StarPolyTab.java

/*******************************************************************************
 * Copyright (c) 2000, 2006 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.swt.examples.graphics;

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.widgets.Combo;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Listener;

public class StarPolyTab extends GraphicsTab {
	static final int	POINTS	= 11;
	Combo				fillRuleCb;

	int[]				radial;

	public StarPolyTab(GraphicsExample example) {
		super(example);
		radial = new int[StarPolyTab.POINTS * 2];
	}

	public void createControlPanel(Composite parent) {
		new Label(parent, SWT.NONE).setText(GraphicsExample.getResourceString("FillRule")); //$NON-NLS-1$
		fillRuleCb = new Combo(parent, SWT.DROP_DOWN);
		fillRuleCb.add("FILL_EVEN_ODD");
		fillRuleCb.add("FILL_WINDING");
		fillRuleCb.select(0);
		fillRuleCb.addListener(SWT.Selection, new Listener() {
			public void handleEvent(Event event) {
				example.redraw();
			}
		});
	}

	public String getCategory() {
		return GraphicsExample.getResourceString("Polygons"); //$NON-NLS-1$
	}

	public String getDescription() {
		return GraphicsExample.getResourceString("StarPolygonDescription"); //$NON-NLS-1$
	}

	public String getText() {
		return GraphicsExample.getResourceString("StarPolygon"); //$NON-NLS-1$
	}

	public void paint(GC gc, int width, int height) {
		int centerX = width / 2;
		int centerY = height / 2;
		int pos = 0;
		for (int i = 0; i < StarPolyTab.POINTS; ++i) {
			double r = Math.PI * 2 * pos / StarPolyTab.POINTS;
			radial[i * 2] = (int) ((1 + Math.cos(r)) * centerX);
			radial[i * 2 + 1] = (int) ((1 + Math.sin(r)) * centerY);
			pos = (pos + StarPolyTab.POINTS / 2) % StarPolyTab.POINTS;
		}
		gc.setFillRule(fillRuleCb.getSelectionIndex() != 0 ? SWT.FILL_WINDING : SWT.FILL_EVEN_ODD);
		gc.setBackground(gc.getDevice().getSystemColor(SWT.COLOR_WHITE));
		gc.fillPolygon(radial);
		gc.drawPolygon(radial);
	}
}