gotosocial/internal/media/util.go
Tobi Smethurst 6f5c045284
Ap (#14)
Big restructuring and initial work on activitypub
2021-05-08 14:25:55 +02:00

336 lines
7.9 KiB
Go

/*
GoToSocial
Copyright (C) 2021 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"
"github.com/buckket/go-blurhash"
"github.com/h2non/filetype"
"github.com/nfnt/resize"
"github.com/superseriousbusiness/exifremove/pkg/exifremove"
)
const (
// MIMEImage is the mime type for image
MIMEImage = "image"
// MIMEJpeg is the jpeg image mime type
MIMEJpeg = "image/jpeg"
// MIMEGif is the gif image mime type
MIMEGif = "image/gif"
// MIMEPng is the png image mime type
MIMEPng = "image/png"
// MIMEVideo is the mime type for video
MIMEVideo = "video"
// MIMEMp4 is the mp4 video mime type
MIMEMp4 = "video/mp4"
// MIMEMpeg is the mpeg video mime type
MIMEMpeg = "video/mpeg"
// MIMEWebm is the webm video mime type
MIMEWebm = "video/webm"
)
// parseContentType parses the MIME content type from a file, returning it as a string in the form (eg., "image/jpeg").
// Returns an error if the content type is not something we can process.
func parseContentType(content []byte) (string, error) {
head := make([]byte, 261)
_, err := bytes.NewReader(content).Read(head)
if err != nil {
return "", fmt.Errorf("could not read first magic bytes of file: %s", err)
}
kind, err := filetype.Match(head)
if err != nil {
return "", err
}
if kind == filetype.Unknown {
return "", errors.New("filetype unknown")
}
return kind.MIME.Value, nil
}
// SupportedImageType checks mime type of an image against a slice of accepted types,
// and returns True if the mime type is accepted.
func SupportedImageType(mimeType string) bool {
acceptedImageTypes := []string{
MIMEJpeg,
MIMEGif,
MIMEPng,
}
for _, accepted := range acceptedImageTypes {
if mimeType == accepted {
return true
}
}
return false
}
// SupportedVideoType checks mime type of a video against a slice of accepted types,
// and returns True if the mime type is accepted.
func SupportedVideoType(mimeType string) bool {
acceptedVideoTypes := []string{
MIMEMp4,
MIMEMpeg,
MIMEWebm,
}
for _, accepted := range acceptedVideoTypes {
if mimeType == accepted {
return true
}
}
return false
}
// supportedEmojiType checks that the content type is image/png -- the only type supported for emoji.
func supportedEmojiType(mimeType string) bool {
acceptedEmojiTypes := []string{
MIMEGif,
MIMEPng,
}
for _, accepted := range acceptedEmojiTypes {
if mimeType == accepted {
return true
}
}
return false
}
// 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(b []byte) ([]byte, error) {
if len(b) == 0 {
return nil, errors.New("passed image was not valid")
}
clean, err := exifremove.Remove(b)
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
}
func deriveGif(b []byte, extension string) (*imageAndMeta, error) {
var g *gif.GIF
var err error
switch extension {
case MIMEGif:
g, err = gif.DecodeAll(bytes.NewReader(b))
if err != nil {
return nil, err
}
default:
return nil, fmt.Errorf("extension %s not recognised", extension)
}
// 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)
bh, err := blurhash.Encode(4, 3, g.Image[0])
if err != nil || bh == "" {
return nil, err
}
out := &bytes.Buffer{}
if err := gif.EncodeAll(out, g); err != nil {
return nil, err
}
return &imageAndMeta{
image: out.Bytes(),
width: width,
height: height,
size: size,
aspect: aspect,
blurhash: bh,
}, nil
}
func deriveImage(b []byte, contentType string) (*imageAndMeta, error) {
var i image.Image
var err error
switch contentType {
case MIMEJpeg:
i, err = jpeg.Decode(bytes.NewReader(b))
if err != nil {
return nil, err
}
case MIMEPng:
i, err = png.Decode(bytes.NewReader(b))
if err != nil {
return nil, err
}
default:
return nil, fmt.Errorf("content type %s not recognised", contentType)
}
width := i.Bounds().Size().X
height := i.Bounds().Size().Y
size := width * height
aspect := float64(width) / float64(height)
bh, err := blurhash.Encode(4, 3, i)
if err != nil {
return nil, err
}
out := &bytes.Buffer{}
if err := jpeg.Encode(out, i, nil); err != nil {
return nil, err
}
return &imageAndMeta{
image: out.Bytes(),
width: width,
height: height,
size: size,
aspect: aspect,
blurhash: bh,
}, 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 MIMEJpeg:
i, err = jpeg.Decode(bytes.NewReader(b))
if err != nil {
return nil, err
}
case MIMEPng:
i, err = png.Decode(bytes.NewReader(b))
if err != nil {
return nil, err
}
case MIMEGif:
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)
out := &bytes.Buffer{}
if err := jpeg.Encode(out, thumb, nil); err != nil {
return nil, err
}
return &imageAndMeta{
image: out.Bytes(),
width: width,
height: height,
size: size,
aspect: aspect,
}, 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 MIMEPng:
i, err = png.Decode(bytes.NewReader(b))
if err != nil {
return nil, err
}
case MIMEGif:
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
}
type imageAndMeta struct {
image []byte
width int
height int
size int
aspect float64
blurhash string
}
// ParseMediaType converts s to a recognized MediaType, or returns an error if unrecognized
func ParseMediaType(s string) (Type, error) {
switch Type(s) {
case Attachment:
return Attachment, nil
case Header:
return Header, nil
case Avatar:
return Avatar, nil
case Emoji:
return Emoji, nil
}
return "", fmt.Errorf("%s not a recognized MediaType", s)
}
// ParseMediaSize converts s to a recognized MediaSize, or returns an error if unrecognized
func ParseMediaSize(s string) (Size, error) {
switch Size(s) {
case Small:
return Small, nil
case Original:
return Original, nil
case Static:
return Static, nil
}
return "", fmt.Errorf("%s not a recognized MediaSize", s)
}