golang gif test server - fork of https://github.com/moddyz/gifserver

gif_test_server.go

package main

import (
	"bytes"
	"fmt"
	"image"
	"image/gif"
	"net/http"

	"github.com/gin-gonic/gin"
	"github.com/justinfx/openimageigo"
)

var cache map[string]*gif.GIF

func serveGif(c *gin.Context, g *gif.GIF) {
	var b bytes.Buffer
	gif.EncodeAll(&b, g)
	c.Data(200, "image/gif", b.Bytes())
}

func previewHandler(c *gin.Context) {
	key := c.Param("key")
	g, ok := cache[key]
	if ok == true {
		fmt.Printf("Found cache for: %v\n", key)
		serveGif(c, g)
		return
	}

	src, err := oiio.NewImageBufPath(key)
	if err != nil {
		err = fmt.Errorf("Cannot read gif: %v\n", err)
		c.AbortWithError(http.StatusBadRequest, err)
		return
	}

	// Make smaller
	roi := oiio.NewROIRegion2D(0, 512, 0, 512)
	dst := oiio.NewImageBuf()
	oiio.Resize(dst, src, oiio.AlgoOpts{ROI: roi})
	src = dst

	// Copy to a new buffer, with alpha
	spec := src.Spec()
	spec = oiio.NewImageSpecSize(spec.Width(), spec.Height(), 4, oiio.TypeUint8)
	dst, _ = oiio.NewImageBufSpec(spec)
	err = dst.CopyPixels(src)
	if err != nil {
		c.AbortWithError(500, fmt.Errorf("Failed to process gif (1): %v", err))
		return
	}

	// Grab the 8bit pixels
	pix, err := dst.GetPixels(oiio.TypeUint8)
	if err != nil {
		c.AbortWithError(500, fmt.Errorf("Failed to process gif (2): %v", err))
		return
	}

	// Manually construct an RGB image with pixels
	img := image.NewRGBA(image.Rect(0, 0, spec.Width(), spec.Height()))
	img.Pix = pix.([]uint8)
	img.Stride = spec.ScanlineBytes(false)

	// Encode to GIF
	var buf bytes.Buffer
	err = gif.Encode(&buf, img, &gif.Options{256, nil, nil})
	if err != nil {
		c.AbortWithError(500, fmt.Errorf("Failed to encode gif: %v", err))
		return
	}

	// Decode from GIF
	g, err = gif.DecodeAll(&buf)
	if err != nil {
		err = fmt.Errorf("Cannot read gif %v\n", err)
		c.AbortWithError(500, err)
		return
	}

	cache[key] = g
	serveGif(c, g)
	fmt.Printf("Set cache for: %v\n", key)
}

func main() {
	cache = make(map[string]*gif.GIF)
	r := gin.Default()
	r.GET("/preview/:key", previewHandler)
	r.Run()
}