LaTeXPanel.java

package org.geogebra.desktop.cas.view;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;

import javax.swing.JPanel;

import org.geogebra.common.awt.GDimension;
import org.geogebra.desktop.awt.GColorD;
import org.geogebra.desktop.awt.GGraphics2DD;
import org.geogebra.desktop.main.AppD;

/**
 * LaTeX panel for CAS output
 *
 */
public class LaTeXPanel extends JPanel {

	private static final long serialVersionUID = 1L;

	private AppD app;
	private String latex;
	private BufferedImage image;
	private Graphics2D g2image;
	private Dimension equSize;

	/**
	 * @param app
	 *            application
	 */
	public LaTeXPanel(AppD app) {
		this.app = app;
		ensureImageSize(100, 100);
	}

	/**
	 * @param latex
	 *            LaTeX text
	 */
	public void setLaTeX(String latex) {
		if (latex.equals(this.latex)) {
			return;
		}

		this.latex = latex;

		updateLaTeX();
	}

	private void updateLaTeX() {
		// draw equation to get its size
		equSize = drawEquationToImage();

		// check if image was big enough for equation
		if (ensureImageSize(equSize.width, equSize.height)) {
			equSize = drawEquationToImage();
		}

		setPreferredSize(equSize);
		setSize(equSize);
		validate();

	}

	@Override
	public void setForeground(Color c) {
		super.setForeground(c);
		// repaint image, but keep size
		drawEquationToImage();
	}

	private Dimension drawEquationToImage() {
		if (g2image == null || latex == null) {
			return new Dimension(0, 0);
		}
		g2image.setBackground(getBackground());
		g2image.clearRect(0, 0, image.getWidth(), image.getHeight());

		GGraphics2DD.setAntialiasing(g2image);

		GDimension fd = app.getDrawEquation().drawEquation(app, null,
				new GGraphics2DD(g2image), 0, 0, latex,
				app.getPlainFontCommon(), false,
				GColorD.newColor(getForeground()),
				GColorD.newColor(getBackground()), true, false, null);

		return new Dimension(fd.getWidth(), fd.getHeight());
	}

	private boolean ensureImageSize(int width, int height) {
		if (image == null || image.getWidth() < width
				|| image.getHeight() < height) {
			image = new BufferedImage(width, height,
					BufferedImage.TYPE_INT_ARGB);
			g2image = image.createGraphics();
			return true;
		}
		return false;
	}

	@Override
	public void setFont(Font f) {
		super.setFont(f);
		if (latex != null) {
			updateLaTeX();
		}
	}

	@Override
	public void paint(Graphics g) {
		if (app.isExporting()) {
			app.getDrawEquation();
			// draw full resolution image directly on g
			app.getDrawEquation().drawEquation(app, null,
					new GGraphics2DD((Graphics2D) g), 0, 0, latex,
					app.getPlainFontCommon(), false,
					GColorD.newColor(getForeground()),
					GColorD.newColor(getBackground()), true, false, null);
		} else {
			// draw part of image that contains equation
			if (image != null && equSize != null) {
				g.drawImage(image, 0, 0, equSize.width, equSize.height, 0, 0,
						equSize.width, equSize.height, null);
			}
		}
	}

}