From d83be6df2d8b0e2fef4cb6866cfdb6434bbef5c4 Mon Sep 17 00:00:00 2001
From: hmhealey <harrisonmhealey@gmail.com>
Date: Thu, 17 Sep 2015 11:08:47 -0400
Subject: PLT-173 Added graphics-go and goexif libraries for image manipulation

---
 .../src/github.com/rwcarlsen/goexif/tiff/tiff.go   | 153 +++++++++++++++++++++
 1 file changed, 153 insertions(+)
 create mode 100644 Godeps/_workspace/src/github.com/rwcarlsen/goexif/tiff/tiff.go

(limited to 'Godeps/_workspace/src/github.com/rwcarlsen/goexif/tiff/tiff.go')

diff --git a/Godeps/_workspace/src/github.com/rwcarlsen/goexif/tiff/tiff.go b/Godeps/_workspace/src/github.com/rwcarlsen/goexif/tiff/tiff.go
new file mode 100644
index 000000000..771e91878
--- /dev/null
+++ b/Godeps/_workspace/src/github.com/rwcarlsen/goexif/tiff/tiff.go
@@ -0,0 +1,153 @@
+// Package tiff implements TIFF decoding as defined in TIFF 6.0 specification at
+// http://partners.adobe.com/public/developer/en/tiff/TIFF6.pdf
+package tiff
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+)
+
+// ReadAtReader is used when decoding Tiff tags and directories
+type ReadAtReader interface {
+	io.Reader
+	io.ReaderAt
+}
+
+// Tiff provides access to a decoded tiff data structure.
+type Tiff struct {
+	// Dirs is an ordered slice of the tiff's Image File Directories (IFDs).
+	// The IFD at index 0 is IFD0.
+	Dirs []*Dir
+	// The tiff's byte-encoding (i.e. big/little endian).
+	Order binary.ByteOrder
+}
+
+// Decode parses tiff-encoded data from r and returns a Tiff struct that
+// reflects the structure and content of the tiff data. The first read from r
+// should be the first byte of the tiff-encoded data and not necessarily the
+// first byte of an os.File object.
+func Decode(r io.Reader) (*Tiff, error) {
+	data, err := ioutil.ReadAll(r)
+	if err != nil {
+		return nil, errors.New("tiff: could not read data")
+	}
+	buf := bytes.NewReader(data)
+
+	t := new(Tiff)
+
+	// read byte order
+	bo := make([]byte, 2)
+	if _, err = io.ReadFull(buf, bo); err != nil {
+		return nil, errors.New("tiff: could not read tiff byte order")
+	}
+	if string(bo) == "II" {
+		t.Order = binary.LittleEndian
+	} else if string(bo) == "MM" {
+		t.Order = binary.BigEndian
+	} else {
+		return nil, errors.New("tiff: could not read tiff byte order")
+	}
+
+	// check for special tiff marker
+	var sp int16
+	err = binary.Read(buf, t.Order, &sp)
+	if err != nil || 42 != sp {
+		return nil, errors.New("tiff: could not find special tiff marker")
+	}
+
+	// load offset to first IFD
+	var offset int32
+	err = binary.Read(buf, t.Order, &offset)
+	if err != nil {
+		return nil, errors.New("tiff: could not read offset to first IFD")
+	}
+
+	// load IFD's
+	var d *Dir
+	prev := offset
+	for offset != 0 {
+		// seek to offset
+		_, err := buf.Seek(int64(offset), 0)
+		if err != nil {
+			return nil, errors.New("tiff: seek to IFD failed")
+		}
+
+		if buf.Len() == 0 {
+			return nil, errors.New("tiff: seek offset after EOF")
+		}
+
+		// load the dir
+		d, offset, err = DecodeDir(buf, t.Order)
+		if err != nil {
+			return nil, err
+		}
+
+		if offset == prev {
+			return nil, errors.New("tiff: recursive IFD")
+		}
+		prev = offset
+
+		t.Dirs = append(t.Dirs, d)
+	}
+
+	return t, nil
+}
+
+func (tf *Tiff) String() string {
+	var buf bytes.Buffer
+	fmt.Fprint(&buf, "Tiff{")
+	for _, d := range tf.Dirs {
+		fmt.Fprintf(&buf, "%s, ", d.String())
+	}
+	fmt.Fprintf(&buf, "}")
+	return buf.String()
+}
+
+// Dir provides access to the parsed content of a tiff Image File Directory (IFD).
+type Dir struct {
+	Tags []*Tag
+}
+
+// DecodeDir parses a tiff-encoded IFD from r and returns a Dir object.  offset
+// is the offset to the next IFD.  The first read from r should be at the first
+// byte of the IFD. ReadAt offsets should generally be relative to the
+// beginning of the tiff structure (not relative to the beginning of the IFD).
+func DecodeDir(r ReadAtReader, order binary.ByteOrder) (d *Dir, offset int32, err error) {
+	d = new(Dir)
+
+	// get num of tags in ifd
+	var nTags int16
+	err = binary.Read(r, order, &nTags)
+	if err != nil {
+		return nil, 0, errors.New("tiff: failed to read IFD tag count: " + err.Error())
+	}
+
+	// load tags
+	for n := 0; n < int(nTags); n++ {
+		t, err := DecodeTag(r, order)
+		if err != nil {
+			return nil, 0, err
+		}
+		d.Tags = append(d.Tags, t)
+	}
+
+	// get offset to next ifd
+	err = binary.Read(r, order, &offset)
+	if err != nil {
+		return nil, 0, errors.New("tiff: falied to read offset to next IFD: " + err.Error())
+	}
+
+	return d, offset, nil
+}
+
+func (d *Dir) String() string {
+	s := "Dir{"
+	for _, t := range d.Tags {
+		s += t.String() + ", "
+	}
+	return s + "}"
+}
-- 
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