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###
chroma.js
Copyright (c) 2011-2013, Gregor Aisch
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
* The name Gregor Aisch may not be used to endorse or promote products
derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL GREGOR AISCH OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
@source: https://github.com/gka/chroma.js
###
# minimal multi-purpose interface
chroma.scale = (colors, positions) ->
# constructor
_mode = 'rgb'
_nacol = chroma '#ccc'
_spread = 0
_fixed = false
_domain = [0, 1]
_colors = []
_out = false
_pos = []
_min = 0
_max = 1
_correctLightness = false
_numClasses = 0
_colorCache = {}
# private methods
setColors = (colors, positions) ->
if not colors?
colors = ['#ddd', '#222']
if colors? and type(colors) == 'string' and chroma.brewer?[colors]?
colors = chroma.brewer[colors]
if type(colors) == 'array'
# make a copy of the colors
colors = colors.slice(0)
# convert to chroma classes
for c in [0..colors.length-1]
col = colors[c]
colors[c] = chroma(col) if type(col) == "string"
# auto-fill color position
if positions?
_pos = positions
else
_pos = []
for c in [0..colors.length-1]
_pos.push c/(colors.length-1)
resetCache()
_colors = colors
setDomain = (domain = []) ->
###
# use this if you want to display a limited number of data classes
# possible methods are "equalinterval", "quantiles", "custom"
###
_domain = domain
_min = domain[0]
_max = domain[domain.length-1]
resetCache()
if domain.length == 2
_numClasses = 0
else
_numClasses = domain.length-1
getClass = (value) ->
if _domain?
n = _domain.length-1
i = 0
while i < n and value >= _domain[i]
i++
return i-1
return 0
tmap = (t) -> t
classifyValue = (value) ->
val = value
if _domain.length > 2
n = _domain.length-1
i = getClass(value)
minc = _domain[0] + (_domain[1]-_domain[0]) * (0 + _spread * 0.5) # center of 1st class
maxc = _domain[n-1] + (_domain[n]-_domain[n-1]) * (1 - _spread * 0.5) # center of last class
val = _min + ((_domain[i] + (_domain[i+1] - _domain[i]) * 0.5 - minc) / (maxc-minc)) * (_max - _min)
val
getColor = (val, bypassMap=false) ->
if isNaN(val) then return _nacol
if not bypassMap
if _domain.length > 2
c = getClass val
t = c / (_numClasses-1)
else
t = f0 = if _min != _max then (val - _min) / (_max - _min) else 0
t = f0 = (val - _min) / (_max - _min)
t = Math.min(1, Math.max(0, t))
else
t = val
if not bypassMap
t = tmap t # lightness correction
k = Math.floor(t * 10000)
if _colorCache[k]
col = _colorCache[k]
else
if type(_colors) == 'array'
for i in [0.._pos.length-1]
p = _pos[i]
if t <= p
col = _colors[i]
break
if t >= p and i == _pos.length-1
col = _colors[i]
break
if t > p and t < _pos[i+1]
t = (t-p)/(_pos[i+1]-p)
col = chroma.interpolate _colors[i], _colors[i+1], t, _mode
break
else if type(_colors) == 'function'
col = _colors t
_colorCache[k] = col
col
resetCache = () ->
_colorCache = {}
setColors colors, positions
# public interface
f = (v) ->
c = getColor v
if _out and c[_out] then c[_out]() else c
f.domain = (domain, classes, mode='e', key) ->
if not arguments.length
return _domain
if classes?
d = chroma.analyze domain, key
if classes == 0
domain = [d.min, d.max]
else
domain = chroma.limits d, mode, classes
setDomain domain
f
f.mode = (_m) ->
if not arguments.length
return _mode
_mode = _m
resetCache()
f
f.range = (colors, _pos) ->
setColors colors, _pos
f
f.out = (_o) ->
_out = _o
f
f.spread = (val) ->
if not arguments.length
return _spread
_spread = val
f
f.correctLightness = (v) ->
if not arguments.length
return _correctLightness
_correctLightness = v
resetCache()
if _correctLightness
tmap = (t) ->
L0 = getColor(0, true).lab()[0]
L1 = getColor(1, true).lab()[0]
pol = L0 > L1
L_actual = getColor(t, true).lab()[0]
L_ideal = L0 + (L1 - L0) * t
L_diff = L_actual - L_ideal
t0 = 0
t1 = 1
max_iter = 20
while Math.abs(L_diff) > 1e-2 and max_iter-- > 0
do () ->
L_diff *= -1 if pol
if L_diff < 0
t0 = t
t += (t1 - t) * 0.5
else
t1 = t
t += (t0 - t) * 0.5
L_actual = getColor(t, true).lab()[0]
L_diff = L_actual - L_ideal
t
else
tmap = (t) -> t
f
f.colors = (out='hex') ->
# returns all colors based on the defined classes
colors = []
samples = []
if _domain.length > 2
for i in [1..._domain.length]
samples.push (_domain[i-1]+_domain[i])*0.5
else
samples = _domain
for i in samples
colors.push f(i)[out]()
colors
f
# some pre-defined color scales:
chroma.scales ?= {}
chroma.scales.cool = ->
chroma.scale [chroma.hsl(180,1,.9), chroma.hsl(250,.7,.4)]
chroma.scales.hot = ->
chroma.scale(['#000','#f00','#ff0','#fff'], [0,.25,.75,1]).mode('rgb')
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