## rgb.api
#
# RGB color values as opaque triples
#
# (red: Float, green: Float, blue: Float)
#
# This is our preferred color representation;
# all other color representations implement
# to_rgb() and from_rgb() conversion functions.
# Compiled by:
# src/lib/x-kit/xclient/xclient-internals.sublib# This api is implemented in:
#
# src/lib/x-kit/xclient/src/color/rgb.pkgapi Rgb {
# RGB colors
#
# We represent an RGB color value by a
# record of 64-bit floats holding
# red, green, blue in that order.
# (The compiler will optimize this to
# a very efficient packed representation.)
#
Rgb = { red: Float,
green: Float,
blue: Float
};
# Predefine a few common colors for convenience:
#
black: Rgb;
gray: Rgb;
white: Rgb;
red: Rgb;
green: Rgb;
blue: Rgb;
cyan: Rgb;
magenta: Rgb;
yellow: Rgb;
# We primarily think of color components as
# ranging from 0.0 -> 1.0 inclusive:
#
rgb_from_floats: (Float, Float, Float) -> Rgb;
rgb_to_floats: Rgb -> (Float, Float, Float);
# The X protocol level likes to think
# of color components as ranging from
# 0 -> 65355 inclusive, so we support
# that for implementation of X protocol
# packet encoding and decoding. This format
# is not otherwise particularly recommended:
#
rgb_from_unts: (Unt, Unt, Unt) -> Rgb;
rgb_to_unts: Rgb -> (Unt, Unt, Unt);
same_rgb: (Rgb, Rgb) -> Bool;
#
# Note that this 'same' function does
# 64-bit float comparisons, and consequently
# is very sensitive to rounding errors: Things
# you expect to compare equal may fail to do so.
#
# If that is an issue in your application, you
# may wish to convert to Rgb8 form (thus discarding
# all but the most significant 8 bits of each color
# component) and then use rgb8::same().
rgb_to_string: Rgb -> String;
rgb_complement: Rgb -> Rgb; # Set each component c to (1.0-c).
rgb_scale: (Float, Rgb) -> Rgb; # Multiply color components by given factor, then clip to 0.0 -> 1.0 range.
rgb_mix01: (Float, Rgb, Rgb) -> Rgb; # Linear interpolation in RGB space. 0.0 yields first color, 1.0 yields second color. (The "01" in name is mnemonic of the 0.0 -> 1.0 arg range.)
rgb_mix11: (Float, Rgb, Rgb) -> Rgb; # Linear interpolation in RGB space. -1.0 yields first color, 1.0 yields second color. (The "11" in name is mnemonic of the -1.0 -> 1.0 arg range.)
rgb_normalize: Rgb -> Rgb; # Ensure all color components are in 0.0 -> 1.0 inclusive.
rgb_from_name: String -> Rgb; # Raises exception lib_base::NOT_FOUND if given string is not in table.
#
# Return a color from x11_color_name::x11_colors table.
rgb_to_grayscale: Rgb -> Float; # Using Rec 601 coefficients -- see http://en.wikipedia.org/wiki/Luma_(video)
rgb_is_light: Rgb -> Bool; # TRUE iff (rgb_to_grayscale c) > 0.5.
};
## COPYRIGHT (c) 1994 by AT&T Bell Laboratories
## Subsequent changes by Jeff Prothero Copyright (c) 2010-2015,
## released per terms of SMLNJ-COPYRIGHT.