109 lines
3.7 KiB
Go
109 lines
3.7 KiB
Go
package app
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import (
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"bytes"
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"context"
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"errors"
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"image"
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"image/color"
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"image/draw"
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"image/jpeg"
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"io"
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"strings"
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"github.com/disintegration/imaging"
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_ "golang.org/x/image/webp"
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)
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const (
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avatarDisplaySize = 640
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avatarThumbnailSize = 256
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maxAvatarPixels = 24_000_000
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)
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// Bound peak decoding memory on small servers. Do not queue decoded photos in
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// memory when multiple clients upload avatars at the same time.
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var avatarProcessing = make(chan struct{}, 1)
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var errAvatarBusy = errors.New("头像正在处理中，请稍后重试")
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type avatarImages struct {
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Display, Thumbnail []byte
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Width, Height int
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}
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// avatarThumbnailURL only derives URLs for object families that are known to
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// publish an immutable 256px sibling. Older and third-party avatars remain
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// unchanged so list clients never receive a URL that cannot exist.
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func avatarThumbnailURL(source string) string {
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if source == "" || strings.ContainsAny(source, "?#") {
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return source
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}
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lower := strings.ToLower(source)
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if strings.HasSuffix(lower, "-thumb.jpg") {
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return source
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}
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if strings.HasSuffix(lower, "-av1.jpg") {
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return source[:len(source)-len(".jpg")] + "-thumb.jpg"
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}
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if strings.Contains(lower, "/test-users/") {
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for _, extension := range []string{".jpeg", ".jpg", ".png", ".webp"} {
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if strings.HasSuffix(lower, extension) {
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return source[:len(source)-len(extension)] + "-thumb.jpg"
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}
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}
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}
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return source
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}
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func createAvatarImages(ctx context.Context, source io.ReadSeeker) (avatarImages, error) {
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select {
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case avatarProcessing <- struct{}{}:
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defer func() { <-avatarProcessing }()
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default:
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return avatarImages{}, errAvatarBusy
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}
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if err := ctx.Err(); err != nil {
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return avatarImages{}, err
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}
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config, format, err := image.DecodeConfig(source)
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if err != nil || (format != "jpeg" && format != "png" && format != "gif" && format != "webp") {
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return avatarImages{}, errors.New("无法读取头像，请选择有效的 JPG、PNG、GIF 或 WebP 图片")
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}
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if config.Width <= 0 || config.Height <= 0 || config.Width > 16384 || config.Height > 16384 || int64(config.Width)*int64(config.Height) > maxAvatarPixels {
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return avatarImages{}, errors.New("头像分辨率过大，请选择不超过 2400 万像素的图片")
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}
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if _, err = source.Seek(0, io.SeekStart); err != nil {
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return avatarImages{}, err
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}
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// Orient phone photos before resizing. Re-encoding also removes EXIF/GPS
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// from the display variants. Animated images use their first decoded frame.
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src, err := imaging.Decode(source, imaging.AutoOrientation(true))
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if err != nil {
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return avatarImages{}, errors.New("头像文件损坏或格式暂不支持，请重新选择图片")
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}
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if err = ctx.Err(); err != nil {
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return avatarImages{}, err
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}
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display := imaging.Fit(src, avatarDisplaySize, avatarDisplaySize, imaging.Lanczos)
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thumbnail := imaging.Fit(display, avatarThumbnailSize, avatarThumbnailSize, imaging.Lanczos)
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result := avatarImages{Width: display.Bounds().Dx(), Height: display.Bounds().Dy()}
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if result.Display, err = avatarJPEG(display, 82); err != nil {
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return avatarImages{}, err
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}
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if result.Thumbnail, err = avatarJPEG(thumbnail, 78); err != nil {
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return avatarImages{}, err
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}
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_, err = source.Seek(0, io.SeekStart)
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return result, err
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}
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func avatarJPEG(src image.Image, quality int) ([]byte, error) {
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// Composite transparency onto white instead of producing black PNG edges.
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opaque := image.NewRGBA(src.Bounds())
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draw.Draw(opaque, opaque.Bounds(), image.NewUniform(color.White), image.Point{}, draw.Src)
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draw.Draw(opaque, opaque.Bounds(), src, src.Bounds().Min, draw.Over)
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var buffer bytes.Buffer
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err := jpeg.Encode(&buffer, opaque, &jpeg.Options{Quality: quality})
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return buffer.Bytes(), err
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}
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