Run Format

Package gif

import "image/gif"

Overview ▾

Package gif implements a GIF image decoder and encoder.

The GIF specification is at http://www.w3.org/Graphics/GIF/spec-gif89a.txt.


const (
        DisposalNone       = 0x01
        DisposalBackground = 0x02
        DisposalPrevious   = 0x03

Disposal Methods.

func Decode

func Decode(r io.Reader) (image.Image, error)

Decode reads a GIF image from r and returns the first embedded image as an image.Image.

func DecodeConfig

func DecodeConfig(r io.Reader) (image.Config, error)

DecodeConfig returns the global color model and dimensions of a GIF image without decoding the entire image.

func Encode

func Encode(w io.Writer, m image.Image, o *Options) error

Encode writes the Image m to w in GIF format.

func EncodeAll

func EncodeAll(w io.Writer, g *GIF) error

EncodeAll writes the images in g to w in GIF format with the given loop count and delay between frames.

type GIF

type GIF struct {
        Image     []*image.Paletted // The successive images.
        Delay     []int             // The successive delay times, one per frame, in 100ths of a second.
        LoopCount int               // The loop count.
        // Disposal is the successive disposal methods, one per frame. For
        // backwards compatibility, a nil Disposal is valid to pass to EncodeAll,
        // and implies that each frame's disposal method is 0 (no disposal
        // specified).
        Disposal []byte
        // Config is the global color table (palette), width and height. A nil or
        // empty-color.Palette Config.ColorModel means that each frame has its own
        // color table and there is no global color table. Each frame's bounds must
        // be within the rectangle defined by the two points (0, 0) and
        // (Config.Width, Config.Height).
        // For backwards compatibility, a zero-valued Config is valid to pass to
        // EncodeAll, and implies that the overall GIF's width and height equals
        // the first frame's bounds' Rectangle.Max point.
        Config image.Config
        // BackgroundIndex is the background index in the global color table, for
        // use with the DisposalBackground disposal method.
        BackgroundIndex byte

GIF represents the possibly multiple images stored in a GIF file.

func DecodeAll

func DecodeAll(r io.Reader) (*GIF, error)

DecodeAll reads a GIF image from r and returns the sequential frames and timing information.

type Options

type Options struct {
        // NumColors is the maximum number of colors used in the image.
        // It ranges from 1 to 256.
        NumColors int

        // Quantizer is used to produce a palette with size NumColors.
        // palette.Plan9 is used in place of a nil Quantizer.
        Quantizer draw.Quantizer

        // Drawer is used to convert the source image to the desired palette.
        // draw.FloydSteinberg is used in place of a nil Drawer.
        Drawer draw.Drawer

Options are the encoding parameters.