Portable SWT ImageButton

net\teumert\swt\ImageButton.java

/*
 * Copyright (c) 2014 Sebastian Teumert (<http://teumert.net>)
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer. 
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package net.teumert.swt;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.PaintEvent;
import org.eclipse.swt.events.PaintListener;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Composite;


/**
 * <p>A simple push button with text below or above the image.</p>
 * 
 * <p>Valid values for text alignment are SWT.LEFT, SWT.CENTER or SWT.RIGHT,
 * valid values for text position are SWT.TOP or SWT.BOTTOM.</p>
 *
 * @author Sebastian Teumert
 *
 */
public class ImageButton extends Button {
	
	private String text = "";
	
	private Image image;
	
	private Point textSize, textPosition, imagePosition;
	
	private int style;
	
	private int padding = 8;

	
	/**
	 * @param arg0
	 */
	public ImageButton (Composite arg0) {
		this(arg0, SWT.BOTTOM | SWT.CENTER);
	}
	
	/**
	 * @param arg0
	 */
	public ImageButton (Composite arg0, int style) {
		super(arg0, SWT.NONE);
		this.style = style;
		
		addPaintListener(new PaintListener() {
			
			/* (non-Javadoc)
			 * @see org.eclipse.swt.events.PaintListener#paintControl(org.eclipse.swt.events.PaintEvent)
			 */
			public void paintControl (PaintEvent arg0) {
				GC gc = arg0.gc;
				//gc.setFont(getFont());
				
				// TODO: Add clipping if text or image is wider then actual width
				
				int textX = 8;
				if ((ImageButton.this.style & SWT.CENTER) == SWT.CENTER) textX = getSize().x / 2 - textSize.x / 2;
				else if ((ImageButton.this.style & SWT.LEFT) == SWT.LEFT) textX = padding;
				else if ((ImageButton.this.style & SWT.RIGHT) == SWT.RIGHT) textX = getSize().x - textSize.x - padding;
				
				if ((ImageButton.this.style & SWT.BOTTOM) == SWT.BOTTOM) {
					imagePosition = new Point((getSize().x - image.getImageData().width)/2, padding);
					textPosition = new Point(textX,  getSize().y - textSize.y - padding);
				}  else if ((ImageButton.this.style & SWT.TOP) == SWT.TOP) {
					imagePosition = new Point((getSize().x - image.getImageData().width)/2, padding + textSize.y + padding);
					textPosition = new Point(textX, padding);
				}
				
				gc.drawImage(image, imagePosition.x, imagePosition.y);
				gc.drawText(text, textPosition.x, textPosition.y, true);
			}
		});
		
	}
	
	/* (non-Javadoc)
	 * @see org.eclipse.swt.widgets.Button#setText(java.lang.String)
	 */
	@Override
	public void setText (String arg0) {
		this.text = arg0;
	}
	
	/* (non-Javadoc)
	 * @see org.eclipse.swt.widgets.Button#getText()
	 */
	@Override
	public String getText () {
		return text;
	}
	
	/* (non-Javadoc)
	 * @see org.eclipse.swt.widgets.Button#setImage(org.eclipse.swt.graphics.Image)
	 */
	@Override
	public void setImage (Image arg0) {
		this.image = arg0;
		computeSize(0, 0, true);
	}
	
	/* (non-Javadoc)
	 * @see org.eclipse.swt.widgets.Button#getImage()
	 */
	@Override
	public Image getImage () {
		return image;
	}
	
	/* (non-Javadoc)
	 * @see org.eclipse.swt.widgets.Widget#checkSubclass()
	 */
	@Override
	protected void checkSubclass () {}
	
	/* (non-Javadoc)
	 * @see org.eclipse.swt.widgets.Control#computeSize(int, int)
	 */
	@Override
	public Point computeSize (int arg0, int arg1) {
		return new Point(Math.max(textSize.x, getImage().getImageData().width) + (2 * padding), getImage().getImageData().height + textSize.y + (3 * padding));
	}
	
	/* (non-Javadoc)
	 * @see org.eclipse.swt.widgets.Button#computeSize(int, int, boolean)
	 */
	@Override
	public Point computeSize (int arg0, int arg1, boolean arg2) {
		if (arg2 || textSize == null) {
			GC gc = new GC(this);
			//gc.setFont(getFont());
			textSize = gc.textExtent(getText());
			gc.dispose();
		}
		return computeSize(arg0, arg1);
	}
	
	/**
	 * @param padding of the button. 
	 * 
	 * <p>The padding is the distance of the
	 * image and text to the border of the button. The padding is also used
	 * for the vertical margin between the image and text.</p>
	 */
	public void setPadding (int padding) {
		this.padding = padding;
	}
	
	
	/**
	 * @return Returns the padding of the button. The padding is the distance of 
	 * the image and text to the border of the button. The padding is also used
	 * for the vertical margin between the image and text.
	 */
	public int getPadding () {
		return padding;
	}
}