bundles/org.eclipse.draw2d/src/org/eclipse/draw2d/AbstractLabeledBorder.java

/*******************************************************************************
 * 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;

import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Font;

import org.eclipse.draw2d.geometry.Dimension;
import org.eclipse.draw2d.geometry.Insets;

/**
 * Provides support for a border with a label describing the contents of which
 * it is surrounding.
 */
public abstract class AbstractLabeledBorder extends AbstractBorder implements
		LabeledBorder {

	private Dimension textExtents;
	private String label;
	private Insets insets;
	private Color textColor = ColorConstants.black;
	private Font font;

	/**
	 * Constructs a default AbstractLabeledBorder with the name of this class
	 * set as its label.
	 * 
	 * @since 2.0
	 */
	public AbstractLabeledBorder() {
		String className = getClass().getName();
		setLabel(className.substring(className.lastIndexOf('.') + 1,
				className.length()));
	}

	/**
	 * Constructs a border with the label set to the String passed in as input.
	 * 
	 * @param s
	 *            Label to be set on the border
	 * @since 2.0
	 */
	public AbstractLabeledBorder(String s) {
		setLabel(s);
	}

	/**
	 * Calculates insets based on the current font and other attributes. This
	 * value will be cached until {@link #invalidate()} is called.
	 * 
	 * @param figure
	 *            The figure to which the border is being applied
	 * @return The Insets
	 */
	protected abstract Insets calculateInsets(IFigure figure);

	/**
	 * Returns the font that this border will use. If no Font has been
	 * specified, the font associated with the input Figure will be used.
	 * 
	 * @param f
	 *            Figure used to get a default font
	 * @return The font for this border
	 */
	protected Font getFont(IFigure f) {
		if (font == null)
			return f.getFont();
		return font;
	}

	/**
	 * Returns the insets, or space associated for this border. Returns any
	 * previously set value if present, else calculates it from the Figure
	 * provided in as input.
	 * 
	 * @param fig
	 *            Figure used to calculate insets
	 * @return The insets
	 */
	public Insets getInsets(IFigure fig) {
		if (insets == null)
			insets = calculateInsets(fig);
		return insets;
	}

	/**
	 * @see org.eclipse.draw2d.LabeledBorder#getLabel()
	 */
	public String getLabel() {
		return label;
	}

	/**
	 * @see org.eclipse.draw2d.Border#getPreferredSize(IFigure)
	 */
	public Dimension getPreferredSize(IFigure fig) {
		return new Dimension(getTextExtents(fig));
	}

	/**
	 * Returns the text Color of this AbstractLabeledBorder's label.
	 * 
	 * @return The text color
	 * @since 2.0
	 */
	public Color getTextColor() {
		return textColor;
	}

	/**
	 * Calculates and returns the size required by this border's label.
	 * 
	 * @param f
	 *            IFigure on which the calculations are to be made
	 * @return Dimensions required by the text of this border's label
	 * @since 2.0
	 */
	protected Dimension getTextExtents(IFigure f) {
		if (textExtents == null)
			textExtents = FigureUtilities.getTextExtents(label, getFont(f));
		return textExtents;
	}

	/**
	 * Resets the internal values and state so that they can be recalculated.
	 * Called whenever a state change has occurred that effects the insets or
	 * text extents of this border.
	 */
	protected void invalidate() {
		insets = null;
		textExtents = null;
	}

	/**
	 * Sets the Font of this border to the input value, and invalidates the
	 * border forcing an update of internal parameters of insets and text
	 * extents.
	 * 
	 * @param font
	 *            The font
	 */
	public void setFont(Font font) {
		this.font = font;
		invalidate();
	}

	/**
	 * @see org.eclipse.draw2d.LabeledBorder#setLabel(String)
	 */
	public void setLabel(String s) {
		label = ((s == null) ? "" : s); //$NON-NLS-1$
		invalidate();
	}

	/**
	 * Sets the color for this border's text.
	 * 
	 * @param color
	 *            Color to be set for this border's text
	 * @since 2.0
	 */
	public void setTextColor(Color color) {
		textColor = color;
	}

}