// Writes an image to a file. The extension of the file is used to determine the
// encoding method.
func CreateImage(i image.Image, file string) error {
ext := filepath.Ext(file)
m := mime.TypeByExtension(ext)
switch m {
case "image/jpeg", "image/png", "image/tiff":
default:
return errors.Newf("unsupported extension/mime type: %s %s", ext, m)
}
f, err := os.Create(file)
if err != nil {
return errors.Wrap(err, "could not create file")
}
defer f.Close()
switch m {
case "image/jpeg":
err = jpeg.Encode(f, i, &jpeg.Options{Quality: 98})
case "image/png":
err = png.Encode(f, i)
case "image/tiff":
err = tiff.Encode(f, i, &tiff.Options{Compression: tiff.Deflate, Predictor: true})
default:
panic("unreachable")
}
if err != nil {
return errors.Wrap(err, "could not encode image")
}
return nil
}
func (handler *ImageUtilsHandler) Save(img image.Image, format string) ([]byte, error) {
// Based on github.com/disintegration/imaging/helpers.go Save()
var err error
writer := new(bytes.Buffer)
switch format {
case ".jpg", ".jpeg":
var rgba *image.RGBA
if nrgba, ok := img.(*image.NRGBA); ok {
if nrgba.Opaque() {
rgba = &image.RGBA{
Pix: nrgba.Pix,
Stride: nrgba.Stride,
Rect: nrgba.Rect,
}
}
}
if rgba != nil {
err = jpeg.Encode(writer, rgba, &jpeg.Options{Quality: 95})
} else {
err = jpeg.Encode(writer, img, &jpeg.Options{Quality: 95})
}
case ".png":
err = png.Encode(writer, img)
case ".tif", ".tiff":
err = tiff.Encode(writer, img, &tiff.Options{Compression: tiff.Deflate, Predictor: true})
case ".bmp":
err = bmp.Encode(writer, img)
default:
return nil, errors.New("Invalid image format")
}
return writer.Bytes(), err
}
// WriteTo implements the io.WriterTo interface, writing a tiff image.
func (c TiffCanvas) WriteTo(w io.Writer) (int64, error) {
wc := writerCounter{Writer: w}
b := bufio.NewWriter(&wc)
if err := tiff.Encode(b, c.img, nil); err != nil {
return wc.n, err
}
err := b.Flush()
return wc.n, err
}
func WriteImage(img image.Image, path string) error {
out, err := os.Create(path)
if err != nil {
return err
}
defer out.Close()
tiff.Encode(out, img, &tiff.Options{tiff.Deflate, true})
return nil
}
// Save saves the image to file with the specified filename.
// The format is determined from the filename extension: "jpg" (or "jpeg"), "png", "tif" (or "tiff") and "bmp" are supported.
func Save(img image.Image, filename string) (err error) {
format := strings.ToLower(filepath.Ext(filename))
okay := false
for _, ext := range []string{".jpg", ".jpeg", ".png", ".tif", ".tiff", ".bmp"} {
if format == ext {
okay = true
break
}
}
if !okay {
return fmt.Errorf(`imaging: unsupported image format: "%s"`, format)
}
file, err := os.Create(filename)
if err != nil {
return
}
defer file.Close()
switch format {
case ".jpg", ".jpeg":
var rgba *image.RGBA
if nrgba, ok := img.(*image.NRGBA); ok {
if nrgba.Opaque() {
rgba = &image.RGBA{
Pix: nrgba.Pix,
Stride: nrgba.Stride,
Rect: nrgba.Rect,
}
}
}
if rgba != nil {
err = jpeg.Encode(file, rgba, &jpeg.Options{Quality: 95})
} else {
err = jpeg.Encode(file, img, &jpeg.Options{Quality: 95})
}
case ".png":
err = png.Encode(file, img)
case ".tif", ".tiff":
err = tiff.Encode(file, img, &tiff.Options{Compression: tiff.Deflate, Predictor: true})
case ".bmp":
err = bmp.Encode(file, img)
}
return
}
// Save saves the image to file with the specified filename.
// The format is determined from the filename extension: "jpg" (or "jpeg"), "png", "tif" (or "tiff"), "bmp", and "gif" are supported.
func Save(img image.Image, filename string) (err error) {
format := strings.ToLower(filepath.Ext(filename))
m, err := regexp.MatchString(`^\.(jpg|jpeg|png|tif|tiff|bmp|gif)$`, format)
if err != nil || !m {
err = fmt.Errorf(`imaging: unsupported image format: "%s"`, format)
return
}
file, err := os.Create(filename)
if err != nil {
return
}
defer file.Close()
switch format {
case ".jpg", ".jpeg":
var rgba *image.RGBA
if nrgba, ok := img.(*image.NRGBA); ok {
if nrgba.Opaque() {
rgba = &image.RGBA{
Pix: nrgba.Pix,
Stride: nrgba.Stride,
Rect: nrgba.Rect,
}
}
}
if rgba != nil {
err = jpeg.Encode(file, rgba, &jpeg.Options{Quality: 95})
} else {
err = jpeg.Encode(file, img, &jpeg.Options{Quality: 95})
}
case ".png":
err = png.Encode(file, img)
case ".tif", ".tiff":
err = tiff.Encode(file, img, &tiff.Options{Compression: tiff.Deflate, Predictor: true})
case ".bmp":
err = bmp.Encode(file, img)
case ".gif":
err = gif.Encode(file, img, &gif.Options{NumColors: 256}))
default:
err = fmt.Errorf(`imaging: unsupported image format: "%s"`, format)
}
return
}