package pngstructure import ( "bufio" "bytes" "io" "os" "github.com/dsoprea/go-logging" "github.com/dsoprea/go-utility/image" ) // PngMediaParser knows how to parse a PNG stream. type PngMediaParser struct { } // NewPngMediaParser returns a new `PngMediaParser` struct. func NewPngMediaParser() *PngMediaParser { // TODO(dustin): Add test return new(PngMediaParser) } // Parse parses a PNG stream given a `io.ReadSeeker`. func (pmp *PngMediaParser) Parse(rs io.ReadSeeker, size int) (mc riimage.MediaContext, err error) { defer func() { if state := recover(); state != nil { err = log.Wrap(state.(error)) } }() // TODO(dustin): Add test ps := NewPngSplitter() err = ps.readHeader(rs) log.PanicIf(err) s := bufio.NewScanner(rs) // Since each segment can be any size, our buffer must be allowed to grow // as large as the file. buffer := []byte{} s.Buffer(buffer, size) s.Split(ps.Split) for s.Scan() != false { } log.PanicIf(s.Err()) return ps.Chunks(), nil } // ParseFile parses a PNG stream given a file-path. func (pmp *PngMediaParser) ParseFile(filepath string) (mc riimage.MediaContext, err error) { defer func() { if state := recover(); state != nil { err = log.Wrap(state.(error)) } }() f, err := os.Open(filepath) log.PanicIf(err) defer f.Close() stat, err := f.Stat() log.PanicIf(err) size := stat.Size() chunks, err := pmp.Parse(f, int(size)) log.PanicIf(err) return chunks, nil } // ParseBytes parses a PNG stream given a byte-slice. func (pmp *PngMediaParser) ParseBytes(data []byte) (mc riimage.MediaContext, err error) { defer func() { if state := recover(); state != nil { err = log.Wrap(state.(error)) } }() // TODO(dustin): Add test br := bytes.NewReader(data) chunks, err := pmp.Parse(br, len(data)) log.PanicIf(err) return chunks, nil } // LooksLikeFormat returns a boolean indicating whether the stream looks like a // PNG image. func (pmp *PngMediaParser) LooksLikeFormat(data []byte) bool { return bytes.Compare(data[:len(PngSignature)], PngSignature[:]) == 0 } var ( // Enforce interface conformance. _ riimage.MediaParser = new(PngMediaParser) )