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-Web colors
-==========
+Utility functions for working with the color names and color value
+formats defined by the HTML and CSS specifications for use in
+documents on the Web.
 
-A simple library for working with the color names and color codes
-defined by the HTML and CSS specifications.
+Support is included for the following formats (RGB colorspace only;
+conversion to/from HSL can be handled by the ``colorsys`` module in
+the Python standard library):
 
+* Six-digit hexadecimal
 
-An overview of HTML and CSS colors
-----------------------------------
+* Three-digit hexadecimal
 
-Colors on the Web are specified in `the sRGB color space`_, where each
-color is made up of a red component, a green component and a blue
-component. This is useful because it maps (fairly) cleanly to the red,
-green and blue components of pixels on a computer display, and to the
-cone cells of a human eye, which come in three sets roughly
-corresponding to the wavelengths of light associated with red, green
-and blue.
+* Integer rgb() triplet
 
-`The HTML 4 standard`_ defines two ways to specify sRGB colors:
+* Percentage rgb() triplet
 
-* A hash mark ('#') followed by three pairs of hexdecimal digits,
-  specifying values for red, green and blue components in that order;
-  for example, ``#0099cc``. Since each pair of hexadecimal digits can
-  express 256 different values, this allows up to 256**3 or 16,777,216
-  unique colors to be specified (though, due to differences in display
-  technology, not all of these colors may be clearly distinguished on
-  any given physical display).
+And for the defined color names of the following specifications:
 
-* A set of predefined color names which correspond to specific
-  hexadecimal values; for example, ``white``. HTML 4 defines sixteen
-  such colors.
+* HTML 4
 
-`The CSS 2 standard`_ allows any valid HTML 4 color specification, and
-adds three new ways to specify sRGB colors:
+* CSS 2
 
-* A hash mark followed by three hexadecimal digits, which is expanded
-  into three hexadecimal pairs by repeating each digit; thus ``#09c``
-  is equivalent to ``#0099cc``.
+* CSS 2.1
 
-* The string 'rgb', followed by parentheses, between which are three
-  numeric values each between 0 and 255, inclusive, which are taken to
-  be the values of the red, green and blue components in that order;
-  for example, ``rgb(0, 153, 204)``.
+* SVG/CSS 3
 
-* The same as above, except using percentages instead of numeric
-  values; for example, ``rgb(0%, 60%, 80%)``.
-
-`The CSS 2.1 revision`_ does not add any new methods of specifying
-sRGB colors, but does add one additional named color.
-
-`The CSS 3 color module`_ (currently a W3C Candidate Recommendation)
-adds one new way to specify sRGB colors:
-
-* A hue-saturation-lightness triple (HSL), using the construct
-  ``hsl()``.
-
-It also adds support for variable opacity of colors, by allowing the
-specification of alpha-channel information, through the ``rgba()`` and
-``hsla()`` constructs, which are identical to ``rgb()`` and ``hsl()``
-with one exception: a fourth value is supplied, indicating the level
-of opacity from ``0.0`` (completely transparent) to ``1.0``
-(completely opaque). Though not technically a color, the keyword
-``transparent`` is also made available in lieu of a color value, and
-corresponds to ``rgba(0,0,0,0)``.
-
-Additionally, CSS3 defines a new set of color names; this set is taken
-directly from the named colors defined for SVG (Scalable Vector
-Graphics) markup, and is a proper superset of the named colors defined
-in CSS 2.1. This set also has significant overlap with traditional X11
-color sets as defined by the ``rgb.txt`` file on many Unix and
-Unix-like operating systems, though the correspondence is not exact;
-the set of X11 colors is not standardized, and the set of CSS3 colors
-contains some definitions which diverge significantly from customary
-X11 definitions (for example, CSS3's ``green`` is not equivalent to
-X11's ``green``; the value which X11 designates ``green`` is
-designated ``lime`` in CSS3).
-
-.. _the sRGB color space: http://www.w3.org/Graphics/Color/sRGB
-.. _The HTML 4 standard: http://www.w3.org/TR/html401/types.html#h-6.5
-.. _The CSS 2 standard: http://www.w3.org/TR/REC-CSS2/syndata.html#value-def-color
-.. _The CSS 2.1 revision: http://www.w3.org/TR/CSS21/
-.. _The CSS 3 color module: http://www.w3.org/TR/css3-color/
-
-What this module supports
--------------------------
-
-The mappings and functions within this module support the following
-methods of specifying sRGB colors, and conversions between them:
-
-* Six-digit hexadecimal.
-
-* Three-digit hexadecimal.
-
-* Integer ``rgb()`` triplet.
-
-* Percentage ``rgb()`` triplet.
-
-* Varying selections of predefined color names (see below).
-
-This module does not support ``hsl()`` triplets, nor does it support
-opacity/alpha-channel information via ``rgba()`` or ``hsla()``.
-
-If you need to convert between RGB-specified colors and HSL-specified
-colors, or colors specified via other means, consult `the colorsys
-module`_ in the Python standard library, which can perform conversions
-amongst several common color spaces.
-
-.. _the colorsys module: http://docs.python.org/library/colorsys.html
-
-Normalization
--------------
-
-For colors specified via hexadecimal values, this module will accept
-input in the following formats:
-
-* A hash mark (#) followed by three hexadecimal digits, where letters
-  may be upper- or lower-case.
-
-* A hash mark (#) followed by six hexadecimal digits, where letters
-  may be upper- or lower-case.
-
-For output which consists of a color specified via hexadecimal values,
-and for functions which perform intermediate conversion to hexadecimal
-before returning a result in another format, this module always
-normalizes such values to the following format:
-
-* A hash mark (#) followed by six hexadecimal digits, with letters
-  forced to lower-case.
-
-The function ``normalize_hex()`` in this module can be used to perform
-this normalization manually if desired; see its documentation for an
-explanation of the normalization process.
-
-For colors specified via predefined names, this module will accept
-input in the following formats:
-
-* An entirely lower-case name, such as ``aliceblue``.
-
-* A name using initial capitals, such as ``AliceBlue``.
-
-For output which consists of a color specified via a predefined name,
-and for functions which perform intermediate conversion to a
-predefined name before returning a result in another format, this
-module always normalizes such values to be entirely lower-case.
-
-Mappings of color names
------------------------
-
-For each set of defined color names -- HTML 4, CSS 2, CSS 2.1 and CSS
-3 -- this module exports two mappings: one of normalized color names
-to normalized hexadecimal values, and one of normalized hexadecimal
-values to normalized color names. These eight mappings are as follows:
-
-``html4_names_to_hex``
-    Mapping of normalized HTML 4 color names to normalized hexadecimal
-    values.
-
-``html4_hex_to_names``
-    Mapping of normalized hexadecimal values to normalized HTML 4
-    color names.
-
-``css2_names_to_hex``
-    Mapping of normalized CSS 2 color names to normalized hexadecimal
-    values. Because CSS 2 defines the same set of named colors as HTML
-    4, this is merely an alias for ``html4_names_to_hex``.
-
-``css2_hex_to_names``
-    Mapping of normalized hexadecimal values to normalized CSS 2 color
-    nams. For the reasons described above, this is merely an alias for
-    ``html4_hex_to_names``.
-
-``css21_names_to_hex``
-    Mapping of normalized CSS 2.1 color names to normalized
-    hexadecimal values. This is identical to ``html4_names_to_hex``,
-    except for one addition: ``orange``.
-
-``css21_hex_to_names``
-    Mapping of normalized hexadecimal values to normalized CSS 2.1
-    color names. As above, this is identical to ``html4_hex_to_names``
-    except for the addition of ``orange``.
-
-``css3_names_to_hex``
-    Mapping of normalized CSS3 color names to normalized hexadecimal
-    values.
-
-``css3_hex_to_names``
-    Mapping of normalized hexadecimal values to normalized CSS3 color
-    names.
-
-Normalization functions
------------------------
-
-``normalize_hex(hex_value)``
-    Normalize a hexadecimal color value to the following form and
-    return the result::
-    
-        #[a-f0-9]{6}
-    
-    In other words, the following transformations are applied as
-    needed:
-    
-    * If the value contains only three hexadecimal digits, it is
-      expanded to six.
-    
-    * The value is normalized to lower-case.
-    
-    If the supplied value cannot be interpreted as a hexadecimal color
-    value, ``ValueError`` is raised.
-    
-    Example:
-    
-    >>> normalize_hex('#09c')
-    '#0099cc'
-
-Conversions from named colors
------------------------------
-
-``name_to_hex(name, spec='css3')``
-    Convert a color name to a normalized hexadecimal color value.
-    
-    The optional keyword argument ``spec`` determines which
-    specification's list of color names will be used; valid values are
-    ``html4``, ``css2``, ``css21`` and ``css3``, and the default is
-    ``css3``.
-    
-    The color name will be normalized to lower-case before being
-    looked up, and when no color of that name exists in the given
-    specification, ``ValueError`` is raised.
-    
-    Example:
-    
-    >>> name_to_hex('deepskyblue')
-    '#00bfff'
-
-``name_to_rgb(name, spec='css3')``
-    Convert a color name to a 3-tuple of integers suitable for use in
-    an ``rgb()`` triplet specifying that color.
-    
-    The optional keyword argument ``spec`` determines which
-    specification's list of color names will be used; valid values are
-    ``html4``, ``css2``, ``css21`` and ``css3``, and the default is
-    ``css3``.
-    
-    The color name will be normalized to lower-case before being
-    looked up, and when no color of that name exists in the given
-    specification, ``ValueError`` is raised.
-    
-    Example:
-    
-    >>> name_to_rgb('navy')
-    (0, 0, 128)
-
-``name_to_rgb_percent(name, spec='css3')``
-    Convert a color name to a 3-tuple of percentages suitable for use
-    in an ``rgb()`` triplet specifying that color.
-    
-    The optional keyword argument ``spec`` determines which
-    specification's list of color names will be used; valid values are
-    ``html4``, ``css2``, ``css21`` and ``css3``, and the default is
-    ``css3``.
-    
-    The color name will be normalized to lower-case before being
-    looked up, and when no color of that name exists in the given
-    specification, ``ValueError`` is raised.
-    
-    Example:
-    
-    >>> name_to_rgb_percent('navy')
-    ('0%', '0%', '50%')
-
-
-Conversions from hexadecimal values
------------------------------------
-
-``hex_to_name(hex_value, spec='css3')``
-    Convert a hexadecimal color value to its corresponding normalized
-    color name, if any such name exists.
-    
-    The optional keyword argument ``spec`` determines which
-    specification's list of color names will be used; valid values are
-    ``html4``, ``css2``, ``css21`` and ``css3``, and the default is
-    ``css3``.
-    
-    The hexadecimal value will be normalized before being looked up,
-    and when no color name for the value is found in the given
-    specification, ``ValueError`` is raised.
-    
-    Example:
-    
-    >>> hex_to_name('#000080')
-    'navy'
-
-``hex_to_rgb(hex_value)``
-    Convert a hexadecimal color value to a 3-tuple of integers
-    suitable for use in an ``rgb()`` triplet specifying that color.
-    
-    The hexadecimal value will be normalized before being converted.
-    
-    Example:
-    
-    >>> hex_to_rgb('#000080')
-    (0, 0, 128)
-
-``hex_to_rgb_percent(hex_value)``
-    Convert a hexadecimal color value to a 3-tuple of percentages
-    suitable for use in an ``rgb()`` triplet representing that color.
-    
-    The hexadecimal value will be normalized before converting.
-    
-    Example:
-
-    >>> hex_to_rgb_percent('#ffffff')
-    ('100%', '100%', '100%')
-
-
-Conversions from integer rgb() triplets
----------------------------------------
-
-``rgb_to_name(rgb_triplet, spec='css3')``
-    Convert a 3-tuple of integers, suitable for use in an ``rgb()``
-    color triplet, to its corresponding normalized color name, if any
-    such name exists.
-    
-    The optional keyword argument ``spec`` determines which
-    specification's list of color names will be used; valid values are
-    ``html4``, ``css2``, ``css21`` and ``css3``, and the default is
-    ``css3``.
-    
-    If there is no matching name, ``ValueError`` is raised.
-    
-    Example:
-    
-    >>> rgb_to_name((0, 0, 0))
-    'black'
-
-``rgb_to_hex(rgb_triplet)``
-    Convert a 3-tuple of integers, suitable for use in an ``rgb()``
-    color triplet, to a normalized hexadecimal value for that color.
-    
-    Example:
-    
-    >>> rgb_to_hex((255, 255, 255))
-    '#ffffff'
-
-``rgb_to_rgb_percent(rgb_triplet)``
-    Convert a 3-tuple of integers, suitable for use in an ``rgb()``
-    color triplet, to a 3-tuple of percentages suitable for use in
-    representing that color.
-    
-    This function makes some trade-offs in terms of the accuracy of
-    the final representation; for some common integer values,
-    special-case logic is used to ensure a precise result (e.g.,
-    integer 128 will always convert to '50%', integer 32 will always
-    convert to '12.5%'), but for all other values a standard Python
-    ``float`` is used and rounded to two decimal places, which may
-    result in a loss of precision for some values.
-    
-    Examples:
-    
-    >>> rgb_to_rgb_percent((255, 255, 255))
-    ('100%', '100%', '100%')
-    >>> rgb_to_rgb_percent((0, 0, 128))
-    ('0%', '0%', '50%')
-    >>> rgb_to_rgb_percent((33, 56, 192))
-    ('12.94%', '21.96%', '75.29%')
-    >>> rgb_to_rgb_percent((64, 32, 16))
-    ('25%', '12.5%', '6.25%')
-
-
-Conversions from percentage rgb() triplets
-------------------------------------------
-
-``rgb_percent_to_name(rgb_percent_triplet, spec='css3')``
-    Convert a 3-tuple of percentages, suitable for use in an ``rgb()``
-    color triplet, to its corresponding normalized color name, if any
-    such name exists.
-    
-    The optional keyword argument ``spec`` determines which
-    specification's list of color names will be used; valid values are
-    ``html4``, ``css2``, ``css21`` and ``css3``, and the default is
-    ``css3``.
-    
-    If there is no matching name, ``ValueError`` is raised.
-    
-    Example:
-    
-    >>> rgb_percent_to_name(('0%', '0%', '50%'))
-    'navy'
-
-``rgb_percent_to_hex(rgb_percent_triplet)``
-    Convert a 3-tuple of percentages, suitable for use in an ``rgb()``
-    color triplet, to a normalized hexadecimal color value for that
-    color.
-    
-    Example:
-
-    >>> rgb_percent_to_hex(('100%', '100%', '0%'))
-    '#ffff00'
-
-``rgb_percent_to_rgb(rgb_percent_triplet)``
-    Convert a 3-tuple of percentages, suitable for use in an ``rgb()``
-    color triplet, to a 3-tuple of integers suitable for use in
-    representing that color.
-    
-    Some precision may be lost in this conversion. See the note
-    regarding precision for ``rgb_to_rgb_percent()`` for details;
-    generally speaking, the following is true for any 3-tuple ``t`` of
-    integers in the range 0...255 inclusive::
-    
-        t == rgb_percent_to_rgb(rgb_to_rgb_percent(t))
-    
-    Examples:
-    
-    >>> rgb_percent_to_rgb(('100%', '100%', '100%'))
-    (255, 255, 255)
-    >>> rgb_percent_to_rgb(('0%', '0%', '50%'))
-    (0, 0, 128)
-    >>> rgb_percent_to_rgb(('25%', '12.5%', '6.25%'))
-    (64, 32, 16)
-    >>> rgb_percent_to_rgb(('12.94%', '21.96%', '75.29%'))
-    (33, 56, 192)
+Full documentation is `available online
+<http://docs.b-list.org/webcolors/1.3.1/`_.