func main() {
flag.Usage = usage
flag.Parse()
r, err := read(flag.Arg(0))
if err != nil {
log.Fatalf("error reading input: %v", err)
}
tx := func(m image.Image) image.Image {
return resize.Resize(width, height, m, resize.NearestNeighbor)
}
err = gifresize.Process(os.Stdout, r, tx)
if err != nil {
log.Fatalf("error processing image: %v", err)
}
}
// Transform the provided image. img should contain the raw bytes of an
// encoded image in one of the supported formats (gif, jpeg, or png). The
// bytes of a similarly encoded image is returned.
func Transform(img []byte, opt Options) ([]byte, error) {
if opt == emptyOptions {
// bail if no transformation was requested
return img, nil
}
// decode image
m, format, err := image.Decode(bytes.NewReader(img))
if err != nil {
return nil, err
}
// transform and encode image
buf := new(bytes.Buffer)
switch format {
case "gif":
fn := func(img image.Image) image.Image {
return transformImage(img, opt)
}
err = gifresize.Process(buf, bytes.NewReader(img), fn)
if err != nil {
return nil, err
}
case "jpeg":
quality := opt.Quality
if quality == 0 {
quality = defaultQuality
}
m = transformImage(m, opt)
err = jpeg.Encode(buf, m, &jpeg.Options{Quality: quality})
if err != nil {
return nil, err
}
case "png":
m = transformImage(m, opt)
err = png.Encode(buf, m)
if err != nil {
return nil, err
}
}
return buf.Bytes(), nil
}