Page 105 Table of Contents Index Page 107
Chapters
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30
A, B, C, D, E


CHAPTER 12. GRAPHICS

because they are commonly used.

=> draw-arrow sheet point-1 point-2 &key ink clipping-region transformation line-style line-thickness
line-unit line-dashes line-cap-shapeto-head from-head head-length head-width [Function]
=> draw-arrow* sheet x1 y1 x2 y2 &key ink clipping-region transformation line-style line-thickness
line-unit line-dashes line-cap-shapefrom-head to-head head-length head-width [Function]
These functions (structured and spread arguments, respectively) draw a line segment on the
sheet sheet from the point point1 to point2 (or from the position (x1,y1) to (x2,y2)). If to-head is
true (the default), then the "to" end of the line is capped by an arrowhead. If from-head is true
(the default is false), then the "from" end of the line is capped by an arrowhead. The arrowhead
has length head-length (default 10) and width head-width (default 5).

The current line style (see Chapter 10) affects the drawing of the line portion of the arrow in the
obvious way, except that the joint shape has no effect. Dashed arrows start dashing at point1.

=> draw-oval sheet center-pt x-radius y-radius &key (filled t) ink clipping-region transformation
line-style line-thickness line-unit line-dashes line-cap-shape [Function]
=> draw-oval* sheet center-x center-y x-radius y-radius &key (filled t) ink clipping-region trans-
formation line-style line-thickness line-unit line-dashes line-cap-shape [Function]


These functions (structured and spread arguments, respectively) draw a filled or unfilled oval
(that is, a "race-track" shape) on the sheet sheet. The oval is centered on center-pt (or (center-
x,center-y)). If x-radius or y-radius is 0, then a circle is drawn with the specified non-zero
radius. Other, a figure is drawn that results from drawing a rectangle with dimension x-radius
by y-radius, and the replacing the two short sides with a semicircular arc of the appropriate size.

12.6 Pixmaps

A pixmap can be thought of as an "off-screen window", that is, a sheet that can be used for
graphical output, but is not visible on any display device. Pixmaps are provided to allow a
programmer to generate a piece of output associated with some display device that can then be
rapidly drawn on a real display device. For example, an electrical CAD system might generate
a pixmap that corresponds to a complex, frequently used part in a VLSI schematic, and then
use copy-from-pixmap to draw the part as needed.

The exact representation of a pixmap is explicitly unspecified. There is no interaction between
the pixmap operations and output recording, that is, displaying a pixmap on a sheet is a pure
drawing operation that affects only the display, not the output history. Some sheets may not
support pixmaps; in this case, an error will be signalled.

=> allocate-pixmap sheet width height [Generic Function]
Allocates and returns a pixmap object that can be used on any sheet that shares the same
characteristics as sheet. (The exact definition of "shared characteristics" will vary from host to
host.) sheet can be a sheet, a medium, or a stream.

Page 105 Table of Contents Index Page 107
Chapters
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30
A, B, C, D, E