It works.

Author: overcat

.gitignore

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+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, built with `go test -c`
+*.test
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+
+# Dependency directories (remove the comment below to include it)
+# vendor/
+

LICENSE

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+MIT License
+
+Copyright (c) 2018 2021
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# stellar-identicon-go

color.go

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+package identicon
+
+import "math"
+
+type HSV struct {
+	H, S, V float64
+}
+
+type RGB struct {
+	R, G, B float64
+}
+
+func (c *HSV) RGB() *RGB {
+	var r, g, b float64
+	if c.S == 0 {
+		r = c.V * 255
+		g = c.V * 255
+		b = c.V * 255
+	} else {
+		h := c.H * 6
+		if h == 6 {
+			h = 0
+		}
+		i := math.Floor(h)
+		v1 := c.V * (1 - c.S)
+		v2 := c.V * (1 - c.S*(h-i))
+		v3 := c.V * (1 - c.S*(1-(h-i)))
+
+		switch i {
+		case 0:
+			r = c.V
+			g = v3
+			b = v1
+		case 1:
+			r = v2
+			g = c.V
+			b = v1
+		case 2:
+			r = v1
+			g = c.V
+			b = v3
+		case 3:
+			r = v3
+			g = v1
+			b = c.V
+		default:
+			r = c.V
+			g = v1
+			b = v2
+		}
+
+		r = r * 255
+		g = g * 255
+		b = b * 255
+	}
+	rgb := &RGB{r, g, b}
+	return rgb
+}

go.mod

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+module github.com/overcat/stellar-identicon-go
+
+go 1.16
+
+require github.com/stellar/go v0.0.0-20210311180751-e33a4571b3e9

go.sum

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+// Package stellar_identicon provides a way to generate identicons for Stellar accounts.
+package identicon
+
+import (
+	"encoding/base32"
+	"errors"
+	"github.com/stellar/go/strkey"
+	"image"
+	"image/color"
+	"math"
+)
+
+const (
+	// Default width of resulting identicon image in pixels
+	Width = 210
+	// Default height of resulting identicon image in pixels
+	Height = 210
+)
+
+const (
+	columns = 7
+	rows    = 7
+)
+
+// This exception will be thrown when an invalid address is used
+var InvalidEd25519PublicKeyError = errors.New("invalid ed25519 public key")
+
+// Generates an identicon for the given stellar address
+func Generate(publicKey string, width, height int) (*image.RGBA, error) {
+	if !strkey.IsValidEd25519PublicKey(publicKey) {
+		return nil, InvalidEd25519PublicKeyError
+	}
+
+	keyData, err := base32.StdEncoding.DecodeString(publicKey)
+	if err != nil {
+		return nil, err
+	}
+
+	keyData = keyData[2:]
+
+	var matrix [7][7]bool
+
+	columnsForCalculation := int(math.Ceil(columns / 2.0))
+	for column := 0; column < columnsForCalculation; column++ {
+		for row := 0; row < rows; row++ {
+			if getBit(column+row*columnsForCalculation, keyData[1:]) {
+				matrix[row][column] = true
+				matrix[row][columns-column-1] = true
+			}
+		}
+	}
+
+	img := image.NewRGBA(image.Rect(0, 0, width, height))
+	foreground := getColor(keyData)
+	blockWidth := width / columns
+	blockHeight := height / rows
+
+	for row, rowColumns := range matrix {
+		for column, cell := range rowColumns {
+			if cell {
+				x0 := column * blockWidth
+				y0 := row * blockHeight
+				x1 := (column+1)*blockWidth - 1
+				y1 := (row+1)*blockHeight - 1
+				for x := x0; x <= x1; x++ {
+					for y := y0; y <= y1; y++ {
+						img.Set(x, y, foreground)
+					}
+				}
+			}
+		}
+	}
+	return img, nil
+}
+
+func getColor(data []byte) color.RGBA {
+	hsv := HSV{
+		H: float64(data[0]) / 255,
+		S: 0.7,
+		V: 0.8,
+	}
+	rgb := hsv.RGB()
+	return color.RGBA{
+		R: uint8(rgb.R), G: uint8(rgb.G), B: uint8(rgb.B), A: 255,
+	}
+}
+
+func getBit(n int, keyData []byte) bool {
+	if keyData[n/8]>>(8-((n%8)+1))&1 == 1 {
+		return true
+	}
+	return false
+}