CODEWITHSUNDEEP
node.jsexpressimage-processing
stackers
stackers

Reputation: 3279

Send image generated with node-gd to client

EDIT: the solution is to use

res.set('Content-Type', 'image/png');
res.end(data, 'binary').

I am trying to dynamically generate images using node-gd. My application is node.js/express.

This code successfully generates an image:

    //create image
    var gd = require('node-gd');
    var img = gd.createSync(200, 80);
    img.colorAllocate(0, 255, 0);

    img.savePng('../test.png', 0, function(error) {
      if (error) throw error;
      img.destroy();
    })

But it saves the image to a file. I don't necessarily want to keep the generated images, just send it to the client.

I was hoping I could just do

res.send(img);

But that just returns an object with metadata about the image.

EDIT: Attempt at outputting the pointer:

    //create image
    var gd = require('node-gd');
    var img = gd.createSync(200, 80);
    img.colorAllocate(0, 255, 0);

    var imageData = img.pngPtr();
    res.set('Content-Type', 'image/png');
    console.log(imageData);
    res.send(imageData);

In my browser I get:

The image “URLHERE” cannot be displayed because it contains errors.

The file isn't empty, it's like 138 bytes, where the actual image is like 2kb.

if I log the PNG data (I didn't expect it to be readable, but still):

PNG

IHDRÈPf£¨óPLTEÿ4^À¨     pHYsÄÄ+IDATHc`£`Q0
FÁ( ½1üñIEND®B`

Upvotes: 1

Views: 860

Answers (3)

pj2494
pj2494

Reputation: 121

send it as a binary:

res.write(buffer,'binary');
res.end(null, 'binary');

The imageptr() generated.

To generate the binary refer this https://github.com/y-a-v-a/node-gd/blob/stable/docs/index.md#saving-graphic-images

I used:

var jpgImageData = img.jpegPtr(0);

Upvotes: 1

Ivan Drinchev
Ivan Drinchev

Reputation: 19581

You can use the pointer ( the buffer ) of the image via the API.

res.set('Content-Type', 'image/png');
res.send( img.pngPtr() );

You can read more about the functions in the official documentation

Upvotes: 3

Ben
Ben

Reputation: 591

Would Express's res.sendFile method work for you?

res.sendFile('/path/to/image.png')

Upvotes: 1

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