sass/accepted/color-4-new-spaces.changes.md

Draft 1.20

• Many small wording and consistency changes.

• Remove outdated references to the possibility of unknown color spaces.

• Remove an outdated reference to the specified hue interpolation method.

• Make color.complement() and color.invert() produce errors when color channels are missing, for forwards-compatibility.

• When passing a legacy color to a color manipulation function that operates in another space, ensure that channels aren't marked as none in the conversion back to the legacy color.

• Properly include alpha as the first channel in color.ie-hex-str() rather than the last.

Draft 1.19

• Be stricter about which colors are allowed with slash-separated strings at the end.

Draft 1.18

• Treat missing channels as distinct from 0 for ==-equality for colors.

• Convert missing channels to 0 before color conversion for color.same().

• Explicitly support none values for alpha in Parsing Color Components and color.change(),

• Clarify how to handle existing missing components in color.adjust() and color.scale().

• Remove language misleadingly indicating that the scaling a number algorithm was guaranteed to return an in-gamut number.

• Ensure that color.invert() and color.grayscale() always return colors in the original color's space.

• Make color.invert() throw an error for an invalid $weight.

• Include CSS-compatibility behavior for color.invert() and color.grayscale().

• Explicitly mandate local-minde gamut-mapping for ie-hex-str().

Draft 1.17

• Treat colors with missing channels as the same as 0 for color.same().

Draft 1.16

• Explicitly require case-sensitivity for channel names in Sass functions.

Draft 1.15

• Add a mandatory $method parameter to color.to-gamut() for forwards-compatibility with better gamut-mapping algorithms.

• Add clip as a gamut-mapping algorithm.

Draft 1.14

• Update the definition of powerless for HWB to match the latest CSS spec.

Draft 1.13

• Remove definitions of powerless channels that are no longer present in CSS Color 4.

• Add channel clamping to color.adjust().

• Convert negative saturation/chroma polar colors to their positive equivalents on creation.

• Give implementations more flexibility in how they serialize out-of-gamut clamped colors.

• Clarify that an error is thrown when passing conflicting legacy channels to color.change(), color.adjust(), and color.scale().

Draft 1.12

• Explicitly indicate which channels are clamped, and apply this clamping only when constructing colors from global functions.

• Serialize colors with out-of-bounds clamped channels so that they parse as the correct out-of-gamut value and the correct color space, per the spec.

Draft 1.11

• Add support for the relative color syntax in the algorithm parsing color arguments, for CSS compatibility.

Draft 1.10

• Properly scale % return values for color.channel().

• Clean up some language related to percent-conversion.

Draft 1.9

• Explicitly define associated units for color space channels.

Draft 1.8

• Require a quoted string for color.is-missing() for consistency with other color functions and ease of use with channels whose names overlap with colors.

Draft 1.7

• Resolve missing alpha channels after premultiplying colors.

Draft 1.6

• Clarify in the known color space definitions that lightness channels are clamped.

Draft 1.5

• Remove clamping and scaling of hsl and hwb color channels.

• Document color.to-gamut() in summary and design decisions.

Draft 1.4

• All lightness channels are now clamped in the [0,100] range.

• Missing channels are not allowed in legacy comma-separated rgb/rgba or hsl/hsla syntaxes.

• Colors conversion is only performed when necessary. Previously, colors could be converted into their current space.

• Color conversion procedure explicitly handles 'carrying forward' missing channels when converting to a space with an analogous component. This was previously only applied to interpolation.

• Allow all color spaces to be used for hue interpolation.

• Remove specified hue interpolation method, and normalize hues to be in the [0,360] range.

Draft 1.3

• Deprecate the color.alpha() function along with the other legacy channel access functions.

• Require quoted strings for channel names in color.is-powerless() and color.channel(), to avoid syntax conflicts between rgb channel names and their respective named colors (e.g. 'red' the channel vs red the color).

• Define how deprecated functions behave as alias functions during the deprecation process.

Draft 1.2

• Clamp hsl saturation & lightness when generating hsl colors, and gamut-map when converting colors into either hsl or hwb, since those spaces cannot properly maintain out-of-gamut color values.

• Ensure that color space names are unquoted strings, and compared insensitive to case.

• Remove support for custom or unknown color spaces. There are too many open questions in the CSS spec, as browsers have not started to implement this feature yet.

• Remove channel indexing, and syntax to access channels by index, since all known color channels have names.

• Allow channel adjustment values to be out-of-gamut, and then normalize the resulting channel values. This allows more flexibility, while ensuring that hsl or hwb clamp out-of-gamut results.

• Channel clamping and scaling for hsl and hwb colors is handled in the normalization process, rather than the individual functions. This also allows it to happen when normalizing the results of color manipulation.

• Throw an error in the color component parsing procedure if a known color space is one of the components, and has a function of it's own (e.g. rgb or oklch). Only custom color spaces and predefined spaces can be defined using the color(<space> <channels>) syntax.

• Add missing $weight to the color.invert() signature, and return early when the specified weight is 0% or 100%.

• Update the color interpolation procedure handling of weight values to error when weight is outside the [0,1] range, and return early when weight is equal to 0 or 1.

• For backwards compatibility, the color.change(), color.scale(), and color.adjust() functions allow manipulating legacy colors in any legacy space, if the $space argument is not explicitly set.

• Remove in prefix from the color interpolation method syntax, since the Sass function syntax is already explicit about which parameter is where.

• color.invert() throws an error when $weight would require mixing in an invalid color.mix() interpolation color space.

• Allow scaling channels with a non-0 minimum value, such as the a and b channels in lab()/oklab().

• Ensure that percentage and percentage-mapped number values are normalized before they are added together in color.adjust().

• Clarify that channel values are stored as raw doubles, and add/remove units as necessary for normalization/serialization.

• Legacy colors with missing channels are serialized using the non-legacy serialization logic. When converting colors into legacy spaces with color.to-space(), all missing components are replaced with 0 for better legacy output.

• color.channel() returns 0 when the channel value is missing, rather than throwing an error.

• Added color.is-missing($color, $channel) to inspect if a channel is set to 'none' (e.g. missing).

• Legacy colors using a space-separated syntax with special number values that are not adjacent to a / symbol are emitted using the legacy (comma-separated) CSS syntax. For example:

  • hsl(20deg 5% var(--foo)) emits hsl(20deg, 5%, var(--foo)).

  • hsl(20deg var(--foo) 5% / 0.5) emits hsl(20deg, var(--foo), 5%, 0.5).

  • hsl(20deg 5% var(--foo) / 0.5) emits hsl(20deg 5% var(--foo)/0.5) since the special value is adjacent to the slash.

Draft 1.1

• Expand the summary section to describe more of the proposal.

Draft 1

• Initial draft