// Generate a text string to a QR code, which you can write to a terminal or file.
func (c *Config) Generate(text string) (string, error) {
code, err := qr.Encode(text, qr.Level(c.Level))
if err != nil {
return "", err
}
// calculate size in blocks
// two bits per block
// add one block for remaining singlebit (if existing)
// add two blocks for border left and right
size := code.Size/2 + (code.Size % 2) + 2
// rune slice
//++ TODO: precalculate size
qrRunes := make([]rune, 0)
// upper border
c.addWhiteRow(&qrRunes, size)
// content
for y := 0; y < code.Size; y += 2 {
if c.UseSGR {
qrRunes = append(qrRunes, []rune(sgr.FgWhite+sgr.BgBlack)...)
}
qrRunes = append(qrRunes, '█')
for x := 0; x < code.Size; x += 2 {
var num int8
if !code.Black(x, y) {
num += 1
}
if !code.Black(x+1, y) {
num += 2
}
if !code.Black(x, y+1) {
num += 4
}
if !code.Black(x+1, y+1) {
num += 8
}
qrRunes = append(qrRunes, blocks[num])
}
qrRunes = append(qrRunes, '█')
if c.UseSGR {
qrRunes = append(qrRunes, []rune(sgr.Reset)...)
}
qrRunes = append(qrRunes, '\n')
}
// add lower border when required (only required when QR size is odd)
if code.Size%2 == 0 {
c.addWhiteRow(&qrRunes, size)
}
return string(qrRunes), nil
}
// GenerateQR generates a for the receiver *Request.
func (r *Request) GenerateQR() (*qr.Code, error) {
// get config for this request
c := r.Config
if c == nil {
c = DefaultConfig
}
var err error
// uriBuf will contain the bytes that are to be encoded into the QR code
uriBuf := &bytes.Buffer{}
// write uri scheme
_, err = uriBuf.WriteString(c.scheme())
if err != nil {
return nil, err
}
// write uri seperator colon
err = uriBuf.WriteByte(':')
if err != nil {
return nil, err
}
// write receiving address
_, err = uriBuf.WriteString(r.Address)
if err != nil {
return nil, err
}
// params contains optional parameters used in the URI
var params = make(map[string]string)
// add amount when not zero
if r.Amount < 0 {
return nil, ErrNegativeAmount
}
if r.Amount != 0 {
params["amount"] = strconv.FormatFloat(r.Amount, 'f', -1, 64)
if err != nil {
return nil, err
}
}
// add label when it is not empty
if len(r.Label) != 0 {
params["label"] = url.QueryEscape(r.Label)
}
// add message when it is not empty
if len(r.Message) != 0 {
params["message"] = url.QueryEscape(r.Message)
}
// add query escaped params (if any)
if r.Params != nil {
for key, value := range r.Params {
params[url.QueryEscape(key)] = url.QueryEscape(value)
}
}
// write all parameters to the uriBuf
q := true
for key, value := range params {
// write '?' or '&' to uriBuf
if q {
q = false
err = uriBuf.WriteByte('?')
if err != nil {
return nil, err
}
} else {
err = uriBuf.WriteByte('&')
if err != nil {
return nil, err
}
}
// write <key>=<value> to uriBuf
_, err = uriBuf.WriteString(key)
if err != nil {
return nil, err
}
err = uriBuf.WriteByte('=')
if err != nil {
return nil, err
}
_, err = uriBuf.WriteString(value)
if err != nil {
return nil, err
}
}
// create qr image
code, err := qr.Encode(uriBuf.String(), qr.Level(c.Level))
if err != nil {
return nil, err
}
// all done
return code, nil
}
