gtsocial-umbx

segment.go (7531B)

---

 package jpegstructure
 
 import (
 	"bytes"
 	"errors"
 	"fmt"
 
 	"crypto/sha1"
 	"encoding/hex"
 
 	"github.com/dsoprea/go-exif/v3"
 	"github.com/dsoprea/go-exif/v3/common"
 	"github.com/dsoprea/go-iptc"
 	"github.com/dsoprea/go-logging"
 	"github.com/dsoprea/go-photoshop-info-format"
 	"github.com/dsoprea/go-utility/v2/image"
 )
 
 const (
 	pirIptcImageResourceId = uint16(0x0404)
 )
 
 var (
 	// exifPrefix is the prefix found at the top of an EXIF slice. This is JPEG-
 	// specific.
 	exifPrefix = []byte{'E', 'x', 'i', 'f', 0, 0}
 
 	xmpPrefix = []byte("http://ns.adobe.com/xap/1.0/\000")
 
 	ps30Prefix = []byte("Photoshop 3.0\000")
 )
 
 var (
 	// ErrNoXmp is returned if XMP data was requested but not found.
 	ErrNoXmp = errors.New("no XMP data")
 
 	// ErrNoIptc is returned if IPTC data was requested but not found.
 	ErrNoIptc = errors.New("no IPTC data")
 
 	// ErrNoPhotoshopData is returned if Photoshop info was requested but not
 	// found.
 	ErrNoPhotoshopData = errors.New("no photoshop data")
 )
 
 // SofSegment has info read from a SOF segment.
 type SofSegment struct {
 	// BitsPerSample is the bits-per-sample.
 	BitsPerSample byte
 
 	// Width is the image width.
 	Width uint16
 
 	// Height is the image height.
 	Height uint16
 
 	// ComponentCount is the number of color components.
 	ComponentCount byte
 }
 
 // String returns a string representation of the SOF segment.
 func (ss SofSegment) String() string {
 
 	// TODO(dustin): Add test
 
 	return fmt.Sprintf("SOF<BitsPerSample=(%d) Width=(%d) Height=(%d) ComponentCount=(%d)>", ss.BitsPerSample, ss.Width, ss.Height, ss.ComponentCount)
 }
 
 // SegmentVisitor describes a segment-visitor struct.
 type SegmentVisitor interface {
 	// HandleSegment is triggered for each segment encountered as well as the
 	// scan-data.
 	HandleSegment(markerId byte, markerName string, counter int, lastIsScanData bool) error
 }
 
 // SofSegmentVisitor describes a visitor that is only called for each SOF
 // segment.
 type SofSegmentVisitor interface {
 	// HandleSof is called for each encountered SOF segment.
 	HandleSof(sof *SofSegment) error
 }
 
 // Segment describes a single segment.
 type Segment struct {
 	MarkerId   byte
 	MarkerName string
 	Offset     int
 	Data       []byte
 
 	photoshopInfo map[uint16]photoshopinfo.Photoshop30InfoRecord
 	iptcTags      map[iptc.StreamTagKey][]iptc.TagData
 }
 
 // SetExif encodes and sets EXIF data into this segment.
 func (s *Segment) SetExif(ib *exif.IfdBuilder) (err error) {
 	defer func() {
 		if state := recover(); state != nil {
 			err = log.Wrap(state.(error))
 		}
 	}()
 
 	ibe := exif.NewIfdByteEncoder()
 
 	exifData, err := ibe.EncodeToExif(ib)
 	log.PanicIf(err)
 
 	l := len(exifPrefix)
 
 	s.Data = make([]byte, l+len(exifData))
 	copy(s.Data[0:], exifPrefix)
 	copy(s.Data[l:], exifData)
 
 	return nil
 }
 
 // Exif returns an `exif.Ifd` instance for the EXIF data we currently have.
 func (s *Segment) Exif() (rootIfd *exif.Ifd, data []byte, err error) {
 	defer func() {
 		if state := recover(); state != nil {
 			err = log.Wrap(state.(error))
 		}
 	}()
 
 	l := len(exifPrefix)
 
 	rawExif := s.Data[l:]
 
 	jpegLogger.Debugf(nil, "Attempting to parse (%d) byte EXIF blob (Exif).", len(rawExif))
 
 	im, err := exifcommon.NewIfdMappingWithStandard()
 	log.PanicIf(err)
 
 	ti := exif.NewTagIndex()
 
 	_, index, err := exif.Collect(im, ti, rawExif)
 	log.PanicIf(err)
 
 	return index.RootIfd, rawExif, nil
 }
 
 // FlatExif parses the EXIF data and just returns a list of tags.
 func (s *Segment) FlatExif() (exifTags []exif.ExifTag, err error) {
 	defer func() {
 		if state := recover(); state != nil {
 			err = log.Wrap(state.(error))
 		}
 	}()
 
 	// TODO(dustin): Add test
 
 	l := len(exifPrefix)
 
 	rawExif := s.Data[l:]
 
 	jpegLogger.Debugf(nil, "Attempting to parse (%d) byte EXIF blob (FlatExif).", len(rawExif))
 
 	exifTags, _, err = exif.GetFlatExifData(rawExif, nil)
 	log.PanicIf(err)
 
 	return exifTags, nil
 }
 
 // EmbeddedString returns a string of properties that can be embedded into an
 // longer string of properties.
 func (s *Segment) EmbeddedString() string {
 	h := sha1.New()
 	h.Write(s.Data)
 
 	// TODO(dustin): Add test
 
 	digestString := hex.EncodeToString(h.Sum(nil))
 
 	return fmt.Sprintf("OFFSET=(0x%08x %10d) ID=(0x%02x) NAME=[%-5s] SIZE=(%10d) SHA1=[%s]", s.Offset, s.Offset, s.MarkerId, markerNames[s.MarkerId], len(s.Data), digestString)
 }
 
 // String returns a descriptive string.
 func (s *Segment) String() string {
 
 	// TODO(dustin): Add test
 
 	return fmt.Sprintf("Segment<%s>", s.EmbeddedString())
 }
 
 // IsExif returns true if EXIF data.
 func (s *Segment) IsExif() bool {
 	if s.MarkerId != MARKER_APP1 {
 		return false
 	}
 
 	// TODO(dustin): Add test
 
 	l := len(exifPrefix)
 
 	if len(s.Data) < l {
 		return false
 	}
 
 	if bytes.Equal(s.Data[:l], exifPrefix) == false {
 		return false
 	}
 
 	return true
 }
 
 // IsXmp returns true if XMP data.
 func (s *Segment) IsXmp() bool {
 	if s.MarkerId != MARKER_APP1 {
 		return false
 	}
 
 	// TODO(dustin): Add test
 
 	l := len(xmpPrefix)
 
 	if len(s.Data) < l {
 		return false
 	}
 
 	if bytes.Equal(s.Data[:l], xmpPrefix) == false {
 		return false
 	}
 
 	return true
 }
 
 // FormattedXmp returns a formatted XML string. This only makes sense for a
 // segment comprised of XML data (like XMP).
 func (s *Segment) FormattedXmp() (formatted string, err error) {
 	defer func() {
 		if state := recover(); state != nil {
 			err = log.Wrap(state.(error))
 		}
 	}()
 
 	// TODO(dustin): Add test
 
 	if s.IsXmp() != true {
 		log.Panicf("not an XMP segment")
 	}
 
 	l := len(xmpPrefix)
 
 	raw := string(s.Data[l:])
 
 	formatted, err = FormatXml(raw)
 	log.PanicIf(err)
 
 	return formatted, nil
 }
 
 func (s *Segment) parsePhotoshopInfo() (photoshopInfo map[uint16]photoshopinfo.Photoshop30InfoRecord, err error) {
 	defer func() {
 		if state := recover(); state != nil {
 			err = log.Wrap(state.(error))
 		}
 	}()
 
 	if s.photoshopInfo != nil {
 		return s.photoshopInfo, nil
 	}
 
 	if s.MarkerId != MARKER_APP13 {
 		return nil, ErrNoPhotoshopData
 	}
 
 	l := len(ps30Prefix)
 
 	if len(s.Data) < l {
 		return nil, ErrNoPhotoshopData
 	}
 
 	if bytes.Equal(s.Data[:l], ps30Prefix) == false {
 		return nil, ErrNoPhotoshopData
 	}
 
 	data := s.Data[l:]
 	b := bytes.NewBuffer(data)
 
 	// Parse it.
 
 	pirIndex, err := photoshopinfo.ReadPhotoshop30Info(b)
 	log.PanicIf(err)
 
 	s.photoshopInfo = pirIndex
 
 	return s.photoshopInfo, nil
 }
 
 // IsIptc returns true if XMP data.
 func (s *Segment) IsIptc() bool {
 	// TODO(dustin): Add test
 
 	// There's a cost to determining if there's IPTC data, so we won't do it
 	// more than once.
 	if s.iptcTags != nil {
 		return true
 	}
 
 	photoshopInfo, err := s.parsePhotoshopInfo()
 	if err != nil {
 		if err == ErrNoPhotoshopData {
 			return false
 		}
 
 		log.Panic(err)
 	}
 
 	// Bail if the Photoshop info doesn't have IPTC data.
 
 	_, found := photoshopInfo[pirIptcImageResourceId]
 	if found == false {
 		return false
 	}
 
 	return true
 }
 
 // Iptc parses Photoshop info (if present) and then parses the IPTC info inside
 // it (if present).
 func (s *Segment) Iptc() (tags map[iptc.StreamTagKey][]iptc.TagData, err error) {
 	defer func() {
 		if state := recover(); state != nil {
 			err = log.Wrap(state.(error))
 		}
 	}()
 
 	// Cache the parse.
 	if s.iptcTags != nil {
 		return s.iptcTags, nil
 	}
 
 	photoshopInfo, err := s.parsePhotoshopInfo()
 	log.PanicIf(err)
 
 	iptcPir, found := photoshopInfo[pirIptcImageResourceId]
 	if found == false {
 		return nil, ErrNoIptc
 	}
 
 	b := bytes.NewBuffer(iptcPir.Data)
 
 	tags, err = iptc.ParseStream(b)
 	log.PanicIf(err)
 
 	s.iptcTags = tags
 
 	return tags, nil
 }
 
 var (
 	// Enforce interface conformance.
 	_ riimage.MediaContext = new(Segment)
 )