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https://github.com/felixdes/colsum
Simple cli tool for overlaying colors implemented in ✨Kotlin✨
https://github.com/felixdes/colsum
css3 gradle graphics kotlin
Last synced: about 11 hours ago
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Simple cli tool for overlaying colors implemented in ✨Kotlin✨
- Host: GitHub
- URL: https://github.com/felixdes/colsum
- Owner: FelixDes
- License: mit
- Created: 2023-08-07T18:13:22.000Z (over 1 year ago)
- Default Branch: main
- Last Pushed: 2023-09-20T20:12:37.000Z (about 1 year ago)
- Last Synced: 2023-09-21T07:12:46.463Z (about 1 year ago)
- Topics: css3, gradle, graphics, kotlin
- Language: Kotlin
- Homepage:
- Size: 151 KB
- Stars: 3
- Watchers: 1
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# $ colsum
Simple command line tool for overlaying colors implemented in Kotlin
```shell
java -jar colsum.jar -b "lightyellow" -e "rgb(55, 12, 2, 0.4) + rgba(calc(0.5 + 0.5), 50, 217, 0.3)"
```
Usage:
— expression, -e -> Expression for computation (always required) { String }
— background, -b [#FFF] -> background color { String }
— help, -h -> Usage info
# Grammar
Grammar of expressions (ABNF):
```abnf
root = color [ " + " color ]*
color = color-function / hex-color / named-color
named-color = white ; https://developer.mozilla.org/en-US/docs/Web/CSS/named-color
color-function = rgb-function / rgba-function / hsl-function / hsla-function
rgb-function =
"rgb(" ( rgb-arg ", " ){2} rgb-arg [ ", " alpha-arg ] ")" /
"rgb(" ( rgb-arg ", " ){2} rgb-arg [ ", " rgb-arg ] ")"
rgba-function =
"rgba(" ( rgb-arg ", " ){2} rgb-arg [ ", " alpha-arg ] ")" /
"rgba(" ( rgb-arg ", " ){2} rgb-arg [ ", " rgb-arg ] ")"
hsl-function =
"hsl(" hue ( ", " percent-or-none ){2} [ ", " alpha-arg ] ) /
"hsl(" hue percent-or-none{2} [ " / " alpha-arg ] ")"
hsla-function =
"hsla(" hue ( ", " percent-or-none ){2} [ ", " alpha-arg ] ) /
"hsla(" hue percent-or-none{2} [ " / " alpha-arg ] ")"
hue = number / angle / none
rgb-arg = number / percent-or-none
percent-or-none = percent / none
alpha-arg = percent / number
hex-color =
"#" hex-group{3} [ hex-group ] /
"#" HEXDIG{3} [ HEXDIG ]
hex-group = HEXDIG HEXDIG
calc-function = "calc(" calc-sum ")"
calc-sum = calc-product [ [ " + " / " - " ] calc-product ]*
calc-product = calc-value [ [ " * " / " / " ] calc-value ]*
calc-value =
number /
percent /
calc-constant /
calc-function /
'(' calc-sum ')'
calc-constant =
e /
pi /
infinity /
-infinity /
NaN
number = 1; regex: ^[+\-]?(?:0|[1-9]\d*)(?:\.\d+)?(?:[eE][+\-]?\d+)?
percent = number "%"
angle = number ("deg" / "grad" / "turn" / "rad")
```
# 🧑💻 For new contributors
If you want to improve the project follow the steps below:
1. Fork the repository
2. Create your branch from `develop`
3. Create merge request to `develop` branch.
4. Check that GitHub workflow completes
# 🔧 Internals
A brief structural components overview
## 🔍️ Translator
The translator was build according to the classical 3-layer scheme: lexer, parser and executor
1. Lexer:
Lexer tries to apply the token patterns to the sources. If token matches the pattern (regular expression) then lexer identifies and classifies it. The result of tokenization process is the list token types and their actual string values.
2. Parser:
Parser builds AST from token sequence. It checks correctness of token subsequences - the way how token chains supplement each other.
3. Executor:
Executor finishes the flow with AST nodes execution. Every node is implemented as a functor that returns AST node or domain-specific data wrapper
## 🎨 Alpha composition formulas
Colors are superimposed like, for example, in the Mozilla Firefox browser. Formulas are presented below:
```
resAlpha = bgAlpha + addingAlpha * (1 - bgAlpha)
resRed = (bgRed * bgAlpha * (1 - addingAlpha) + addingRed * addingAlpha) / resAlpha
```