ref: d48a98c477a818d28008d9771050d2681e63e880
dir: /resources/images/exif/exif.go/
// 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"
"github.com/bep/tmc"
_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
Tags Tags
}
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, Tags: 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 ""
}
var tcodec *tmc.Codec
func init() {
var err error
tcodec, err = tmc.New()
if err != nil {
panic(err)
}
}
type Tags map[string]interface{}
func (v *Tags) UnmarshalJSON(b []byte) error {
vv := make(map[string]interface{})
if err := tcodec.Unmarshal(b, &vv); err != nil {
return err
}
*v = vv
return nil
}
func (v Tags) MarshalJSON() ([]byte, error) {
return tcodec.Marshal(v)
}