In addition to its color, width, and style, a pen can have a pen stipple bitmap. Drawing with a stipple pen is similar to calling draw-bitmap with the stipple bitmap in region painted by the pen.

A pen style is one of the following:

• 'transparent — Draws with no effect (on the outline of the drawn shape).

• 'solid — Draws using the pen’s color. If a (monochrome) pen stipple is installed into the pen, black pixels from the stipple are transferred to the destination using the brush’s color, and white pixels from the stipple are not transferred.

• 'xor — The same as 'solid, accepted only for partial backward compatibility.

• 'hilite — Draws with black and a 0.3 alpha.

• The following special pen modes use the pen’s color, and they only apply when a pen stipple is not used:

  • 'dot

  • 'long-dash

  • 'short-dash

  • 'dot-dash

  • 'xor-dot

  • 'xor-long-dash

  • 'xor-short-dash

  • 'xor-dot-dash

To avoid creating multiple pens with the same characteristics, use the global pen-list% object the-pen-list, or provide a color, width, and style to set-pen in dc<%>.

When drawing in 'smoothed or 'aligned mode, a pen’s size is truncated after scaling to an integral size. A pen of size 0 (after truncation, if applicable) uses a non-zero, scale-insensitive line size for the destination drawing context: 1/4 unit (after scaling) for post-script-dc% or pdf-dc% contexts in 'smoothed mode, or 1 unit (after scaling) for any other context. For example, in unscaled canvas and bitmap contexts, a zero-width pen behaves the same as a pen of size 1.

See also make-pen.

This code draws three diagonal lines, one with each of the possible caps ('round, 'butt, and then 'projecting) and puts a little red dot on the end points of the line.

Examples:

> (define (plot-line dc x1 y1 x2 y2 cap)     (send dc set-pen           (send the-pen-list find-or-create-pen                 "black" 40 'solid cap))     (send dc draw-line x1 y1 x2 y2)     (send dc set-brush "red" 'solid)     (send dc set-pen "black" 1 'transparent)     (send dc draw-ellipse (- x1 4) (- y1 4) 8 8)     (send dc draw-ellipse (- x2 4) (- y2 4) 8 8)) > (dc    (λ (dc dx dy)      (define old-pen (send dc get-pen))      (define old-brush (send dc get-brush))         (plot-line dc 20 30 80 90 'round)      (plot-line dc 100 30 160 90 'butt)      (plot-line dc 180 30 240 90 'projecting)         (send dc set-pen old-pen)      (send dc set-brush old-brush))    270 120)

This code shows the three join styles ('round, 'bevel and then 'miter) by drawing a sequence of lines, first with a sharp corner and then with a right-angle. Each of the end points of the lines i with a red dot.

Examples:

> (define points '((100 . 100)                    (0 . 0)                    (0 . 100)                    (40 . 100))) > (define (connect-points dc dx dy join)     (send dc set-pen           (send the-pen-list find-or-create-pen                 "black" 40 'solid 'round join))     (send dc draw-lines points dx dy)     (send dc set-brush "red" 'solid)     (send dc set-pen "black" 1 'transparent)     (for ([pt (in-list points)])       (send dc draw-ellipse             (+ dx (car pt) -4) (+ dy (cdr pt) -4)             8 8))) > (dc    (λ (dc dx dy)      (define old-pen (send dc get-pen))      (define old-brush (send dc get-brush))         (connect-points dc 20 50 'round)      (connect-points dc 180 50 'bevel)      (connect-points dc 340 50 'miter)         (send dc set-pen old-pen)      (send dc set-brush old-brush))    460 170)

A pen cannot be modified if it was obtained from a pen-list% or while it is selected into a drawing context.

A pen cannot be modified if it was obtained from a pen-list% or while it is selected into a drawing context.

A pen cannot be modified if it was obtained from a pen-list% or while it is selected into a drawing context.

If bitmap is modified while is associated with a pen, the effect on the pen is unspecified. A pen cannot be modified if it was obtained from a pen-list% or while it is selected into a drawing context.

A pen cannot be modified if it was obtained from a pen-list% or while it is selected into a drawing context.