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package sixel
import (
"fmt"
"io"
"strings"
)
// ErrInvalidRepeat is returned when a Repeat is invalid.
var ErrInvalidRepeat = fmt.Errorf("invalid repeat")
// WriteRepeat writes a Repeat to a writer. A repeat character is in the range
// of '?' (0x3F) to '~' (0x7E).
func WriteRepeat(w io.Writer, count int, char byte) (int, error) {
return fmt.Fprintf(w, "%c%d%c", RepeatIntroducer, count, char) //nolint:wrapcheck
}
// Repeat represents a Sixel repeat introducer.
type Repeat struct {
Count int
Char byte
}
// WriteTo writes a Repeat to a writer.
func (r Repeat) WriteTo(w io.Writer) (int64, error) {
n, err := WriteRepeat(w, r.Count, r.Char)
return int64(n), err
}
// String returns the Repeat as a string.
func (r Repeat) String() string {
var b strings.Builder
r.WriteTo(&b) //nolint:errcheck,gosec
return b.String()
}
// DecodeRepeat decodes a Repeat from a byte slice. It returns the Repeat and
// the number of bytes read.
func DecodeRepeat(data []byte) (r Repeat, n int) {
if len(data) == 0 || data[0] != RepeatIntroducer {
return r, n
}
if len(data) < 3 { // The minimum length is 3: the introducer, a digit, and a character.
return r, n
}
for n = 1; n < len(data); n++ {
if data[n] >= '0' && data[n] <= '9' {
r.Count = r.Count*10 + int(data[n]-'0')
} else {
r.Char = data[n]
n++ // Include the character in the count.
break
}
}
return r, n
}
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