Java tutorial
/******************************************************************************* * Copyright (c) 2004, 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 *******************************************************************************/ package org.eclipse.ui.forms.widgets; import org.eclipse.swt.SWT; import org.eclipse.swt.accessibility.ACC; import org.eclipse.swt.accessibility.Accessible; import org.eclipse.swt.accessibility.AccessibleAdapter; import org.eclipse.swt.accessibility.AccessibleControlAdapter; import org.eclipse.swt.accessibility.AccessibleControlEvent; import org.eclipse.swt.accessibility.AccessibleEvent; import org.eclipse.swt.graphics.Color; import org.eclipse.swt.graphics.GC; import org.eclipse.swt.graphics.Point; import org.eclipse.swt.graphics.Rectangle; import org.eclipse.swt.widgets.Composite; import org.eclipse.ui.forms.FormColors; import org.eclipse.ui.internal.forms.widgets.FormUtil; /** * Hyperlink is a concrete implementation of the abstract base class that draws * text in the client area. Text can be wrapped and underlined. Hyperlink is * typically added to the hyperlink group so that certain properties are managed * for all the hyperlinks that belong to it. * <p> * Hyperlink can be extended. * <p> * <dl> * <dt><b>Styles:</b></dt> * <dd>SWT.WRAP</dd> * </dl> * * @see org.eclipse.ui.forms.HyperlinkGroup * @since 3.0 */ public class Hyperlink extends AbstractHyperlink { private String text; private static final String ELLIPSIS = "..."; //$NON-NLS-1$ private boolean underlined; // The tooltip is used for two purposes - the application can set // a tooltip or the tooltip can be used to display the full text when the // the text has been truncated due to the label being too short. // The appToolTip stores the tooltip set by the application. Control.tooltiptext // contains whatever tooltip is currently being displayed. private String appToolTipText; /** * Creates a new hyperlink control in the provided parent. * * @param parent * the control parent * @param style * the widget style */ public Hyperlink(Composite parent, int style) { super(parent, style); initAccessible(); } protected void initAccessible() { Accessible accessible = getAccessible(); accessible.addAccessibleListener(new AccessibleAdapter() { @Override public void getName(AccessibleEvent e) { e.result = getText(); if (e.result == null) getHelp(e); } @Override public void getHelp(AccessibleEvent e) { e.result = getToolTipText(); } }); accessible.addAccessibleControlListener(new AccessibleControlAdapter() { @Override public void getChildAtPoint(AccessibleControlEvent e) { Point pt = toControl(new Point(e.x, e.y)); e.childID = (getBounds().contains(pt)) ? ACC.CHILDID_SELF : ACC.CHILDID_NONE; } @Override public void getLocation(AccessibleControlEvent e) { Rectangle location = getBounds(); Point pt = toDisplay(new Point(location.x, location.y)); e.x = pt.x; e.y = pt.y; e.width = location.width; e.height = location.height; } @Override public void getChildCount(AccessibleControlEvent e) { e.detail = 0; } @Override public void getRole(AccessibleControlEvent e) { e.detail = ACC.ROLE_LINK; } @Override public void getDefaultAction(AccessibleControlEvent e) { e.result = SWT.getMessage("SWT_Press"); //$NON-NLS-1$ } @Override public void getState(AccessibleControlEvent e) { int state = ACC.STATE_NORMAL; if (Hyperlink.this.getSelection()) state = ACC.STATE_SELECTED | ACC.STATE_FOCUSED; e.detail = state; } }); } /** * Sets the underlined state. It is not necessary to call this method when * in a hyperlink group. * * @param underlined * if <samp>true </samp>, a line will be drawn below the text for * each wrapped line. */ public void setUnderlined(boolean underlined) { this.underlined = underlined; redraw(); } /** * Returns the underline state of the hyperlink. * * @return <samp>true </samp> if text is underlined, <samp>false </samp> * otherwise. */ public boolean isUnderlined() { return underlined; } /** * Overrides the parent by incorporating the margin. */ @Override public Point computeSize(int wHint, int hHint, boolean changed) { checkWidget(); int innerWidth = wHint; if (innerWidth != SWT.DEFAULT) innerWidth -= marginWidth * 2; Point textSize = computeTextSize(innerWidth, hHint); int textWidth = textSize.x + 2 * marginWidth; int textHeight = textSize.y + 2 * marginHeight; return new Point(textWidth, textHeight); } /** * Returns the current hyperlink text. * * @return hyperlink text */ @Override public String getText() { return text; } @Override public String getToolTipText() { checkWidget(); return appToolTipText; } @Override public void setToolTipText(String string) { super.setToolTipText(string); appToolTipText = super.getToolTipText(); } /** * Sets the text of this hyperlink. * * @param text * the hyperlink text */ public void setText(String text) { if (text != null) this.text = text; else this.text = ""; //$NON-NLS-1$ redraw(); } /** * Paints the hyperlink text. * * @param gc * graphic context */ @Override protected void paintHyperlink(GC gc) { Rectangle carea = getClientArea(); Rectangle bounds = new Rectangle(marginWidth, marginHeight, carea.width - marginWidth - marginWidth, carea.height - marginHeight - marginHeight); paintText(gc, bounds); } /** * Paints the hyperlink text in provided bounding rectangle. * * @param gc * graphic context * @param bounds * the bounding rectangle in which to paint the text */ protected void paintText(GC gc, Rectangle bounds) { gc.setFont(getFont()); Color fg = isEnabled() ? getForeground() : new Color(gc.getDevice(), FormColors.blend(getBackground().getRGB(), getForeground().getRGB(), 70)); try { gc.setForeground(fg); if ((getStyle() & SWT.WRAP) != 0) { FormUtil.paintWrapText(gc, text, bounds, underlined); } else { Point totalSize = computeTextSize(SWT.DEFAULT, SWT.DEFAULT); boolean shortenText = false; if (bounds.width < totalSize.x) { // shorten shortenText = true; } int textWidth = Math.min(bounds.width, totalSize.x); int textHeight = totalSize.y; String textToDraw = getText(); if (shortenText) { textToDraw = shortenText(gc, getText(), bounds.width); if (appToolTipText == null) { super.setToolTipText(getText()); } } else { super.setToolTipText(appToolTipText); } gc.drawText(textToDraw, bounds.x, bounds.y, true); if (underlined) { int descent = gc.getFontMetrics().getDescent(); int lineY = bounds.y + textHeight - descent + 1; gc.drawLine(bounds.x, lineY, bounds.x + textWidth, lineY); } } } finally { if (!isEnabled() && fg != null) fg.dispose(); } } protected String shortenText(GC gc, String t, int width) { if (t == null) return null; int w = gc.textExtent(ELLIPSIS).x; if (width <= w) return t; int l = t.length(); int max = l / 2; int min = 0; int mid = (max + min) / 2 - 1; if (mid <= 0) return t; while (min < mid && mid < max) { String s1 = t.substring(0, mid); String s2 = t.substring(l - mid, l); int l1 = gc.textExtent(s1).x; int l2 = gc.textExtent(s2).x; if (l1 + w + l2 > width) { max = mid; mid = (max + min) / 2; } else if (l1 + w + l2 < width) { min = mid; mid = (max + min) / 2; } else { min = max; } } if (mid == 0) return t; return t.substring(0, mid) + ELLIPSIS + t.substring(l - mid, l); } protected Point computeTextSize(int wHint, int hHint) { Point extent; GC gc = new GC(this); gc.setFont(getFont()); if ((getStyle() & SWT.WRAP) != 0 && wHint != SWT.DEFAULT) { extent = FormUtil.computeWrapSize(gc, getText(), wHint); } else { extent = gc.textExtent(getText()); if ((getStyle() & SWT.WRAP) == 0 && wHint != SWT.DEFAULT) extent.x = wHint; } gc.dispose(); return extent; } }