Superclass for User Interface Elements

/**
 * A superclass for all User Interface Elements
 */
public abstract class GUIelement {
 
  //Six instance variables that all GUI elements need.
  protected double xCentre;
  protected double yCentre;
  protected double halfWidth;
  protected double halfHeight;
  protected boolean highlighted;
  protected String text;

  //A normal constructor
  public GUIelement(double xc, double yc, double hw, double hh,
                   String txt, boolean hilite) {
    xCentre = xc;
    yCentre = yc;
    halfWidth = hw;
    halfHeight = hh;
    text = txt;
    highlighted = hilite;
  }

  //A no-parameters constructor that leaves everything at default values.
  public GUIelement(){ }
 
  //The basic draw() method will erase the rectanglular area, and then
  //outline it with a thin black box.
  public void draw(){
    StdDraw.setPenColor(StdDraw.WHITE);
    StdDraw.filledRectangle(xCentre,yCentre,halfWidth,halfHeight);
    StdDraw.setPenColor(StdDraw.BLACK);
    StdDraw.setPenRadius(); //Default thin line.
    StdDraw.rectangle(xCentre,yCentre,halfWidth,halfHeight);
  }
 
  //All subclasses will need to know when a click is in the rectangle
  //for this particulat GUI element.
  public boolean handleClick(double x, double y) {
    return (x >= xCentre-halfWidth) &&
           (x <= xCentre+halfWidth) &&
           (y >= yCentre-halfHeight) &&
           (y <= yCentre+halfHeight);
  }
 
  //Only textboxes will override this one.
  public boolean handleCharTyped(char c){
    return false;
  }
 
  //Accessors
 
  public boolean isHighlighted(){
    return highlighted;
  }
 
  public String getText(){
    return text;
  }
 
}//GUIelement