39c3b8ebf9
* Image logic refactor * Add missing translations * Improve prepareImage * Use iota * Limit image encoder concurrency * Unexport validation methods * Avoid shortening on exported names * Remove unnecessary complexity
67 строки
1.9 KiB
Go
67 строки
1.9 KiB
Go
// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
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// See LICENSE.txt for license information.
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package imaging
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import (
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"bytes"
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"fmt"
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"image"
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"image/jpeg"
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"github.com/disintegration/imaging"
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)
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// GeneratePreview generates the preview for the given image.
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func GeneratePreview(img image.Image, width int) image.Image {
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preview := img
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w := img.Bounds().Dx()
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if w > width {
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preview = imaging.Resize(img, width, 0, imaging.Lanczos)
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}
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return preview
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}
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// GenerateThumbnail generates the thumbnail for the given image.
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func GenerateThumbnail(img image.Image, width, height int) image.Image {
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thumb := img
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w := img.Bounds().Dx()
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h := img.Bounds().Dy()
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expectedRatio := float64(height) / float64(width)
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if h > height || w > width {
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ratio := float64(h) / float64(w)
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if ratio < expectedRatio {
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// we pre-calculate the thumbnail's width to make sure we are not upscaling.
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targetWidth := int(float64(height) * float64(w) / float64(h))
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if targetWidth <= w {
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thumb = imaging.Resize(img, 0, height, imaging.Lanczos)
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} else {
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thumb = imaging.Resize(img, width, 0, imaging.Lanczos)
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}
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} else {
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// we pre-calculate the thumbnail's height to make sure we are not upscaling.
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targetHeight := int(float64(width) * float64(h) / float64(w))
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if targetHeight <= h {
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thumb = imaging.Resize(img, width, 0, imaging.Lanczos)
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} else {
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thumb = imaging.Resize(img, 0, height, imaging.Lanczos)
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}
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}
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}
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return thumb
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}
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// GenerateMiniPreviewImage generates the mini preview for the given image.
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func GenerateMiniPreviewImage(img image.Image, w, h, q int) ([]byte, error) {
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var buf bytes.Buffer
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preview := imaging.Resize(img, w, h, imaging.Lanczos)
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if err := jpeg.Encode(&buf, preview, &jpeg.Options{Quality: q}); err != nil {
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return nil, fmt.Errorf("failed to encode image to JPEG format: %w", err)
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}
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return buf.Bytes(), nil
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}
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