How to do composite with gm node.js?

After struggling for an hour, here is my solution for your question:

gm composite -gravity center change_image_url base_image_urlgm().command("composite") .in("-gravity", "center").in(change_image_url).in(base_image_url).write( output_file, function (err) {  if (!err)     console.log(' hooray! ');  else    console.log(err);});

Good luck! Hope it will be helpful to others as well :)

Install gm, (make sure you already install graphicsmagick

npm install gm

following is my example code to merge two image together (use gm.in)

var gm = require('gm');gm() .in('-page', '+0+0') .in('bg.jpg') .in('-page', '+10+20') // location of smallIcon.jpg is x,y -> 10, 20 .in('smallIcon.jpg') .mosaic() .write('tesOutput.jpg', function (err) {    if (err) console.log(err); });

i am doing that this way:

var exec = require('child_process').execvar command = [        '-composite',        '-watermark', '20x50',        '-gravity', 'center',         '-quality', 100,        'images/watermark.png',        'images/input.jpg', //input        'images/watermarked.png'  //output        ];         // making watermark through exec - child_process        exec(command.join(' '), function(err, stdout, stderr) {             if (err) console.log(err);        });