFeature(String name, Command command, ImageResource imageResource, String title)
    {
        ToggleButton button = null;
        if (getTextArea().getCommandManager().isSupported(command)) {
            button = new ToggleButton(new Image(imageResource));
            saveRegistration(button.addClickHandler(this));
            button.setTitle(title);
            toolBarExtension.addFeature(name, button);
            buttons.put(button, command);
        }
        return button;
    }

    @Override
    public void destroy()
    {
        for (ToggleButton button : buttons.keySet()) {
            button.removeFromParent();
        }
        buttons.clear();

        toolBarExtension.clearFeatures();

        super.destroy();
    }

    @Override
    public void onClick(ClickEvent event)
    {
        Command command = buttons.get(event.getSource());
        if (command != null && ((FocusWidget) event.getSource()).isEnabled()) {
            getTextArea().setFocus(true);
            getTextArea().getCommandManager().execute(command);
        }
    }

    @Override
    public void update()
    {
        for (Map.Entry<ToggleButton, Command> entry : buttons.entrySet()) {
            if (entry.getKey().isEnabled()) {
                entry.getKey().setDown(getTextArea().getCommandManager().isExecuted(entry.getValue()));
            }
        }
    }
}