ColorEditor.java

/*******************************************************************************
 * Copyright (c) 2000, 2003 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.rubypeople.rdt.internal.ui.preferences;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.DisposeEvent;
import org.eclipse.swt.events.DisposeListener;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.RGB;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.ColorDialog;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;

import org.eclipse.jface.resource.JFaceResources;

/**
 * A "button" of a certain color determined by the color picker.
 * 
 * @since 2.1
 */
class ColorEditor {
	
	/** The extent. */
	private Point fExtent;
	/** The image for the push button. */
	private Image fImage;
	/** The current RGB color value. */
	private RGB fColorValue;
	/** The current color. */
	private Color fColor;
	/** The image push button which open the color dialog. */
	private Button fButton;
	
	/**
	 * Creates and returns a new color editor.
	 * 
	 * @param parent the parent composite of this color editor
	 */
	public ColorEditor(Composite parent) {
		
		fButton= new Button(parent, SWT.PUSH);
		fExtent= computeImageSize(parent);
		fImage= new Image(parent.getDisplay(), fExtent.x, fExtent.y);
		
		GC gc= new GC(fImage);
		gc.setBackground(fButton.getBackground());
		gc.fillRectangle(0, 0, fExtent.x, fExtent.y);
		gc.dispose();
		
		fButton.setImage(fImage);
		fButton.addSelectionListener(new SelectionAdapter() {
			public void widgetSelected(SelectionEvent event) {
				ColorDialog colorDialog= new ColorDialog(fButton.getShell());
				colorDialog.setRGB(fColorValue);
				RGB newColor = colorDialog.open();
				if (newColor != null) {
					fColorValue= newColor;
					updateColorImage();
				}
			}
		});
		
		fButton.addDisposeListener(new DisposeListener() {
			public void widgetDisposed(DisposeEvent event) {
				if (fImage != null)  {
					fImage.dispose();
					fImage= null;
				}
				if (fColor != null) {
					fColor.dispose();
					fColor= null;
				}
			}
		});
	}
	
	/**
	 * Returns the current RGB color value.
	 * 
	 * @return an rgb with the current color value
	 */
	public RGB getColorValue() {
		return fColorValue;
	}
	
	/**
	 * Sets the current RGB color value.
	 * 
	 * @param rgb the new value for the rgb color value
	 */
	public void setColorValue(RGB rgb) {
		fColorValue= rgb;
		updateColorImage();
	}
	
	/**
	 * Returns the image push button.
	 * 
	 * @return the button which shows the current color as image
	 */
	public Button getButton() {
		return fButton;
	}
	
	/**
	 * Updates the color of the button image.
	 */
	protected void updateColorImage() {
		
		Display display= fButton.getDisplay();
		
		GC gc= new GC(fImage);
		gc.setForeground(display.getSystemColor(SWT.COLOR_BLACK));
		gc.drawRectangle(0, 2, fExtent.x - 1, fExtent.y - 4);
		
		if (fColor != null)
			fColor.dispose();
			
		fColor= new Color(display, fColorValue);
		gc.setBackground(fColor);
		gc.fillRectangle(1, 3, fExtent.x - 2, fExtent.y - 5);
		gc.dispose();
		
		fButton.setImage(fImage);
	}
	
	
	/**
	 * Computes the size for the image.
	 * 
	 * @param window the window on which to render the image
	 * @return the point with the image size
	 */
	protected Point computeImageSize(Control window) {
		GC gc= new GC(window);
		Font f= JFaceResources.getFontRegistry().get(JFaceResources.DEFAULT_FONT);
		gc.setFont(f);
		int height= gc.getFontMetrics().getHeight();
		gc.dispose();
		Point p= new Point(height * 3 - 6, height);
		return p;
	}
}