Package fastjpeg uses djpeg(1), from the Independent JPEG Group's ( jpeg package, to quickly down-sample images on load. It can sample images by a factor of 1, 2, 4 or 8. This reduces the amount of data that must be decompressed into memory when the full resolution image isn't required, i.e. in the case of generating thumbnails.



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    var (
    	ErrDjpegNotFound = errors.New("fastjpeg: djpeg not found in path")


    func Available

    func Available() bool

    func DecodeDownsample

    func DecodeDownsample(r io.Reader, factor int) (image.Image, error)

      DecodeDownsample decodes JPEG data in r, down-sampling it by factor. If djpeg is not found, err is ErrDjpegNotFound and r is not read from. If the execution of djpeg, or decoding the resulting PNM fails, error will be of type DjpegFailedError.

      func Factor

      func Factor(w, h, sw, sh int) int

        Factor returns the sample factor DecodeSample should use to generate a sampled image greater than or equal to sw x sh pixels given a source image of w x h pixels.


        type DjpegFailedError

        type DjpegFailedError struct {
        	Err error

          DjpegFailedError wraps errors returned when calling djpeg and handling its response. Used for type asserting and retrying with other jpeg decoders, i.e. the standard library's jpeg.Decode.

          func (DjpegFailedError) Error

          func (dfe DjpegFailedError) Error() string

          Source Files