Ellipses

• ((draw-ellipse viewport) posn width height color)
  draw-ellipse takes a viewport descriptor. It returns a function that draws an ellipse border in the viewport. The posn, width, and height arguments are as in draw-rectangle; the ellispse is inscribed within the specified rectangle. The optional color argument defaults to black.
• ((clear-ellipse viewport) posn width height color)
  clear-ellipse takes a viewport descriptor. It returns a function that clears an ellipse border in the viewport. The posn, width, and height arguments are as in clear-rectangle; the ellispse is inscribed within the specified rectangle. The optional color argument defaults to black.
• ((flip-ellipse viewport) posn width height color)
  flip-ellipse takes a viewport descriptor. It returns a function that flips an ellipse border in the viewport. The posn, width, and height arguments are as in flip-rectangle; the ellispse is inscribed within the specified rectangle. The optional color argument defaults to black.
• ((draw-solid-ellipse viewport) posn width height color)
  draw-solid-ellipse takes a viewport descriptor. It returns a function that paints a solid ellipse in the viewport. The posn, width, and height arguments are as in draw-rectangle; the ellispse is inscribed within the specified rectangle. The optional color argument defaults to black.
• ((clear-solid-ellipse viewport) posn width height color)
  clear-solid-ellipse takes a viewport descriptor. It returns a function that erases a solid ellipse in the viewport. The posn, width, and height arguments are as in clear-rectangle; the ellispse is be inscribed within the specified rectangle. The optional color argument defaults to black.
• ((flip-solid-ellipse viewport) posn width height color)
  flip-solid-ellipse takes a viewport descriptor. It returns a function that flips a solid ellipse in the viewport. The posn, width, and height arguments are as in flip-rectangle; the ellispse is be inscribed within the specified rectangle. The optional color argument defaults to black.