/*
 * @(#)CPieChartUI.java		0.0.1 99/07/29
 *
 * Copyright (c) 1999 by Willie Wheeler.  All rights reserved.
 */
package stats.plaf.concrete;

import java.awt.*;
import javax.swing.*;
import javax.swing.plaf.*;
import stats.*;
import stats.plaf.*;

/**
 * @version	0.0.1 07/29/99
 * @author	Willie Wheeler
 */
public class CPieChartUI extends PieChartUI {
    protected static final int		PAD = 5;
    protected static final double	DEG_TO_RAD = Math.PI / 180.0;

    protected static ComponentUI	ui = new CPieChartUI();

    public static ComponentUI createUI(JComponent c) { return ui; }

    public void installUI(JComponent c) { c.setOpaque(false); }

    public void uninstallUI(JComponent c) { }

    public void paint(Graphics g, JComponent c) {
	PieChart chart = (PieChart)c;
	int numStates = chart.getNumStates();
	int chartWidth = chart.getSize().width;
	int chartHeight = chart.getSize().height;
	int centerX = chartWidth / 2;
	int centerY = chartHeight / 2;
	int radius = (centerX < centerY ? chartWidth : chartHeight) / 2 - PAD;
	int cornerX = centerX - radius;
	int cornerY = centerY - radius;
	FontMetrics fm = g.getFontMetrics();
	int fontAscent = fm.getAscent();

	// Compute the sum of the values.
	double sum = 0.0;
	for (int i = 0; i < numStates; i++) { sum += chart.getStateValue(i); }
	
	// Compute the start angles and arc angles.
	double[] startAngles = new double[numStates];
	double[] arcAngles = new double[numStates];
	startAngles[0] = 0.0;
	arcAngles[0] = (chart.getStateValue(0) * 360.0) / sum;
	for (int i = 1; i < numStates; i++) {
	    startAngles[i] = startAngles[i-1] + arcAngles[i-1];
	    arcAngles[i] = (chart.getStateValue(i) * 360.0) / sum;
	}

	// Paint the pie slices.
	for (int i = 0; i < numStates; i++) {
	    g.setColor(chart.getStateColor(i));
	    g.fillArc(cornerX, cornerY, 2*radius, 2*radius,
		      (int)Math.floor(startAngles[i]),
		      (int)Math.ceil(arcAngles[i]));

	    // We draw this part of the outline here because doing so makes
	    // a better fit than drawing a circle afterwards--don't ask me
	    // why.
	    g.setColor(Color.black);
	    g.drawArc(cornerX, cornerY, 2*radius, 2*radius,
		      (int)Math.floor(startAngles[i]),
		      (int)Math.ceil(arcAngles[i]));
	}

	// Paint the value labels.  We use a separate loop so that the labels
	// aren't obscured by the pie slices.
	for (int i = 0; i < numStates; i++) {
	    String label = chart.getStateValueAsString(i);
	    int labelWidth = fm.stringWidth(label);
	    double midAngle =
		(startAngles[i] + 0.5 * arcAngles[i]) * DEG_TO_RAD;
	    int labelX = centerX +
		(int)(0.75 * radius * Math.cos(midAngle)) - labelWidth/2;
	    int labelY = centerY -
		(int)(0.75 * radius * Math.sin(midAngle)) + fontAscent/2;

	    // Clear a little background space.
	    g.setColor(Color.white);
	    for (int j = -2; j <= 2; j++) {
		for (int k = -1; k <= 1; k++) {
		    g.drawString(label, labelX + j, labelY + k);
		}
	    }

	    // And draw the label.
	    g.setColor(Color.black);
	    g.drawString(label, labelX, labelY);
	}
    }
}