org.eclipse.swt.widgets.Link.java Source code

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/*******************************************************************************
 * Copyright (c) 2002, 2016 Innoopract Informationssysteme GmbH 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:
 *    Innoopract Informationssysteme GmbH - initial API and implementation
 *    EclipseSource - ongoing development
 ******************************************************************************/
package org.eclipse.swt.widgets;

import org.eclipse.rap.rwt.internal.lifecycle.WidgetLCA;
import org.eclipse.rap.rwt.internal.textsize.TextSizeUtil;
import org.eclipse.rap.rwt.theme.BoxDimensions;
import org.eclipse.swt.SWT;
import org.eclipse.swt.SWTException;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.events.SelectionListener;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.internal.widgets.ILinkAdapter;
import org.eclipse.swt.internal.widgets.linkkit.LinkLCA;

/**
 * Instances of this class represent a selectable
 * user interface object that displays a text with
 * links.
 * <p>
 * <dl>
 * <dt><b>Styles:</b></dt>
 * <dd>(none)</dd>
 * <dt><b>Events:</b></dt>
 * <dd>Selection</dd>
 * </dl>
 * <p>
 * IMPORTANT: This class is <em>not</em> intended to be subclassed.
 * </p>
 *
 * @since 1.0
 */
public class Link extends Control {

    private String text;
    private String displayText;
    private Point[] offsets;
    private String[] ids;
    private int[] mnemonics;
    private transient ILinkAdapter linkAdapter;

    /**
     * Constructs a new instance of this class given its parent
     * and a style value describing its behavior and appearance.
     * <p>
     * The style value is either one of the style constants defined in
     * class <code>SWT</code> which is applicable to instances of this
     * class, or must be built by <em>bitwise OR</em>'ing together
     * (that is, using the <code>int</code> "|" operator) two or more
     * of those <code>SWT</code> style constants. The class description
     * lists the style constants that are applicable to the class.
     * Style bits are also inherited from superclasses.
     * </p>
     *
     * @param parent a composite control which will be the parent of the new instance (cannot be null)
     * @param style the style of control to construct
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the parent is null</li>
     * </ul>
     * @exception SWTException <ul>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li>
     *    <li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li>
     * </ul>
     *
     * @see Widget#checkSubclass
     * @see Widget#getStyle
     */
    public Link(Composite parent, int style) {
        super(parent, style);
        text = "";
        displayText = "";
    }

    @Override
    void initState() {
        addState(THEME_BACKGROUND);
    }

    /**
     * Sets the receiver's text.
     * <p>
     * The string can contain both regular text and hyperlinks.  A hyperlink
     * is delimited by an anchor tag, &lt;A&gt; and &lt;/A&gt;.  Within an
     * anchor, a single HREF attribute is supported.  When a hyperlink is
     * selected, the text field of the selection event contains either the
     * text of the hyperlink or the value of its HREF, if one was specified.
     * In the rare case of identical hyperlinks within the same string, the
     * HREF tag can be used to distinguish between them.  The string may
     * include the mnemonic character and line delimiters.
     * </p>
     *
     * @param string the new text
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the text is null</li>
     * </ul>
     * @exception SWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
     * </ul>
     */
    public void setText(String string) {
        checkWidget();
        if (string == null) {
            SWT.error(SWT.ERROR_NULL_ARGUMENT);
        }
        if (!string.equals(text)) {
            displayText = parse(string);
            text = string;
        }
    }

    /**
     * Returns the receiver's text, which will be an empty
     * string if it has never been set.
     *
     * @return the receiver's text
     *
     * @exception SWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
     * </ul>
     */
    public String getText() {
        checkWidget();
        return text;
    }

    ///////////////////////////////////////
    // Listener registration/deregistration

    /**
     * Adds the listener to the collection of listeners who will
     * be notified when the control is selected, by sending
     * it one of the messages defined in the <code>SelectionListener</code>
     * interface.
     * <p>
     * <code>widgetSelected</code> is called when the control is selected.
     * <code>widgetDefaultSelected</code> is not called.
     * </p>
     *
     * @param listener the listener which should be notified
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
     * </ul>
     * @exception SWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
     * </ul>
     *
     * @see SelectionListener
     * @see #removeSelectionListener
     * @see SelectionEvent
     */
    public void addSelectionListener(SelectionListener listener) {
        checkWidget();
        if (listener == null) {
            SWT.error(SWT.ERROR_NULL_ARGUMENT);
        }
        TypedListener typedListener = new TypedListener(listener);
        addListener(SWT.Selection, typedListener);
        addListener(SWT.DefaultSelection, typedListener);
    }

    /**
     * Removes the listener from the collection of listeners who will
     * be notified when the control is selected.
     *
     * @param listener the listener which should no longer be notified
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
     * </ul>
     * @exception SWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
     * </ul>
     *
     * @see SelectionListener
     * @see #addSelectionListener
     */
    public void removeSelectionListener(SelectionListener listener) {
        checkWidget();
        if (listener == null) {
            SWT.error(SWT.ERROR_NULL_ARGUMENT);
        }
        removeListener(SWT.Selection, listener);
        removeListener(SWT.DefaultSelection, listener);
    }

    @Override
    public Point computeSize(int wHint, int hHint, boolean changed) {
        checkWidget();
        int width = 0;
        int height = 0;
        if ((displayText.length() > 0)) {
            // Replace '&' with '&&' to ensure proper size calculation with one '&',
            // because the other will be escaped in
            // TextSizeUtil#createMeasureString()
            String string = escapeAmpersand(displayText);
            Point extent = TextSizeUtil.textExtent(getFont(), string, wHint);
            width = extent.x;
            height = extent.y;
        }
        if (wHint != SWT.DEFAULT) {
            width = wHint;
        }
        if (hHint != SWT.DEFAULT) {
            height = hHint;
        }
        BoxDimensions border = getBorder();
        BoxDimensions padding = getPadding();
        width += border.left + border.right + padding.left + padding.right;
        height += border.top + border.bottom + padding.top + padding.bottom;
        return new Point(width, height);
    }

    private static String escapeAmpersand(String string) {
        StringBuilder result = new StringBuilder();
        for (int i = 0; i < string.length(); i++) {
            if (string.charAt(i) == '&') {
                result.append("&&");
            } else {
                result.append(string.charAt(i));
            }
        }
        return result.toString();
    }

    @Override
    @SuppressWarnings("unchecked")
    public <T> T getAdapter(Class<T> adapter) {
        if (adapter == ILinkAdapter.class) {
            if (linkAdapter == null) {
                linkAdapter = new ILinkAdapter() {
                    @Override
                    public String getDisplayText() {
                        return displayText;
                    }

                    @Override
                    public Point[] getOffsets() {
                        return offsets;
                    }

                    @Override
                    public String[] getIds() {
                        return ids;
                    }
                };
            }
            return (T) linkAdapter;
        }
        if (adapter == WidgetLCA.class) {
            return (T) LinkLCA.INSTANCE;
        }
        return super.getAdapter(adapter);
    }

    @Override
    boolean isTabGroup() {
        return true;
    }

    @Override
    String getNameText() {
        return getText();
    }

    /* verbatim copy from SWT */
    @SuppressWarnings("all")
    String parse(String string) {
        int length = string.length();
        offsets = new Point[length / 4];
        ids = new String[length / 4];
        mnemonics = new int[length / 4 + 1];
        StringBuffer result = new StringBuffer();
        char[] buffer = new char[length];
        string.getChars(0, string.length(), buffer, 0);
        int index = 0, state = 0, linkIndex = 0;
        int start = 0, tagStart = 0, linkStart = 0, endtagStart = 0, refStart = 0;
        while (index < length) {
            char c = Character.toLowerCase(buffer[index]);
            switch (state) {
            case 0:
                if (c == '<') {
                    tagStart = index;
                    state++;
                }
                break;
            case 1:
                if (c == 'a') {
                    state++;
                }
                break;
            case 2:
                switch (c) {
                case 'h':
                    state = 7;
                    break;
                case '>':
                    linkStart = index + 1;
                    state++;
                    break;
                default:
                    if (Character.isWhitespace(c)) {
                        break;
                    } else {
                        state = 13;
                    }
                }
                break;
            case 3:
                if (c == '<') {
                    endtagStart = index;
                    state++;
                }
                break;
            case 4:
                state = c == '/' ? state + 1 : 3;
                break;
            case 5:
                state = c == 'a' ? state + 1 : 3;
                break;
            case 6:
                if (c == '>') {
                    mnemonics[linkIndex] = parseMnemonics(buffer, start, tagStart, result);
                    int offset = result.length();
                    parseMnemonics(buffer, linkStart, endtagStart, result);
                    offsets[linkIndex] = new Point(offset, result.length() - 1);
                    if (ids[linkIndex] == null) {
                        ids[linkIndex] = new String(buffer, linkStart, endtagStart - linkStart);
                    }
                    linkIndex++;
                    start = tagStart = linkStart = endtagStart = refStart = index + 1;
                    state = 0;
                } else {
                    state = 3;
                }
                break;
            case 7:
                state = c == 'r' ? state + 1 : 0;
                break;
            case 8:
                state = c == 'e' ? state + 1 : 0;
                break;
            case 9:
                state = c == 'f' ? state + 1 : 0;
                break;
            case 10:
                state = c == '=' ? state + 1 : 0;
                break;
            case 11:
                if (c == '"') {
                    state++;
                    refStart = index + 1;
                } else {
                    state = 0;
                }
                break;
            case 12:
                if (c == '"') {
                    ids[linkIndex] = new String(buffer, refStart, index - refStart);
                    state = 2;
                }
                break;
            case 13:
                if (Character.isWhitespace(c)) {
                    state = 0;
                } else if (c == '=') {
                    state++;
                }
                break;
            case 14:
                state = c == '"' ? state + 1 : 0;
                break;
            case 15:
                if (c == '"') {
                    state = 2;
                }
                break;
            default:
                state = 0;
                break;
            }
            index++;
        }
        if (start < length) {
            int tmp = parseMnemonics(buffer, start, tagStart, result);
            int mnemonic = parseMnemonics(buffer, Math.max(tagStart, linkStart), length, result);
            if (mnemonic == -1) {
                mnemonic = tmp;
            }
            mnemonics[linkIndex] = mnemonic;
        } else {
            mnemonics[linkIndex] = -1;
        }
        if (offsets.length != linkIndex) {
            Point[] newOffsets = new Point[linkIndex];
            System.arraycopy(offsets, 0, newOffsets, 0, linkIndex);
            offsets = newOffsets;
            String[] newIDs = new String[linkIndex];
            System.arraycopy(ids, 0, newIDs, 0, linkIndex);
            ids = newIDs;
            int[] newMnemonics = new int[linkIndex + 1];
            System.arraycopy(mnemonics, 0, newMnemonics, 0, linkIndex + 1);
            mnemonics = newMnemonics;
        }
        return result.toString();
    }

    /* verbatim copy from SWT */
    int parseMnemonics(char[] buffer, int start, int end, StringBuffer result) {
        int mnemonic = -1, index = start;
        while (index < end) {
            if (buffer[index] == '&') {
                if (index + 1 < end && buffer[index + 1] == '&') {
                    result.append(buffer[index]);
                    index++;
                } else {
                    mnemonic = result.length();
                }
            } else {
                result.append(buffer[index]);
            }
            index++;
        }
        return mnemonic;
    }

}