Exemple #1
0
// DecodeConfig returns the color model and dimensions of a JPEG image without decoding the entire image.
func DecodeConfig(r io.Reader) (config image.Config, err error) {
	// Recover panic
	defer func() {
		if r := recover(); r != nil {
			var ok bool
			err, ok = r.(error)
			if !ok {
				err = fmt.Errorf("JPEG error: %v", r)
			}
		}
	}()

	dinfo := C.new_decompress()
	defer C.destroy_decompress(dinfo)

	srcManager := makeSourceManager(r, dinfo)
	defer releaseSourceManager(srcManager)

	C.jpeg_read_header(dinfo, C.TRUE)

	config = image.Config{
		ColorModel: color.YCbCrModel,
		Width:      int(dinfo.image_width),
		Height:     int(dinfo.image_height),
	}
	return
}
Exemple #2
0
// DecodeIntoRGB reads a JPEG data stream from r and returns decoded image as an rgb.Image with RGB colors.
func DecodeIntoRGB(r io.Reader, options *DecoderOptions) (dest *rgb.Image, err error) {
	// Recover panic
	defer func() {
		if r := recover(); r != nil {
			log.Println(r)
			if _, ok := r.(error); !ok {
				err = fmt.Errorf("JPEG error: %v", r)
			}
		}
	}()

	dinfo := C.new_decompress()
	defer C.destroy_decompress(dinfo)

	srcManager := makeSourceManager(r, dinfo)
	defer releaseSourceManager(srcManager)

	C.jpeg_read_header(dinfo, C.TRUE)
	setupDecoderOptions(dinfo, options)

	C.jpeg_calc_output_dimensions(dinfo)
	dest = rgb.NewImage(image.Rect(0, 0, int(dinfo.output_width), int(dinfo.output_height)))

	dinfo.out_color_space = C.JCS_RGB
	readScanLines(dinfo, dest.Pix, dest.Stride)
	return
}
Exemple #3
0
// DecodeIntoRGBA reads a JPEG data stream from r and returns decoded image as an image.RGBA with RGBA colors.
// This function only works with libjpeg-trubo, not libjpeg.
func DecodeIntoRGBA(r io.Reader, options *DecoderOptions) (dest *image.RGBA, err error) {
	// Recover panic
	defer func() {
		if r := recover(); r != nil {
			log.Println(r)
			if _, ok := r.(error); !ok {
				err = fmt.Errorf("JPEG error: %v", r)
			}
		}
	}()

	dinfo := C.new_decompress()
	defer C.destroy_decompress(dinfo)

	srcManager := makeSourceManager(r, dinfo)
	defer releaseSourceManager(srcManager)

	C.jpeg_read_header(dinfo, C.TRUE)
	setupDecoderOptions(dinfo, options)

	C.jpeg_calc_output_dimensions(dinfo)
	dest = image.NewRGBA(image.Rect(0, 0, int(dinfo.output_width), int(dinfo.output_height)))

	colorSpace := C.getJCS_EXT_RGBA()
	if colorSpace == C.JCS_UNKNOWN {
		return nil, errors.New("JCS_EXT_RGBA is not supported (probably built without libjpeg-trubo)")
	}

	dinfo.out_color_space = colorSpace
	readScanLines(dinfo, dest.Pix, dest.Stride)
	return
}
Exemple #4
0
// Decode reads a JPEG data stream from r and returns decoded image as an image.Image.
// Output image has YCbCr colors or 8bit Grayscale.
func Decode(r io.Reader, options *DecoderOptions) (dest image.Image, err error) {
	// Recover panic
	defer func() {
		if r := recover(); r != nil {
			log.Println(r)
			if _, ok := r.(error); !ok {
				err = fmt.Errorf("JPEG error: %v", r)
			}
		}
	}()

	dinfo := C.new_decompress()
	defer C.destroy_decompress(dinfo)

	srcManager := makeSourceManager(r, dinfo)
	defer releaseSourceManager(srcManager)

	C.jpeg_read_header(dinfo, C.TRUE)
	setupDecoderOptions(dinfo, options)

	switch dinfo.num_components {
	case 1:
		if dinfo.jpeg_color_space != C.JCS_GRAYSCALE {
			return nil, errors.New("Image has unsupported colorspace")
		}
		dest, err = decodeGray(dinfo)
	case 3:
		switch dinfo.jpeg_color_space {
		case C.JCS_YCbCr:
			dest, err = decodeYCbCr(dinfo)
		case C.JCS_RGB:
			dest, err = decodeRGB(dinfo)
		default:
			return nil, errors.New("Image has unsupported colorspace")
		}
	}
	return
}