| 1 | package main |
| 2 | |
| 3 | import ( |
| 4 | "bytes" |
| 5 | "fmt" |
| 6 | "image" |
| 7 | "image/jpeg" |
| 8 | _ "image/png" |
| 9 | "path/filepath" |
| 10 | "strings" |
| 11 | |
| 12 | "golang.org/x/image/draw" |
| 13 | ) |
| 14 | |
| 15 | func compressImage(data []byte, quality int, width int) ([]byte, error) { |
| 16 | exif := stripGPS(extractExif(data)) |
| 17 | img, _, err := image.Decode(bytes.NewReader(data)) |
| 18 | if err != nil { |
| 19 | return nil, fmt.Errorf("Failed to decode image: %w", err) |
| 20 | } |
| 21 | if width > 0 && width != img.Bounds().Dx() { |
| 22 | src := img |
| 23 | bounds := src.Bounds() |
| 24 | aspect := float64(bounds.Dy()) / float64(bounds.Dx()) |
| 25 | height := int(float64(width)*aspect + 0.5) |
| 26 | dst := image.NewRGBA(image.Rect(0, 0, width, height)) |
| 27 | draw.CatmullRom.Scale(dst, dst.Bounds(), src, bounds, draw.Over, nil) |
| 28 | img = dst |
| 29 | } |
| 30 | if quality < 1 { |
| 31 | quality = 1 |
| 32 | } |
| 33 | if quality > 100 { |
| 34 | quality = 100 |
| 35 | } |
| 36 | var out bytes.Buffer |
| 37 | if err := jpeg.Encode(&out, img, &jpeg.Options{Quality: quality}); err != nil { |
| 38 | return nil, fmt.Errorf("JPEG encoding failed: %w", err) |
| 39 | } |
| 40 | return injectExif(out.Bytes(), exif), nil |
| 41 | } |
| 42 | |
| 43 | func buildDownloadFilename(original, newExt string) string { |
| 44 | stem := strings.TrimSuffix(filepath.Base(original), filepath.Ext(filepath.Base(original))) |
| 45 | if stem == "" { |
| 46 | stem = "compressed" |
| 47 | } |
| 48 | return stem + "_compressed." + newExt |
| 49 | } |