org.eclipse.help.ui/src/org/eclipse/help/ui/internal/HyperlinkLabel.java

/*******************************************************************************
 * Copyright (c) 2000, 2003 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/

package org.eclipse.help.ui.internal;

import org.eclipse.swt.*;
import org.eclipse.swt.accessibility.*;
import org.eclipse.swt.events.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;

/**
 *
 * A canvas holding a hyperlink label. Need this to deal with focus selection.
 */
public class HyperlinkLabel extends Canvas{
	private Label label;
	private boolean hasFocus;

	/**
	 * Constructor for Hyperlink.
	 * @param parent
	 * @param style
	 */
	public HyperlinkLabel(Composite parent, int style) {
		super(parent, style);
		
		GridLayout layout = new GridLayout();
		layout.marginHeight = 3;
		layout.marginWidth = 2;
		layout.numColumns = 1;
		this.setLayout(layout);
		
		this.label = new Label(this, style);
		
		addPaintListener(new PaintListener() {
			public void paintControl(PaintEvent e) {
				paint(e);
			}
		});
		
		addKeyListener(new KeyAdapter() {
			public void keyPressed(KeyEvent e) {
				if (e.character == '\r') {
					// Activation
					notifyListeners(SWT.DefaultSelection);
				}
			}
		});
		
		addListener(SWT.Traverse, new Listener () {
			public void handleEvent(Event e) {
				switch (e.detail) {
					case SWT.TRAVERSE_PAGE_NEXT:
					case SWT.TRAVERSE_PAGE_PREVIOUS:
					case SWT.TRAVERSE_ARROW_NEXT:
					case SWT.TRAVERSE_ARROW_PREVIOUS:
					case SWT.TRAVERSE_RETURN:
					e.doit = false;
					return;
				}
				e.doit = true;
			}
		});
		
		addFocusListener(new FocusListener() {
			public void focusGained(FocusEvent e) {
				if (!hasFocus) {
				   hasFocus=true;
				   notifyListeners(SWT.Selection);
				   redraw();
				}
			}
			public void focusLost(FocusEvent e) {
				if (hasFocus) {
					hasFocus=false;
					notifyListeners(SWT.Selection);
					redraw();
				}
			}
		});
		
		GridData data = new GridData();
		data.horizontalAlignment = GridData.HORIZONTAL_ALIGN_BEGINNING;
		data.verticalAlignment = GridData.VERTICAL_ALIGN_BEGINNING;
		label.setLayoutData(data);

		initAccessible(this);
	}

	public void setText(String text)
	{
		label.setText(text);
	}
	
	public boolean getSelection() {
		return hasFocus;
	}

	public Label getLabel()
	{
		return label;
	}
	
	private void notifyListeners(int eventType) {
		Event event = new Event();
		event.type = eventType;
		event.widget = this;
		notifyListeners(eventType, event);
	}

	protected void paint(PaintEvent e) {
		if (hasFocus) {
			GC gc = e.gc;
			Point size = getSize();
			gc.setForeground(getForeground());
			gc.drawFocus(0, 0, size.x, size.y);
		}
	}
	
	public void addSelectionListener(SelectionListener listener) {
		checkWidget ();
		if (listener == null) return;
		TypedListener typedListener = new TypedListener (listener);
		addListener (SWT.Selection,typedListener);
		addListener (SWT.DefaultSelection,typedListener);
	}
	
	public void removeSelectionListener(SelectionListener listener) {
		checkWidget ();
		if (listener == null) return;
		removeListener (SWT.Selection, listener);
		removeListener (SWT.DefaultSelection, listener);
	}
	
	public Point computeSize(int wHint, int hHint, boolean changed) {
		int innerWidth = wHint;
		if (innerWidth!=SWT.DEFAULT)
		   innerWidth -= 4;
		Point textSize = label.computeSize(wHint, hHint, changed);//computeTextSize(innerWidth, hHint);
		int textWidth = textSize.x + 4;
		int textHeight = textSize.y + 6;
		return new Point(textWidth, textHeight);
	}
	
	public void addMouseListener(MouseListener l) {
		//super.addMouseListener(l);
		label.addMouseListener(l);
	}
	
	public void addMouseTrackListener(MouseTrackListener l) {
		//super.addMouseTrackListener(l);
		label.addMouseTrackListener(l);
	}
	
	public void addPaintListener(PaintListener l) {
		super.addPaintListener(l);
		label.addPaintListener(l);
	}
	
	public void addListener(int e, Listener l) {
		super.addListener(e, l);
		//label.addListener(e, l);
	}
		
	public void setBackground(Color c) {
		super.setBackground(c);
		label.setBackground(c);
	}
	
	public void setForeground(Color c) {
		super.setForeground(c);
		label.setForeground(c);
	}
	
	public void setCursor(Cursor c) {
		super.setCursor(c);
		label.setCursor(c);
	}
	
	private void initAccessible(final Control control) {
		Accessible accessible = control.getAccessible();
		accessible.addAccessibleListener(new AccessibleAdapter() {
			public void getName(AccessibleEvent e) {
				e.result = label.getText();
			}

			public void getHelp(AccessibleEvent e) {
				e.result = label.getToolTipText();
			}
		});

		accessible
			.addAccessibleControlListener(new AccessibleControlAdapter() {
			public void getChildAtPoint(AccessibleControlEvent e) {
				Point pt = label.toControl(new Point(e.x, e.y));
				e.childID =
					(control.getBounds().contains(pt))
						? ACC.CHILDID_SELF
						: ACC.CHILDID_NONE;
			}

			public void getLocation(AccessibleControlEvent e) {
				Rectangle location = label.getBounds();
				Point pt = control.toDisplay(new Point(location.x, location.y));
				e.x = pt.x;
				e.y = pt.y;
				e.width = location.width;
				e.height = location.height;
			}

			public void getChildCount(AccessibleControlEvent e) {
				e.detail = 0;
			}

			public void getRole(AccessibleControlEvent e) {
				e.detail = ACC.ROLE_TEXT;
			}

			public void getState(AccessibleControlEvent e) {
				e.detail = ACC.STATE_READONLY;
			}
		});
	}
}