Flip Commands

Where ``draw-'' commands make pixels black, a ``flip-'' commands cause them to change:

•   ((flip-viewport viewport))
  flip-viewport takes a viewport descriptor. It returns a function that flips the contents of viewport.
•   ((flip-pixel viewport) p)
  flip-pixel takes a viewport descriptor. It returns a function that flips a pixel in viewport at the specified position.
•   ((flip-line viewport) p1 p2)
  flip-line takes a viewport descriptor. It returns a function that flips a line in viewport connecting positions p1 and p2.
•   ((flip-rectangle viewport) pos width height color)
  flip-rectangle takes a viewport descriptor. It returns a function that flips a rectangle border in the viewport with the top-left of the rectangle at the position pos and with sides width across and height tall. The optional color argument defaults to black.
•   ((flip-solid-rectangle viewport) pos width height color)
  flip-solid-rectangle takes a viewport descriptor. It returns a function that flips a solid rectangle in the viewport with the top-left of the rectangle at the position pos and with sides width across and height tall. The optional color argument defaults to black.
•   ((flip-ellipse viewport) pos width height color)
  flip-ellipse takes a viewport descriptor. It returns a function that flips an ellipse border in the viewport. The pos, width, and height arguments are as in flip-rectangle; the ellispse is inscribed within the specified rectangle. The optional color argument defaults to black.
•   ((flip-solid-ellipse viewport) pos width height color)
  flip-solid-ellipse takes a viewport descriptor. It returns a function that flips a solid ellipse in the viewport. The pos, 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.
•   ((flip-string viewport) p string)
  flip-string takes a viewport descriptor. It returns a function that flips a string at a specified location in viewport. The lower left of the string begins at p.
•   ((flip-pixmap w) filename p)
  flip-pixmap flips an X bitmap into viewport with its upper left corner at p.