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@Section
@Title { Colour }
@Tag { colour }
@Begin
@PP
Colour is obtained in much the same way that fonts and language changes
colour. @Index @Code "@Colour"
color. @Index @Code "@Color"
are, using the @Code "@Colour" (or equivalently {@Code "@Color"}) symbol:
@ID @Code "grey @Colour { Hello, world }"
produces
@ID grey @Colour { Hello, world }
The @Code "@Colour" symbol will accept any of the following colours:
@QD @HAdjust @Tab
vmargin { 0.5vx }
hmargin { 0.2c }
@Fmta { @Col A @Colour @FilledBox ! @Col @Code A ! @Col !
@Col B @Colour @FilledBox ! @Col @Code B ! @Col !
@Col C @Colour @FilledBox ! @Col @Code C }
@Fmtb { @Col A @Colour @FilledBox ! @Col @Code A ! @Col !
@Col B @Colour @FilledBox ! @Col @Code B ! @Col !
@Col ! @Col }
{
@Rowa A { darkred } B { red } C { lightred }
@Rowa A { darkgreen } B { green } C { lightgreen }
@Rowa A { darkblue } B { blue } C { lightblue }
@Rowa A { darkcyan } B { cyan } C { lightcyan }
@Rowa A { darkmagenta } B { magenta } C { lightmagenta }
@Rowa A { darkyellow } B { yellow } C { lightyellow }
@Rowa A { darkgrey } B { grey } C { lightgrey }
@Rowa A { darkgray } B { gray } C { lightgray }
@Rowb A { black } B { white }
}
Monochrome output devices will render them as shades of grey. Colouring
something @Code white makes it invisible (unless printed on a coloured
background), which is sometimes useful. See Appendix {@NumberOf morecolours}
to get many more colour names, using the @Code xrgb include file
and its @Code "@Xrgb" symbol.
@PP
In addition to the list of colours given above, there is a special
{@Code nochange} colour which produces whatever colour you already
happen to be using; you can also use an empty object to ask for this. And
you can get lots more colours by specifying them using numbers, like this:
@ID @Code "{ rgb 0.5 0.5 1.0 } @Colour { Hello, world }"
which means use red at intensity 0.5, green at intensity 0.5, and
blue at intensity 1.0, producing
@ID { rgb 0.5 0.5 1.0 } @Colour { Hello, world }
In the strange world of colour coordinates, in which 0 is dark and 1 is
light, this is a light blue. You can also use the CMYK system:
@ID @Code "{ cmyk 0.5 0.5 1.0 1.0 } @Colour { Hello, world }"
produces
@ID { cmyk 0.5 0.5 1.0 1.0 } @Colour { Hello, world }
Wherever in this document it says that that you can use any colour
from this section, it means any of the names above, or {@Code nochange},
or an object beginning with @Code "rgb" or @Code "cmyk" as shown.
@PP
Whether the colours produced by @Code "@Colour" actually
correspond with the names depends on the output device; the same
nominal colour can look quite different on screen and on paper.
@End @Section
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