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.Color; import org.eclipse.swt.graphics.Device; import org.eclipse.swt.graphics.GC; import org.eclipse.swt.graphics.Image; 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.widgets.Composite; import org.eclipse.swt.widgets.Display; import org.eclipse.swt.widgets.Menu; import org.eclipse.swt.widgets.ToolBar; import org.eclipse.swt.widgets.ToolItem; /** * This tab draws an image consisting of gradients of two colors. * */ public class GradientTab extends GraphicsTab { ToolBar toolBar; ToolItem colorItem1, colorItem2; Menu menu1, menu2; GraphicsBackground colorGB1, colorGB2; public GradientTab(GraphicsExample example) { super(example); } /** * Dispose resources created by this tab. * */ @Override public void dispose() { if (menu1 != null) { menu1.dispose(); menu1 = null; } if (menu2 != null) { menu2.dispose(); menu2 = null; } } @Override public String getCategory() { return GraphicsExample.getResourceString("Gradient"); //$NON-NLS-1$ } @Override public String getText() { return GraphicsExample.getResourceString("GradImage"); //$NON-NLS-1$ } @Override public String getDescription() { return GraphicsExample.getResourceString("GradientImageDescription"); //$NON-NLS-1$ } @Override public void createControlPanel(final Composite parent) { final Display display = parent.getDisplay(); toolBar = new ToolBar(parent, SWT.FLAT); ColorMenu colorMenu = new ColorMenu(); // menu for colorItem1 menu1 = colorMenu.createMenu(parent.getParent(), gb -> { colorGB1 = gb; colorItem1.setImage(gb.getThumbNail()); example.redraw(); }); // initialize the background to the 5th item in the menu (blue) colorGB1 = (GraphicsBackground) menu1.getItem(4).getData(); // toolbar item for color1 colorItem1 = new ToolItem(toolBar, SWT.PUSH); colorItem1.setText(GraphicsExample.getResourceString("GradientTabItem1")); colorItem1.setImage(colorGB1.getThumbNail()); colorItem1.addListener(SWT.Selection, event -> { final ToolItem toolItem = (ToolItem) event.widget; final ToolBar toolBar = toolItem.getParent(); Rectangle toolItemBounds = toolItem.getBounds(); Point point = toolBar.toDisplay(new Point(toolItemBounds.x, toolItemBounds.y)); menu1.setLocation(point.x, point.y + toolItemBounds.height); menu1.setVisible(true); }); // menu for colorItem2 menu2 = colorMenu.createMenu(parent.getParent(), gb -> { colorGB2 = gb; colorItem2.setImage(gb.getThumbNail()); example.redraw(); }); // initialize the background to the 3rd item in the menu (red) colorGB2 = (GraphicsBackground) menu2.getItem(2).getData(); // toolbar item for color2 colorItem2 = new ToolItem(toolBar, SWT.PUSH); colorItem2.setText(GraphicsExample.getResourceString("GradientTabItem2")); colorItem2.setImage(colorGB2.getThumbNail()); colorItem2.addListener(SWT.Selection, event -> { final ToolItem toolItem = (ToolItem) event.widget; final ToolBar toolBar = toolItem.getParent(); Rectangle toolItemBounds = toolItem.getBounds(); Point point = toolBar.toDisplay(new Point(toolItemBounds.x, toolItemBounds.y)); menu2.setLocation(point.x, point.y + toolItemBounds.height); menu2.setVisible(true); }); // toolbar item for swapping colors ToolItem swapItem = new ToolItem(toolBar, SWT.PUSH); swapItem.setText(GraphicsExample.getResourceString("SwapColors")); //$NON-NLS-1$ swapItem.setImage(example.loadImage(display, "swap.gif")); swapItem.addListener(SWT.Selection, event -> { GraphicsBackground tmp = colorGB1; colorGB1 = colorGB2; colorGB2 = tmp; colorItem1.setImage(colorGB1.getThumbNail()); colorItem2.setImage(colorGB2.getThumbNail()); example.redraw(); }); } /** * This method draws the gradient patterns that make up the image. The image * consists of 4 rows, each consisting of 4 gradient patterns (total of 16). */ @Override public void paint(GC gc, int width, int height) { if (!example.checkAdvancedGraphics()) return; Device device = gc.getDevice(); Image image = createImage(device, colorGB1.getBgColor1(), colorGB2.getBgColor1(), width, height); Pattern p = new Pattern(device, image); gc.setBackgroundPattern(p); gc.fillRectangle(0, 0, width, height); p.dispose(); image.dispose(); } /** * Creates and returns an image made up of gradient patterns. The image takes up * a quarter of the area of the total drawing surface. * * @param device * A Device * @param color1 * A Color * @param color2 * A Color * @param width * Width of the drawing surface * @param height * Height of the drawing surface */ Image createImage(Device device, Color color1, Color color2, int width, int height) { Image image = new Image(device, width / 2, height / 2); GC gc = new GC(image); Rectangle rect = image.getBounds(); Pattern pattern1 = new Pattern(device, rect.x, rect.y, rect.width / 2f, rect.height / 2f, color1, color2); gc.setBackgroundPattern(pattern1); Path path = new Path(device); path.addRectangle(0, 0, width / 4f, height / 4f); path.addRectangle(width / 4f, height / 4f, width / 4f, height / 4f); gc.fillPath(path); path.dispose(); Pattern pattern2 = new Pattern(device, rect.width, 0, rect.width / 2f, rect.height / 2f, color1, color2); gc.setBackgroundPattern(pattern2); path = new Path(device); path.addRectangle(width / 4f, 0, width / 4f, height / 4f); path.addRectangle(0, height / 4f, width / 4f, height / 4f); gc.fillPath(path); path.dispose(); gc.dispose(); pattern1.dispose(); pattern2.dispose(); return image; } }