status-im/status-go

package ring

import (
    "bytes"
    "fmt"
    "image"
    "image/png"
    "math"

    "github.com/fogleman/gg"

    "github.com/status-im/status-go/multiaccounts"
)

type Theme int

const (
    LightTheme Theme = 1
    DarkTheme  Theme = 2
)

var (
    lightThemeIdenticonRingColors = []string{
        "#000000", "#726F6F", "#C4C4C4", "#E7E7E7", "#FFFFFF", "#00FF00",
        "#009800", "#B8FFBB", "#FFC413", "#9F5947", "#FFFF00", "#A8AC00",
        "#FFFFB0", "#FF5733", "#FF0000", "#9A0000", "#FF9D9D", "#FF0099",
        "#C80078", "#FF00FF", "#900090", "#FFB0FF", "#9E00FF", "#0000FF",
        "#000086", "#9B81FF", "#3FAEF9", "#9A6600", "#00FFFF", "#008694",
        "#C2FFFF", "#00F0B6"}
    darkThemeIdenticonRingColors = []string{
        "#000000", "#726F6F", "#C4C4C4", "#E7E7E7", "#FFFFFF", "#00FF00",
        "#009800", "#B8FFBB", "#FFC413", "#9F5947", "#FFFF00", "#A8AC00",
        "#FFFFB0", "#FF5733", "#FF0000", "#9A0000", "#FF9D9D", "#FF0099",
        "#C80078", "#FF00FF", "#900090", "#FFB0FF", "#9E00FF", "#0000FF",
        "#000086", "#9B81FF", "#3FAEF9", "#9A6600", "#00FFFF", "#008694",
        "#C2FFFF", "#00F0B6"}
)

type DrawRingParam struct {
    Theme      Theme                   `json:"theme"`
    ColorHash  multiaccounts.ColorHash `json:"colorHash"`
    ImageBytes []byte                  `json:"imageBytes"`
    Height     int                     `json:"height"`
    Width      int                     `json:"width"`
    RingWidth  float64                 `json:"ringWidth"`
}

func DrawRing(param *DrawRingParam) ([]byte, error) {
    var colors []string
    switch param.Theme {
    case LightTheme:
        colors = lightThemeIdenticonRingColors
    case DarkTheme:
        colors = darkThemeIdenticonRingColors
    default:
        return nil, fmt.Errorf("unknown theme")
    }

    dc := gg.NewContext(param.Width, param.Height)
    img, _, err := image.Decode(bytes.NewReader(param.ImageBytes))
    if err != nil {
        return nil, err
    }
    dc.DrawImage(img, 0, 0)

    radius := (float64(param.Height) - param.RingWidth) / 2
    arcPos := 0.0

    totalRingUnits := 0
    for i := 0; i < len(param.ColorHash); i++ {
        totalRingUnits += param.ColorHash[i][0]
    }
    unitRadLen := 2 * math.Pi / float64(totalRingUnits)

    for i := 0; i < len(param.ColorHash); i++ {
        dc.SetHexColor(colors[param.ColorHash[i][1]])
        dc.DrawArc(float64(param.Width/2), float64(param.Height/2), radius, arcPos, arcPos+unitRadLen*float64(param.ColorHash[i][0]))
        dc.SetLineWidth(param.RingWidth)
        dc.SetLineCapButt()
        dc.Stroke()
        arcPos += unitRadLen * float64(param.ColorHash[i][0])
    }

    buf := new(bytes.Buffer)
    err = png.Encode(buf, dc.Image())
    if err != nil {
        return nil, err
    }

    return buf.Bytes(), nil
}