3 Color Operations

A color can be represented in three ways: as a color index (an integer in 0 to 299, inclusive), as a color name string, or as a rgb value. All drawing functions which take a color argument accept colors in any form. An rgb value is assigned to an index with change-color.

(struct   rgb   (red green blue))

red : (real-in 0 1)

green : (real-in 0 1)

blue : (real-in 0 1)

Takes three values in the range 0 (dark) to 1 (bright) and returns an rgb (a color).

(change-color index rgb) → void?

index : (integer-in 0 299)

rgb : rgb?

Changes the color at index in the color table to the color specified in rgb. Only the first twenty-one indices are initialized; a color index should not be used until it has been initialized.

(default-display-is-color?) → boolean?

Returns #t if the default display screen for viewports is in color or #f otherwise.