encode and decode gifs

decode.go

@@ -0,0 +1,90 @@
+package gifenc
+
+import (
+	"fmt"
+	"image"
+	"image/draw"
+	"image/gif"
+	"image/png"
+	"io"
+	"os"
+)
+
+func (config Config) Decode(path string) error {
+	// Open the GIF
+	file, err := os.Open(path)
+	if err != nil {
+		return fmt.Errorf("error while opening file: %s", err)
+	}
+
+	split(file, config.Width, config.Height, config.Output)
+
+	return nil
+}
+
+// Split the GIF into images
+func split(file io.Reader, width int, height int, output Output) (err error) {
+	defer func() {
+		if recv := recover(); recv != nil {
+			err = fmt.Errorf("error while decoding file: %s", recv)
+		}
+	}()
+
+	gif, err := gif.DecodeAll(file)
+	if err != nil {
+		return fmt.Errorf("error while decoding file: %s", err)
+	}
+
+	x, y := getArea(gif)
+	if width == 0 {
+		width = x
+	}
+	if height == 0 {
+		height = y
+	}
+
+	dst := image.NewRGBA(image.Rect(0, 0, width, height))
+	draw.Draw(dst, dst.Bounds(), gif.Image[0], image.Point{}, draw.Src)
+
+	for i, img := range gif.Image {
+		draw.Draw(dst, dst.Bounds(), img, image.Point{}, draw.Over)
+
+		file, err := os.Create(fmt.Sprintf("%s%s%d%s", output.Path, output.Name, i, ".png"))
+		if err != nil {
+			return fmt.Errorf("error while creating image: %s", err)
+		}
+
+		err = png.Encode(file, dst)
+		if err != nil {
+			return fmt.Errorf("error while creating image: %s", err)
+		}
+
+		file.Close()
+	}
+
+	return nil
+}
+
+func getArea(gif *gif.GIF) (x, y int) {
+	var xLow int
+	var xHigh int
+	var yLow int
+	var yHigh int
+
+	for _, img := range gif.Image {
+		if img.Rect.Min.X < xLow {
+			xLow = img.Rect.Min.X
+		}
+		if img.Rect.Min.Y < yLow {
+			yLow = img.Rect.Min.Y
+		}
+		if img.Rect.Max.X > xHigh {
+			xHigh = img.Rect.Max.X
+		}
+		if img.Rect.Max.Y > yHigh {
+			yHigh = img.Rect.Max.Y
+		}
+	}
+
+	return xHigh - xLow, yHigh - yLow
+}

encode.go

@@ -0,0 +1,62 @@
+package gifenc
+
+import (
+	"fmt"
+	"image"
+	"image/color/palette"
+	"image/draw"
+	"image/gif"
+	"image/png"
+	"os"
+)
+
+func (config Config) Encode(path string) error {
+	files, err := os.ReadDir(path)
+	if err != nil {
+		return fmt.Errorf("error while opening dir: %s", err)
+	}
+
+	var allFiles []string
+	for _, file := range files {
+		fmt.Print(file.Name())
+		allFiles = append(allFiles, file.Name())
+	}
+
+	animated := gif.GIF{
+		LoopCount: len(allFiles),
+	}
+
+	for _, file := range allFiles {
+		reader, err := os.Open(path + file)
+		if err != nil {
+			return fmt.Errorf("error while opening file: %s", err)
+		}
+		defer reader.Close()
+
+		img, err := png.Decode(reader)
+		if err != nil {
+			return fmt.Errorf("error while decoding image: %s", err)
+		}
+		bounds := img.Bounds()
+		drawer := draw.FloydSteinberg
+
+		paletted := image.NewPaletted(bounds, palette.Plan9)
+
+		drawer.Draw(paletted, img.Bounds(), img, image.Point{})
+		animated.Image = append(animated.Image, paletted)
+		animated.Delay = append(animated.Delay, config.Delay)
+	}
+
+	file, err := os.Create(config.Output.Name)
+	if err != nil {
+		return fmt.Errorf("error while creating file: %s", err)
+	}
+	defer file.Close()
+
+	encodeErr := gif.EncodeAll(file, &animated)
+	if encodeErr != nil {
+		return fmt.Errorf("error while creating file: %s", err)
+	}
+
+	return nil
+}

go.mod

@@ -0,0 +1,3 @@
+module github.com/Nota30/gifenc
+
+go 1.21.6

types.go

@@ -0,0 +1,13 @@
+package gifenc
+
+type Output struct {
+	Name string `default:"img"`
+	Path string
+}
+
+type Config struct {
+	Output Output
+	Delay  int // encode delay
+	Width  int // decode width
+	Height int // decode height
+}