// output static file as base64 string
// image must exist as file in /static
func imagefileAsBase64(w http.ResponseWriter, r *http.Request, m map[string]interface{}) {
c := appengine.NewContext(r)
p := r.FormValue("p")
if p == "" {
p = "static/chartbg_400x960__480x1040__12x10.png"
}
f, err := os.Open(p)
util_err.Err_http(w, r, err, false)
defer f.Close()
img, whichFormat, err := image.Decode(f)
util_err.Err_http(w, r, err, false)
c.Infof("format %v - subtype %T\n", whichFormat, img)
imgRGBA, ok := img.(*image.RGBA)
util_err.Err_http(w, r, ok, true, "source image was not convertible to image.RGBA - gifs or jpeg?")
// => header with mime prefix always prepended
// and its always image/PNG
str_b64 := conv.Rgba_img_to_base64_str(imgRGBA)
w.Header().Set("Content-Type", "text/html")
io.WriteString(w, "<p>Image embedded in HTML as Base64:</p><img width=200px src=\"")
io.WriteString(w, str_b64)
io.WriteString(w, "\"> ")
}
func SaveImageToDatastore(w http.ResponseWriter, r *http.Request, i *image.RGBA, key string) string {
s := conv.Rgba_img_to_base64_str(i)
internalType := fmt.Sprintf("%T", i)
//buffBytes, _ := StringToVByte(s) // instead of []byte(s)
key_combi, err := dsu.BufPut(w, r, dsu.WrapBlob{Name: key, VByte: []byte(s), S: internalType}, key)
util_err.Err_http(w, r, err, false)
return key_combi
}