// decodeConfigPPM reads and parses a PPM header, either "raw" (binary) or
// "plain" (ASCII).
func decodeConfigPPM(r io.Reader) (image.Config, error) {
// We really want a bufio.Reader. If we were given one, use it. If
// not, create a new one.
br, ok := r.(*bufio.Reader)
if !ok {
br = bufio.NewReader(r)
}
nr := newNetpbmReader(br)
// Parse the PPM header.
header, ok := nr.GetNetpbmHeader()
if !ok {
err := nr.Err()
if err == nil {
err = errors.New("Invalid PPM header")
}
return image.Config{}, err
}
// Store and return the image configuration.
var cfg image.Config
cfg.Width = header.Width
cfg.Height = header.Height
if header.Maxval < 256 {
cfg.ColorModel = npcolor.RGBMModel{M: uint8(header.Maxval)}
} else {
cfg.ColorModel = npcolor.RGBM64Model{M: uint16(header.Maxval)}
}
return cfg, nil
}
// decodeConfigPBM reads and parses a PBM header, either "raw" (binary) or
// "plain" (ASCII).
func decodeConfigPBM(r io.Reader) (image.Config, error) {
// We really want a bufio.Reader. If we were given one, use it. If
// not, create a new one.
br, ok := r.(*bufio.Reader)
if !ok {
br = bufio.NewReader(r)
}
nr := newNetpbmReader(br)
// Parse the PBM header.
header, ok := nr.GetNetpbmHeader()
if !ok {
err := nr.Err()
if err == nil {
err = errors.New("Invalid PBM header")
}
return image.Config{}, err
}
// Store the image configuration.
var cfg image.Config
cfg.Width = header.Width
cfg.Height = header.Height
// A PBM file's color map is 0=white, 1=black.
colorMap := make(color.Palette, 2)
colorMap[0] = color.RGBA{255, 255, 255, 255}
colorMap[1] = color.RGBA{0, 0, 0, 255}
cfg.ColorModel = colorMap
return cfg, nil
}
// DecodeConfig returns dimensions of imagefile image.
func DecodeConfig(r io.Reader) (image.Config, error) {
var cfg image.Config
buff := make([]uint8, 17)
_, err := io.ReadFull(r, buff)
cfg.ColorModel = color.NRGBAModel
be := binary.BigEndian
cfg.Width = int(be.Uint32(buff[9:13]))
cfg.Height = int(be.Uint32(buff[13:17]))
return cfg, err
}