NAME

    Convert::Color - color space conversions and named lookups

SYNOPSIS

       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 . '">';

DESCRIPTION

    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

CONSTRUCTOR

 new

       $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.

METHODS

 rgb

       ( $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.

COLOR SPACE CONVERSIONS

    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 )

 convert_to

       $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 AUTOLOADed if they do not yet exist,
    but this feature should not be relied upon - see below.

AUTOLOADED CONVERSION METHODS

    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.

OTHER METHODS

    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.

SUBCLASS METHODS

    This base class is intended to be subclassed to provide more color
    spaces.

 register_color_space

       $class->register_color_space( $space )

    A subclass should call this method to register itself as a named color
    space.

 register_palette

       $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.

 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.

AUTHOR

    Paul Evans <leonerd@leonerd.org.uk>

