README.md

resigif

Animated GIF resizing library w/o cgo nor any third-party Libraries

Installation

You can install resigif with the go get command

go get -u github.com/logica0419/resigif

Quick Start

The only API of this library is Resize() function.
You can easily resize an animated GIF image by passing *gif.GIF struct and the target size.

Here's a simple example:

package main

import (
  "context"
  "image/gif"
  "os"

  "github.com/logica0419/resigif"
)

func main() {
  ctx := context.Background()

  src, err := os.Open("image.gif")
  if err != nil {
    panic(err)
  }
  defer src.Close()

  srcImg, err := gif.DecodeAll(src)
  if err != nil {
    panic(err)
  }

  width := 480
  height := 360

  dstImg, err := resigif.Resize(ctx, srcImg, width, height)
  if err != nil {
    panic(err)
  }

  dst, err := os.OpenFile("resized.gif", os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0o644)
  if err != nil {
    panic(err)
  }
  defer dst.Close()

  err = gif.EncodeAll(dst, dstImg)
  if err != nil {
    panic(err)
  }
}

Customization

• Aspect Ratio Preservation
  • You can choose from Ignore or Maintain

dstImg, err := resigif.Resize(
  ctx,
  srcImg,
  width,
  height,
  resigif.WithAspectRatio(resigif.Maintain),
)

dstImg, err := resigif.Resize(
  ctx,
  srcImg,
  width,
  height,
  resigif.WithAspectRatio(resigif.Ignore),
)

• Resizing algorithm
  • You can use you own resizing algorithm by implementing ImageResizeFunc interface and passing it to WithImageResizeFunc()
  • If you want to use golang.org/x/image/draw.Scaler, you can use FromDrawScaler() to convert it to ImageResizeFunc

dstImg, err := resigif.Resize(
  ctx,
  srcImg,
  width,
  height,
  resigif.WithImageResizeFunc(resigif.FromDrawScaler(draw.BiLinear)),
)

• Parallelism
  • You can control the number of goroutine used for resizing by passing WithParallel()

dstImg, err := resigif.Resize(
  ctx,
  srcImg,
  width,
  height,
  resigif.WithParallel(3),
)