NAME

Graphics::ColorNames - defines RGB values for common color names

REQUIREMENTS

Graphics::ColorNames should work on Perl 5.005.

It uses only standard modules.

Installation

Installation is pretty standard:

perl Makefile.PL
make
make test
make install

SYNOPSIS

use Graphics::ColorNames qw( hex2tuple tuple2hex );

tie %NameTable, 'Graphics::ColorNames', 'X';

my $rgbhex = $NameTable{'green'};    # returns '00ff00'
my $rgbhex = tuple2hex( 0, 255, 0 )  # returns '00ff00'
my @rgbtup = hex2tuple( $rgbhex );   # returns (0, 255, 0)

DESCRIPTION

This module defines RGB values for common color names. The intention is to (1) provide a common module that authors can use with other modules to specify colors; and (2) free module authors from having to "re-invent the wheel" whenever they decide to give the users the option of specifying a color by name rather than RGB value.

For example,

use Graphics::ColorNames 'hex2tuple';
tie %COLORS, 'Graphics::ColorNames';

use GD;

$img = new GD::Image(100, 100);

$bgColor = $img->colorAllocate( hex2tuple( $COLORS{'CadetBlue3'} ) );

Though a little 'bureaucratic', the meaning of this code is clearer: $bgColor (or background color) is 'CadetBlue3' (which is easier to for one to understand than 0x7A, 0xC5, 0xCD). The variable is named for its function, not form (ie, $CadetBlue3) so that if the author later changes the background color, the variable name need not be changed.

Usage

The interface is through a tied hash:

tie %NAMETABLE, 'Graphics::ColorNames', SCHEME

where %NAMETABLE is the tied hash and SCHEME is the color scheme. Currently three schemes are available:

X

550 color names used in X-Windows. This is the default naming scheme, since it provides the most names.

HTML

16 common color names defined in the HTML 4.0 specification. These names are also used with CSS and SVG.

Windows

16 commom color names used with Microsoft Windows and related products. These are actually the same colors as HTML, although with different names.

RGB values can be retrieved with a case-insensitive hash key:

$rgb = $colors{'AliceBlue'};

The value returned is in the six-digit hexidecimal format used in HTML and CSS (without the initial '#'). To convert it to separate red, green, and blue values (between 0 and 255), use the hex2tuple function:

@rgb = hex2tuple( $colors{'AliceBlue'} );

or

($red, $green, $blue) = hex2tuple( $colors{'AliceBlue'});

To convert separated red, green, and blue values into the corresponding RGB hexidecimal format, use the tuple2hex function:

$rgb = tuple2hex( $red, $green, $blue );

The hex2tuple and tuple2hex functions are not exported by default. You must specify them explicitly when you 'use' the module.

CAVEAT

This module is experimental. The interface may change.

AUTHOR

Robert Rothenberg <rrwo@cpan.org>

CONTRIBUTORS

Alan D. Salewski <alans@cji.com> for feedback and the addition of tuple2hex.

LICENSE

Copyright (c) 2001 Robert Rothenberg. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

cpanm Graphics::ColorNames

perl -MCPAN -e shell
install Graphics::ColorNames