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PieChartPainter.javaAPI DocExample2935Thu Oct 24 20:14:26 BST 2002None

PieChartPainter

public class PieChartPainter extends ChartPainter

Fields Summary
protected static PieChartPainter
chartUI
protected int
originX
protected int
originY
protected int
radius
private static double
piby2
private static double
twopi
private static double
d2r
private static int
xGap
private static int
inset
Constructors Summary
Methods Summary
public static javax.swing.plaf.ComponentUIcreateUI(javax.swing.JComponent c)

    return chartUI;
public voiddrawLabel(java.awt.Graphics g, java.lang.String text, double angle)

    g.setFont(textFont);
    g.setColor(textColor);
    double radians = angle * d2r;
    int x = (int) ((radius + xGap) * Math.cos(radians));
    int y = (int) ((radius + xGap) * Math.sin(radians));
    if (x < 0) { 
      x -= SwingUtilities.computeStringWidth(g.getFontMetrics(), text);
    }
    if (y < 0) {
      y -= g.getFontMetrics().getHeight();
    }
    g.drawString(text, x + originX, originY - y);
public intindexOfEntryAt(java.awt.event.MouseEvent me)


      
    int x = me.getX() - originX;
    int y = originY - me.getY();  // Upside-down coordinate system.
    
    // Is (x,y) in the circle?
    if (Math.sqrt(x*x + y*y) > radius) { return -1; }

    double percent = Math.atan2(Math.abs(y), Math.abs(x));
    if (x >= 0) {
      if (y <= 0) { // (IV)
        percent = (piby2 - percent) + 3 * piby2; // (IV)
      }
    }
    else {
      if (y >= 0) { // (II)
        percent = Math.PI - percent;
      }
      else { // (III)
        percent = Math.PI + percent;
      }
    }
    percent /= twopi;
    double t = 0.0;
    if (values != null) {
      for (int i = 0; i < values.length; i++) {
        if (t + values[i] > percent) {
          return i;
        }
        t += values[i];
      }
    }
    return -1;
public voidpaint(java.awt.Graphics g, javax.swing.JComponent c)

    Dimension size = c.getSize();
    originX = size.width / 2;
    originY = size.height / 2;
    int diameter = (originX < originY ? size.width - inset 
                                      : size.height - inset);
    radius = (diameter / 2) + 1;
    int cornerX = (originX - (diameter / 2));
    int cornerY = (originY - (diameter / 2));
    
    int startAngle = 0;
    int arcAngle = 0;
    for (int i = 0; i < values.length; i++) {
      arcAngle = (int)(i < values.length - 1 ?
                       Math.round(values[i] * 360) :
                       360 - startAngle);
      g.setColor(colors[i % colors.length]);
      g.fillArc(cornerX, cornerY, diameter, diameter, 
                startAngle, arcAngle);
      drawLabel(g, labels[i], startAngle + (arcAngle / 2));
      startAngle += arcAngle;
    }
    g.setColor(Color.black);
    g.drawOval(cornerX, cornerY, diameter, diameter);  // Cap the circle.