CustomAlphaTab.java

/*******************************************************************************
 * Copyright (c) 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.Device;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Path;
import org.eclipse.swt.graphics.Pattern;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.graphics.Transform;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Menu;
import org.eclipse.swt.widgets.Spinner;

/**
 * This tab demonstrates the use of alpha blending. It allows a user to specify a custom alpha value.
 */
public class CustomAlphaTab extends AnimatedGraphicsTab {

	private Spinner				alphaSpinner;
	private int					angle;
	private GraphicsBackground	background;
	private Button				colorButton;
	private Menu				menu;

	public CustomAlphaTab(GraphicsExample example) {
		super(example);
	}

	/**
	 * Creates the widgets used to control the drawing.
	 */
	public void createControlPanel(Composite parent) {
		super.createControlPanel(parent);

		// create drop down combo for choosing clipping
		Composite comp;

		// create spinner for line width
		comp = new Composite(parent, SWT.NONE);
		comp.setLayout(new GridLayout(2, false));
		new Label(comp, SWT.CENTER).setText(GraphicsExample.getResourceString("Alpha")); //$NON-NLS-1$
		alphaSpinner = new Spinner(comp, SWT.BORDER | SWT.WRAP);
		alphaSpinner.setMinimum(0);
		alphaSpinner.setMaximum(255);
		alphaSpinner.setSelection(127);
		alphaSpinner.addListener(SWT.Selection, new Listener() {
			public void handleEvent(Event event) {
				example.redraw();
			}
		});

		// color menu
		ColorMenu cm = new ColorMenu();
		cm.setPatternItems(example.checkAdvancedGraphics());
		menu = cm.createMenu(parent.getParent(), new ColorListener() {
			public void setColor(GraphicsBackground gb) {
				background = gb;
				colorButton.setImage(gb.getThumbNail());
				example.redraw();
			}
		});

		// initialize the background to the 5th item in the menu (blue)
		background = (GraphicsBackground) menu.getItem(4).getData();

		// color button
		comp = new Composite(parent, SWT.NONE);
		comp.setLayout(new GridLayout(2, false));

		colorButton = new Button(comp, SWT.PUSH);
		colorButton.setText(GraphicsExample.getResourceString("Color")); //$NON-NLS-1$
		colorButton.setImage(background.getThumbNail());
		colorButton.addListener(SWT.Selection, new Listener() {
			public void handleEvent(Event event) {
				final Button button = (Button) event.widget;
				final Composite parent = button.getParent();
				Rectangle bounds = button.getBounds();
				Point point = parent.toDisplay(new Point(bounds.x, bounds.y));
				menu.setLocation(point.x, point.y + bounds.height);
				menu.setVisible(true);
			}
		});
	}

	public void dispose() {
		if (menu != null) {
			menu.dispose();
			menu = null;
		}
	}

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

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

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

	public void next(int width, int height) {

		angle = (angle + 1) % 360;
	}

	public void paint(GC gc, int width, int height) {
		if (!example.checkAdvancedGraphics())
			return;
		Device device = gc.getDevice();

		Pattern pattern = null;
		if (background.getBgColor1() != null)
			gc.setBackground(background.getBgColor1());
		else if (background.getBgImage() != null) {
			pattern = new Pattern(device, background.getBgImage());
			gc.setBackgroundPattern(pattern);
		}

		gc.setAntialias(SWT.ON);
		gc.setAlpha(alphaSpinner.getSelection());

		// rotate on center
		Transform transform = new Transform(device);
		transform.translate(width / 2, height / 2);
		transform.rotate(-angle);
		transform.translate(-width / 2, -height / 2);
		gc.setTransform(transform);
		transform.dispose();

		// choose the smallest between height and width
		int diameter = height < width ? height : width;

		Path path = new Path(device);
		path.addArc((width - diameter / 5) / 2, (height - diameter / 5) / 2, diameter / 5, diameter / 5, 0, 360);
		path.addArc(5 * (width - diameter / 8) / 12, 4 * (height - diameter / 8) / 12, diameter / 8, diameter / 8, 0,
				360);
		path.addArc(7 * (width - diameter / 8) / 12, 8 * (height - diameter / 8) / 12, diameter / 8, diameter / 8, 0,
				360);
		path.addArc(6 * (width - diameter / 12) / 12, 3 * (height - diameter / 12) / 12, diameter / 12, diameter / 12,
				0, 360);
		path.addArc(6 * (width - diameter / 12) / 12, 9 * (height - diameter / 12) / 12, diameter / 12, diameter / 12,
				0, 360);
		path.addArc(11.5f * (width - diameter / 18) / 20, 5 * (height - diameter / 18) / 18, diameter / 18,
				diameter / 18, 0, 360);
		path.addArc(8.5f * (width - diameter / 18) / 20, 13 * (height - diameter / 18) / 18, diameter / 18,
				diameter / 18, 0, 360);
		path.addArc(62f * (width - diameter / 25) / 100, 32 * (height - diameter / 25) / 100, diameter / 25,
				diameter / 25, 0, 360);
		path.addArc(39f * (width - diameter / 25) / 100, 67 * (height - diameter / 25) / 100, diameter / 25,
				diameter / 25, 0, 360);

		gc.fillPath(path);
		path.dispose();

		if (pattern != null)
			pattern.dispose();
	}
}