package images import ( "bytes" "image/color" "image/png" "io/ioutil" "strings" "github.com/fogleman/gg" "golang.org/x/image/font" "golang.org/x/image/font/opentype" ) type RGBA struct { R, G, B, A float64 } var parsedFont *opentype.Font = nil func ExtractInitials(fullName string, amountInitials int) string { if fullName == "" { return "" } var initials strings.Builder namesList := strings.Fields(fullName) for _, name := range namesList { if len(initials.String()) >= amountInitials { break } if name != "" { initials.WriteString(strings.ToUpper(name[0:1])) } } return initials.String() } // GenerateInitialsImage uppercaseRatio is <height of any upper case> / dc.FontHeight() (line height) // 0.60386123 for Inter-UI-Medium.otf func GenerateInitialsImage(initials string, bgColor, fontColor color.Color, fontFile string, size int, fontSize float64, uppercaseRatio float64) ([]byte, error) { // Load otf file fontBytes, err := ioutil.ReadFile(fontFile) if err != nil { return nil, err } if parsedFont == nil { parsedFont, err = opentype.Parse(fontBytes) if err != nil { return nil, err } } halfSize := float64(size / 2) dc := gg.NewContext(size, size) dc.DrawCircle(halfSize, halfSize, halfSize) dc.SetColor(bgColor) dc.Fill() // Load font face, err := opentype.NewFace(parsedFont, &opentype.FaceOptions{ Size: fontSize, DPI: 72, Hinting: font.HintingNone, }) if err != nil { return nil, err } dc.SetFontFace(face) // Draw initials dc.SetColor(fontColor) dc.DrawStringAnchored(initials, halfSize, halfSize, 0.5, uppercaseRatio/2) img := dc.Image() buffer := new(bytes.Buffer) err = png.Encode(buffer, img) if err != nil { return nil, err } return buffer.Bytes(), nil }