Created
January 16, 2023 21:14
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| package main | |
| import ( | |
| "bufio" | |
| "fmt" | |
| "image" | |
| "image/draw" | |
| "image/gif" | |
| "image/png" | |
| "io" | |
| "os" | |
| "path/filepath" | |
| ) | |
| func main() { | |
| const GIF = `some.gif` | |
| fd, err := os.Open(GIF) | |
| if err != nil { | |
| panic(err) | |
| } | |
| defer fd.Close() | |
| frames, err := GetAnimatedGifFrames(bufio.NewReader(fd)) | |
| if err != nil { | |
| panic(err) | |
| } | |
| i := 0 | |
| for frame := range frames { | |
| fp := filepath.Join("img", fmt.Sprintf("%03d.png", i)) | |
| { | |
| fd, err := os.OpenFile(fp, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0750) | |
| if err != nil { | |
| panic(err) | |
| } | |
| bout := bufio.NewWriter(fd) | |
| png.Encode(bout, frame) | |
| bout.Flush() | |
| fd.Close() | |
| } | |
| i++ | |
| } | |
| } | |
| func GetAnimatedGifFrames(in io.Reader) (<-chan *image.RGBA, error) { | |
| g, err := gif.DecodeAll(in) | |
| if err != nil { | |
| return nil, err | |
| } | |
| imgchan := make(chan *image.RGBA) | |
| go func() { | |
| rect := g.Image[0].Rect | |
| dst := image.NewRGBA(rect) | |
| noDisposeIndex := -1 | |
| draw.Draw(dst, rect, g.Image[0], image.ZP, draw.Src) | |
| imgchan <- dst | |
| for index := 1; index < len(g.Image); index++ { | |
| switch g.Disposal[index-1] { | |
| case gif.DisposalNone: | |
| draw.Draw(dst, rect, g.Image[index], image.ZP, draw.Over) | |
| noDisposeIndex = index - 1 | |
| case gif.DisposalBackground: | |
| draw.Draw(dst, rect, g.Image[index], image.ZP, draw.Src) | |
| case gif.DisposalPrevious: | |
| if noDisposeIndex >= 0 { | |
| draw.Draw(dst, rect, g.Image[noDisposeIndex], image.ZP, draw.Src) | |
| draw.Draw(dst, rect, g.Image[index], image.ZP, draw.Over) | |
| } else { | |
| draw.Draw(dst, rect, g.Image[index], image.ZP, draw.Src) | |
| } | |
| default: | |
| draw.Draw(dst, rect, g.Image[index], image.ZP, draw.Over) | |
| } | |
| imgchan <- dst | |
| } | |
| close(imgchan) | |
| }() | |
| return imgchan, nil | |
| } |
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