Java tutorial
/******************************************************************************* * Copyright (c) 2006, 2016 IBM Corporation and others. * * This program and the accompanying materials * are made available under the terms of the Eclipse Public License 2.0 * which accompanies this distribution, and is available at * https://www.eclipse.org/legal/epl-2.0/ * * SPDX-License-Identifier: EPL-2.0 * * 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.Label; 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 Button colorButton; private GraphicsBackground background; private Menu menu; private int angle; public CustomAlphaTab(GraphicsExample example) { super(example); } @Override public String getCategory() { return GraphicsExample.getResourceString("Alpha"); //$NON-NLS-1$ } @Override public String getText() { return GraphicsExample.getResourceString("CustomAlpha"); //$NON-NLS-1$ } @Override public String getDescription() { return GraphicsExample.getResourceString("CustomAlphaDescription"); //$NON-NLS-1$ } @Override public void dispose() { if (menu != null) { menu.dispose(); menu = null; } } /** * Creates the widgets used to control the drawing. */ @Override 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, event -> example.redraw()); // color menu ColorMenu cm = new ColorMenu(); cm.setPatternItems(example.checkAdvancedGraphics()); menu = cm.createMenu(parent.getParent(), 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, event -> { final Button button = (Button) event.widget; final Composite parent1 = button.getParent(); Rectangle bounds = button.getBounds(); Point point = parent1.toDisplay(new Point(bounds.x, bounds.y)); menu.setLocation(point.x, point.y + bounds.height); menu.setVisible(true); }); } @Override public void next(int width, int height) { angle = (angle + 1) % 360; } @Override 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(); } }