5c0722429b
- attach.VariantKey: a thumbnail's copy in another format next to it - attach/webp (separate package, so only binaries that import it link the encoder): Encode at quality 80 and Variant, which writes the WebP copy of a thumbnail once and leaves no file on a failed encode - github.com/gen2brain/webp v0.6.4, decided in .planning/notes/2026-10-28-webp-gen2brain.md - lagoon README and docs/database/attachments.md
29 lines
1.0 KiB
Go
29 lines
1.0 KiB
Go
package attach
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import (
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"path"
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"strings"
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)
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// VariantKey is the blob key of a thumbnail's copy in another image format,
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// stored next to the thumbnail: thumbKey with its extension replaced by
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// format, so thumb_42_480_0_0_0_auto.jpg becomes
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// thumb_42_480_0_0_0_auto.webp. When the thumbnail already carries that
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// extension (a thumbnail of a .webp original holds JPEG bytes under the
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// original's name, see ThumbKey), format is appended instead
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// (thumb_42_480_0_0_0_auto.webp.webp), so the variant never overwrites the
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// thumbnail. format follows the token rule of ThumbFilename ([a-z0-9]+,
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// lower-cased first); an empty thumbKey or a format outside the rule
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// answers "".
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func VariantKey(thumbKey, format string) string {
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format = strings.ToLower(format)
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if thumbKey == "" || !thumbToken.MatchString(format) {
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return ""
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}
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ext := path.Ext(thumbKey)
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if strings.EqualFold(strings.TrimPrefix(ext, "."), format) {
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return thumbKey + "." + format
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}
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return strings.TrimSuffix(thumbKey, ext) + "." + format
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}
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