Merge pull request #110 from facelessuser/enhance/interp-fit

Don't fit spaces when interpolating unless they cannot be represented

coloraide/interpolate.py

@@ -481,8 +481,9 @@ def color_lerp(
     """Color interpolation."""
 
     # Convert to the color space and ensure the color fits inside
-    color1 = color1.convert(space, fit=True)
-    color2 = color1._handle_color_input(color2).convert(space, fit=True)
+    fit = not color1.CS_MAP[space].EXTENDED_RANGE
+    color1 = color1.convert(space, fit=fit)
+    color2 = color1._handle_color_input(color2).convert(space, fit=fit)
 
     # Adjust hues if we have two valid hues
     if isinstance(color1._space, Cylindrical):

coloraide/spaces/__init__.py

@@ -171,6 +171,12 @@ class Space(
     #   gamut, when evaluated with a threshold, may appear to be in gamut enough, but when checking the original color
     #   space, the values can be greatly out of specification (looking at you HSL).
     GAMUT_CHECK = None  # type: Optional[str]
+    # When set to `True`, this denotes that the color space has the ability to represent out of gamut in colors in an
+    # extended range. When interpolation is done, if colors are interpolated in a smaller gamut than the colors being
+    # interpolated, the colors will usually be gamut mapped, but if the interpolation space happens to support extended
+    # ranges, then the colors will not be gamut mapped even if their gamut is larger than the target interpolation
+    # space.
+    EXTENDED_RANGE = False
     # Bounds of channels. Range could be suggested or absolute as not all spaces have definitive ranges.
     BOUNDS = tuple()  # type: Tuple[Bounds, ...]
     # White point

coloraide/spaces/srgb/__init__.py

@@ -59,6 +59,7 @@ class SRGB(Space):
     }
     WHITE = "D65"
 
+    EXTENDED_RANGE = True
     BOUNDS = (
         GamutBound(0.0, 1.0, FLG_OPT_PERCENT),
         GamutBound(0.0, 1.0, FLG_OPT_PERCENT),

docs/src/markdown/about/changelog.md

@@ -2,14 +2,21 @@
 
 ## 0.9.0
 
+!!! warning "Breaking Change"
+    Custom gamut mapping plugins no longer return coordinates and require the method to update the passed in color.
+
 - **NEW**: Improved, faster gamut mapping algorithm.
-- **NEW**: FIT plugins (gamut mapping) no longer return coordinates but should modify the color passed in. 
+- **NEW**: FIT plugins (gamut mapping) no longer return coordinates but should modify the color passed in.
 - **NEW**: Expose default interpolation space as a class variable that can be controlled when creating a custom class
   via class inheritance.
 - **NEW**: Colors can now directly specify the ∆E method that is used when interpolating color steps and using
   `max_delta_e` via the new `delta_e` argument. If the `delta_e` parameter is omitted, the color object's default ∆E
   method will be used.
 - **NEW**: Oklab is now the default interpolation color space.
+- **NEW**: Interpolation will now avoid fitting colors that are out of gamut unless the color space cannot represent
+  out of gamut colors. Currently, all of the RGB colors (`srgb`, `display-p3`, etc.) all support extended ranges, but
+  the HSL, HWB, and HSV color models for `srgb` (including spaces such as `okhsl` and `okhsv`) do not support extended
+  ranges and will still be gamut mapped.
 - **FIX**: Remove some incorrect code from the gamut mapping algorithm that would shortcut the mapping to reduce chroma
   to zero.
 

docs/src/markdown/plugins/index.md

@@ -141,6 +141,12 @@ class XYZD65(Space):
     #   gamut, when evaluated with a threshold, may appear to be in gamut enough, but when checking the original color
     #   space, the values can be greatly out of specification (looking at you HSL).
     GAMUT_CHECK = None
+    # When set to `True`, this denotes that the color space has the ability to represent out of gamut in colors in an
+    # extended range. When interpolation is done, if colors are interpolated in a smaller gamut than the colors being
+    # interpolated, the colors will usually be gamut mapped, but if the interpolation space happens to support extended
+    # ranges, then the colors will not be gamut mapped even if their gamut is larger than the target interpolation
+    # space.
+    EXTENDED_RANGE = False
 
     ############################
     # Getters and setters for non-alpha properties