source: trunk/org.modelica.mdt.ui/src/org/modelica/mdt/ui/hover/HTMLTextPresenter.java

package org.modelica.mdt.ui.hover;

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

import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.StyleRange;
import org.eclipse.swt.graphics.Drawable;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.FontData;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.widgets.Display;

import org.modelica.mdt.ui.hover.HTML2TextReader;
import org.modelica.mdt.ui.hover.LineBreakingReader;
import org.eclipse.jface.text.DefaultInformationControl;
import org.eclipse.jface.text.Region;
import org.eclipse.jface.text.TextPresentation;


public class HTMLTextPresenter implements DefaultInformationControl.IInformationPresenter, DefaultInformationControl.IInformationPresenterExtension {

    private static final String LINE_DELIM= System.getProperty("line.separator", "\n"); //$NON-NLS-1$ //$NON-NLS-2$

    private int fCounter;
    private boolean fEnforceUpperLineLimit;

    /**
     * Enables using bold font in order not to clip the text.
     * <p>
     * <em>Enabling this is a hack.</em>
     * 
     * @since 3.2
     */
    private boolean fUseBoldFont= false;

    public HTMLTextPresenter(boolean enforceUpperLineLimit) {
        super();
        fEnforceUpperLineLimit= enforceUpperLineLimit;
    }

    public HTMLTextPresenter() {
        this(true);
    }

    protected HTML2TextReader createReader(String hoverInfo, TextPresentation presentation) {
        return new HTML2TextReader(new StringReader(hoverInfo), presentation);
    }

    protected void adaptTextPresentation(TextPresentation presentation, int offset, int insertLength) {

        int yoursStart= offset;
        int yoursEnd=   offset + insertLength -1;
        yoursEnd= Math.max(yoursStart, yoursEnd);

        Iterator<?> e= presentation.getAllStyleRangeIterator();
        while (e.hasNext()) {

            StyleRange range= (StyleRange) 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(StringBuffer 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)) + " "; //$NON-NLS-1$
    }

    /*
     * @see IHoverInformationPresenter#updatePresentation(Display display, String, TextPresentation, int, int)
     */
    public String updatePresentation(Display display, String hoverInfo, TextPresentation presentation, int maxWidth, int maxHeight) {
        return updatePresentation((Drawable)display, hoverInfo, presentation, maxWidth, maxHeight);
    }
    
    /*
     * @see IHoverInformationPresenterExtension#updatePresentation(Drawable drawable, String, TextPresentation, int, int)
     * @since 3.2
     */
    public String updatePresentation(Drawable drawable, String hoverInfo, TextPresentation presentation, int maxWidth, int maxHeight) {

        if (hoverInfo == null)
            return null;

        GC gc= new GC(drawable);
        
        Font font= null;
        if (fUseBoldFont) {
            font= gc.getFont();
            FontData[] fontData= font.getFontData();
            for (int i= 0; i < fontData.length; i++)
                fontData[i].setStyle(SWT.BOLD);
            font= new Font(gc.getDevice(), fontData);
            gc.setFont(font);
        }
        
        try {

            StringBuffer buffer= new StringBuffer();
            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 && buffer.length() > 0) {
                append(buffer, LINE_DELIM, lineFormatted ? presentation : null);
                append(buffer, "", presentation);
            }

            return trim(buffer, presentation);

        } catch (IOException e) {

            e.printStackTrace();
            return null;

        } finally {
            if (font != null)
                font.dispose(); 
            gc.dispose();
        }
    }
    
    private String trim(StringBuffer 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();
    }
}