org.eclipse.mylyn.wikitext.ui.viewer.HtmlTextPresenter.java Source code

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Here is the source code for org.eclipse.mylyn.wikitext.ui.viewer.HtmlTextPresenter.java
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/*******************************************************************************
 * Copyright (c) 2007, 2011 David Green 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:
 *     David Green - initial API and implementation
 *******************************************************************************/
package org.eclipse.mylyn.wikitext.ui.viewer;

import java.util.regex.Pattern;

import org.eclipse.jface.resource.JFaceResources;
import org.eclipse.jface.text.DefaultInformationControl;
import org.eclipse.jface.text.TextPresentation;
import org.eclipse.mylyn.internal.wikitext.ui.viewer.HtmlTextPresentationParser;
import org.eclipse.swt.graphics.Drawable;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.widgets.Display;

/**
 * An information presenter that supports HTML markup. Uses the {@link HtmlTextPresentationParser HTML parser} to parse
 * the HTML to readable text, and creates the appropriate corresponding {@link TextPresentation text presentation}.
 * 
 * @author David Green
 * @since 1.0
 */
public class HtmlTextPresenter implements DefaultInformationControl.IInformationPresenter,
        DefaultInformationControl.IInformationPresenterExtension {

    private static Pattern HTML_OPEN_TAG_PATTERN = Pattern.compile("<html", Pattern.CASE_INSENSITIVE); //$NON-NLS-1$

    @SuppressWarnings("deprecation")
    public String updatePresentation(Display display, String hoverInfo, TextPresentation presentation, int maxWidth,
            int maxHeight) {
        return updatePresentation((Drawable) display, hoverInfo, presentation, maxWidth, maxHeight);
    }

    public String updatePresentation(Drawable drawable, String hoverInfo, TextPresentation presentation,
            int maxWidth, int maxHeight) {
        if (hoverInfo == null || hoverInfo.length() == 0) {
            return hoverInfo;
        }
        HtmlTextPresentationParser parser = new HtmlTextPresentationParser();
        parser.setPresentation(presentation);
        parser.setDefaultFont(JFaceResources.getFontRegistry().defaultFont());
        String html = hoverInfo;
        if (!HTML_OPEN_TAG_PATTERN.matcher(html).find()) {
            html = "<html><body>" + html + "</body></html>"; //$NON-NLS-1$ //$NON-NLS-2$
        }

        GC gc = new GC(drawable);
        try {
            html = html.replaceAll("<br>", "<br/>"); //$NON-NLS-1$ //$NON-NLS-2$
            parser.setMaxWidth(maxWidth);
            parser.setGC(gc);
            parser.parse(html);
            return parser.getText();
        } catch (Exception e) {
            return exceptionToHoverInfo(hoverInfo, presentation, e);
        } finally {
            gc.dispose();
        }
    }

    protected String exceptionToHoverInfo(String hoverInfo, TextPresentation presentation, Exception e) {
        presentation.clear();
        return hoverInfo;
    }

}