ByteEdit/src/org/fife/ui/rsyntaxtextarea/VisibleWhitespaceTokenPainter.java

/*
 * 03/16/2013
 *
 * VisibleWhitespaceTokenPainter - Renders tokens in an instance of
 * RSyntaxTextArea, with special glyphs to denote spaces and tabs.
 *
 * 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.FontMetrics;
import java.awt.Graphics2D;
import javax.swing.text.TabExpander;


/**
 * A token painter that visibly renders whitespace (spaces and tabs).<p>
 *
 * The current implementation paints as follows:
 * <ul>
 *   <li>The first tab or space, if any, is found in the token.</li>
 *   <li>If a tab was found, all characters up to it are painted as a
 *       group.</li>
 *   <li>If a space was found, all characters up to and including it are
 *       painted (it is painted with a special symbol to denote it as
 *       a space).</li>
 *   <li>If neither a tab nor a whitespace was found, all characters in the
 *       token are painted.</li>
 *   <li>Repeat until all characters are painted.</li>
 * </ul>
 * This means that rendering hints are applied to all groups of characters
 * within a token, excluding whitespace and tabs.<p>
 *
 * A problem with this implementation is that FontMetrics.charsWidth() is still
 * used to calculate the width of a group of chars painted.  Thus, the group of
 * characters will be painted with the rendering hints specified, but the
 * following tab (or group of characters if the current group was the end of a
 * token) will not necessarily be painted at the proper x-coordinate (as
 * FontMetrics.charsWidth() returns an <code>int</code> and not a
 * <code>float</code>).  The way around this would be to calculate the token's
 * width in such a way that a float is returned (Font.getStringBounds()?).
 *
 * @author Robert Futrell
 * @version 1.0
 */
class VisibleWhitespaceTokenPainter extends DefaultTokenPainter {


	/**
	 * {@inheritDoc}
	 */
	@Override
	protected float paintImpl(Token token, Graphics2D g, float x, float y,
			RSyntaxTextArea host, TabExpander e, float clipStart,
			boolean selected, boolean useSTC) {

		int origX = (int)x;
		int textOffs = token.getTextOffset();
		char[] text = token.getTextArray();
		int end = textOffs + token.length();
		float nextX = x;
		int flushLen = 0;
		int flushIndex = textOffs;
		Color fg = useSTC ? host.getSelectedTextColor() :
			host.getForegroundForToken(token);
		Color bg = selected ? null : host.getBackgroundForToken(token);
		g.setFont(host.getFontForTokenType(token.getType()));
		FontMetrics fm = host.getFontMetricsForTokenType(token.getType());

		int ascent = fm.getAscent();
		int height = fm.getHeight();

		for (int i=textOffs; i<end; i++) {

			switch (text[i]) {

				case '\t':

					// Fill in background.
					nextX = x+fm.charsWidth(text, flushIndex,flushLen);
					float nextNextX = e.nextTabStop(nextX, 0);
					if (bg!=null) {
						paintBackground(x,y, nextNextX-x,height, g,
										ascent, host, bg);
					}
					g.setColor(fg);

					// Paint chars cached before the tab.
					if (flushLen > 0) {
						g.drawChars(text, flushIndex, flushLen, (int)x,(int)y);
						flushLen = 0;
					}
					flushIndex = i + 1;

					// Draw an arrow representing the tab.
					int halfHeight = height / 2;
					int quarterHeight = halfHeight / 2;
					int ymid = (int)y - ascent + halfHeight;
					g.drawLine((int)nextX,ymid, (int)nextNextX,ymid);
					g.drawLine((int)nextNextX,ymid, (int)nextNextX-4,ymid-quarterHeight);
					g.drawLine((int)nextNextX,ymid, (int)nextNextX-4,ymid+quarterHeight);

					x = nextNextX;
					break;

				case ' ':

					// NOTE:  There is a little bit of a "fudge factor"
					// here when "smooth text" is enabled, as "width"
					// below may well not be the width given to the space
					// by fm.charsWidth() (it depends on how it places the
					// space with respect to the preceding character).
					// But, we assume the approximation is close enough for
					// our drawing a dot for the space.

					// "flushLen+1" ensures text is aligned correctly (or,
					// aligned the same as in getWidth()).
					nextX = x+fm.charsWidth(text, flushIndex,flushLen+1);
					int width = fm.charWidth(' ');

					// Paint background.
					if (bg!=null) {
						paintBackground(x,y, nextX-x,height, g,
										ascent, host, bg);
					}
					g.setColor(fg);

					// Paint chars before space.
					if (flushLen>0) {
						g.drawChars(text, flushIndex, flushLen, (int)x,(int)y);
						flushLen = 0;
					}

					// Paint a dot representing the space.
					int dotX = (int)(nextX - width/2f); // "2.0f" for FindBugs
					int dotY = (int)(y - ascent + height/2f); // Ditto
					g.drawLine(dotX, dotY, dotX, dotY);
					flushIndex = i + 1;
					x = nextX;
					break;


				case '\f':
					// ???
					// fall-through for now.

				default:
					flushLen += 1;
					break;

			}
		}

		nextX = x+fm.charsWidth(text, flushIndex,flushLen);

		if (flushLen>0 && nextX>=clipStart) {
			if (bg!=null) {
				paintBackground(x,y, nextX-x,height, g,
							ascent, host, bg);
			}
			g.setColor(fg);
			g.drawChars(text, flushIndex, flushLen, (int)x,(int)y);
		}

		if (host.getUnderlineForToken(token)) {
			g.setColor(fg);
			int y2 = (int)(y+1);
			g.drawLine(origX,y2, (int)nextX,y2);
		}

		// Don't check if it's whitespace - some TokenMakers may return types
		// other than Token.WHITESPACE for spaces (such as Token.IDENTIFIER).
		// This also allows us to paint tab lines for MLC's.
		if (host.getPaintTabLines() && origX==host.getMargin().left) {// && isWhitespace()) {
			paintTabLines(token, origX, (int)y, (int)nextX, g, e, host);
		}

		return nextX;

	}


}