FoldPanel.java

package org.sigmah.client.ui.widget.panel;

/*
 * #%L
 * Sigmah
 * %%
 * Copyright (C) 2010 - 2016 URD
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 * 
 * This program 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 General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public
 * License along with this program.  If not, see
 * <http://www.gnu.org/licenses/gpl-3.0.html>.
 * #L%
 */

import java.util.ArrayList;
import java.util.Iterator;

import com.google.gwt.dom.client.Style;
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.FlowPanel;
import com.google.gwt.user.client.ui.HasVerticalAlignment;
import com.google.gwt.user.client.ui.HorizontalPanel;
import com.google.gwt.user.client.ui.Image;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.Widget;

/**
 * A FoldPanel contains a header and a body.<br>
 * <br>
 * This widget can have one of the 3 following states :
 * <ul>
 * <li>Expanded : the full content of the FoldPanel is displayed</li>
 * <li>Folded : only the header of the FoldPanel and of its contained FoldPanels are displayed</li>
 * <li>Collapsed : only the header of the FoldPanel is displayed</li>
 * </ul>
 * This widget can hide and show RichTextElements without making them crash in Firefox and Webkit.
 * 
 * @author Raphaël Calabro (rcalabro@ideia.fr) (v1.3)
 * @author Mehdi Benabdeslam (mehdi.benabdeslam@netapsys.fr) (v2.0)
 * @author Denis Colliot (dcolliot@ideia.fr) (v2.0)
 */
public class FoldPanel extends FlowPanel {

	private final ArrayList<Widget> list = new ArrayList<Widget>();

	public static final int STATE_EXPANDED = 0;
	public static final int STATE_FOLDED = 1;
	public static final int STATE_COLLAPSED = 2;
	private static final int HEADER_INDEX = 0;
	private static final int BODY_INDEX = 1;

	private int state;

	/**
	 * Creates a new and empty fold panel.
	 */
	public FoldPanel() {

		addStyleName("fold");

		final HorizontalPanel titleBar = new HorizontalPanel();
		titleBar.getElement().getStyle().setDisplay(Style.Display.NONE);
		titleBar.setVerticalAlignment(HasVerticalAlignment.ALIGN_MIDDLE);

		final Label heading = new Label();
		heading.addStyleName("fold-title");
		heading.addClickHandler(new ClickHandler() {

			@Override
			public void onClick(ClickEvent event) {
				if (state == STATE_EXPANDED)
					collapse();
				else
					expand(true);
			}
		});
		heading.addStyleName("fold-expanded");
		titleBar.add(heading);
		titleBar.setCellWidth(heading, "100%");

		final FlowPanel toolButtonPanel = new FlowPanel();
		titleBar.add(toolButtonPanel);

		final FlowPanel content = new FlowPanel();

		super.add(titleBar);
		super.add(content);
	}

	/**
	 * Defines the header of this fold panel.
	 * 
	 * @param text
	 *          Text to display in the header of this fold panel.
	 */
	public void setHeading(String text) {
		final HorizontalPanel titleBar = (HorizontalPanel) super.getWidget(HEADER_INDEX);
		final Label heading = (Label) titleBar.getWidget(0);
		heading.setText(text);

		if (text != null && !"".equals(text)) {
			super.getWidget(BODY_INDEX).addStyleName("fold-content");
			titleBar.getElement().getStyle().setProperty("display", "");

		} else {
			super.getWidget(BODY_INDEX).removeStyleName("fold-content");
			titleBar.getElement().getStyle().setDisplay(Style.Display.NONE);
		}
	}

	@Override
	public void add(Widget w) {
		((FlowPanel) super.getWidget(BODY_INDEX)).add(w);
		list.add(w);
	}

	@Override
	public Widget getWidget(int index) {
		return ((FlowPanel) super.getWidget(BODY_INDEX)).getWidget(index);
	}

	@Override
	public int getWidgetCount() {
		return ((FlowPanel) super.getWidget(BODY_INDEX)).getWidgetCount();
	}

	/**
	 * Adds a button with the specified <code>image</code> and <code>action</code> in the top right corner of this panel.
	 * 
	 * @param image
	 *          Image of the button.
	 * @param action
	 *          Action to execute when the button is clicked.
	 */
	public void addToolButton(ImageResource image, ClickHandler action) {
		final Image button = new Image(image);
		button.addStyleName("fold-tool-button");
		button.addClickHandler(action);

		final HorizontalPanel titleBar = (HorizontalPanel) super.getWidget(HEADER_INDEX);
		final FlowPanel toolButtonPanel = (FlowPanel) titleBar.getWidget(1);

		toolButtonPanel.add(button);

		toolButtonPanel.setWidth(16 * toolButtonPanel.getWidgetCount() + "px");
	}

	/**
	 * Edits a tool button by replacing its current image by the one provided.
	 * 
	 * @param index
	 *          The index of the button to edit.
	 * @param image
	 *          The new image to display.
	 */
	public void setToolButtonImage(int index, ImageResource image) {
		final HorizontalPanel titleBar = (HorizontalPanel) super.getWidget(HEADER_INDEX);
		final FlowPanel toolButtonPanel = (FlowPanel) titleBar.getWidget(1);

		final Image button = (Image) toolButtonPanel.getWidget(index);
		button.setResource(image);
	}

	/**
	 * Returns the current number of tool buttons displayed by this panel.
	 * 
	 * @return the number of tool button.
	 */
	public int getToolButtonCount() {
		final HorizontalPanel titleBar = (HorizontalPanel) super.getWidget(HEADER_INDEX);
		final FlowPanel toolButtonPanel = (FlowPanel) titleBar.getWidget(1);
		return toolButtonPanel.getWidgetCount();
	}

	public void collapse() {
		final FlowPanel content = (FlowPanel) super.getWidget(BODY_INDEX);

		for (final Widget widget : list)
			content.remove(widget);

		setState(STATE_COLLAPSED);
	}

	public void fold(boolean propagate) {
		final FlowPanel content = (FlowPanel) super.getWidget(BODY_INDEX);

		boolean collapse = true;

		for (int index = 0; index < list.size(); index++) {
			final Widget child = list.get(index);

			if (child instanceof FoldPanel) {
				collapse = false;

				if (propagate)
					((FoldPanel) child).fold(propagate);
			} else {
				content.remove(child);
			}
		}

		setState(collapse ? STATE_COLLAPSED : STATE_FOLDED);
	}

	public void expand(boolean propagate) {
		final FlowPanel content = (FlowPanel) super.getWidget(BODY_INDEX);

		Widget next = null;
		final Iterator<Widget> children = content.iterator();
		if (children.hasNext())
			next = children.next();

		for (int index = 0; index < list.size(); index++) {
			final Widget widget = list.get(index);

			if (widget != next) {
				content.insert(widget, index);

			} else {
				if (children.hasNext())
					next = children.next();
				else
					next = null;
			}

			if (propagate && widget instanceof FoldPanel)
				((FoldPanel) widget).expand(propagate);
		}

		setState(STATE_EXPANDED);
	}

	private void setState(int state) {
		// Removing the previous style
		final HorizontalPanel titleBar = (HorizontalPanel) super.getWidget(HEADER_INDEX);
		final Widget header = titleBar.getWidget(0);

		switch (this.state) {
			case STATE_EXPANDED:
				header.removeStyleName("fold-expanded");
				break;
			case STATE_FOLDED:
				header.removeStyleName("fold-folded");
				break;
			case STATE_COLLAPSED:
				header.removeStyleName("fold-collapsed");
				break;
		}

		// Adding the new style
		switch (state) {
			case STATE_EXPANDED:
				header.addStyleName("fold-expanded");
				break;
			case STATE_FOLDED:
				header.addStyleName("fold-folded");
				break;
			case STATE_COLLAPSED:
				header.addStyleName("fold-collapsed");
				break;
		}

		this.state = state;
	}
}