||User Contributed Perl Documentation
"Convert::Color" - color space conversions and named lookups
my $color = Convert::Color->new( 'hsv:76,0.43,0.89' );
my ( $red, $green, $blue ) = $color->rgb;
# GTK uses 16-bit values
my $gtk_col = Gtk2::Gdk::Color->new( $color->as_rgb16->rgb16 );
# HTML uses #rrggbb in hex
my $html = '<td bgcolor="#' . $color->as_rgb8->hex . '">';
This module provides conversions between commonly used ways to express colors.
It provides conversions between color spaces such as RGB and HSV, and it
provides ways to look up colors by a name.
This class provides a base for subclasses which represent
particular color values in particular spaces. The base class provides
methods to represent the color in a few convenient forms, though subclasses
may provide more specific details for the space in question.
For more detail, read the documentation on these classes;
- Convert::Color::RGB - red/green/blue as floats between 0 and 1
- Convert::Color::RGB8 - red/green/blue as 8-bit integers
- Convert::Color::RGB16 - red/green/blue as 16-bit integers
- Convert::Color::HSV - hue/saturation/value
- Convert::Color::HSL - hue/saturation/lightness
- Convert::Color::CMY - cyan/magenta/yellow
- Convert::Color::CMYK - cyan/magenta/yellow/key (blackness)
The following classes are subclasses of one of the above, which
provide a way to access predefined colors by names:
Return a new value to represent the color specified by the string. This string
should be prefixed by the name of the color space to which it applies. For
- Convert::Color::VGA - named lookup for the basic VGA colors
- Convert::Color::X11 - named lookup of colors from X11's
For more detail, see the constructor of the color space subclass
Returns the individual red, green and blue color components of the color value.
For RGB values, this is done directly. For values in other spaces, this is
done by first converting them to an RGB value using their
Cross-conversion between color spaces is provided by the
"convert_to()" method, assisted by helper
methods in the two color space classes involved.
When converting $color from color space
SRC to color space DEST, the following operations are attemped, in this
order. SRC and DEST refer to the names of the color spaces, e.g.
- If SRC and DEST are equal, return $color as it
- If the SRC space's class provides a
"convert_to_DEST" method, use it.
- If the DEST space's class provides a
"new_from_SRC" constructor, call it and
- If the DEST space's class provides a
"new_rgb" constructor, convert
$color to red/green/blue components then call
- If none of these operations worked, then throw an exception.
These functions may be called in the following ways:
$other = $color->convert_to_DEST()
$other = Dest::Class->new_from_SRC( $color )
$other = Dest::Class->new_rgb( $color->rgb )
Attempt to convert the color into its representation in the given space. See
above for the various ways this may be achieved.
If the relevant subclass has already been loaded (either
explicitly, or implicitly by either the
"convert_to" methods), then a specific
conversion method will be installed in the class.
$other = $color->as_$space
Methods of this form are currently
"AUTOLOAD"ed if they do not yet exist, but
this feature should not be relied upon - see below.
This class provides "AUTOLOAD" and
"can" behaviour which automatically
constructs conversion methods. The following method calls are identical:
The generated method will be stored in the package, so that future
calls will not have the AUTOLOAD overhead.
This feature is deprecated and should not be relied upon, due to
the delicate nature of "AUTOLOAD".
As well as the above, it is likely the subclass will provide accessors to
directly obtain the components of its representation in the specific space.
For more detail, see the documentation for the specific subclass in question.
This base class is intended to be subclassed to provide more color spaces.
A subclass should call this method to register itself as a named color space.
A subclass that provides a fixed set of color values should call this method, to
set up automatic conversions that look for the closest match within the set.
This conversion process is controlled by the %args:
- enumerate => STRING or CODE
- A method name or anonymous CODE reference which will be used to generate
the list of color values.
- enumerate_once => STRING or CODE
- As per "enumerate", but will be called
only once and the results cached.
This method creates a new class method on the calling package,
$color = $pkg->closest_to(
$orig, $space )
Returns the color in the space closest to the given value. The
distance is measured in the named space; defaulting to
"rgb" if this is not provided.
In the case of a tie, where two or more colors have the same
distance from the target, the first one will be chosen.
Paul Evans <firstname.lastname@example.org>
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