NativeGraphicsSource.java

/*******************************************************************************
 * Copyright (c) 2005 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.widgets.Control;

import org.eclipse.draw2d.geometry.Rectangle;

/**
 * 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;
}

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

}