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Graphics::ColorNames - defines RGB values for common color names |
Graphics::ColorNames - defines RGB values for common color names
use Graphics::ColorNames 2.10;
$po = new Graphics::ColorNames(qw( X ));
$rgb = $po->hex('green'); # returns '00ff00'
$rgb = $po->hex('green', '0x'); # returns '0x00ff00'
$rgb = $po->hex('green', '#'); # returns '#00ff00'
$rgb = $po->rgb('green'); # returns '0,255,0'
@rgb = $po->rgb('green'); # returns (0, 255, 0)
$rgb = $po->green; # same as $po->hex('green');
tie %ph, 'Graphics::ColorNames', (qw( X ));
$rgb = $ph{green}; # same as $po->hex('green');
This module provides a common interface for obtaining the RGB values of colors by standard names. The intention is to (1) provide a common module that authors can use with other modules to specify colors by name; 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 2.10;
use GD;
$pal = new Graphics::ColorNames;
$img = new GD::Image(100, 100);
$bgColor = $img->colorAllocate( $pal->rgb('CadetBlue3') );
Although this is a little ``bureaucratic'', the meaning of this code is clear:
$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.
You can also define Custom Color Schemes for specialised palettes for websites or institutional publications:
$color = $pal->hex('MenuBackground');
As an added feature, a hexidecimal RGB value in the form of #RRGGBB, 0xRRGGBB or RRGGBB will return itself:
$color = $pal->hex('#123abc'); # returns '123abc'
The standard interface (prior to version 0.40) is through a tied hash:
tie %pal, 'Graphics::ColorNames', @schemes;
where %pal is the tied hash and @schemes is a list of
color schemes.
A valid color scheme may be the name of a color scheme (such as X
or a full module name such as Graphics::ColorNames::X), a reference
to a color scheme hash or subroutine, or to the path or open
filehandle for a rgb.txt file.
As of version 2.1002, one can also use the Color::Library manpage dictionaries:
tie %pal, 'Graphics::ColorNames', qw(Color::Library::Dictionary::HTML);
This is an experimental feature which may change in later versions (see SEE ALSO for a discussion of the differences between modules).
Multiple schemes can be used:
tie %pal, 'Graphics::ColorNames', qw(HTML Netscape);
In this case, if the name is not a valid HTML color, the Netscape name will be used.
One can load all available schemes in the Graphics::ColorNames namespace (as of version 2.0):
use Graphics::ColorNames 2.0, 'all_schemes'; tie %NameTable, 'Graphics::ColorNames', all_schemes();
When multiple color schemes define the same name, then the earlier one listed has priority (however, hash-based color schemes always have priority over code-based color schemes).
When no color scheme is specified, the X-Windows scheme is assumed.
Color names are case insensitive, and spaces or punctuation are ignored. So ``Alice Blue'' returns the same value as ``aliceblue'', ``ALICE-BLUE'' and ``a*lICEbl-ue''. (If you are using color names based on user input, you may want to add additional validation of the color names.)
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.
If you prefer, an object-oriented interface is available:
use Graphics::ColorNames 0.40;
$obj = Graphics::ColorNames->new('/etc/rgb.txt');
$hex = $obj->hex('skyblue'); # returns "87ceeb"
@rgb = $obj->rgb('skyblue'); # returns (0x87, 0xce, 0xeb)
The interface is similar to the the Color::Rgb manpage module:
$obj = Graphics::ColorNames->new( @SCHEMES );
Creates the object, using the default color schemes.
If none are specified, it uses the X scheme.
$obj->load_scheme( $scheme );
Loads a scheme dynamically. The scheme may be any hash or code reference.
$hex = $obj->hex($name, $prefix);
Returns a 6-digit hexidecimal RGB code for the color. If an optional prefix is specified, it will prefix the code with that string. For example,
$hex = $obj->hex('blue', '#'); # returns "#0000ff"
@rgb = $obj->rgb($name);
$rgb = $obj->rgb($name, $separator);
If called in a list context, returns a triplet.
If called in a scalar context, returns a string separated by an optional separator (which defauls to a comma). For example,
@rgb = $obj->rgb('blue'); # returns (0, 0, 255)
$rgb = $obj->rgb('blue', ','); # returns "0,0,255"
Since version 2.10_02, the interface will assume method names are color names and return the hex value,
$obj->black eq $obj->hex("black")
Method names are case-insensitive, and underscores are ignored.
These functions are not exported by default, so much be specified to be used:
use Graphics::ColorNames qw( all_schemes hex2tuple tuple2hex );
@schemes = all_schemes();
Returns a list of all available color schemes installed on the machine in the Graphics::ColorNames namespace.
The order has no significance.
($red, $green, $blue) = hex2tuple( $colors{'AliceBlue'});
$rgb = tuple2hex( $red, $green, $blue );
The following schemes are available by default:
This scheme may be deprecated in future versions, but available as a separate module.
Rather than a color scheme, the path or open filehandle for a rgb.txt file may be specified.
Additional color schemes may be available on CPAN.
You can add naming scheme files by creating a Perl module is the name
Graphics::ColorNames::SCHEMENAME which has a subroutine named
NamesRgbTable that returns a hash of color names and RGB values.
(Schemes with a different base namespace will require the fill namespace
to be given.)
The color names must be in all lower-case, and the RGB values must be 24-bit numbers containing the red, green, and blue values in most- significant to least- significant byte order.
An example naming schema is below:
package Graphics::ColorNames::Metallic;
sub NamesRgbTable() {
use integer;
return {
copper => 0xb87333,
gold => 0xcd7f32,
silver => 0xe6e8fa,
};
}
You would use the above schema as follows:
tie %colors, 'Graphics::ColorNames', 'Metallic';
The behavior of specifying multiple keys with the same name is undefined as to which one takes precedence.
As of version 2.10, case, spaces and punctuation are ignored in color names. So a name like ``Willy's Favorite Shade-of-Blue'' is treated the same as ``willysfavoroteshadeofblue''. (If your scheme does not include duplicate entrieswith spaces and punctuation, then the minimum version of the Graphics::ColorNames manpage should be 2.10 in your requirements.)
An example of an additional module is the the Graphics::ColorNames::Mozilla manpage module by Steve Pomeroy.
Since version 1.03, NamesRgbTable may also return a code reference:
package Graphics::ColorNames::Orange;
sub NamesRgbTable() {
return sub {
my $name = shift;
return 0xffa500;
};
}
See the Graphics::ColorNames::GrayScale manpage for an example.
The alias ``Graphics::ColourNames'' (British spelling) is no longer available as of version 2.01.
It seems absurd to maintain it when all the modules does is provide an alternative spelling for the module name without doing anything about the component colors of each scheme, and when most other modules (and non-Perl software) does not bother with such things.
the Color::Library manpage provides an extensive library of color schemes. A notable difference is that it supports more complex schemes which contain additional information about individual colors and map multiple colors to a single name.
the Color::Rgb manpage has a similar function to this module, but parses an rgb.txt file.
the Graphics::ColorObject manpage can convert between RGB and other color space types.
the Acme::AutoColor manpage provides subroutines corresponding to color names.
Robert Rothenberg <rrwo at cpan.org>
Alan D. Salewski <alans at cji.com> for feedback and the addition of
tuple2hex.
Steve Pomeroy <xavier at cpan.org>, ``chemboy'' <chemboy at perlmonk.org> and ``magnus'' <magnus at mbox604.swipnet.se> who pointed out issues with various color schemes.
Feedback is always welcome. Please use the CPAN Request Tracker at http://rt.cpan.org to submit bug reports.
There is a Sourceforge project for this package at http://sourceforge.net/projects/colornames/.
If you create additional color schemes, please make them available separately in CPAN rather than submit them to me for inclusion into this module.
Copyright (c) 2001-2008 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.
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Graphics::ColorNames - defines RGB values for common color names |