ifd_enumerate: Now parse the GPS info.

- Moved some IFD functionality out to its own file.
- Tweaked the permissions on some assets.

gps.go

@@ -0,0 +1,37 @@
+package exif
+
+import (
+    "fmt"
+    "time"
+)
+
+
+type GpsDegrees struct {
+    Orientation byte
+    Degrees, Minutes, Seconds int
+}
+
+func (d GpsDegrees) String() string {
+    return fmt.Sprintf("Degrees<O=[%s] D=(%d) M=(%d) S=(%d)>", string([]byte { d.Orientation }), d.Degrees, d.Minutes, d.Seconds)
+}
+
+func (d GpsDegrees) Decimal() float64 {
+    decimal := float64(d.Degrees) + float64(d.Minutes) / 60.0 + float64(d.Seconds) / 3600.0
+
+    if d.Orientation == 'S' || d.Orientation == 'W' {
+        return -decimal
+    } else {
+        return decimal
+    }
+}
+
+
+type GpsInfo struct {
+    Latitude, Longitude GpsDegrees
+    Altitude int
+    Timestamp time.Time
+}
+
+func (gi GpsInfo) String() string {
+    return fmt.Sprintf("GpsInfo<LAT=(%.05f) LON=(%.05f) ALT=(%d) TIME=[%s]>", gi.Latitude.Decimal(), gi.Longitude.Decimal(), gi.Altitude, gi.Timestamp)
+}

ifd.go

@@ -0,0 +1,132 @@
+package exif
+
+import (
+    "fmt"
+
+    "github.com/dsoprea/go-logging"
+)
+
+const (
+    IfdStandard = "IFD"
+
+    IfdExif = "Exif"
+    IfdGps = "GPSInfo"
+    IfdIop = "Iop"
+
+    IfdExifId = 0x8769
+    IfdGpsId = 0x8825
+    IfdIopId = 0xA005
+)
+
+type IfdNameAndIndex struct {
+    Ii IfdIdentity
+    Index int
+}
+
+var (
+// TODO(dustin): !! Get rid of this in favor of one of the two lookups, just below.
+    validIfds = []string {
+        IfdStandard,
+        IfdExif,
+        IfdGps,
+        IfdIop,
+    }
+
+    // A lookup for IFDs by their parents.
+// TODO(dustin): !! We should switch to indexing by their unique integer IDs (defined below) rather than exposing ourselves to non-unique IFD names (even if we *do* manage the naming ourselves).
+    IfdTagIds = map[string]map[string]uint16 {
+        "": map[string]uint16 {
+            // A root IFD type. Not allowed to be a child (tag-based) IFD.
+            IfdStandard: 0x0,
+        },
+
+        IfdStandard: map[string]uint16 {
+            IfdExif: IfdExifId,
+            IfdGps: IfdGpsId,
+        },
+
+        IfdExif: map[string]uint16 {
+            IfdIop: IfdIopId,
+        },
+    }
+
+    // IfdTagNames contains the tag ID-to-name mappings and is populated by
+    // init().
+    IfdTagNames = map[string]map[uint16]string {}
+
+    // IFD Identities. These are often how we refer to IFDs, from call to call.
+
+    // The NULL-type instance for search misses and empty responses.
+    ZeroIi = IfdIdentity{}
+
+    RootIi = IfdIdentity{ IfdName: IfdStandard }
+    ExifIi = IfdIdentity{ ParentIfdName: IfdStandard, IfdName: IfdExif }
+    GpsIi = IfdIdentity{ ParentIfdName: IfdStandard, IfdName: IfdGps }
+    ExifIopIi = IfdIdentity{ ParentIfdName: IfdExif, IfdName: IfdIop }
+
+    // Produce a list of unique IDs for each IFD that we can pass around (so we
+    // don't always have to be comparing parent and child names).
+    //
+    // For lack of need, this is just static.
+    //
+    // (0) is reserved for not-found/miss responses.
+    IfdIds = map[IfdIdentity]int {
+        RootIi: 1,
+        ExifIi: 2,
+        GpsIi: 3,
+        ExifIopIi: 4,
+    }
+
+    IfdDesignations = map[string]IfdNameAndIndex {
+        "ifd0": { RootIi, 0 },
+        "ifd1": { RootIi, 1 },
+        "exif": { ExifIi, 0 },
+        "gps": { GpsIi, 0 },
+        "iop": { ExifIopIi, 0 },
+    }
+
+    IfdDesignationsR = make(map[IfdNameAndIndex]string)
+)
+
+var (
+    ifdLogger = log.NewLogger("exif.ifd")
+)
+
+func IfdDesignation(ii IfdIdentity, index int) string {
+    if ii == RootIi {
+        return fmt.Sprintf("%s%d", ii.IfdName, index)
+    } else {
+        return ii.IfdName
+    }
+}
+
+
+type IfdIdentity struct {
+    ParentIfdName string
+    IfdName string
+}
+
+func (ii IfdIdentity) String() string {
+    return fmt.Sprintf("IfdIdentity<PARENT-NAME=[%s] NAME=[%s]>", ii.ParentIfdName, ii.IfdName)
+}
+
+func (ii IfdIdentity) Id() int {
+    return IfdIdWithIdentityOrFail(ii)
+}
+
+
+func init() {
+    for ifdName, tags := range IfdTagIds {
+        tagsR := make(map[uint16]string)
+
+        for tagName, tagId := range tags {
+            tagsR[tagId] = tagName
+        }
+
+        IfdTagNames[ifdName] = tagsR
+    }
+
+    for designation, ni := range IfdDesignations {
+        IfdDesignationsR[ni] = designation
+    }
+}

ifd_enumerate.go

@@ -6,6 +6,8 @@ import (
     "strings"
     "errors"
     "reflect"
+    "time"
+    "strconv"
 
     "encoding/binary"
 
@@ -14,8 +16,11 @@ import (
 
 var (
     ifdEnumerateLogger = log.NewLogger("exifjpeg.ifd")
+)
 
+var (
     ErrNoThumbnail = errors.New("no thumbnail")
+    ErrNoGpsTags = errors.New("no gps tags")
 )
 
 
@@ -796,6 +801,137 @@ func (ifd *Ifd) DumpTree() []string {
     return ifd.dumpTree(nil, 0)
 }
 
+// GpsInfo parses and consolidates the GPS info. This can only be called on the
+// GPS IFD.
+func (ifd *Ifd) GpsInfo() (gi *GpsInfo, err error) {
+    defer func() {
+        if state := recover(); state != nil {
+            err = log.Wrap(state.(error))
+        }
+    }()
+
+    gi = new(GpsInfo)
+
+    if ifd.Ii != GpsIi {
+        log.Panicf("GPS can only be read on GPS IFD: [%s] != [%s]", ifd.Ii, GpsIi)
+    }
+
+    if tags, found := ifd.EntriesByTagId[TagVersionId]; found == false {
+        log.Panic(ErrNoGpsTags)
+    } else if bytes.Compare(tags[0].value, []byte { 2, 2, 0, 0}) != 0 {
+        log.Panic(ErrNoGpsTags)
+    }
+
+
+    tags, found := ifd.EntriesByTagId[TagLatitudeId]
+    if found == false {
+        log.Panicf("latitude not found")
+    }
+
+    latitudeValue, err := ifd.TagValue(tags[0])
+    log.PanicIf(err)
+
+    tags, found = ifd.EntriesByTagId[TagLatitudeRefId]
+    if found == false {
+        log.Panicf("latitude-ref not found")
+    }
+
+    latitudeRefValue, err := ifd.TagValue(tags[0])
+    log.PanicIf(err)
+
+    tags, found = ifd.EntriesByTagId[TagLongitudeId]
+    if found == false {
+        log.Panicf("longitude not found")
+    }
+
+    longitudeValue, err := ifd.TagValue(tags[0])
+    log.PanicIf(err)
+
+    tags, found = ifd.EntriesByTagId[TagLongitudeRefId]
+    if found == false {
+        log.Panicf("longitude-ref not found")
+    }
+
+    longitudeRefValue, err := ifd.TagValue(tags[0])
+    log.PanicIf(err)
+
+
+    // Parse location.
+
+    latitudeRaw := latitudeValue.([]Rational)
+
+    gi.Latitude = GpsDegrees{
+        Orientation: latitudeRefValue.(string)[0],
+        Degrees: int(float64(latitudeRaw[0].Numerator) / float64(latitudeRaw[0].Denominator)),
+        Minutes: int(float64(latitudeRaw[1].Numerator) / float64(latitudeRaw[1].Denominator)),
+        Seconds: int(float64(latitudeRaw[2].Numerator) / float64(latitudeRaw[2].Denominator)),
+    }
+
+    longitudeRaw := longitudeValue.([]Rational)
+
+    gi.Longitude = GpsDegrees{
+        Orientation: longitudeRefValue.(string)[0],
+        Degrees: int(float64(longitudeRaw[0].Numerator) / float64(longitudeRaw[0].Denominator)),
+        Minutes: int(float64(longitudeRaw[1].Numerator) / float64(longitudeRaw[1].Denominator)),
+        Seconds: int(float64(longitudeRaw[2].Numerator) / float64(longitudeRaw[2].Denominator)),
+    }
+
+
+    // Parse altitude.
+
+    altitudeTags, foundAltitude := ifd.EntriesByTagId[TagAltitudeId]
+    altitudeRefTags, foundAltitudeRef := ifd.EntriesByTagId[TagAltitudeRefId]
+
+    if foundAltitude == true && foundAltitudeRef == true {
+        altitudeValue, err := ifd.TagValue(altitudeTags[0])
+        log.PanicIf(err)
+
+        altitudeRefValue, err := ifd.TagValue(altitudeRefTags[0])
+        log.PanicIf(err)
+
+        altitudeRaw := altitudeValue.([]Rational)
+        altitude := int(altitudeRaw[0].Numerator / altitudeRaw[0].Denominator)
+        if altitudeRefValue.([]byte)[0] == 1 {
+            altitude *= -1
+        }
+
+        gi.Altitude = altitude
+    }
+
+
+    // Parse time.
+
+    timestampTags, foundTimestamp := ifd.EntriesByTagId[TagTimestampId]
+    datestampTags, foundDatestamp := ifd.EntriesByTagId[TagDatestampId]
+
+    if foundTimestamp == true && foundDatestamp == true {
+        datestampValue, err := ifd.TagValue(datestampTags[0])
+        log.PanicIf(err)
+
+        dateParts := strings.Split(datestampValue.(string), ":")
+
+        year, err1 := strconv.ParseUint(dateParts[0], 10, 16)
+        month, err2 := strconv.ParseUint(dateParts[1], 10, 8)
+        day, err3 := strconv.ParseUint(dateParts[2], 10, 8)
+
+        if err1 == nil && err2 == nil && err3 == nil {
+            timestampValue, err := ifd.TagValue(timestampTags[0])
+            log.PanicIf(err)
+
+            timestampRaw := timestampValue.([]Rational)
+
+            hour := int(timestampRaw[0].Numerator / timestampRaw[0].Denominator)
+            minute := int(timestampRaw[1].Numerator / timestampRaw[1].Denominator)
+            second := int(timestampRaw[2].Numerator / timestampRaw[2].Denominator)
+
+            gi.Timestamp = time.Date(int(year), time.Month(month), int(day), hour, minute, second, 0, time.UTC)
+        }
+    }
+
+    return gi, nil
+}
+
+
 type QueuedIfd struct {
     Ii IfdIdentity
     TagId uint16

ifd_enumerate_test.go

@@ -4,6 +4,7 @@ import (
     "path"
     "testing"
     "bytes"
+    "fmt"
 
     "encoding/binary"
     "io/ioutil"
@@ -291,3 +292,62 @@ func Test_Ifd_Thumbnail(t *testing.T) {
         t.Fatalf("thumbnail not correct")
     }
 }
+
+func TestIfd_GpsInfo(t *testing.T) {
+    defer func() {
+        if state := recover(); state != nil {
+            err := log.Wrap(state.(error))
+            log.PrintErrorf(err, "Test failure.")
+        }
+    }()
+
+    filepath := path.Join(assetsPath, "20180428_212312.jpg")
+
+    rawExif, err := SearchFileAndExtractExif(filepath)
+    log.PanicIf(err)
+
+    _, index, err := Collect(rawExif)
+    log.PanicIf(err)
+
+    ifd, err := index.RootIfd.ChildWithIfdIdentity(GpsIi)
+    log.PanicIf(err)
+
+    gi, err := ifd.GpsInfo()
+    log.PanicIf(err)
+
+    if gi.Latitude.Orientation != 'N' || gi.Latitude.Degrees != 26 || gi.Latitude.Minutes != 35 || gi.Latitude.Seconds != 12 {
+        t.Fatalf("latitude not correct")
+    } else if gi.Longitude.Orientation != 'W' || gi.Longitude.Degrees != 80 || gi.Longitude.Minutes != 3 || gi.Longitude.Seconds != 13 {
+        t.Fatalf("longitude not correct")
+    } else if gi.Altitude != 0 {
+        t.Fatalf("altitude not correct")
+    } else if gi.Timestamp.Unix() != 1524964977 {
+        t.Fatalf("timestamp not correct")
+    } else if gi.Altitude != 0 {
+        t.Fatalf("altitude not correct")
+    }
+}
+
+
+func ExampleIfd_GpsInfo() {
+    filepath := path.Join(assetsPath, "20180428_212312.jpg")
+
+    rawExif, err := SearchFileAndExtractExif(filepath)
+    log.PanicIf(err)
+
+    _, index, err := Collect(rawExif)
+    log.PanicIf(err)
+
+    ifd, err := index.RootIfd.ChildWithIfdIdentity(GpsIi)
+    log.PanicIf(err)
+
+    gi, err := ifd.GpsInfo()
+    log.PanicIf(err)
+
+    fmt.Printf("%s\n", gi)
+
+    // Output:
+    // GpsInfo<LAT=(26.58667) LON=(-80.05361) ALT=(0) TIME=[2018-04-29 01:22:57 +0000 UTC]>
+}
+
+

ifd_tag_entry.go

@@ -29,7 +29,8 @@ type IfdTagEntry struct {
     // IfdName is the IFD that this tag belongs to.
     Ii IfdIdentity
 
-// TODO(dustin): !! We now parse and read the value immediately. Update the rest of the logic to use this and get rid of all ofthe staggered and different resolution mechanisms.
+
+// TODO(dustin): !! We now parse and read the value immediately. Update the rest of the logic to use this and get rid of all of the staggered and different resolution mechanisms.
     value []byte
     isUnhandledUnknown bool
 }

tags.go

@@ -10,81 +10,30 @@ import (
 )
 
 const (
-    IfdStandard = "IFD"
-
-    IfdExif = "Exif"
-    IfdGps = "GPSInfo"
-    IfdIop = "Iop"
-
-    IfdExifId = 0x8769
-    IfdGpsId = 0x8825
-    IfdIopId = 0xA005
+    // IFD1
 
     ThumbnailOffsetTagId = 0x0201
     ThumbnailSizeTagId = 0x0202
-)
 
-type IfdNameAndIndex struct {
-    Ii IfdIdentity
-    Index int
-}
+    // Exif
+
+    TagVersionId = 0x0000
+
+    TagLatitudeId = 0x0002
+    TagLatitudeRefId = 0x0001
+    TagLongitudeId = 0x0004
+    TagLongitudeRefId = 0x0003
+
+    TagTimestampId = 0x0007
+    TagDatestampId = 0x001d
+
+    TagAltitudeId = 0x0006
+    TagAltitudeRefId = 0x0005
+)
 
 var (
     tagDataFilepath = ""
 
-// TODO(dustin): !! Get rid of this in favor of one of the two lookups, just below.
-    validIfds = []string {
-        IfdStandard,
-        IfdExif,
-        IfdGps,
-        IfdIop,
-    }
-
-    // A lookup for IFDs by their parents.
-// TODO(dustin): !! We should switch to indexing by their unique integer IDs (defined below) rather than exposing ourselves to non-unique IFD names (even if we *do* manage the naming ourselves).
-    IfdTagIds = map[string]map[string]uint16 {
-        "": map[string]uint16 {
-            // A root IFD type. Not allowed to be a child (tag-based) IFD.
-            IfdStandard: 0x0,
-        },
-
-        IfdStandard: map[string]uint16 {
-            IfdExif: IfdExifId,
-            IfdGps: IfdGpsId,
-        },
-
-        IfdExif: map[string]uint16 {
-            IfdIop: IfdIopId,
-        },
-    }
-
-    // IfdTagNames contains the tag ID-to-name mappings and is populated by
-    // init().
-    IfdTagNames = map[string]map[uint16]string {}
-
-    // IFD Identities. These are often how we refer to IFDs, from call to call.
-
-    // The NULL-type instance for search misses and empty responses.
-    ZeroIi = IfdIdentity{}
-
-    RootIi = IfdIdentity{ IfdName: IfdStandard }
-    ExifIi = IfdIdentity{ ParentIfdName: IfdStandard, IfdName: IfdExif }
-    GpsIi = IfdIdentity{ ParentIfdName: IfdStandard, IfdName: IfdGps }
-    ExifIopIi = IfdIdentity{ ParentIfdName: IfdExif, IfdName: IfdIop }
-
-    // Produce a list of unique IDs for each IFD that we can pass around (so we
-    // don't always have to be comparing parent and child names).
-    //
-    // For lack of need, this is just static.
-    //
-    // (0) is reserved for not-found/miss responses.
-    IfdIds = map[IfdIdentity]int {
-        RootIi: 1,
-        ExifIi: 2,
-        GpsIi: 3,
-        ExifIopIi: 4,
-    }
-
     // tagsWithoutAlignment is a tag-lookup for tags whose value size won't
     // necessarily be a multiple of its tag-type.
     tagsWithoutAlignment = map[uint16]struct{} {
@@ -94,44 +43,12 @@ var (
     }
 
     tagIndex *TagIndex
-
-    IfdDesignations = map[string]IfdNameAndIndex {
-        "ifd0": { RootIi, 0 },
-        "ifd1": { RootIi, 1 },
-        "exif": { ExifIi, 0 },
-        "gps": { GpsIi, 0 },
-        "iop": { ExifIopIi, 0 },
-    }
-
-    IfdDesignationsR = make(map[IfdNameAndIndex]string)
 )
 
 var (
     tagsLogger = log.NewLogger("exif.tags")
 )
 
-func IfdDesignation(ii IfdIdentity, index int) string {
-    if ii == RootIi {
-        return fmt.Sprintf("%s%d", ii.IfdName, index)
-    } else {
-        return ii.IfdName
-    }
-}
-
-
-type IfdIdentity struct {
-    ParentIfdName string
-    IfdName string
-}
-
-func (ii IfdIdentity) String() string {
-    return fmt.Sprintf("IfdIdentity<PARENT-NAME=[%s] NAME=[%s]>", ii.ParentIfdName, ii.IfdName)
-}
-
-func (ii IfdIdentity) Id() int {
-    return IfdIdWithIdentityOrFail(ii)
-}
-
 
 // File structures.
 
@@ -410,19 +327,5 @@ func init() {
     assetsPath := path.Join(goPath, "src", "github.com", "dsoprea", "go-exif", "assets")
     tagDataFilepath = path.Join(assetsPath, "tags.yaml")
 
-    for ifdName, tags := range IfdTagIds {
-        tagsR := make(map[uint16]string)
-
-        for tagName, tagId := range tags {
-            tagsR[tagId] = tagName
-        }
-
-        IfdTagNames[ifdName] = tagsR
-    }
-
-    for designation, ni := range IfdDesignations {
-        IfdDesignationsR[ni] = designation
-    }
-
     tagIndex = NewTagIndex()
 }