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gotosocial/internal/media/image.go

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/*
GoToSocial
Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package media
import (
"bytes"
"errors"
"fmt"
"image"
"image/gif"
"image/jpeg"
"image/png"
"strings"
"time"
"github.com/buckket/go-blurhash"
"github.com/nfnt/resize"
"github.com/superseriousbusiness/exifremove/pkg/exifremove"
"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
"github.com/superseriousbusiness/gotosocial/internal/id"
"github.com/superseriousbusiness/gotosocial/internal/uris"
)
const (
thumbnailMaxWidth = 512
thumbnailMaxHeight = 512
)
type imageAndMeta struct {
image []byte
width int
height int
size int
aspect float64
blurhash string
}
func (m *manager) processImage(data []byte, contentType string) (*gtsmodel.MediaAttachment, error) {
var clean []byte
var err error
var original *imageAndMeta
var small *imageAndMeta
switch contentType {
case mimeImageJpeg, mimeImagePng:
// first 'clean' image by purging exif data from it
var exifErr error
if clean, exifErr = purgeExif(data); exifErr != nil {
return nil, fmt.Errorf("error cleaning exif data: %s", exifErr)
}
original, err = decodeImage(clean, contentType)
case mimeImageGif:
// gifs are already clean - no exif data to remove
clean = data
original, err = decodeGif(clean, contentType)
default:
err = fmt.Errorf("content type %s not a recognized image type", contentType)
}
if err != nil {
return nil, err
}
small, err = deriveThumbnail(clean, contentType, thumbnailMaxWidth, thumbnailMaxHeight)
if err != nil {
return nil, fmt.Errorf("error deriving thumbnail: %s", err)
}
// now put it in storage, take a new id for the name of the file so we don't store any unnecessary info about it
extension := strings.Split(contentType, "/")[1]
attachmentID, err := id.NewRandomULID()
if err != nil {
return nil, err
}
originalURL := uris.GenerateURIForAttachment(minAttachment.AccountID, string(TypeAttachment), string(SizeOriginal), attachmentID, extension)
smallURL := uris.GenerateURIForAttachment(minAttachment.AccountID, string(TypeAttachment), string(SizeSmall), attachmentID, "jpeg") // all thumbnails/smalls are encoded as jpeg
// we store the original...
originalPath := fmt.Sprintf("%s/%s/%s/%s.%s", minAttachment.AccountID, TypeAttachment, SizeOriginal, attachmentID, extension)
if err := m.storage.Put(originalPath, original.image); err != nil {
return nil, fmt.Errorf("storage error: %s", err)
}
// and a thumbnail...
smallPath := fmt.Sprintf("%s/%s/%s/%s.jpeg", minAttachment.AccountID, TypeAttachment, SizeSmall, attachmentID) // all thumbnails/smalls are encoded as jpeg
if err := m.storage.Put(smallPath, small.image); err != nil {
return nil, fmt.Errorf("storage error: %s", err)
}
minAttachment.FileMeta.Original = gtsmodel.Original{
Width: original.width,
Height: original.height,
Size: original.size,
Aspect: original.aspect,
}
minAttachment.FileMeta.Small = gtsmodel.Small{
Width: small.width,
Height: small.height,
Size: small.size,
Aspect: small.aspect,
}
attachment := &gtsmodel.MediaAttachment{
ID: attachmentID,
StatusID: minAttachment.StatusID,
URL: originalURL,
RemoteURL: minAttachment.RemoteURL,
CreatedAt: minAttachment.CreatedAt,
UpdatedAt: minAttachment.UpdatedAt,
Type: gtsmodel.FileTypeImage,
FileMeta: minAttachment.FileMeta,
AccountID: minAttachment.AccountID,
Description: minAttachment.Description,
ScheduledStatusID: minAttachment.ScheduledStatusID,
Blurhash: small.blurhash,
Processing: 2,
File: gtsmodel.File{
Path: originalPath,
ContentType: contentType,
FileSize: len(original.image),
UpdatedAt: time.Now(),
},
Thumbnail: gtsmodel.Thumbnail{
Path: smallPath,
ContentType: mimeJpeg, // all thumbnails/smalls are encoded as jpeg
FileSize: len(small.image),
UpdatedAt: time.Now(),
URL: smallURL,
RemoteURL: minAttachment.Thumbnail.RemoteURL,
},
Avatar: minAttachment.Avatar,
Header: minAttachment.Header,
}
return attachment, nil
}
func decodeGif(b []byte, extension string) (*imageAndMeta, error) {
var g *gif.GIF
var err error
switch extension {
case mimeGif:
g, err = gif.DecodeAll(bytes.NewReader(b))
default:
err = fmt.Errorf("extension %s not recognised", extension)
}
if err != nil {
return nil, err
}
// use the first frame to get the static characteristics
width := g.Config.Width
height := g.Config.Height
size := width * height
aspect := float64(width) / float64(height)
return &imageAndMeta{
image: b,
width: width,
height: height,
size: size,
aspect: aspect,
}, nil
}
func decodeImage(b []byte, contentType string) (*imageAndMeta, error) {
var i image.Image
var err error
switch contentType {
case mimeImageJpeg:
i, err = jpeg.Decode(bytes.NewReader(b))
case mimeImagePng:
i, err = png.Decode(bytes.NewReader(b))
default:
err = fmt.Errorf("content type %s not recognised", contentType)
}
if err != nil {
return nil, err
}
if i == nil {
return nil, errors.New("processed image was nil")
}
width := i.Bounds().Size().X
height := i.Bounds().Size().Y
size := width * height
aspect := float64(width) / float64(height)
return &imageAndMeta{
image: b,
width: width,
height: height,
size: size,
aspect: aspect,
}, nil
}
// deriveThumbnail returns a byte slice and metadata for a thumbnail of width x and height y,
// of a given jpeg, png, or gif, or an error if something goes wrong.
//
// Note that the aspect ratio of the image will be retained,
// so it will not necessarily be a square, even if x and y are set as the same value.
func deriveThumbnail(b []byte, contentType string, x uint, y uint) (*imageAndMeta, error) {
var i image.Image
var err error
switch contentType {
case mimeImageJpeg:
i, err = jpeg.Decode(bytes.NewReader(b))
if err != nil {
return nil, err
}
case mimeImagePng:
i, err = png.Decode(bytes.NewReader(b))
if err != nil {
return nil, err
}
case mimeImageGif:
i, err = gif.Decode(bytes.NewReader(b))
if err != nil {
return nil, err
}
default:
return nil, fmt.Errorf("content type %s not recognised", contentType)
}
thumb := resize.Thumbnail(x, y, i, resize.NearestNeighbor)
width := thumb.Bounds().Size().X
height := thumb.Bounds().Size().Y
size := width * height
aspect := float64(width) / float64(height)
tiny := resize.Thumbnail(32, 32, thumb, resize.NearestNeighbor)
bh, err := blurhash.Encode(4, 3, tiny)
if err != nil {
return nil, err
}
out := &bytes.Buffer{}
if err := jpeg.Encode(out, thumb, &jpeg.Options{
Quality: 75,
}); err != nil {
return nil, err
}
return &imageAndMeta{
image: out.Bytes(),
width: width,
height: height,
size: size,
aspect: aspect,
blurhash: bh,
}, nil
}
// deriveStaticEmojji takes a given gif or png of an emoji, decodes it, and re-encodes it as a static png.
func deriveStaticEmoji(b []byte, contentType string) (*imageAndMeta, error) {
var i image.Image
var err error
switch contentType {
case mimeImagePng:
i, err = png.Decode(bytes.NewReader(b))
if err != nil {
return nil, err
}
case mimeImageGif:
i, err = gif.Decode(bytes.NewReader(b))
if err != nil {
return nil, err
}
default:
return nil, fmt.Errorf("content type %s not allowed for emoji", contentType)
}
out := &bytes.Buffer{}
if err := png.Encode(out, i); err != nil {
return nil, err
}
return &imageAndMeta{
image: out.Bytes(),
}, nil
}
// purgeExif is a little wrapper for the action of removing exif data from an image.
// Only pass pngs or jpegs to this function.
func purgeExif(data []byte) ([]byte, error) {
if len(data) == 0 {
return nil, errors.New("passed image was not valid")
}
clean, err := exifremove.Remove(data)
if err != nil {
return nil, fmt.Errorf("could not purge exif from image: %s", err)
}
if len(clean) == 0 {
return nil, errors.New("purged image was not valid")
}
return clean, nil
}