NativeGraphicsSource.java

/*******************************************************************************
 * Copyright (c) 2005, 2010, 2012 IBM Corporation, Gerhardt Informatics Kft. 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
 *     Gerhardt Informatics Kft. - GEFGWT port
 *******************************************************************************/

package org.eclipse.draw2d;

import org.eclipse.draw2d.geometry.Rectangle;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.widgets.Control;

/**
 * A graphics source that posts a paint request to the control rather than
 * constructing GC on it directly. This allows the OS's native painting
 * mechanism to be used directly, including any double-buffering that the OS may
 * provide for free.
 * 
 * @since 3.2
 */
public final class NativeGraphicsSource implements GraphicsSource {

	private final Control canvas;

	/**
	 * Constructs a new graphics source on the given control.
	 * 
	 * @param canvas
	 *            the control
	 * @since 3.2
	 */
	public NativeGraphicsSource(Control canvas) {
		this.canvas = canvas;
	}

	/**
	 * Always returns <code>null</code>, because
	 * 
	 * @see GraphicsSource#getGraphics(Rectangle)
	 */
	public Graphics getGraphics(Rectangle r) {
		// canvas.redraw(r.x, r.y, r.width, r.height, false);
		// canvas.update();
		// return null;
		GC gc = new GC(canvas);
		gc.setClipping(r.x, r.y, r.width, r.height);
		Graphics g = new SWTGraphics(gc);
		return g;
	}

	/**
	 * Does nothing.
	 * 
	 * @see GraphicsSource#flushGraphics(Rectangle)
	 */
	public void flushGraphics(Rectangle region) {
	}

}