Draw Operations

These are the basic graphics operations for drawing to a viewport. Each function takes a viewport as its argument and returns a function operating within that viewport. Further arguments, if any, are curried. For example, (draw-line viewport) returns a function, that can then be applied to the proper arguments to draw a line in the viewport corresponding to viewport descriptor viewport. An example follows.

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