/
smart.go
114 lines (101 loc) · 2.84 KB
/
smart.go
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package thumb
import (
"encoding/base64"
"image"
"image/jpeg"
"os"
"github.com/disintegration/imaging"
"github.com/muesli/smartcrop"
"github.com/muesli/smartcrop/nfnt"
)
type SubImager interface {
SubImage(r image.Rectangle) image.Image
}
// SmartCrop64 convert the image to base64 and add prefix "data:image/jpeg;base64,"
func SmartCrop64(imgPath, dstPath string) error {
img, err := OpenImage(imgPath)
if err != nil {
return err
}
if img, err = smartCropResize(img); err != nil {
return err
}
return jpegEncodeBase64ToFile(dstPath, img, 0)
}
func SmartCropBytes64(imgBytes []byte, dstPath string) error {
img, err := ReadImage(imgBytes)
if err != nil {
return err
}
if img, err = smartCropResize(img); err != nil {
return err
}
return jpegEncodeBase64ToFile(dstPath, img, 0)
}
func OpenImage(imgPath string) (image.Image, error) {
f, err := os.Open(imgPath)
if err != nil {
return nil, err
}
defer f.Close()
return imaging.Decode(f, imaging.AutoOrientation(true))
}
func resizeSquare(img image.Image, cropped image.Rectangle, side uint) image.Image {
img = img.(SubImager).SubImage(cropped)
resizer := nfnt.NewDefaultResizer()
return resizer.Resize(img, side, side)
}
func smartCropResize(img image.Image) (image.Image, error) {
analyzer := smartcrop.NewAnalyzer(nfnt.NewDefaultResizer())
side := shortSide(img.Bounds())
cropped, err := analyzer.FindBestCrop(img, side, side)
if err != nil {
return nil, err
}
img = resizeSquare(img, cropped, defaultThumbSize)
return img, nil
}
// ResizeToFile resizes the image if it's long side bigger than limit.
// Use default limit 900 if limit is set to zero.
// Use default quality 85 if quality is set to zero.
func ResizeToFile(dst string, src []byte, limit float64, quality int) error {
img, err := ReadImage(src)
if err != nil {
return err
}
w, h := limitWidthHeight(img.Bounds(), limit)
small := imaging.Resize(img, w, h, imaging.Lanczos)
return jpegEncodeToFile(dst, small, quality)
}
// Use default quality(85) if quality is set to zero.
// dst is the output file path.
func jpegEncodeToFile(dst string, src image.Image, quality int) error {
if quality == 0 {
quality = defaultQuality
}
file, err := os.Create(dst)
if err != nil {
return err
}
defer file.Close()
return jpeg.Encode(file, src, &jpeg.Options{Quality: quality})
}
// Use default quality(85) if quality is set to zero.
// dst is the output file path.
func jpegEncodeBase64ToFile(dst string, src image.Image, quality int) error {
if quality == 0 {
quality = defaultQuality
}
file, err := os.Create(dst)
if err != nil {
return err
}
defer file.Close()
prefix := []byte("data:image/jpeg;base64,")
if _, err = file.Write(prefix); err != nil {
return err
}
encoder64 := base64.NewEncoder(base64.StdEncoding, file)
defer encoder64.Close()
return jpeg.Encode(encoder64, src, &jpeg.Options{Quality: quality})
}