Ecosyste.ms: Awesome
An open API service indexing awesome lists of open source software.
https://github.com/mazznoer/colorgrad
Go (Golang) color scales library for maps, charts, data-visualization & creative coding.
https://github.com/mazznoer/colorgrad
color color-scales colormap data-visualization gradient visual-encoding visualization
Last synced: 3 months ago
JSON representation
Go (Golang) color scales library for maps, charts, data-visualization & creative coding.
- Host: GitHub
- URL: https://github.com/mazznoer/colorgrad
- Owner: mazznoer
- License: other
- Created: 2020-07-24T15:07:19.000Z (over 4 years ago)
- Default Branch: master
- Last Pushed: 2024-08-15T14:08:40.000Z (6 months ago)
- Last Synced: 2024-08-16T03:25:04.954Z (6 months ago)
- Topics: color, color-scales, colormap, data-visualization, gradient, visual-encoding, visualization
- Language: Go
- Homepage:
- Size: 777 KB
- Stars: 209
- Watchers: 7
- Forks: 11
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Funding: .github/FUNDING.yml
- License: LICENSE
Awesome Lists containing this project
README
# colorgrad
[](https://github.com/mazznoer/colorgrad/releases/latest)
[](https://pkg.go.dev/github.com/mazznoer/colorgrad)

[](https://goreportcard.com/report/github.com/mazznoer/colorgrad)Go (Golang) _color scales_ library for data visualization, charts, games, maps, generative art and others.
## Support This Project
[](https://liberapay.com/mazznoer/donate)
## Index
* [Custom Gradient](#custom-gradient)
* [Preset Gradients](#preset-gradients)
* [Using the Gradient](#using-the-gradient)
* [Examples](#examples)
* [Playground](#playground)```go
import "github.com/mazznoer/colorgrad"
```## Custom Gradient
### Basic
```go
grad, err := colorgrad.NewGradient().Build()
```
### Custom Colors
```go
grad, err := colorgrad.NewGradient().
Colors(
colorgrad.Rgb8(0, 206, 209, 255),
colorgrad.Rgb8(255, 105, 180, 255),
colorgrad.Rgb(0.274, 0.5, 0.7, 1),
colorgrad.Hsv(50, 1, 1, 1),
colorgrad.Hsv(348, 0.9, 0.8, 1),
).
Build()
```
### Using Web Color Format
`HtmlColors()` method accepts [named colors](https://www.w3.org/TR/css-color-4/#named-colors), hexadecimal (`#rgb`, `#rgba`, `#rrggbb`, `#rrggbbaa`), `rgb()`, `rgba()`, `hsl()`, `hsla()`, `hwb()`, and `hsv()`.
```go
grad, err := colorgrad.NewGradient().
HtmlColors("#C41189", "#00BFFF", "#FFD700").
Build()
```
```go
grad, err := colorgrad.NewGradient().
HtmlColors("gold", "hotpink", "darkturquoise").
Build()
```
```go
grad, err := colorgrad.NewGradient().
HtmlColors(
"rgb(125,110,221)",
"rgb(90%,45%,97%)",
"hsl(229,79%,85%)",
).
Build()
```
### Domain & Color Position
Default domain is [0..1].
```go
grad, err := colorgrad.NewGradient().
HtmlColors("deeppink", "gold", "seagreen").
Build()
```
Set the domain to [0..100].
```go
grad, err := colorgrad.NewGradient().
HtmlColors("deeppink", "gold", "seagreen").
Domain(0, 100).
Build()
```
Set the domain to [-1..1].
```go
grad, err := colorgrad.NewGradient().
HtmlColors("deeppink", "gold", "seagreen").
Domain(-1, 1).
Build()
```
Set exact position for each color. The domain is [0..1].
```go
grad, err := colorgrad.NewGradient().
HtmlColors("deeppink", "gold", "seagreen").
Domain(0, 0.7, 1).
Build()
```
Set exact position for each color. The domain is [15..80].
```go
grad, err := colorgrad.NewGradient().
HtmlColors("deeppink", "gold", "seagreen").
Domain(15, 30, 80).
Build()
```
### Blending Mode
```go
grad, err := colorgrad.NewGradient().
HtmlColors("#FFF", "#00F").
Mode(colorgrad.BlendRgb).
Build()
```
### Interpolation Mode
```go
grad, err := colorgrad.NewGradient().
HtmlColors("#C41189", "#00BFFF", "#FFD700").
Interpolation(colorgrad.InterpolationLinear).
Build()
````InterpolationLinear`
`InterpolationCatmullRom`
`InterpolationBasis`
## Preset Gradients
See [PRESET.md](PRESET.md)
## Parsing GIMP Gradient
```go
import "os"foreground := colorgrad.Rgb(0, 0, 0, 1)
background := colorgrad.Rgb(1, 1, 1, 1)
file, err := os.Open("Abstract_1.ggr")if err != nil {
panic(err)
}defer file.Close()
grad, name, err2 := colorgrad.ParseGgr(file, foreground, background)
fmt.Println(name) // Abstract 1
```
## Using the Gradient
### Get the domain
```go
grad := colorgrad.Rainbow()fmt.Println(grad.Domain()) // 0 1
```### Get single color at certain position
```go
grad := colorgrad.Rainbow()fmt.Println(grad.At(0.0).HexString()) // #6e40aa
fmt.Println(grad.At(0.5).HexString()) // #aff05b
fmt.Println(grad.At(1.0).HexString()) // #6e40aa
```### Get n colors evenly spaced across gradient
```go
grad := colorgrad.Rainbow()for _, c := range grad.Colors(10) {
fmt.Println(c.HexString())
}
```Output:
```console
#6e40aa
#c83dac
#ff5375
#ff8c38
#c9d33a
#7cf659
#5dea8d
#48b8d0
#4775de
#6e40aa
```### Hard-Edged Gradient
Convert gradient to hard-edged gradient with 11 segments and 0 smoothness.
```go
grad := colorgrad.Rainbow().Sharp(11, 0)
```
This is the effect of different smoothness.

## Examples
### Gradient Image
```go
package mainimport (
"image"
"image/png"
"os""github.com/mazznoer/colorgrad"
)func main() {
grad, _ := colorgrad.NewGradient().
HtmlColors("#C41189", "#00BFFF", "#FFD700").
Build()w := 1500
h := 70
fw := float64(w)img := image.NewRGBA(image.Rect(0, 0, w, h))
for x := 0; x < w; x++ {
col := grad.At(float64(x) / fw)
for y := 0; y < h; y++ {
img.Set(x, y, col)
}
}file, err := os.Create("gradient.png")
if err != nil {
panic(err.Error())
}
defer file.Close()
png.Encode(file, img)
}
```Example output:

### Colored Noise
```go
package mainimport (
"image"
"image/png"
"os""github.com/mazznoer/colorgrad"
"github.com/ojrac/opensimplex-go"
)func main() {
w := 600
h := 350
scale := 0.02grad := colorgrad.Rainbow().Sharp(7, 0.2)
noise := opensimplex.NewNormalized(996)
img := image.NewRGBA(image.Rect(0, 0, w, h))for y := 0; y < h; y++ {
for x := 0; x < w; x++ {
t := noise.Eval2(float64(x)*scale, float64(y)*scale)
img.Set(x, y, grad.At(t))
}
}file, err := os.Create("noise.png")
if err != nil {
panic(err.Error())
}
defer file.Close()
png.Encode(file, img)
}
```Example output:

## Playground
* [Basic](https://play.golang.org/p/PlMov8BKfRc)
* [Random colors](https://play.golang.org/p/d67x9di4sAF)## Dependencies
* [csscolorparser](https://github.com/mazznoer/csscolorparser)
## Inspirations
* [chroma.js](https://gka.github.io/chroma.js/#color-scales)
* [d3-scale-chromatic](https://github.com/d3/d3-scale-chromatic/)
* colorful's [gradientgen.go](https://github.com/lucasb-eyer/go-colorful/blob/master/doc/gradientgen/gradientgen.go)## Links
* [colorgrad-rs](https://github.com/mazznoer/colorgrad-rs) - Rust port of this library