Add image.Exif

Note that we will probably need to add some metadata cache for this to scale.

Fixes #4600

10 files changed, 480 insertions, 2 deletions

diff --git a/resources/image.go b/resources/image.go
index 7113284f7..b06a84522 100644
--- a/resources/image.go
+++ b/resources/image.go
@@ -21,6 +21,9 @@ import (
 	_ "image/png"
 	"os"
 	"strings"
+	"sync"
+
+	"github.com/gohugoio/hugo/resources/images/exif"
 
 	"github.com/gohugoio/hugo/resources/internal"
 
@@ -48,12 +51,56 @@ var (
 type imageResource struct {
 	*images.Image
 
+	// When a image is processed in a chain, this holds the reference to the
+	// original (first).
+	root *imageResource
+
+	exifInit    sync.Once
+	exifInitErr error
+	exif        *exif.Exif
+
 	baseResource
 }
 
+// ImageData contains image related data, typically Exif.
+type ImageData map[string]interface{}
+
+func (i *imageResource) Exif() (*exif.Exif, error) {
+	return i.root.getExif()
+}
+
+func (i *imageResource) getExif() (*exif.Exif, error) {
+
+	i.exifInit.Do(func() {
+		supportsExif := i.Format == images.JPEG || i.Format == images.TIFF
+		if !supportsExif {
+			return
+		}
+
+		f, err := i.root.ReadSeekCloser()
+		if err != nil {
+			i.exifInitErr = err
+			return
+		}
+		defer f.Close()
+
+		x, err := i.getSpec().imaging.DecodeExif(f)
+		if err != nil {
+			i.exifInitErr = err
+			return
+		}
+
+		i.exif = x
+
+	})
+
+	return i.exif, i.exifInitErr
+}
+
 func (i *imageResource) Clone() resource.Resource {
 	gr := i.baseResource.Clone().(baseResource)
 	return &imageResource{
+		root:         i.root,
 		Image:        i.WithSpec(gr),
 		baseResource: gr,
 	}
@@ -74,6 +121,7 @@ func (i *imageResource) cloneWithUpdates(u *transformationUpdate) (baseResource,
 	}
 
 	return &imageResource{
+		root:         i.root,
 		Image:        img,
 		baseResource: base,
 	}, nil
@@ -217,6 +265,7 @@ func (i *imageResource) clone(img image.Image) *imageResource {
 
 	return &imageResource{
 		Image:        image,
+		root:         i.root,
 		baseResource: spec,
 	}
 }
diff --git a/resources/image_test.go b/resources/image_test.go
index 330a3af4b..4968190e9 100644
--- a/resources/image_test.go
+++ b/resources/image_test.go
@@ -332,6 +332,32 @@ func TestSVGImageContent(t *testing.T) {
 	c.Assert(content.(string), qt.Contains, `<svg height="100" width="100">`)
 }
 
+func TestImageExif(t *testing.T) {
+	c := qt.New(t)
+	image := fetchImage(c, "sunset.jpg")
+
+	x, err := image.Exif()
+	c.Assert(err, qt.IsNil)
+	c.Assert(x, qt.Not(qt.IsNil))
+
+	c.Assert(x.Date.Format("2006-01-02"), qt.Equals, "2017-10-27")
+
+	// Malaga: https://goo.gl/taazZy
+	c.Assert(x.Lat, qt.Equals, float64(36.59744166666667))
+	c.Assert(x.Long, qt.Equals, float64(-4.50846))
+
+	v, found := x.Values["LensModel"]
+	c.Assert(found, qt.Equals, true)
+	lensModel, ok := v.(string)
+	c.Assert(ok, qt.Equals, true)
+	c.Assert(lensModel, qt.Equals, "smc PENTAX-DA* 16-50mm F2.8 ED AL [IF] SDM")
+
+	resized, _ := image.Resize("300x200")
+	x2, _ := resized.Exif()
+	c.Assert(x2, qt.Equals, x)
+
+}
+
 func TestImageOperationsGolden(t *testing.T) {
 	c := qt.New(t)
 	c.Parallel()
diff --git a/resources/images/config.go b/resources/images/config.go
index b6121efa5..a290922ab 100644
--- a/resources/images/config.go
+++ b/resources/images/config.go
@@ -119,6 +119,11 @@ func DecodeConfig(m map[string]interface{}) (Imaging, error) {
 		i.ResampleFilter = filter
 	}
 
+	if strings.TrimSpace(i.Exif.IncludeFields) == "" && strings.TrimSpace(i.Exif.ExcludeFields) == "" {
+		// Don't change this for no good reason. Please don't.
+		i.Exif.ExcludeFields = "GPS|Exif|Exposure[M|P|B]|Contrast|Resolution|Sharp|JPEG|Metering|Sensing|Saturation|ColorSpace|Flash|WhiteBalance"
+	}
+
 	return i, nil
 }
 
@@ -279,4 +284,29 @@ type Imaging struct {
 
 	// The anchor to use in Fill. Default is "smart", i.e. Smart Crop.
 	Anchor string
+
+	Exif ExifConfig
+}
+
+type ExifConfig struct {
+
+	// Regexp matching the Exif fields you want from the (massive) set of Exif info
+	// available. As we cache this info to disk, this is for performance and
+	// disk space reasons more than anything.
+	// If you want it all, put ".*" in this config setting.
+	// Note that if neither this or ExcludeFields is set, Hugo will return a small
+	// default set.
+	IncludeFields string
+
+	// Regexp matching the Exif fields you want to exclude. This may be easier to use
+	// than IncludeFields above, depending on what you want.
+	ExcludeFields string
+
+	// Hugo extracts the "photo taken" date/time into .Date by default.
+	// Set this to true to turn it off.
+	DisableDate bool
+
+	// Hugo extracts the "photo taken where" (GPS latitude and longitude) into
+	// .Long and .Lat. Set this to true to turn it off.
+	DisableLatLong bool
 }
diff --git a/resources/images/config_test.go b/resources/images/config_test.go
index 91f4b663a..46b0c9858 100644
--- a/resources/images/config_test.go
+++ b/resources/images/config_test.go
@@ -64,6 +64,16 @@ func TestDecodeConfig(t *testing.T) {
 	})
 	c.Assert(err, qt.IsNil)
 	c.Assert(imaging.Anchor, qt.Equals, "smart")
+
+	imaging, err = DecodeConfig(map[string]interface{}{
+		"exif": map[string]interface{}{
+			"disableLatLong": true,
+		},
+	})
+	c.Assert(err, qt.IsNil)
+	c.Assert(imaging.Exif.DisableLatLong, qt.Equals, true)
+	c.Assert(imaging.Exif.ExcludeFields, qt.Equals, "GPS|Exif|Exposure[M|P|B]|Contrast|Resolution|Sharp|JPEG|Metering|Sensing|Saturation|ColorSpace|Flash|WhiteBalance")
+
 }
 
 func TestDecodeImageConfig(t *testing.T) {
diff --git a/resources/images/exif/exif.go b/resources/images/exif/exif.go
new file mode 100644
index 000000000..7a3c982c1
--- /dev/null
+++ b/resources/images/exif/exif.go
@@ -0,0 +1,242 @@
+// Copyright 2019 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package exif
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"math/big"
+	"regexp"
+	"strings"
+	"time"
+	"unicode"
+	"unicode/utf8"
+
+	_exif "github.com/rwcarlsen/goexif/exif"
+	"github.com/rwcarlsen/goexif/tiff"
+)
+
+const exifTimeLayout = "2006:01:02 15:04:05"
+
+type Exif struct {
+	Lat    float64
+	Long   float64
+	Date   time.Time
+	Values map[string]interface{}
+}
+
+type Decoder struct {
+	includeFieldsRe  *regexp.Regexp
+	excludeFieldsrRe *regexp.Regexp
+	noDate           bool
+	noLatLong        bool
+}
+
+func IncludeFields(expression string) func(*Decoder) error {
+	return func(d *Decoder) error {
+		re, err := compileRegexp(expression)
+		if err != nil {
+			return err
+		}
+		d.includeFieldsRe = re
+		return nil
+	}
+}
+
+func ExcludeFields(expression string) func(*Decoder) error {
+	return func(d *Decoder) error {
+		re, err := compileRegexp(expression)
+		if err != nil {
+			return err
+		}
+		d.excludeFieldsrRe = re
+		return nil
+	}
+}
+
+func WithLatLongDisabled(disabled bool) func(*Decoder) error {
+	return func(d *Decoder) error {
+		d.noLatLong = disabled
+		return nil
+	}
+}
+
+func WithDateDisabled(disabled bool) func(*Decoder) error {
+	return func(d *Decoder) error {
+		d.noDate = disabled
+		return nil
+	}
+}
+
+func compileRegexp(expression string) (*regexp.Regexp, error) {
+	expression = strings.TrimSpace(expression)
+	if expression == "" {
+		return nil, nil
+	}
+	if !strings.HasPrefix(expression, "(") {
+		// Make it case insensitive
+		expression = "(?i)" + expression
+	}
+
+	return regexp.Compile(expression)
+
+}
+
+func NewDecoder(options ...func(*Decoder) error) (*Decoder, error) {
+	d := &Decoder{}
+	for _, opt := range options {
+		if err := opt(d); err != nil {
+			return nil, err
+		}
+	}
+
+	return d, nil
+}
+
+func (d *Decoder) Decode(r io.Reader) (ex *Exif, err error) {
+	defer func() {
+		if r := recover(); r != nil {
+			err = fmt.Errorf("Exif failed: %v", r)
+		}
+	}()
+
+	var x *_exif.Exif
+	x, err = _exif.Decode(r)
+	if err != nil {
+		if err.Error() == "EOF" {
+
+			// Found no Exif
+			return nil, nil
+		}
+		return
+	}
+
+	var tm time.Time
+	var lat, long float64
+
+	if !d.noDate {
+		tm, _ = x.DateTime()
+	}
+
+	if !d.noLatLong {
+		lat, long, _ = x.LatLong()
+	}
+
+	walker := &exifWalker{x: x, vals: make(map[string]interface{}), includeMatcher: d.includeFieldsRe, excludeMatcher: d.excludeFieldsrRe}
+	if err = x.Walk(walker); err != nil {
+		return
+	}
+
+	ex = &Exif{Lat: lat, Long: long, Date: tm, Values: walker.vals}
+
+	return
+}
+
+func decodeTag(x *_exif.Exif, f _exif.FieldName, t *tiff.Tag) (interface{}, error) {
+	switch t.Format() {
+	case tiff.StringVal, tiff.UndefVal:
+		s := nullString(t.Val)
+		if strings.Contains(string(f), "DateTime") {
+			if d, err := tryParseDate(x, s); err == nil {
+				return d, nil
+			}
+		}
+		return s, nil
+	case tiff.OtherVal:
+		return "unknown", nil
+	}
+
+	var rv []interface{}
+
+	for i := 0; i < int(t.Count); i++ {
+		switch t.Format() {
+		case tiff.RatVal:
+			n, d, _ := t.Rat2(i)
+			rat := big.NewRat(n, d)
+			if n == 1 {
+				rv = append(rv, rat)
+			} else {
+				f, _ := rat.Float64()
+				rv = append(rv, f)
+			}
+
+		case tiff.FloatVal:
+			v, _ := t.Float(i)
+			rv = append(rv, v)
+		case tiff.IntVal:
+			v, _ := t.Int(i)
+			rv = append(rv, v)
+		}
+	}
+
+	if t.Count == 1 {
+		if len(rv) == 1 {
+			return rv[0], nil
+		}
+	}
+
+	return rv, nil
+
+}
+
+// Code borrowed from exif.DateTime and adjusted.
+func tryParseDate(x *_exif.Exif, s string) (time.Time, error) {
+	dateStr := strings.TrimRight(s, "\x00")
+	// TODO(bep): look for timezone offset, GPS time, etc.
+	timeZone := time.Local
+	if tz, _ := x.TimeZone(); tz != nil {
+		timeZone = tz
+	}
+	return time.ParseInLocation(exifTimeLayout, dateStr, timeZone)
+
+}
+
+type exifWalker struct {
+	x              *_exif.Exif
+	vals           map[string]interface{}
+	includeMatcher *regexp.Regexp
+	excludeMatcher *regexp.Regexp
+}
+
+func (e *exifWalker) Walk(f _exif.FieldName, tag *tiff.Tag) error {
+	name := string(f)
+	if e.excludeMatcher != nil && e.excludeMatcher.MatchString(name) {
+		return nil
+	}
+	if e.includeMatcher != nil && !e.includeMatcher.MatchString(name) {
+		return nil
+	}
+	val, err := decodeTag(e.x, f, tag)
+	if err != nil {
+		return err
+	}
+	e.vals[name] = val
+	return nil
+}
+
+func nullString(in []byte) string {
+	var rv bytes.Buffer
+	for _, b := range in {
+		if unicode.IsPrint(rune(b)) {
+			rv.WriteByte(b)
+		}
+	}
+	rvs := rv.String()
+	if utf8.ValidString(rvs) {
+		return rvs
+	}
+
+	return ""
+}
diff --git a/resources/images/exif/exif_test.go b/resources/images/exif/exif_test.go
new file mode 100644
index 000000000..eee60c089
--- /dev/null
+++ b/resources/images/exif/exif_test.go
@@ -0,0 +1,83 @@
+// Copyright 2019 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package exif
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/gohugoio/hugo/htesting/hqt"
+
+	qt "github.com/frankban/quicktest"
+)
+
+func TestExif(t *testing.T) {
+	c := qt.New(t)
+	f, err := os.Open(filepath.FromSlash("../../testdata/sunset.jpg"))
+	c.Assert(err, qt.IsNil)
+	defer f.Close()
+
+	d, err := NewDecoder(IncludeFields("Lens|Date"))
+	c.Assert(err, qt.IsNil)
+	x, err := d.Decode(f)
+	c.Assert(err, qt.IsNil)
+	c.Assert(x.Date.Format("2006-01-02"), qt.Equals, "2017-10-27")
+
+	// Malaga: https://goo.gl/taazZy
+	c.Assert(x.Lat, qt.Equals, float64(36.59744166666667))
+	c.Assert(x.Long, qt.Equals, float64(-4.50846))
+
+	v, found := x.Values["LensModel"]
+	c.Assert(found, qt.Equals, true)
+	lensModel, ok := v.(string)
+	c.Assert(ok, qt.Equals, true)
+	c.Assert(lensModel, qt.Equals, "smc PENTAX-DA* 16-50mm F2.8 ED AL [IF] SDM")
+
+	v, found = x.Values["DateTime"]
+	c.Assert(found, qt.Equals, true)
+	c.Assert(v, hqt.IsSameType, time.Time{})
+
+}
+
+func TestExifPNG(t *testing.T) {
+	c := qt.New(t)
+
+	f, err := os.Open(filepath.FromSlash("../../testdata/gohugoio.png"))
+	c.Assert(err, qt.IsNil)
+	defer f.Close()
+
+	d, err := NewDecoder()
+	c.Assert(err, qt.IsNil)
+	_, err = d.Decode(f)
+	c.Assert(err, qt.Not(qt.IsNil))
+}
+
+func BenchmarkDecodeExif(b *testing.B) {
+	c := qt.New(b)
+	f, err := os.Open(filepath.FromSlash("../../testdata/sunset.jpg"))
+	c.Assert(err, qt.IsNil)
+	defer f.Close()
+
+	d, err := NewDecoder()
+	c.Assert(err, qt.IsNil)
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		_, err = d.Decode(f)
+		c.Assert(err, qt.IsNil)
+		f.Seek(0, 0)
+	}
+}
diff --git a/resources/images/image.go b/resources/images/image.go
index d04c1e93d..aa7d567aa 100644
--- a/resources/images/image.go
+++ b/resources/images/image.go
@@ -22,6 +22,8 @@ import (
 	"io"
 	"sync"
 
+	"github.com/gohugoio/hugo/resources/images/exif"
+
 	"github.com/disintegration/gift"
 	"golang.org/x/image/bmp"
 	"golang.org/x/image/tiff"
@@ -154,8 +156,33 @@ func (i *Image) initConfig() error {
 	return nil
 }
 
+func NewImageProcessor(cfg Imaging) (*ImageProcessor, error) {
+	e := cfg.Exif
+	exifDecoder, err := exif.NewDecoder(
+		exif.WithDateDisabled(e.DisableDate),
+		exif.WithLatLongDisabled(e.DisableLatLong),
+		exif.ExcludeFields(e.ExcludeFields),
+		exif.IncludeFields(e.IncludeFields),
+	)
+
+	if err != nil {
+		return nil, err
+	}
+
+	return &ImageProcessor{
+		Cfg:         cfg,
+		exifDecoder: exifDecoder,
+	}, nil
+
+}
+
 type ImageProcessor struct {
-	Cfg Imaging
+	Cfg         Imaging
+	exifDecoder *exif.Decoder
+}
+
+func (p *ImageProcessor) DecodeExif(r io.Reader) (*exif.Exif, error) {
+	return p.exifDecoder.Decode(r)
 }
 
 func (p *ImageProcessor) ApplyFiltersFromConfig(src image.Image, conf ImageConfig) (image.Image, error) {
diff --git a/resources/resource/resourcetypes.go b/resources/resource/resourcetypes.go
index 4322b3c1f..f6b6d2af1 100644
--- a/resources/resource/resourcetypes.go
+++ b/resources/resource/resourcetypes.go
@@ -17,6 +17,7 @@ import (
 	"github.com/disintegration/gift"
 	"github.com/gohugoio/hugo/langs"
 	"github.com/gohugoio/hugo/media"
+	"github.com/gohugoio/hugo/resources/images/exif"
 
 	"github.com/gohugoio/hugo/common/hugio"
 )
@@ -49,6 +50,7 @@ type ImageOps interface {
 	Fit(spec string) (Image, error)
 	Resize(spec string) (Image, error)
 	Filter(filters ...gift.Filter) (Image, error)
+	Exif() (*exif.Exif, error)
 }
 
 type ResourceTypesProvider interface {
diff --git a/resources/resource_spec.go b/resources/resource_spec.go
index 528a2bd58..cd8d61470 100644
--- a/resources/resource_spec.go
+++ b/resources/resource_spec.go
@@ -47,7 +47,10 @@ func NewSpec(
 		return nil, err
 	}
 
-	imaging := &images.ImageProcessor{Cfg: imgConfig}
+	imaging, err := images.NewImageProcessor(imgConfig)
+	if err != nil {
+		return nil, err
+	}
 
 	if logger == nil {
 		logger = loggers.NewErrorLogger()
@@ -273,6 +276,7 @@ func (r *Spec) newResource(sourceFs afero.Fs, fd ResourceSourceDescriptor) (reso
 				Image:        images.NewImage(imgFormat, r.imaging, nil, gr),
 				baseResource: gr,
 			}
+			ir.root = ir
 			return newResourceAdapter(gr.spec, fd.LazyPublish, ir), nil
 		}
 
diff --git a/resources/transform.go b/resources/transform.go
index 0792515c4..eb282eab6 100644
--- a/resources/transform.go
+++ b/resources/transform.go
@@ -22,6 +22,7 @@ import (
 	"sync"
 
 	"github.com/disintegration/gift"
+	"github.com/gohugoio/hugo/resources/images/exif"
 	"github.com/spf13/afero"
 
 	bp "github.com/gohugoio/hugo/bufferpool"
@@ -181,6 +182,10 @@ func (r *resourceAdapter) Height() int {
 	return r.getImageOps().Height()
 }
 
+func (r *resourceAdapter) Exif() (*exif.Exif, error) {
+	return r.getImageOps().Exif()
+}
+
 func (r *resourceAdapter) Key() string {
 	r.init(false, false)
 	return r.target.(resource.Identifier).Key()