source: other-projects/rsyntax-textarea/src/java/org/fife/ui/rsyntaxtextarea/SquiggleUnderlineHighlightPainter.java@ 25584

/*
 * 09/13/2005
 *
 * SquiggleUnderlineHighlightPainter.java - Highlighter that draws a squiggle
 * underline under "highlighted" text, similar to error markers in Microsoft
 * Visual Studio or Eclipse.
 * 
 * This library is distributed under a modified BSD license.  See the included
 * RSyntaxTextArea.License.txt file for details.
 */
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;
        }
    }


}