SquiggleUnderlineHighlightPainter.java

/*
 * 09/13/2005
 *
 * SquiggleUnderlineHighlightPainter.java - Highlighter that draws a squiggle
 * underline under "highlighted" text, similar to error markers in Microsoft
 * Visual Studio or Eclipse.
 * Copyright (C) 2005 Robert Futrell
 * robert_futrell at users.sourceforge.net
 * http://fifesoft.com/rsyntaxtextarea
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA.
 */
package org.fife.ui.rsyntaxtextarea;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.awt.Shape;
import javax.swing.text.BadLocationException;
import javax.swing.text.JTextComponent;
import javax.swing.text.Position;
import javax.swing.text.View;

/**
 * Highlight painter that paints a squiggly underline underneath text, similar to what popular IDE's such as Visual
 * Studio and Eclipse do to indicate errors, warnings, etc.
 * <p>
 * 
 * This class must be used as a <code>LayerPainter</code>.
 * 
 * @author Robert Futrell
 * @version 1.0
 */
public class SquiggleUnderlineHighlightPainter
        extends ChangeableColorHighlightPainter {

    private static final int AMT = 2;

    /**
     * Constructor.
     * 
     * @param color
     *            The color of the squiggle. This cannot be <code>null</code>.
     */
    public SquiggleUnderlineHighlightPainter(Color color) {
        super(color);
        setColor(color);
    }

    /**
     * Paints a portion of a highlight.
     * 
     * @param g
     *            the graphics context
     * @param offs0
     *            the starting model offset >= 0
     * @param offs1
     *            the ending model offset >= offs1
     * @param bounds
     *            the bounding box of the view, which is not necessarily the region to paint.
     * @param c
     *            the editor
     * @param view
     *            View painting for
     * @return region drawing occurred in
     */
    public Shape paintLayer(Graphics g, int offs0, int offs1,
            Shape bounds, JTextComponent c, View view) {

        g.setColor(getColor());

        if (offs0 == view.getStartOffset() && offs1 == view.getEndOffset()) {
            // Contained in view, can just use bounds.
            Rectangle alloc;
            if (bounds instanceof Rectangle)
                alloc = (Rectangle) bounds;
            else
                alloc = bounds.getBounds();
            paintSquiggle(g, alloc);
            return alloc;
        }

        // Otherwise, should only render part of View.
        try {
            // --- determine locations ---
            Shape shape = view.modelToView(offs0, Position.Bias.Forward,
                    offs1, Position.Bias.Backward,
                    bounds);
            Rectangle r = (shape instanceof Rectangle) ?
                    (Rectangle) shape : shape.getBounds();
            paintSquiggle(g, r);
            return r;
        } catch (BadLocationException e) {
            e.printStackTrace(); // can't render
        }

        // Only if exception
        return null;

    }

    /**
     * Paints a squiggle underneath text in the specified rectangle.
     * 
     * @param g
     *            The graphics context with which to paint.
     * @param r
     *            The rectangle containing the text.
     */
    protected void paintSquiggle(Graphics g, Rectangle r) {
        int x = r.x;
        int y = r.y + r.height - 1;
        int delta = -AMT;
        while (x < r.x + r.width) {
            g.drawLine(x, y, x + AMT, y + delta);
            y += delta;
            delta = -delta;
            x += AMT;
        }
    }

}