go/src/image/format.go

var ErrFormat …

type format …

var formatsMu …

var atomicFormats …

// RegisterFormat registers an image format for use by [Decode].
// Name is the name of the format, like "jpeg" or "png".
// Magic is the magic prefix that identifies the format's encoding. The magic
// string can contain "?" wildcards that each match any one byte.
// [Decode] is the function that decodes the encoded image.
// [DecodeConfig] is the function that decodes just its configuration.
func RegisterFormat(name, magic string, decode func(io.Reader) (Image, error), decodeConfig func(io.Reader) (Config, error)) { … }

type reader …

// asReader converts an io.Reader to a reader.
func asReader(r io.Reader) reader { … }

// match reports whether magic matches b. Magic may contain "?" wildcards.
func match(magic string, b []byte) bool { … }

// sniff determines the format of r's data.
func sniff(r reader) format { … }

// Decode decodes an image that has been encoded in a registered format.
// The string returned is the format name used during format registration.
// Format registration is typically done by an init function in the codec-
// specific package.
func Decode(r io.Reader) (Image, string, error) { … }

// DecodeConfig decodes the color model and dimensions of an image that has
// been encoded in a registered format. The string returned is the format name
// used during format registration. Format registration is typically done by
// an init function in the codec-specific package.
func DecodeConfig(r io.Reader) (Config, string, error) { … }