Java tutorial
/******************************************************************************* * Copyright (c) 2000, 2015 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 * Chriss Gross (schtoo@schtoo.com) - fix for 61670 *******************************************************************************/ package org.eclipse.ui.forms.widgets; import org.eclipse.swt.SWT; import org.eclipse.swt.events.DisposeEvent; import org.eclipse.swt.events.DisposeListener; import org.eclipse.swt.graphics.GC; import org.eclipse.swt.graphics.Image; import org.eclipse.swt.graphics.Point; import org.eclipse.swt.graphics.Rectangle; import org.eclipse.swt.widgets.Composite; import org.eclipse.swt.widgets.Event; /** * This class extends hyperlink widget by adding the capability to render an * image relative to the text. If no text has been set, only image will be * shown. Images for hover and active states can be set in addition to the * normal state image. * <p> * When image is taller than the text, additional style can be provided to * control vertical alignment (supported values are SWT.TOP, SWT.BOTTOM and * SWT.CENTER). * <p> * The class does not need to be subclassed but it is allowed to do so if some * aspect of the image hyperlink needs to be modified. * <p> * <dl> * <dt><b>Styles:</b></dt> * <dd>SWT.WRAP, SWT.BOTTOM, SWT.TOP, SWT.MIDDLE, SWT.LEFT, SWT.RIGHT</dd> * </dl> * * @since 3.0 */ public class ImageHyperlink extends Hyperlink { /** * Amount of pixels between the image and the text (default is 5). */ public int textSpacing = 5; private Image image; private Image hoverImage; private Image activeImage; private Image disabledImage; private int state; private static final int HOVER = 1 << 1; private static final int ACTIVE = 1 << 2; private int verticalAlignment = SWT.CENTER; private int horizontalAlignment = SWT.LEFT; /** * Creates the image hyperlink instance. * * @param parent * the control parent * @param style * the control style (SWT.WRAP, BOTTOM, TOP, MIDDLE, LEFT, RIGHT) */ public ImageHyperlink(Composite parent, int style) { super(parent, removeAlignment(style)); extractAlignment(style); addDisposeListener(new DisposeListener() { @Override public void widgetDisposed(DisposeEvent e) { if (disabledImage != null) disabledImage.dispose(); } }); } @Override protected void paintHyperlink(GC gc) { paintHyperlink(gc, getClientArea()); } protected void paintHyperlink(GC gc, Rectangle bounds) { Image image = null; if (!isEnabled()) { createDisabledImage(); image = disabledImage; } else { if ((state & ACTIVE) != 0) image = activeImage; else if ((state & HOVER) != 0) image = hoverImage; if (image == null) image = this.image; } Rectangle ibounds = image != null ? image.getBounds() : new Rectangle(0, 0, 0, 0); Point maxsize = computeMaxImageSize(); int spacing = image != null ? textSpacing : 0; int textWidth = bounds.width - maxsize.x - spacing - marginWidth - marginWidth; int y = bounds.y + marginHeight + maxsize.y / 2 - ibounds.height / 2; if (horizontalAlignment == SWT.LEFT) { int x = bounds.x + marginWidth + maxsize.x / 2 - ibounds.width / 2; int textX = bounds.x + marginWidth + maxsize.x + spacing; if (image != null) gc.drawImage(image, x, y); if (getText() != null) drawText(gc, bounds, textX, textWidth); } else if (horizontalAlignment == SWT.RIGHT) { int x = bounds.x + marginWidth; if (getText() != null) { x += drawText(gc, bounds, x, textWidth); } x += maxsize.x / 2 - ibounds.width / 2 + spacing; if (image != null) gc.drawImage(image, x, y); } } private int drawText(GC gc, Rectangle clientArea, int textX, int textWidth) { Point textSize = computeTextSize(textWidth, SWT.DEFAULT); int slotHeight = clientArea.height - marginHeight - marginHeight; int textY; textWidth = textSize.x; int textHeight = textSize.y; if (verticalAlignment == SWT.BOTTOM) { textY = marginHeight + slotHeight - textHeight; } else if (verticalAlignment == SWT.CENTER) { textY = marginHeight + slotHeight / 2 - textHeight / 2; } else { textY = marginHeight; } paintText(gc, new Rectangle(textX, textY, textWidth, textHeight)); return textWidth; } /** * Computes the control size by reserving space for images in addition to * text. * * @param wHint * width hint * @param hHint * height hint * @param changed * if <code>true</code>, any cached layout data should be * computed anew */ @Override public Point computeSize(int wHint, int hHint, boolean changed) { checkWidget(); Point isize = computeMaxImageSize(); int spacing = isize.x > 0 ? textSpacing : 0; Point textSize = null; if (getText() != null) { int innerWHint = wHint; if (wHint != SWT.DEFAULT) { innerWHint = wHint - 2 * marginWidth - isize.x - spacing; } textSize = super.computeSize(innerWHint, hHint, changed); } int width = isize.x; int height = isize.y; if (textSize != null) { width += spacing; width += textSize.x; height = Math.max(height, textSize.y); } width += 2 * marginWidth; height += 2 * marginHeight; return new Point(width, height); } @Override protected void handleEnter(Event e) { state = HOVER; super.handleEnter(e); } @Override protected void handleExit(Event e) { state = 0; super.handleExit(e); } @Override protected void handleActivate(Event e) { state &= ACTIVE; redraw(); super.handleActivate(e); state &= ~ACTIVE; if (!isDisposed()) redraw(); } /** * Returns active image. * * @return active image or <code>null</code> if not set. */ public Image getActiveImage() { return activeImage; } /** * Sets the image to show when link is activated. * * @param activeImage * */ public void setActiveImage(Image activeImage) { this.activeImage = activeImage; } /** * Returns the hover image. * * @return hover image or <code>null</code> if not set. */ public Image getHoverImage() { return hoverImage; } /** * Sets the image to show when link is hover state (on mouse over). * * @param hoverImage */ public void setHoverImage(Image hoverImage) { this.hoverImage = hoverImage; } /** * Returns the image to show in the normal state. * * @return normal image or <code>null</code> if not set. */ public Image getImage() { return image; } /** * Sets the image to show when link is in the normal state. * * @param image */ public void setImage(Image image) { this.image = image; if (disabledImage != null) disabledImage.dispose(); if (image == null) { disabledImage = null; } } private void createDisabledImage() { if (this.image != null && !this.image.isDisposed()) disabledImage = new Image(this.image.getDevice(), this.image, SWT.IMAGE_DISABLE); } private Point computeMaxImageSize() { int x = 0; int y = 0; if (image != null) { x = Math.max(image.getBounds().width, x); y = Math.max(image.getBounds().height, y); } if (hoverImage != null) { x = Math.max(hoverImage.getBounds().width, x); y = Math.max(hoverImage.getBounds().height, y); } if (activeImage != null) { x = Math.max(activeImage.getBounds().width, x); y = Math.max(activeImage.getBounds().height, y); } return new Point(x, y); } private static int removeAlignment(int style) { int resultStyle = style; if ((style & SWT.CENTER) != 0) { resultStyle &= (~SWT.CENTER); } if ((style & SWT.TOP) != 0) { resultStyle &= (~SWT.TOP); } if ((style & SWT.BOTTOM) != 0) { resultStyle &= (~SWT.BOTTOM); } if ((style & SWT.LEFT) != 0) { resultStyle &= (~SWT.LEFT); } if ((style & SWT.RIGHT) != 0) { resultStyle &= (~SWT.RIGHT); } return resultStyle; } private void extractAlignment(int style) { if ((style & SWT.CENTER) != 0) { verticalAlignment = SWT.CENTER; } else if ((style & SWT.TOP) != 0) { verticalAlignment = SWT.TOP; } else if ((style & SWT.BOTTOM) != 0) { verticalAlignment = SWT.BOTTOM; } if ((style & SWT.LEFT) != 0) { horizontalAlignment = SWT.LEFT; } else if ((style & SWT.RIGHT) != 0) { horizontalAlignment = SWT.RIGHT; } } @Override public void setEnabled(boolean enabled) { if (!enabled && (disabledImage == null || disabledImage.isDisposed()) && image != null && !image.isDisposed()) { disabledImage = new Image(image.getDevice(), image, SWT.IMAGE_DISABLE); } super.setEnabled(enabled); if (enabled && disabledImage != null) { disabledImage.dispose(); disabledImage = null; } } }