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rgb.elv
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rgb.elv
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# Copyright (c) 2018, 2020-2021, Cody Opel <[email protected]>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
use github.com/chlorm/elvish-stl/map
fn -validate-decimal-rgb {|decRgbMap|
for i [ (map:keys $decRgbMap) ] {
if (or (< $decRgbMap[$i] 0) (> $decRgbMap[$i] 255)) {
var err = 'RGB decimal out of range: '$decRgbMap[$i]
fail $err
}
}
}
fn hexstr-to-map {|hexStr|
if (==s $hexStr[0..1] '#') {
set hexStr = $hexStr[1..]
}
if (not (== (count $hexStr) 6)) {
# FIXME: improve error
fail 'Got a non-rgb string'
}
put [
&r=$hexStr[0..2]
&g=$hexStr[2..4]
&b=$hexStr[4..6]
]
}
# Convert hexadecimal to decimal RGB.
fn hex-to-dec {|hexRgbMap|
# Truncate all hex RGB values to 2 digits.
put [
&r=(base 10 '0x'$hexRgbMap['r'][0..2])
&g=(base 10 '0x'$hexRgbMap['g'][0..2])
&b=(base 10 '0x'$hexRgbMap['b'][0..2])
]
}
fn -base16 {|int|
var b16 = (base 16 $int)
# 00 gets truncated to 0
if (< (count $b16) 2) {
set b16 = '0'$b16
}
put $b16
}
# Convert decimal to hexadecimal RGB.
fn dec-to-hex {|decRgbMap|
put [
&r=(-base16 $decRgbMap['r'])
&g=(-base16 $decRgbMap['g'])
&b=(-base16 $decRgbMap['b'])
]
}
# ITU-R BT.709 Section 3.2
fn get-luma {|decRgbMap|
var r = (* 0.2126 $decRgbMap['r'])
var g = (* 0.7152 $decRgbMap['g'])
var b = (* 0.0722 $decRgbMap['b'])
var luma = (+ $r $g $b)
put $luma
}