def test_rgba():
# four args (css-style)
assert calc('rgba(128, 192, 224, 0.5)') == Color.from_rgb(128/255, 192/255, 224/255, 0.5)
assert calc('rgba(20%, 40%, 60%, 0.7)') == Color.from_rgb(0.2, 0.4, 0.6, 0.7)
# two args (modify alpha of existing color)
assert calc('rgba(red, 0.4)') == Color.from_rgb(1., 0., 0., 0.4)
def test_rgba(calc):
# four args (css-style)
assert calc('rgba(128, 192, 224, 0.5)') == Color.from_rgb(128/255, 192/255, 224/255, 0.5)
assert calc('rgba(20%, 40%, 60%, 0.7)') == Color.from_rgb(0.2, 0.4, 0.6, 0.7)
# two args (modify alpha of existing color)
assert calc('rgba(red, 0.4)') == Color.from_rgb(1., 0., 0., 0.4)
def test_reference_operations():
"""Test the example expressions in the reference document:
http://sass-lang.com/docs/yardoc/file.SASS_REFERENCE.html#operations
"""
# TODO: break this into its own file and add the entire reference guide
# Need to build the calculator manually to get at its namespace, and need
# to use calculate() instead of evaluate_expression() so interpolation
# works
ns = CoreExtension.namespace.derive()
calc = Calculator(ns).calculate
# Simple example
assert calc('1in + 8pt') == Number(1.1111111111111112, "in")
# Division
ns.set_variable('$width', Number(1000, "px"))
ns.set_variable('$font-size', Number(12, "px"))
ns.set_variable('$line-height', Number(30, "px"))
assert calc('10px/8px') == String('10px / 8px') # plain CSS; no division
assert calc('$width/2') == Number(500,
"px") # uses a variable; does division
assert calc('(500px/2)') == Number(250, "px") # uses parens; does division
assert calc('5px + 8px/2px') == Number(9, "px") # uses +; does division
# TODO, again: Ruby Sass correctly renders this without spaces
assert calc('#{$font-size}/#{$line-height}') == String('12px / 30px')
# uses #{}; does no division
# Color operations
ns.set_variable('$translucent-red', Color.from_rgb(1, 0, 0, 0.5))
ns.set_variable('$green', Color.from_name('lime'))
assert calc('#010203 + #040506') == Color.from_hex('#050709')
assert calc('#010203 * 2') == Color.from_hex('#020406')
assert calc(
'rgba(255, 0, 0, 0.75) + rgba(0, 255, 0, 0.75)') == Color.from_rgb(
1, 1, 0, 0.75)
assert calc('opacify($translucent-red, 0.3)') == Color.from_rgb(
1, 0, 0, 0.8)
assert calc('transparentize($translucent-red, 0.25)') == Color.from_rgb(
1, 0, 0, 0.25)
assert calc(
"progid:DXImageTransform.Microsoft.gradient(enabled='false', startColorstr='#{ie-hex-str($green)}', endColorstr='#{ie-hex-str($translucent-red)}')"
).render(
) == "progid:DXImageTransform.Microsoft.gradient(enabled='false', startColorstr='#FF00FF00', endColorstr='#80FF0000')"
# String operations
ns.set_variable('$value', Null())
assert_strict_string_eq(calc('e + -resize'), String('e-resize',
quotes=None))
assert_strict_string_eq(calc('"Foo " + Bar'), String('Foo Bar',
quotes='"'))
assert_strict_string_eq(calc('sans- + "serif"'),
String('sans-serif', quotes=None))
assert calc('3px + 4px auto') == List(
[Number(7, "px"), String('auto', quotes=None)])
assert_strict_string_eq(calc('"I ate #{5 + 10} pies!"'),
String('I ate 15 pies!', quotes='"'))
assert_strict_string_eq(calc('"I ate #{$value} pies!"'),
String('I ate pies!', quotes='"'))
def test_hsl(calc):
# Examples from the CSS 3 color spec, which Sass uses
# (http://www.w3.org/TR/css3-color/#hsl-color)
assert calc('hsl(0, 100%, 50%)') == Color.from_rgb(1., 0., 0.)
assert calc('hsl(120, 100%, 50%)') == Color.from_rgb(0., 1., 0.)
assert calc('hsl(120, 100%, 25%)') == Color.from_rgb(0., 0.5, 0.)
assert calc('hsl(120, 100%, 75%)') == Color.from_rgb(0.5, 1., 0.5)
assert calc('hsl(120, 75%, 75%)') == Color.from_rgb(0.5625, 0.9375, 0.5625)
def test_hsl():
# Examples from the CSS 3 color spec, which Sass uses
# (http://www.w3.org/TR/css3-color/#hsl-color)
assert calc('hsl(0, 100%, 50%)') == Color.from_rgb(1., 0., 0.)
assert calc('hsl(120, 100%, 50%)') == Color.from_rgb(0., 1., 0.)
assert calc('hsl(120, 100%, 25%)') == Color.from_rgb(0., 0.5, 0.)
assert calc('hsl(120, 100%, 75%)') == Color.from_rgb(0.5, 1., 0.5)
assert calc('hsl(120, 75%, 75%)') == Color.from_rgb(0.5625, 0.9375, 0.5625)
def test_hsla():
# Examples from the CSS 3 color spec
assert calc('hsla(120, 100%, 50%, 1)') == Color.from_rgb(
0.,
1.,
0.,
)
assert calc('hsla(240, 100%, 50%, 0.5)') == Color.from_rgb(0., 0., 1., 0.5)
assert calc('hsla(30, 100%, 50%, 0.1)') == Color.from_rgb(1., 0.5, 0., 0.1)
def test_reference_operations():
"""Test the example expressions in the reference document:
http://sass-lang.com/docs/yardoc/file.SASS_REFERENCE.html#operations
"""
# TODO: break this into its own file and add the entire reference guide
# Need to build the calculator manually to get at its namespace, and need
# to use calculate() instead of evaluate_expression() so interpolation
# works
ns = CoreExtension.namespace.derive()
calc = Calculator(ns).calculate
# Simple example
assert calc('1in + 8pt') == Number(1.1111111111111112, "in")
# Division
ns.set_variable('$width', Number(1000, "px"))
ns.set_variable('$font-size', Number(12, "px"))
ns.set_variable('$line-height', Number(30, "px"))
assert calc('10px/8px') == String('10px / 8px') # plain CSS; no division
assert calc('$width/2') == Number(500, "px") # uses a variable; does division
assert calc('(500px/2)') == Number(250, "px") # uses parens; does division
assert calc('5px + 8px/2px') == Number(9, "px") # uses +; does division
# TODO, again: Ruby Sass correctly renders this without spaces
assert calc('#{$font-size}/#{$line-height}') == String('12px / 30px')
# uses #{}; does no division
# Modulo
assert calc('29 % 12') == Number(5)
assert calc('29px % 12') == Number(5, 'px')
assert calc('29px % 12px') == Number(5, 'px')
# Color operations
ns.set_variable('$translucent-red', Color.from_rgb(1, 0, 0, 0.5))
ns.set_variable('$green', Color.from_name('lime'))
assert calc('#010203 + #040506') == Color.from_hex('#050709')
assert calc('#010203 * 2') == Color.from_hex('#020406')
assert calc('rgba(255, 0, 0, 0.75) + rgba(0, 255, 0, 0.75)') == Color.from_rgb(1, 1, 0, 0.75)
assert calc('opacify($translucent-red, 0.3)') == Color.from_rgb(1, 0, 0, 0.8)
assert calc('transparentize($translucent-red, 0.25)') == Color.from_rgb(1, 0, 0, 0.25)
assert calc("progid:DXImageTransform.Microsoft.gradient(enabled='false', startColorstr='#{ie-hex-str($green)}', endColorstr='#{ie-hex-str($translucent-red)}')"
).render() == "progid:DXImageTransform.Microsoft.gradient(enabled='false', startColorstr='#FF00FF00', endColorstr='#80FF0000')"
# String operations
ns.set_variable('$value', Null())
assert_strict_string_eq(calc('e + -resize'), String('e-resize', quotes=None))
assert_strict_string_eq(calc('"Foo " + Bar'), String('Foo Bar', quotes='"'))
assert_strict_string_eq(calc('sans- + "serif"'), String('sans-serif', quotes=None))
assert calc('3px + 4px auto') == List([Number(7, "px"), String('auto', quotes=None)])
assert_strict_string_eq(calc('"I ate #{5 + 10} pies!"'), String('I ate 15 pies!', quotes='"'))
assert_strict_string_eq(calc('"I ate #{$value} pies!"'), String('I ate pies!', quotes='"'))
def transparentize(color, amount):
r, g, b, a = color.rgba
if amount.is_simple_unit('%'):
amt = amount.value / 100
else:
amt = amount.value
return Color.from_rgb(r, g, b, alpha=a - amt)
def opacify(color, amount):
r, g, b, a = color.rgba
if amount.is_simple_unit('%'):
amt = amount.value / 100
else:
amt = amount.value
return Color.from_rgb(r, g, b, alpha=a + amt)
def transparentize(color, amount):
r, g, b, a = color.rgba
if amount.is_simple_unit("%"):
amt = amount.value / 100
else:
amt = amount.value
return Color.from_rgb(r, g, b, alpha=a - amt)
def opacify(color, amount):
r, g, b, a = color.rgba
if amount.is_simple_unit("%"):
amt = amount.value / 100
else:
amt = amount.value
return Color.from_rgb(r, g, b, alpha=a + amt)
def change_color(color, red=None, green=None, blue=None, hue=None, saturation=None, lightness=None, alpha=None):
do_rgb = red or green or blue
do_hsl = hue or saturation or lightness
if do_rgb and do_hsl:
raise ValueError("Can't change both RGB and HSL channels at the same time")
if alpha is None:
alpha = color.alpha
else:
alpha = alpha.value
if do_rgb:
channels = list(color.rgba[:3])
if red:
channels[0] = _interpret_percentage(red, relto=255)
if green:
channels[1] = _interpret_percentage(green, relto=255)
if blue:
channels[2] = _interpret_percentage(blue, relto=255)
return Color.from_rgb(*channels, alpha=alpha)
else:
channels = list(color.hsl)
if hue:
expect_type(hue, Number, unit=None)
channels[0] = (hue.value / 360) % 1
# Ruby sass treats plain numbers for saturation and lightness as though
# they were percentages, just without the %
if saturation:
channels[1] = _interpret_percentage(saturation, relto=100)
if lightness:
channels[2] = _interpret_percentage(lightness, relto=100)
return Color.from_hsl(*channels, alpha=alpha)
def rgba(r, g, b, a):
r = _interpret_percentage(r, relto=255)
g = _interpret_percentage(g, relto=255)
b = _interpret_percentage(b, relto=255)
a = _interpret_percentage(a, relto=1)
return Color.from_rgb(r, g, b, a)
def adjust_color(
color, red=None, green=None, blue=None,
hue=None, saturation=None, lightness=None, alpha=None):
do_rgb = red or green or blue
do_hsl = hue or saturation or lightness
if do_rgb and do_hsl:
raise ValueError(
"Can't adjust both RGB and HSL channels at the same time")
zero = Number(0)
a = color.alpha + (alpha or zero).value
if do_rgb:
r, g, b = color.rgba[:3]
channels = [
current + (adjustment or zero).value / 255
for (current, adjustment) in zip(color.rgba, (red, green, blue))]
return Color.from_rgb(*channels, alpha=a)
else:
h, s, l = color.hsl
h = (h + (hue or zero).value / 360) % 1
s += _interpret_percentage(saturation or zero, relto=100, clamp=False)
l += _interpret_percentage(lightness or zero, relto=100, clamp=False)
return Color.from_hsl(h, s, l, a)
def rgba_(color, a=None):
if a is None:
alpha = 1
else:
alpha = _interpret_percentage(a)
return Color.from_rgb(*color.rgba[:3], alpha=alpha)
def rgba_(color, a=None):
if a is None:
alpha = 1
else:
alpha = _interpret_percentage(a)
return Color.from_rgb(*color.rgba[:3], alpha=alpha)
def adjust_color(
color, red=None, green=None, blue=None,
hue=None, saturation=None, lightness=None, alpha=None):
do_rgb = red or green or blue
do_hsl = hue or saturation or lightness
if do_rgb and do_hsl:
raise ValueError(
"Can't adjust both RGB and HSL channels at the same time")
zero = Number(0)
a = color.alpha + (alpha or zero).value
if do_rgb:
r, g, b = color.rgba[:3]
channels = [
current + (adjustment or zero).value / 255
for (current, adjustment) in zip(color.rgba, (red, green, blue))]
return Color.from_rgb(*channels, alpha=a)
else:
h, s, l = color.hsl
h = (h + (hue or zero).value / 360) % 1
s += _interpret_percentage(saturation or zero, relto=100, clamp=False)
l += _interpret_percentage(lightness or zero, relto=100, clamp=False)
return Color.from_hsl(h, s, l, a)
def scale_color(color,
red=None,
green=None,
blue=None,
saturation=None,
lightness=None,
alpha=None):
do_rgb = red or green or blue
do_hsl = saturation or lightness
if do_rgb and do_hsl:
raise ValueError(
"Can't scale both RGB and HSL channels at the same time")
scaled_alpha = _scale_channel(color.alpha, alpha)
if do_rgb:
channels = [
_scale_channel(channel, scaleby)
for channel, scaleby in zip(color.rgba, (red, green, blue))
]
return Color.from_rgb(*channels, alpha=scaled_alpha)
else:
channels = [
_scale_channel(channel, scaleby)
for channel, scaleby in zip(color.hsl, (None, saturation,
lightness))
]
return Color.from_hsl(*channels, alpha=scaled_alpha)
def rgba(r, g, b, a):
r = _interpret_percentage(r, relto=255)
g = _interpret_percentage(g, relto=255)
b = _interpret_percentage(b, relto=255)
a = _interpret_percentage(a, relto=1)
return Color.from_rgb(r, g, b, a)
def invert(color):
"""
Returns the inverse (negative) of a color.
The red, green, and blue values are inverted, while the opacity is left alone.
"""
r, g, b, a = color.rgba
return Color.from_rgb(1 - r, 1 - g, 1 - b, alpha=a)
def change_color(color, red=None, green=None, blue=None, hue=None, saturation=None, lightness=None, alpha=None):
do_rgb = red or green or blue
do_hsl = hue or saturation or lightness
if do_rgb and do_hsl:
raise ValueError("Can't change both RGB and HSL channels at the same time")
if alpha is None:
alpha = color.alpha
else:
alpha = alpha.value
if do_rgb:
channels = list(color.rgba[:3])
if red:
channels[0] = _interpret_percentage(red, relto=255)
if green:
channels[1] = _interpret_percentage(green, relto=255)
if blue:
channels[2] = _interpret_percentage(blue, relto=255)
return Color.from_rgb(*channels, alpha=alpha)
else:
channels = list(color.hsl)
if hue:
expect_type(hue, Number, unit=None)
channels[0] = (hue.value / 360) % 1
# Ruby sass treats plain numbers for saturation and lightness as though
# they were percentages, just without the %
if saturation:
channels[1] = _interpret_percentage(saturation, relto=100)
if lightness:
channels[2] = _interpret_percentage(lightness, relto=100)
return Color.from_hsl(*channels, alpha=alpha)
def invert(color):
"""
Returns the inverse (negative) of a color.
The red, green, and blue values are inverted, while the opacity is left alone.
"""
r, g, b, a = color.rgba
return Color.from_rgb(1 - r, 1 - g, 1 - b, alpha=a)
def test_adjust_hue():
# Examples from the Ruby docs
assert calc('adjust-hue(hsl(120, 30%, 90%), 60deg)') == calc(
'hsl(180, 30%, 90%)')
assert calc('adjust-hue(hsl(120, 30%, 90%), -60deg)') == calc(
'hsl(60, 30%, 90%)')
assert calc('adjust-hue(#811, 45deg)') == Color.from_rgb(
136 / 255, 106.25 / 255, 17 / 255)
def test_functions(calc):
calc = Calculator(CoreExtension.namespace).calculate
assert calc('grayscale(red)') == Color.from_rgb(0.5, 0.5, 0.5)
assert calc('grayscale(1)') == String('grayscale(1)', quotes=None) # Misusing css built-in functions (with scss counterpart)
assert calc('skew(1)') == String('skew(1)', quotes=None) # Missing css-only built-in functions
with pytest.raises(SassEvaluationError):
calc('unitless("X")') # Misusing non-css built-in scss funtions
def test_functions(calc):
ns = Namespace(functions=CORE_LIBRARY)
calc = Calculator(ns).calculate
assert calc('grayscale(red)') == Color.from_rgb(0.5, 0.5, 0.5)
assert calc('grayscale(1)') == String('grayscale(1)', quotes=None) # Misusing css built-in functions (with scss counterpart)
assert calc('skew(1)') == String('skew(1)', quotes=None) # Missing css-only built-in functions
with pytest.raises(TypeError):
calc('unitless("X")') # Misusing non-css built-in scss funtions
def test_functions(calc):
calc = Calculator(CoreExtension.namespace).calculate
assert calc('grayscale(red)') == Color.from_rgb(0.5, 0.5, 0.5)
assert calc('grayscale(1)') == String(
'grayscale(1)',
quotes=None) # Misusing css built-in functions (with scss counterpart)
assert calc('skew(1)') == String(
'skew(1)', quotes=None) # Missing css-only built-in functions
with pytest.raises(SassEvaluationError):
calc('unitless("X")') # Misusing non-css built-in scss funtions
def invert(color):
"""Returns the inverse (negative) of a color. The red, green, and blue
values are inverted, while the opacity is left alone.
"""
if isinstance(color, Number):
# invert(n) and invert(n%) are CSS3 filters and should be left
# intact
return String.unquoted("invert(%s)" % (color.render(),))
expect_type(color, Color)
r, g, b, a = color.rgba
return Color.from_rgb(1 - r, 1 - g, 1 - b, alpha=a)
def invert(color):
"""Returns the inverse (negative) of a color. The red, green, and blue
values are inverted, while the opacity is left alone.
"""
if isinstance(color, Number):
# invert(n) and invert(n%) are CSS3 filters and should be left
# intact
return String.unquoted("invert(%s)" % (color.render(), ))
expect_type(color, Color)
r, g, b, a = color.rgba
return Color.from_rgb(1 - r, 1 - g, 1 - b, alpha=a)
def scale_color(color, red=None, green=None, blue=None, saturation=None, lightness=None, alpha=None):
do_rgb = red or green or blue
do_hsl = saturation or lightness
if do_rgb and do_hsl:
raise ValueError("Can't scale both RGB and HSL channels at the same time")
scaled_alpha = _scale_channel(color.alpha, alpha)
if do_rgb:
channels = [_scale_channel(channel, scaleby) for channel, scaleby in zip(color.rgba, (red, green, blue))]
return Color.from_rgb(*channels, alpha=scaled_alpha)
else:
channels = [
_scale_channel(channel, scaleby) for channel, scaleby in zip(color.hsl, (None, saturation, lightness))
]
return Color.from_hsl(*channels, alpha=scaled_alpha)
def test_grayscale():
assert calc('grayscale(black)') == Color.from_rgb(0., 0., 0.)
assert calc('grayscale(white)') == Color.from_rgb(1., 1., 1.)
assert calc('grayscale(yellow)') == Color.from_rgb(0.5, 0.5, 0.5)
def test_saturate():
# Examples from the Ruby docs
assert calc('saturate(hsl(120, 30%, 90%), 20%)') == calc(
'hsl(120, 50%, 90%)')
assert calc('saturate(#855, 20%)') == Color.from_rgb(
158.1 / 255, 62.9 / 255, 62.9 / 255)
def test_desaturate():
# Examples from the Ruby docs
assert calc('desaturate(hsl(120, 30%, 90%), 20%)') == calc(
'hsl(120, 10%, 90%)')
assert calc('desaturate(#855, 20%)') == Color.from_rgb(
113.9 / 255, 107.1 / 255, 107.1 / 255)
def test_adjust_hue(calc):
# Examples from the Ruby docs
assert calc('adjust-hue(hsl(120, 30%, 90%), 60deg)') == calc('hsl(180, 30%, 90%)')
assert calc('adjust-hue(hsl(120, 30%, 90%), -60deg)') == calc('hsl(60, 30%, 90%)')
assert calc('adjust-hue(#811, 45deg)') == Color.from_rgb(136/255, 106.25/255, 17/255)
def opacify(color, amount):
r, g, b, a = color.rgba
return Color.from_rgb(r, g, b, alpha=color.alpha + amount.value)
def mix(color1, color2, weight=Number(50, "%")):
"""
Mixes together two colors. Specifically, takes the average of each of the
RGB components, optionally weighted by the given percentage.
The opacity of the colors is also considered when weighting the components.
Specifically, takes the average of each of the RGB components,
optionally weighted by the given percentage.
The opacity of the colors is also considered when weighting the components.
The weight specifies the amount of the first color that should be included
in the returned color.
50%, means that half the first color
and half the second color should be used.
25% means that a quarter of the first color
and three quarters of the second color should be used.
For example:
mix(#f00, #00f) => #7f007f
mix(#f00, #00f, 25%) => #3f00bf
mix(rgba(255, 0, 0, 0.5), #00f) => rgba(63, 0, 191, 0.75)
"""
# This algorithm factors in both the user-provided weight
# and the difference between the alpha values of the two colors
# to decide how to perform the weighted average of the two RGB values.
#
# It works by first normalizing both parameters to be within [-1, 1],
# where 1 indicates "only use color1", -1 indicates "only use color 0",
# and all values in between indicated a proportionately weighted average.
#
# Once we have the normalized variables w and a,
# we apply the formula (w + a)/(1 + w*a)
# to get the combined weight (in [-1, 1]) of color1.
# This formula has two especially nice properties:
#
# * When either w or a are -1 or 1, the combined weight is also that
# number (cases where w * a == -1 are undefined, and handled as a
# special case).
#
# * When a is 0, the combined weight is w, and vice versa
#
# Finally, the weight of color1 is renormalized to be within [0, 1]
# and the weight of color2 is given by 1 minus the weight of color1.
#
# Algorithm from the Sass project: http://sass-lang.com/
p = _interpret_percentage(weight)
# Scale weight to [-1, 1]
w = p * 2 - 1
# Compute difference in alpha channels
a = color1.alpha - color2.alpha
# Weight of first color
if w * a == -1:
# Avoid zero-div case
scaled_weight1 = w
else:
scaled_weight1 = (w + a) / (1 + w * a)
# Unscale back to [0, 1] and get the weight of the other color
w1 = (scaled_weight1 + 1) / 2
w2 = 1 - w1
# Do the scaling. Note that alpha isn't scaled by alpha, as that wouldn't
# make much sense; it uses the original untwiddled weight, p.
channels = [
ch1 * w1 + ch2 * w2
for (ch1, ch2) in zip(color1.rgba[:3], color2.rgba[:3])]
alpha = color1.alpha * p + color2.alpha * (1 - p)
return Color.from_rgb(*channels, alpha=alpha)
def test_hsla(calc):
# Examples from the CSS 3 color spec
assert calc('hsla(120, 100%, 50%, 1)') == Color.from_rgb(0., 1., 0.,)
assert calc('hsla(240, 100%, 50%, 0.5)') == Color.from_rgb(0., 0., 1., 0.5)
assert calc('hsla(30, 100%, 50%, 0.1)') == Color.from_rgb(1., 0.5, 0., 0.1)
def test_rgb(calc):
assert calc('rgb(128, 192, 224)') == Color.from_rgb(128/255, 192/255, 224/255)
assert calc('rgb(20%, 40%, 60%)') == Color.from_rgb(0.2, 0.4, 0.6)
def test_rgb():
assert calc('rgb(128, 192, 224)') == Color.from_rgb(
128 / 255, 192 / 255, 224 / 255)
assert calc('rgb(20%, 40%, 60%)') == Color.from_rgb(0.2, 0.4, 0.6)
def test_complement(calc):
assert calc('complement(black)') == Color.from_rgb(0., 0., 0.)
assert calc('complement(white)') == Color.from_rgb(1., 1., 1.)
assert calc('complement(yellow)') == Color.from_rgb(0., 0., 1.)
def test_invert(calc):
assert calc('invert(black)') == Color.from_rgb(1., 1., 1.)
assert calc('invert(white)') == Color.from_rgb(0., 0., 0.)
assert calc('invert(yellow)') == Color.from_rgb(0., 0., 1.)
def test_grayscale(calc):
assert calc('grayscale(black)') == Color.from_rgb(0., 0., 0.)
assert calc('grayscale(white)') == Color.from_rgb(1., 1., 1.)
assert calc('grayscale(yellow)') == Color.from_rgb(0.5, 0.5, 0.5)
def test_desaturate(calc):
# Examples from the Ruby docs
assert calc('desaturate(hsl(120, 30%, 90%), 20%)') == calc('hsl(120, 10%, 90%)')
assert calc('desaturate(#855, 20%)') == Color.from_rgb(113.9/255, 107.1/255, 107.1/255)
def transparentize(color, amount):
r, g, b, a = color.rgba
return Color.from_rgb(r, g, b, alpha=color.alpha - amount.value)
def test_complement():
assert calc('complement(black)') == Color.from_rgb(0., 0., 0.)
assert calc('complement(white)') == Color.from_rgb(1., 1., 1.)
assert calc('complement(yellow)') == Color.from_rgb(0., 0., 1.)
def opacify(color, amount):
r, g, b, a = color.rgba
return Color.from_rgb(
r, g, b,
alpha=color.alpha + amount.value)
def test_invert():
assert calc('invert(black)') == Color.from_rgb(1., 1., 1.)
assert calc('invert(white)') == Color.from_rgb(0., 0., 0.)
assert calc('invert(yellow)') == Color.from_rgb(0., 0., 1.)
def mix(color1, color2, weight=Number(50, "%")):
"""
Mixes together two colors. Specifically, takes the average of each of the
RGB components, optionally weighted by the given percentage.
The opacity of the colors is also considered when weighting the components.
Specifically, takes the average of each of the RGB components,
optionally weighted by the given percentage.
The opacity of the colors is also considered when weighting the components.
The weight specifies the amount of the first color that should be included
in the returned color.
50%, means that half the first color
and half the second color should be used.
25% means that a quarter of the first color
and three quarters of the second color should be used.
For example:
mix(#f00, #00f) => #7f007f
mix(#f00, #00f, 25%) => #3f00bf
mix(rgba(255, 0, 0, 0.5), #00f) => rgba(63, 0, 191, 0.75)
"""
# This algorithm factors in both the user-provided weight
# and the difference between the alpha values of the two colors
# to decide how to perform the weighted average of the two RGB values.
#
# It works by first normalizing both parameters to be within [-1, 1],
# where 1 indicates "only use color1", -1 indicates "only use color 0",
# and all values in between indicated a proportionately weighted average.
#
# Once we have the normalized variables w and a,
# we apply the formula (w + a)/(1 + w*a)
# to get the combined weight (in [-1, 1]) of color1.
# This formula has two especially nice properties:
#
# * When either w or a are -1 or 1, the combined weight is also that
# number (cases where w * a == -1 are undefined, and handled as a
# special case).
#
# * When a is 0, the combined weight is w, and vice versa
#
# Finally, the weight of color1 is renormalized to be within [0, 1]
# and the weight of color2 is given by 1 minus the weight of color1.
#
# Algorithm from the Sass project: http://sass-lang.com/
p = _interpret_percentage(weight)
# Scale weight to [-1, 1]
w = p * 2 - 1
# Compute difference in alpha channels
a = color1.alpha - color2.alpha
# Weight of first color
if w * a == -1:
# Avoid zero-div case
scaled_weight1 = w
else:
scaled_weight1 = (w + a) / (1 + w * a)
# Unscale back to [0, 1] and get the weight of the other color
w1 = (scaled_weight1 + 1) / 2
w2 = 1 - w1
# Do the scaling. Note that alpha isn't scaled by alpha, as that wouldn't
# make much sense; it uses the original untwiddled weight, p.
channels = [
ch1 * w1 + ch2 * w2
for (ch1, ch2) in zip(color1.rgba[:3], color2.rgba[:3])]
alpha = color1.alpha * p + color2.alpha * (1 - p)
return Color.from_rgb(*channels, alpha=alpha)
def test_image_color():
libextra.image_color(Color.from_rgb(1, 1, 0))
assert True
def transparentize(color, amount):
r, g, b, a = color.rgba
return Color.from_rgb(
r, g, b,
alpha=color.alpha - amount.value)
def test_saturate(calc):
# Examples from the Ruby docs
assert calc('saturate(hsl(120, 30%, 90%), 20%)') == calc('hsl(120, 50%, 90%)')
assert calc('saturate(#855, 20%)') == Color.from_rgb(158.1/255, 62.9/255, 62.9/255)
def test_image_color():
libextra.image_color(Color.from_rgb(1, 1, 0))
assert True