HTMLTextPresenter.java

/*******************************************************************************
 * Copyright (c) 2000, 2016 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
 *     QNX Software System
 *******************************************************************************/
package org.eclipse.cdt.internal.autotools.ui;

import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.util.Iterator;

import org.eclipse.cdt.autotools.ui.AutotoolsUIPlugin;
import org.eclipse.jface.text.DefaultInformationControl;
import org.eclipse.jface.text.Region;
import org.eclipse.jface.text.TextPresentation;
import org.eclipse.swt.custom.StyleRange;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.widgets.Display;


public class HTMLTextPresenter implements DefaultInformationControl.IInformationPresenter {
	
	private static final String LINE_DELIM= System.getProperty("line.separator", "\n"); //$NON-NLS-1$ //$NON-NLS-2$
	
	private int fCounter;
	private boolean fEnforceUpperLineLimit;
	
	public HTMLTextPresenter(boolean enforceUpperLineLimit) {
		super();
		fEnforceUpperLineLimit= enforceUpperLineLimit;
	}
	
	public HTMLTextPresenter() {
		this(true);
	}
	
	protected Reader createReader(String hoverInfo, TextPresentation presentation) {
		return new HTML2TextReader(new StringReader(hoverInfo), presentation);
	}
	
	protected void adaptTextPresentation(TextPresentation presentation, int offset, int insertLength) {
				
		int yoursStart= offset;
		
		Iterator<StyleRange> e = presentation.getAllStyleRangeIterator();
		while (e.hasNext()) {
			
			StyleRange range= e.next();
		
			int myStart= range.start;
			int myEnd=   range.start + range.length -1;
			myEnd= Math.max(myStart, myEnd);
			
			if (myEnd < yoursStart)
				continue;
			
			if (myStart < yoursStart)
				range.length += insertLength;
			else
				range.start += insertLength;
		}
	}
	
	private void append(StringBuilder buffer, String string, TextPresentation presentation) {
		
		int length= string.length();
		buffer.append(string);
		
		if (presentation != null)
			adaptTextPresentation(presentation, fCounter, length);
			
		fCounter += length;
	}
	
	private String getIndent(String line) {
		int length= line.length();
		
		int i= 0;
		while (i < length && Character.isWhitespace(line.charAt(i))) ++i;
		
		return (i == length ? line : line.substring(0, i)) + " "; //$NON-NLS-1$
	}
	
	@Override
	public String updatePresentation(Display display, String hoverInfo, TextPresentation presentation, int maxWidth, int maxHeight) {
		
		if (hoverInfo == null)
			return null;
			
		GC gc= new GC(display);
		try {
			
			StringBuilder buffer= new StringBuilder();
			int maxNumberOfLines= Math.round((float)maxHeight / gc.getFontMetrics().getHeight());
			
			fCounter= 0;
			LineBreakingReader reader= new LineBreakingReader(createReader(hoverInfo, presentation), gc, maxWidth);
			
			boolean lastLineFormatted= false;
			String lastLineIndent= null;
			
			String line=reader.readLine();
			boolean lineFormatted= reader.isFormattedLine();
			boolean firstLineProcessed= false;
			
			while (line != null) {
				
				if (fEnforceUpperLineLimit && maxNumberOfLines <= 0)
					break;
				
				if (firstLineProcessed) {
					if (!lastLineFormatted)
						append(buffer, LINE_DELIM, null);
					else {
						append(buffer, LINE_DELIM, presentation);
						if (lastLineIndent != null)
							append(buffer, lastLineIndent, presentation);
					}
				}
				
				append(buffer, line, null);
				firstLineProcessed= true;
				
				lastLineFormatted= lineFormatted;
				if (!lineFormatted)
					lastLineIndent= null;
				else if (lastLineIndent == null)
					lastLineIndent= getIndent(line);
					
				line= reader.readLine();
				lineFormatted= reader.isFormattedLine();
				
				maxNumberOfLines--;
			}
			
			if (line != null) {
				append(buffer, LINE_DELIM, lineFormatted ? presentation : null);
				append(buffer, (""), presentation); //$NON-NLS-1$
			}
			
			return trim(buffer, presentation);
			
		} catch (IOException e) {
			
			AutotoolsUIPlugin.log(e);
			return null;
			
		} finally {
			gc.dispose();
		}
	}
	
	private String trim(StringBuilder buffer, TextPresentation presentation) {
		
		int length= buffer.length();
				
		int end= length -1;
		while (end >= 0 && Character.isWhitespace(buffer.charAt(end)))
			-- end;
		
		if (end == -1)
			return ""; //$NON-NLS-1$
			
		if (end < length -1)
			buffer.delete(end + 1, length);
		else
			end= length;
			
		int start= 0;
		while (start < end && Character.isWhitespace(buffer.charAt(start)))
			++ start;
			
		buffer.delete(0, start);
		presentation.setResultWindow(new Region(start, buffer.length()));
		return buffer.toString();
	}
}