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package themagicpipe
import (
"encoding/base64"
"errors"
"gopkg.in/gographics/imagick.v3/imagick"
"strings"
)
// Where the magic happens, the base64 data url image is sent through Imagemagick
// and converted to indexed colors 400x200 png
func DataURLConverter(dataURL string) (string, error) {
if !strings.HasPrefix(dataURL, "data:image/png;base64,") {
return "", errors.New("invalid dataURL")
}
imageBase64 := strings.TrimPrefix(dataURL, "data:image/png;base64,")
imageRaw, err := base64.StdEncoding.DecodeString(imageBase64)
if err != nil {
return "", err
}
// doing conversion inline soothes the soul
imagick.Initialize()
defer imagick.Terminate()
magick := imagick.NewMagickWand()
defer magick.Destroy()
// read in from base64
err = magick.ReadImageBlob(imageRaw)
if err != nil {
return "", err
}
// swap all transparent pixels with white
transparent := imagick.NewPixelWand()
defer transparent.Destroy()
transparent.SetColor("none")
whiteFill := imagick.NewPixelWand()
defer whiteFill.Destroy()
whiteFill.SetColor("#ffffff")
err = magick.OpaquePaintImage(transparent, whiteFill, 5, false)
if err != nil {
return "", err
}
err = magick.ResizeImage(400, 200, imagick.FILTER_POINT)
if err != nil {
return "", err
}
imageBytesProcessed, err := magick.GetImageBlob()
if err != nil {
return "", err
}
imageBase64Processed := base64.StdEncoding.EncodeToString(imageBytesProcessed)
return "data:image/png;base64," + imageBase64Processed, nil
}
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