README
¶
image/gif
A modified image/gif package from the go standard library (originally by Andy). The change is to allow streaming gif to a file or to any io.writer.
Example usage
e := gif.NewStreamEncoder(someFile, &StreamEncoderOptions{ })
for recording {
image := takeScreenShot()
delay := 1
if err := e.Encode(image, delay, gif.DisposalNone); err != nil {
handleError(err)
}
}
if err := e.Close(); err != nil {
handleError(err)
}
Documentation
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Overview ¶
Package gif implements a GIF image decoder and encoder.
The GIF specification is at https://www.w3.org/Graphics/GIF/spec-gif89a.txt.
Index ¶
Constants ¶
const ( DisposalNone = 0x01 DisposalBackground = 0x02 DisposalPrevious = 0x03 )
Disposal Methods.
Variables ¶
This section is empty.
Functions ¶
func Decode ¶
Decode reads a GIF image from r and returns the first embedded image as an image.Image.
func DecodeConfig ¶
DecodeConfig returns the global color model and dimensions of a GIF image without decoding the entire image.
Types ¶
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 controls the number of times an animation will be
// restarted during display.
// A LoopCount of 0 means to loop forever.
// A LoopCount of -1 means to show each frame only once.
// Otherwise, the animation is looped LoopCount+1 times.
LoopCount int
// 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.
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.
type StreamEncoder ¶
type StreamEncoder struct {
// contains filtered or unexported fields
}
StreamEncoder allows encoding and writing images to w one at a time without accumulating an array of images. Use this to reduce memory consumption.
func NewStreamEncoder ¶
func NewStreamEncoder(w io.Writer, options *StreamEncoderOptions) *StreamEncoder
Creates a streamer.
func (*StreamEncoder) Close ¶
func (e *StreamEncoder) Close() error
Closes the streamer, which finalizes the write to w. Returns an error if streamer.Encode() is not called at least once, or if config is invalid. Note: not concurrent-safe
type StreamEncoderOptions ¶
type StreamEncoderOptions struct {
// LoopCount controls the number of times an animation will be
// restarted during display.
// A LoopCount of 0 means to loop forever.
// A LoopCount of -1 means to show each frame only once.
// Otherwise, the animation is looped LoopCount+1 times.
LoopCount int
// 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
}
Source Files