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/*******************************************************************************
 * Copyright (c) 2000, 2010 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.draw2d.widgets;

import org.eclipse.swt.SWT;
import org.eclipse.swt.accessibility.ACC;
import org.eclipse.swt.accessibility.AccessibleAdapter;
import org.eclipse.swt.accessibility.AccessibleControlAdapter;
import org.eclipse.swt.accessibility.AccessibleControlEvent;
import org.eclipse.swt.accessibility.AccessibleEvent;
import org.eclipse.swt.events.KeyAdapter;
import org.eclipse.swt.events.KeyEvent;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.widgets.Composite;

import org.eclipse.draw2d.Border;
import org.eclipse.draw2d.ColorConstants;
import org.eclipse.draw2d.FigureCanvas;
import org.eclipse.draw2d.FocusEvent;
import org.eclipse.draw2d.Graphics;
import org.eclipse.draw2d.MarginBorder;
import org.eclipse.draw2d.Viewport;
import org.eclipse.draw2d.geometry.Point;
import org.eclipse.draw2d.text.FlowPage;
import org.eclipse.draw2d.text.TextFlow;

/**
 * A widget for displaying a multi-line string. The label will have a vertical
 * or horizontal scrollbar when needed. Unlike the platform Label, this label is
 * focusable and accessible to screen-readers.
 * 
 * @author hudsonr
 */
public final class MultiLineLabel extends FigureCanvas {

	private TextFlow textFlow;
	static final Border MARGIN = new MarginBorder(2);
	private Image image;

	class FocusableViewport extends Viewport {
		FocusableViewport() {
			super(true);
			setFocusTraversable(true);
			setBorder(MARGIN);
		}

		public void handleFocusGained(FocusEvent event) {
			super.handleFocusGained(event);
			repaint();
		}

		public void handleFocusLost(FocusEvent event) {
			super.handleFocusLost(event);
			repaint();
		}

		protected void paintBorder(Graphics graphics) {
			super.paintBorder(graphics);
			if (hasFocus()) {
				graphics.setForegroundColor(ColorConstants.black());
				graphics.setBackgroundColor(ColorConstants.white());
				graphics.drawFocus(getBounds().getResized(-1, -1));
			}
		}
	}

	/**
	 * Constructs a new MultiLineLabel with the given parent.
	 * 
	 * @param parent
	 *            the parent
	 */
	public MultiLineLabel(Composite parent) {
		super(parent);
		setViewport(new FocusableViewport());

		FlowPage page = new FlowPage();
		textFlow = new TextFlow();
		page.add(textFlow);

		setContents(page);
		getViewport().setContentsTracksWidth(true);
		addAccessibility();
	}

	private void addAccessibility() {
		getAccessible()
				.addAccessibleControlListener(new AccessibleControlAdapter() {
					public void getRole(AccessibleControlEvent e) {
						e.detail = ACC.ROLE_LABEL;
					}

					public void getState(AccessibleControlEvent e) {
						e.detail = ACC.STATE_READONLY;
					}
				});
		getAccessible().addAccessibleListener(new AccessibleAdapter() {
			public void getName(AccessibleEvent e) {
				e.result = getText();
			}
		});
		addKeyListener(new KeyAdapter() {
			public void keyPressed(KeyEvent e) {
				Point p = getViewport().getViewLocation();
				int dy = getFont().getFontData()[0].getHeight();
				int dx = dy * 3 / 2;
				boolean mirrored = (e.widget.getStyle() & SWT.MIRRORED) != 0;
				if (e.keyCode == SWT.ARROW_DOWN) {
					scrollToY(p.y + dy / 2);
					scrollToY(p.y + dy);
					scrollToY(p.y + dy * 3 / 2);
					scrollToY(p.y + dy * 2);
				} else if (e.keyCode == SWT.ARROW_UP) {
					scrollToY(p.y - dy / 2);
					scrollToY(p.y - dy);
					scrollToY(p.y - dy * 3 / 2);
					scrollToY(p.y - dy * 2);
				} else if ((!mirrored && e.keyCode == SWT.ARROW_RIGHT)
						|| (mirrored && e.keyCode == SWT.ARROW_LEFT)) {
					scrollToX(p.x + dx);
					scrollToX(p.x + dx * 2);
					scrollToX(p.x + dx * 3);
				} else if ((!mirrored && e.keyCode == SWT.ARROW_LEFT)
						|| (mirrored && e.keyCode == SWT.ARROW_RIGHT)) {
					scrollToX(p.x - dx);
					scrollToX(p.x - dx * 2);
					scrollToX(p.x - dx * 3);
				}
			}
		});
	}

	/**
	 * @see org.eclipse.swt.widgets.Control#setEnabled(boolean)
	 */
	public void setEnabled(boolean enabled) {
		super.setEnabled(enabled);
		textFlow.setEnabled(getEnabled());
	}

	/**
	 * @return the Image for this label, or null if there is none
	 * @see #setImage(Image)
	 */
	public Image getImage() {
		return image;
	}

	/**
	 * Returns the text in this label.
	 * 
	 * @return the text
	 */
	public String getText() {
		return textFlow.getText();
	}

	/**
	 * @see org.eclipse.swt.widgets.Canvas#setFont(org.eclipse.swt.graphics.Font)
	 */
	public void setFont(Font font) {
		super.setFont(font);
		textFlow.revalidate();
	}

	/**
	 * @param image
	 *            The Image to be used for this label. It can be
	 *            null.
	 */
	public void setImage(Image image) {
		this.image = image;
		if (image != null)
			setBorder(new ImageBorder(image));
		else
			setBorder(null);
	}

	/**
	 * Sets the text for this label.
	 * 
	 * @param text
	 *            the new text
	 */
	public void setText(String text) {
		textFlow.setText(text);
	}

}