77 lines
2.2 KiB
Go
77 lines
2.2 KiB
Go
/*
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Package thumb provides JPEG resampling and thumbnail generation.
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Copyright (c) 2018 - 2022 PhotoPrism UG. All rights reserved.
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This program is free software: you can redistribute it and/or modify
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it under Version 3 of the GNU Affero General Public License (the "AGPL"):
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<https://docs.photoprism.app/license/agpl>
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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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The AGPL is supplemented by our Trademark and Brand Guidelines,
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which describe how our Brand Assets may be used:
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<https://photoprism.app/trademark>
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Feel free to send an email to hello@photoprism.app if you have questions,
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want to support our work, or just want to say hello.
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Additional information can be found in our Developer Guide:
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<https://docs.photoprism.app/developer-guide/>
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*/
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package thumb
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import (
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"fmt"
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"math"
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_ "image/gif"
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_ "image/jpeg"
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_ "image/png"
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_ "golang.org/x/image/bmp"
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_ "golang.org/x/image/tiff"
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_ "golang.org/x/image/webp"
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"github.com/photoprism/photoprism/internal/event"
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)
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var log = event.Log
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// Url returns a thumbnail url based on hash, thumb name, cdn uri, and preview token.
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func Url(h, name, contentUri, previewToken string) string {
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return fmt.Sprintf("%s/t/%s/%s/%s", contentUri, h, previewToken, name)
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}
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// Thumb represents a photo thumbnail.
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type Thumb struct {
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W int `json:"w"`
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H int `json:"h"`
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Src string `json:"src"`
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}
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// New creates a new photo thumbnail.
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func New(w, h int, hash string, s Size, contentUri, previewToken string) Thumb {
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if s.Width >= w && s.Height >= h {
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// Smaller
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return Thumb{W: w, H: h, Src: Url(hash, s.Name.String(), contentUri, previewToken)}
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}
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srcAspectRatio := float64(w) / float64(h)
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maxAspectRatio := float64(s.Width) / float64(s.Height)
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var newW, newH int
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if srcAspectRatio > maxAspectRatio {
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newW = s.Width
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newH = int(math.Round(float64(newW) / srcAspectRatio))
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} else {
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newH = s.Height
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newW = int(math.Round(float64(newH) * srcAspectRatio))
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}
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return Thumb{W: newW, H: newH, Src: Url(hash, s.Name.String(), contentUri, previewToken)}
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}
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