Convert a Buffer Array into an image

Question

I have the following code on an express server, to read an image and send it to the client via api

router.get("/file",async (req,res)=>{
    const objImg = {img:null}
    const result = await SELECT("...");
    if(result.length>0){        
        var bitMap= fs.readFileSync(`./src/logosClient/${result.nombImg}`)        
        objImg.img=new Buffer.from(bitMap,"base64")
    }
    res.json(objImg)
})

The api data arrives as follows

data:{type: "Buffer", data: [137, 80, 78, 71, 13, 10, 26, 10, 0, 0, 0, 13, 73, 72, 68, 82, 0, 0, 0, 192, 0, 0, 0, 46, 8, 6......]}

In my ReactJs client, I have the following code to receive it

    import React, {useEffect, useState} from 'react';
    import muestra from '../../../../resources/images/muestra.png'
    
    const Index = () => {
    const [previewImg, setPreviewImg] = useState(null) 
    
    useEffect(()=>{        
        RunApi("/generales/file","GET",null,null).then(result=>{
            if(result.img){
                setPreviewImg("data:image/png;base64," + result.img.data)
            }
        }).catch(error=>{
            addToast("error","Error",error)
        })
    },[])
    
    return(
      <img src={previewImg?previewImg:muestra} className="align-self-center mr-3" alt="..."/>
    )
    
}

I can't see the image but it doesn't generate any error message either

Did you check what data do you receive client-side? Do you actually receive the base64 string in the response? — ulentini
– ulentini, Commented Mar 27, 2020 at 19:33
The api data arrives as follows data:{type: "Buffer", data: [137, 80, 78, 71, 13, 10, 26, 10, 0, 0, 0, 13, 73, 72, 68, 82, 0, 0, 0, 192, 0, 0, 0, 46, 8, 6......]} — Jose Fdo
– Jose Fdo, Commented Mar 27, 2020 at 19:36

ppichier · Accepted Answer · 2020-03-27 19:37:14Z

9

Try to convert your image to base64 string like

objImg.img = new Buffer.from(bitMap).toString("base64")

And then set your state like

setPreviewImg("data:image/png;base64," + result.img)

answered Mar 27, 2020 at 19:37

ppichier

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