Refactor: pngmeta rewrite
This commit is contained in:
Grail Finder
@@ -1,116 +1,112 @@
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package pngmeta
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import (
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"bytes"
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"elefant/models"
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"encoding/base64"
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"encoding/binary"
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"encoding/json"
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"errors"
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"fmt"
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"hash/crc32"
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"io"
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"os"
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)
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// import (
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// "bytes"
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// "encoding/binary"
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// "errors"
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// "fmt"
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// "hash/crc32"
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// "io"
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// )
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type Writer struct {
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w io.Writer
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}
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// type Writer struct {
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// w io.Writer
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// }
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func NewPNGWriter(w io.Writer) (*Writer, error) {
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if _, err := io.WriteString(w, writeHeader); err != nil {
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return nil, err
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}
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return &Writer{w}, nil
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}
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// func NewPNGWriter(w io.Writer) (*Writer, error) {
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// if _, err := io.WriteString(w, writeHeader); err != nil {
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// return nil, err
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// }
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// return &Writer{w}, nil
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// }
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func (w *Writer) WriteChunk(length int32, typ string, r io.Reader) error {
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if err := binary.Write(w.w, binary.BigEndian, length); err != nil {
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return err
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}
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if _, err := w.w.Write([]byte(typ)); err != nil {
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return err
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}
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checksummer := crc32.NewIEEE()
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checksummer.Write([]byte(typ))
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if _, err := io.CopyN(io.MultiWriter(w.w, checksummer), r, int64(length)); err != nil {
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return err
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}
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if err := binary.Write(w.w, binary.BigEndian, checksummer.Sum32()); err != nil {
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return err
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}
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return nil
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}
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// func (w *Writer) WriteChunk(length int32, typ string, r io.Reader) error {
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// if err := binary.Write(w.w, binary.BigEndian, length); err != nil {
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// return err
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// }
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// if _, err := w.w.Write([]byte(typ)); err != nil {
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// return err
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// }
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// checksummer := crc32.NewIEEE()
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// checksummer.Write([]byte(typ))
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// if _, err := io.CopyN(io.MultiWriter(w.w, checksummer), r, int64(length)); err != nil {
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// return err
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// }
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// if err := binary.Write(w.w, binary.BigEndian, checksummer.Sum32()); err != nil {
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// return err
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// }
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// return nil
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// }
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func WriteToPng(c *models.CharCardSpec, fpath, outfile string) error {
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data, err := os.ReadFile(fpath)
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if err != nil {
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return err
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}
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jsonData, err := json.Marshal(c)
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if err != nil {
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return err
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}
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// Base64 encode the JSON data
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base64Data := base64.StdEncoding.EncodeToString(jsonData)
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pe := PngEmbed{
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Key: cKey,
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Value: base64Data,
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}
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w, err := WritetEXtToPngBytes(data, pe)
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if err != nil {
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return err
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}
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return os.WriteFile(outfile, w.Bytes(), 0666)
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}
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// func WWriteToPngriteToPng(c *models.CharCardSpec, fpath, outfile string) error {
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// data, err := os.ReadFile(fpath)
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// if err != nil {
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// return err
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// }
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// jsonData, err := json.Marshal(c)
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// if err != nil {
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// return err
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// }
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// // Base64 encode the JSON data
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// base64Data := base64.StdEncoding.EncodeToString(jsonData)
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// pe := PngEmbed{
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// Key: cKey,
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// Value: base64Data,
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// }
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// w, err := WritetEXtToPngBytes(data, pe)
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// if err != nil {
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// return err
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// }
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// return os.WriteFile(outfile, w.Bytes(), 0666)
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// }
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func WritetEXtToPngBytes(inputBytes []byte, pe PngEmbed) (outputBytes bytes.Buffer, err error) {
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if !(string(inputBytes[:8]) == header) {
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return outputBytes, errors.New("wrong file format")
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}
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reader := bytes.NewReader(inputBytes)
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pngr, err := NewPNGStepReader(reader)
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if err != nil {
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return outputBytes, fmt.Errorf("NewReader(): %s", err)
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}
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pngw, err := NewPNGWriter(&outputBytes)
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if err != nil {
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return outputBytes, fmt.Errorf("NewWriter(): %s", err)
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}
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for {
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chunk, err := pngr.Next()
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if err != nil {
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if errors.Is(err, io.EOF) {
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break
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}
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return outputBytes, fmt.Errorf("NextChunk(): %s", err)
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}
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if chunk.Type() != embType {
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// IENDChunkType will only appear on the final iteration of a valid PNG
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if chunk.Type() == IEND {
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// This is where we inject tEXtChunkType as the penultimate chunk with the new value
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newtEXtChunk := []byte(fmt.Sprintf(tEXtChunkDataSpecification, pe.Key, pe.Value))
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if err := pngw.WriteChunk(int32(len(newtEXtChunk)), embType, bytes.NewBuffer(newtEXtChunk)); err != nil {
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return outputBytes, fmt.Errorf("WriteChunk(): %s", err)
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}
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// Now we end the buffer with IENDChunkType chunk
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if err := pngw.WriteChunk(chunk.length, chunk.Type(), chunk); err != nil {
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return outputBytes, fmt.Errorf("WriteChunk(): %s", err)
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}
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} else {
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// writes back original chunk to buffer
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if err := pngw.WriteChunk(chunk.length, chunk.Type(), chunk); err != nil {
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return outputBytes, fmt.Errorf("WriteChunk(): %s", err)
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}
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}
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} else {
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if _, err := io.Copy(io.Discard, chunk); err != nil {
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return outputBytes, fmt.Errorf("io.Copy(io.Discard, chunk): %s", err)
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}
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}
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if err := chunk.Close(); err != nil {
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return outputBytes, fmt.Errorf("chunk.Close(): %s", err)
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}
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}
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return outputBytes, nil
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}
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// func WritetEXtToPngBytes(inputBytes []byte, pe PngEmbed) (outputBytes bytes.Buffer, err error) {
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// if !(string(inputBytes[:8]) == header) {
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// return outputBytes, errors.New("wrong file format")
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// }
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// reader := bytes.NewReader(inputBytes)
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// pngr, err := NewPNGStepReader(reader)
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// if err != nil {
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// return outputBytes, fmt.Errorf("NewReader(): %s", err)
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// }
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// pngw, err := NewPNGWriter(&outputBytes)
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// if err != nil {
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// return outputBytes, fmt.Errorf("NewWriter(): %s", err)
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// }
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// for {
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// chunk, err := pngr.Next()
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// if err != nil {
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// if errors.Is(err, io.EOF) {
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// break
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// }
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// return outputBytes, fmt.Errorf("NextChunk(): %s", err)
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// }
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// if chunk.Type() != embType {
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// // IENDChunkType will only appear on the final iteration of a valid PNG
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// if chunk.Type() == IEND {
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// // This is where we inject tEXtChunkType as the penultimate chunk with the new value
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// newtEXtChunk := []byte(fmt.Sprintf(tEXtChunkDataSpecification, pe.Key, pe.Value))
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// if err := pngw.WriteChunk(int32(len(newtEXtChunk)), embType, bytes.NewBuffer(newtEXtChunk)); err != nil {
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// return outputBytes, fmt.Errorf("WriteChunk(): %s", err)
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// }
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// // Now we end the buffer with IENDChunkType chunk
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// if err := pngw.WriteChunk(chunk.length, chunk.Type(), chunk); err != nil {
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// return outputBytes, fmt.Errorf("WriteChunk(): %s", err)
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// }
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// } else {
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// // writes back original chunk to buffer
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// if err := pngw.WriteChunk(chunk.length, chunk.Type(), chunk); err != nil {
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// return outputBytes, fmt.Errorf("WriteChunk(): %s", err)
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// }
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// }
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// } else {
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// if _, err := io.Copy(io.Discard, chunk); err != nil {
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// return outputBytes, fmt.Errorf("io.Copy(io.Discard, chunk): %s", err)
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// }
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// }
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// if err := chunk.Close(); err != nil {
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// return outputBytes, fmt.Errorf("chunk.Close(): %s", err)
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// }
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// }
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// return outputBytes, nil
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// }
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