"Convert::Color" - color space conversions and named lookups
use Convert::Color;
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; namely:
- •
- 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:
- •
- Convert::Color::VGA - named lookup for the basic VGA
colors
- •
- Convert::Color::X11 - named lookup of colors from X11's
rgb.txt
$color = Convert::Color->new( STRING )
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
example
rgb:RED,GREEN,BLUE
rgb8:RRGGBB
rgb16:RRRRGGGGBBBB
hsv:HUE,SAT,VAL
hsl:HUE,SAT,LUM
cmy:CYAN,MAGENTA,YELLOW
cmyk:CYAN,MAGENTA,YELLOW,KEY
vga:NAME
vga:INDEX
x11:NAME
For more detail, see the constructor of the color space subclass in question.
( $red, $green, $blue ) = $color->rgb
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 "to_rgb()"
method.
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. "rgb".
- 1.
- If SRC and DEST are equal, return $color as it stands.
- 2.
- If the SRC space's class provides a
"convert_to_DEST" method, use it.
- 3.
- If the DEST space's class provides a
"new_from_SRC" constructor, call it and pass $color.
- 4.
- If the DEST space's class provides a "new_rgb"
constructor, convert $color to red/green/blue components then call
it.
- 5.
- 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 )
$other = $color->convert_to( $space )
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 "new" or "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:
$color->convert_to('rgb')
$color->as_rgb
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.
$class->register_color_space( $space )
A subclass should call this method to register itself as a named color space.
$class->register_palette( %args )
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, called
"closest_to".
$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 <
[email protected]>