7.6. COLORS

85

For example, the following program extends our previous example, by specifying

that the text on the label should be displayed in a 60 point bold face Helvetica

font:

(define w

(window "Hello"

(label "Hello again" (HelveticaBold 60))))

(.pack w)

(.show w)

The (.pack w) expression changes the size of the window so that it is just large

enough to fit the label.

One can also specify other fonts using the Font. procedure. This requires

you to specify the name of the font, the style (bold, italic, plain), and the size

(in points).

(define w

(window "Hello"

(label "Hello again"

(Font. "New Century Schoolbook" Font.BOLD$ 32))))

(.pack w)

(.show w)

The style is specified by using one of the following style names:

Font.BOLD$

Font.Plain$

Font.Italic$

The name of the font is a string (enclosed in curly braces), and the point size

is any positive integer. Note: this will cause an error if you ask for a font that

the computer does not have access to.

7.6

Colors

There are several ways to specify colors. The simplest is to use one of the named

colors. The current set of named colors for JLIB is

white, lightGray gray darkGray black

red pink orange yellow green magentan cyan blue

You can also specify a color by specifying how much red, green, and blue light

should be mixed to form the color:

(color RED GREEN BLUE)

where RED, GREEN, BLUE are numbers between 0 and 255. Note that this is

additive color mixing which is quite different from the subtractive color mixing

of paints. For example to get yellow you mix red and green, to get white you

mix red, green, and blue. Some of the color mixes are shown below: