288 lines
6.8 KiB
Go
288 lines
6.8 KiB
Go
/*
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GoToSocial
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Copyright (C) 2021 GoToSocial Authors admin@gotosocial.org
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU Affero General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Affero General Public License for more details.
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You should have received a copy of the GNU Affero General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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package media
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import (
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"bytes"
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"errors"
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"fmt"
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"image"
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"image/gif"
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"image/jpeg"
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"image/png"
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"github.com/buckket/go-blurhash"
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"github.com/h2non/filetype"
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"github.com/nfnt/resize"
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"github.com/superseriousbusiness/exifremove/pkg/exifremove"
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)
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// parseContentType parses the MIME content type from a file, returning it as a string in the form (eg., "image/jpeg").
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// Returns an error if the content type is not something we can process.
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func parseContentType(content []byte) (string, error) {
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head := make([]byte, 261)
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_, err := bytes.NewReader(content).Read(head)
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if err != nil {
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return "", fmt.Errorf("could not read first magic bytes of file: %s", err)
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}
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kind, err := filetype.Match(head)
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if err != nil {
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return "", err
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}
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if kind == filetype.Unknown {
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return "", errors.New("filetype unknown")
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}
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return kind.MIME.Value, nil
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}
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// supportedImageType checks mime type of an image against a slice of accepted types,
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// and returns True if the mime type is accepted.
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func supportedImageType(mimeType string) bool {
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acceptedImageTypes := []string{
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"image/jpeg",
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"image/gif",
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"image/png",
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}
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for _, accepted := range acceptedImageTypes {
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if mimeType == accepted {
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return true
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}
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}
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return false
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}
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// supportedVideoType checks mime type of a video against a slice of accepted types,
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// and returns True if the mime type is accepted.
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func supportedVideoType(mimeType string) bool {
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acceptedVideoTypes := []string{
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"video/mp4",
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"video/mpeg",
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"video/webm",
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}
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for _, accepted := range acceptedVideoTypes {
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if mimeType == accepted {
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return true
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}
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}
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return false
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}
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// supportedEmojiType checks that the content type is image/png -- the only type supported for emoji.
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func supportedEmojiType(mimeType string) bool {
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acceptedEmojiTypes := []string{
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"image/gif",
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"image/png",
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}
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for _, accepted := range acceptedEmojiTypes {
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if mimeType == accepted {
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return true
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}
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}
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return false
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}
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// purgeExif is a little wrapper for the action of removing exif data from an image.
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// Only pass pngs or jpegs to this function.
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func purgeExif(b []byte) ([]byte, error) {
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if len(b) == 0 {
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return nil, errors.New("passed image was not valid")
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}
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clean, err := exifremove.Remove(b)
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if err != nil {
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return nil, fmt.Errorf("could not purge exif from image: %s", err)
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}
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if len(clean) == 0 {
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return nil, errors.New("purged image was not valid")
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}
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return clean, nil
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}
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func deriveGif(b []byte, extension string) (*imageAndMeta, error) {
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var g *gif.GIF
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var err error
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switch extension {
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case "image/gif":
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g, err = gif.DecodeAll(bytes.NewReader(b))
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if err != nil {
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return nil, err
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}
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default:
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return nil, fmt.Errorf("extension %s not recognised", extension)
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}
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// use the first frame to get the static characteristics
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width := g.Config.Width
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height := g.Config.Height
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size := width * height
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aspect := float64(width) / float64(height)
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bh, err := blurhash.Encode(4, 3, g.Image[0])
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if err != nil || bh == "" {
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return nil, err
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}
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out := &bytes.Buffer{}
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if err := gif.EncodeAll(out, g); err != nil {
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return nil, err
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}
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return &imageAndMeta{
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image: out.Bytes(),
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width: width,
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height: height,
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size: size,
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aspect: aspect,
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blurhash: bh,
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}, nil
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}
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func deriveImage(b []byte, contentType string) (*imageAndMeta, error) {
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var i image.Image
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var err error
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switch contentType {
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case "image/jpeg":
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i, err = jpeg.Decode(bytes.NewReader(b))
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if err != nil {
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return nil, err
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}
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case "image/png":
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i, err = png.Decode(bytes.NewReader(b))
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if err != nil {
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return nil, err
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}
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default:
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return nil, fmt.Errorf("content type %s not recognised", contentType)
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}
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width := i.Bounds().Size().X
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height := i.Bounds().Size().Y
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size := width * height
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aspect := float64(width) / float64(height)
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bh, err := blurhash.Encode(4, 3, i)
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if err != nil {
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return nil, err
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}
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out := &bytes.Buffer{}
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if err := jpeg.Encode(out, i, nil); err != nil {
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return nil, err
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}
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return &imageAndMeta{
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image: out.Bytes(),
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width: width,
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height: height,
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size: size,
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aspect: aspect,
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blurhash: bh,
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}, nil
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}
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// deriveThumbnail returns a byte slice and metadata for a thumbnail of width x and height y,
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// of a given jpeg, png, or gif, or an error if something goes wrong.
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//
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// Note that the aspect ratio of the image will be retained,
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// so it will not necessarily be a square, even if x and y are set as the same value.
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func deriveThumbnail(b []byte, contentType string, x uint, y uint) (*imageAndMeta, error) {
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var i image.Image
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var err error
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switch contentType {
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case "image/jpeg":
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i, err = jpeg.Decode(bytes.NewReader(b))
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if err != nil {
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return nil, err
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}
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case "image/png":
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i, err = png.Decode(bytes.NewReader(b))
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if err != nil {
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return nil, err
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}
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case "image/gif":
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i, err = gif.Decode(bytes.NewReader(b))
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if err != nil {
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return nil, err
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}
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default:
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return nil, fmt.Errorf("content type %s not recognised", contentType)
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}
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thumb := resize.Thumbnail(x, y, i, resize.NearestNeighbor)
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width := thumb.Bounds().Size().X
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height := thumb.Bounds().Size().Y
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size := width * height
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aspect := float64(width) / float64(height)
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out := &bytes.Buffer{}
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if err := jpeg.Encode(out, thumb, nil); err != nil {
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return nil, err
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}
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return &imageAndMeta{
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image: out.Bytes(),
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width: width,
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height: height,
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size: size,
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aspect: aspect,
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}, nil
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}
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// deriveStaticEmojji takes a given gif or png of an emoji, decodes it, and re-encodes it as a static png.
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func deriveStaticEmoji(b []byte, contentType string) (*imageAndMeta, error) {
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var i image.Image
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var err error
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switch contentType {
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case "image/png":
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i, err = png.Decode(bytes.NewReader(b))
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if err != nil {
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return nil, err
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}
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case "image/gif":
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i, err = gif.Decode(bytes.NewReader(b))
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if err != nil {
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return nil, err
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}
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default:
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return nil, fmt.Errorf("content type %s not allowed for emoji", contentType)
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}
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out := &bytes.Buffer{}
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if err := png.Encode(out, i); err != nil {
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return nil, err
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}
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return &imageAndMeta{
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image: out.Bytes(),
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}, nil
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}
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type imageAndMeta struct {
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image []byte
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width int
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height int
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size int
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aspect float64
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blurhash string
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}
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