Rectangle

Rectangle Class

Programs can use Rectangle objects to describe and draw four-sided square and rectangular shapes.

Although the Rectangle objects are meant to be displayed on X11Pane displays that require only the origin and extent of a rectangle to display it, the class defines each side’s line separately, in case a program needs to work with all of the object’s dimensions.

The methods drawWithPen and fillWithPen draw either the sides of a rectangle or a filled rectangle, using the line width and color defined by a Pen object. The methods draw and fill use a default line width of one pixel and the color black.

Here is a simple example program.

int main () {
  X11Pane new xPane;
  InputEvent new e;
  Pen new bluePen;
  Rectangle new rectangle;

  xPane initialize 10, 10, 100, 100;
  xPane map;
  xPane raiseWindow;
  xPane openEventStream;

  /*  
   *  The rectangle's sides are four Line objects:
   *  top, bottom, left, and right.  There is also
   *  a "dimensions" method that fills in all of 
   *  the sides' dimensions.
   */
  rectangle top start x = 10;
  rectangle top start y = 10;
  rectangle right end x = 80;
  rectangle right end y = 80;

  bluePen width = 3;
  bluePen colorName = "blue";

  while (TRUE) {
    xPane inputStream queueInput;
    if (xPane inputStream eventPending) {
      e become xPane inputStream inputQueue unshift;
      switch (e eventClass value)
        {
        case WINDELETE:
          xPane deleteAndClose;
          exit (0);
          break;
        case EXPOSE:
        case RESIZENOTIFY:
	  /*
	   *  To draw only the outline of the rectangle,
	   *  use the "draw" method instead.
	   */
	  rectangle fillWithPen xPane, bluePen;
          break;
        default:
          break;
        }
    }
  }
}

Instance Variables

top

right

bottom

left

Line objects that contain the dimensions of each of the rectangle’s sides. Each Line instance variable in turn contains Point objects that contain the endpoints of each side.

Note: Unlike Line objects, which specify endpoints as absolute window coordinates, Rectangle objects specify the endpoints of each side as relative to the origin of the Rectangle object; that is, as height and width dimensions. See Line.

Instance Methods

clear (X11Pane paneObject)

Clear the rectangle defined by the receiver to the background color of paneObject. This method requires that the dimensions of the rectangle be completely defined. The easiest way to do this is with the dimensions method, below.

draw (X11Pane paneObject)

Draw an outline of the receiver’s rectangle dimensions on paneObject’s display area, using a line width of one pixel and the color black.

drawWithPen (X11Pane paneObject, Pen penObject)

pDraw an outline of the receiver’s rectangle dimensions on paneObject’s display area, using the line width and color given by penObject.

dimensions (Integer xOrigin, Integer yOrigin, Integer xSize, Integer ySize)

A convenience method that fills in the dimensions of each of the receiver’s sides from the arguments, which specify the origin, height, and width of the receiver.

fill (X11Pane paneObject)

Draw a solid rectangle on paneObject’s display area, using a default line width of one pixel and the default color, black.

fillWithPen (X11Pane paneObject, Pen penObject)

Draw a solid rectangle on paneObject’s display area, using the color given by penObject.