diamondicon.java

The Definitive Guide to Java Swing, Third Edition by John Zukowski (Author) 源码

import javax.swing.*;
import java.awt.*;
public class DiamondIcon implements Icon {
  private Color color;
  private boolean selected;
  private int width;
  private int height;
  private Polygon poly;
  private static final int DEFAULT_WIDTH = 10;
  private static final int DEFAULT_HEIGHT = 10;
  public DiamondIcon(Color color) {
    this (color, true, DEFAULT_WIDTH, DEFAULT_HEIGHT);
  }
  public DiamondIcon(Color color, boolean selected) {
    this (color, selected, DEFAULT_WIDTH, DEFAULT_HEIGHT);
  }
  public DiamondIcon (Color color, boolean selected, int width, int height) {
    this.color = color;
    this.selected = selected;
    this.width = width;
    this.height = height;
    initPolygon();
  }
  private void initPolygon() {
    poly = new Polygon();
    int halfWidth = width/2;
    int halfHeight = height/2;
    poly.addPoint (0, halfHeight);
    poly.addPoint (halfWidth, 0);
    poly.addPoint (width, halfHeight);
    poly.addPoint (halfWidth, height);
  }
  public int getIconHeight() {
    return height;
  }
  public int getIconWidth() {
    return width;
  }
  public void paintIcon(Component c, Graphics g, int x, int y) {
    g.setColor (color);
    g.translate (x, y);
    if (selected) {
      g.fillPolygon (poly);
    } else {
      g.drawPolygon (poly);
    }
    g.translate (-x, -y);
  }
}