fungraph.scm library provides the procedures for
producing graphical images described in Concrete Abstractions.
Because these procedures operate like mathematical functions, we refer
to them as functional graphics, hence the name fungraph.
In addition to the procedures described in the textbook, there are two additional ones:
(mirror-image image)
quarter-turn-right or invert, this
takes an image and makes another, related image. In the case of
mirror-image, the new image is the same size as the
original, and is formed by flipping the original image around a
vertical axis, as though it were viewed in a mirror.
(resize-image image width height)
(resize-image image size)
(resize-image image size size),
i.e., the specified size is used as both the width and the height
of the new image.
(resize-image image)
(resize-image image default-image-size default-image-size),
i.e., the width and height are both taken as the value of
default-image-size. As described below, this is the same
name that controls the size of the images created by line
and filled-triangle.
The images produced by line and
filled-triangle are of a size determined by the value of
the name default-image-size. Initially this name is
defined as 100. This is a compromise size, a bit small for the
fractals in chapter 4 and rather large for each basic block of the
quilts in chapters 1-3. You can redefine it to another value (which
must be an exact, positive integer) to suit your own needs. Or, you
can use the resize-image procedure described above. For
example, when defining the basic blocks for quilting, it may make
sense to do so as in the following example:
(define test-bb (resize-image (filled-triangle 0 1 0 -1 1 -1) 25))
The images produced by the procedures in this library show up in separate windows, with numbered titles, like Img1, Img2. The title is also shown in the read-eval-print-loop's window, where the value normally would go. That way you can keep track of which image was generated by each evaluation.