use exif-terminator

vendor/github.com/dsoprea/go-png-image-structure/v2/media_parser.go

@@ -0,0 +1,118 @@
+package pngstructure
+
+import (
+	"bufio"
+	"bytes"
+	"image"
+	"io"
+	"os"
+
+	"image/png"
+
+	"github.com/dsoprea/go-logging"
+	"github.com/dsoprea/go-utility/v2/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
+}
+
+// GetImage returns an image.Image-compatible struct.
+func (pmp *PngMediaParser) GetImage(r io.Reader) (img image.Image, err error) {
+	img, err = png.Decode(r)
+	log.PanicIf(err)
+
+	return img, nil
+}
+
+var (
+	// Enforce interface conformance.
+	_ riimage.MediaParser = new(PngMediaParser)
+)