How to do composite with gm node.js? - image

Question

How to do 'gm composite -gravity center change_image_url base_image_url' with GM Node.js?
How to call gm().command() & gm().in() or gm().out() to achieve the above?

Answer 1

After struggling for an hour, here is my solution for your question:
gm composite -gravity center change_image_url base_image_url
gm()
.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 :)

Answer 2

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);
});

Answer 3

i am doing that this way:
var exec = require('child_process').exec
var 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);
});

Answer 4

Why does nobody use composite command? (https://github.com/aheckmann/gm)
var gm = require('gm');
var bgImage = 'bg.jpg',
frontImage = 'front.jpg',
resultImage = 'result.jpg',
xy = '+100+150';
gm(bgImage)
.composite(frontImage)
.geometry(xy)
.write(resultImage, function (err) {
if (!err) console.log('All done');
});
UPDATE Oh, I watched history of source of this method. It becomes available only on 2014

Answer 5

If you want to resize and merge, you can use this:
gm()
.in('-geometry', '+0+0')
.in('./img/img1.png')
.in('-geometry', '300x300+100+200')
.in('./img/img2.png')
.flatten()
.write('resultGM.png', function (err) {
if (err) console.log(err);
});

Answer 6

Having the pleasure of being confined to a windows machine for the moment I solved this problem eventually by not using the "gm" module at all. For some reason, even though I have installed graphics-magick via its installer the node module refused to find it in my environment variables. But that could have something to do with the fact that I am trying to make an application with Electron.js (which is similar to Node.js but has its "gotcha's").
var exec = require("child_process").execSync;
var commandArray = [
__dirname + "/bin/graphicsMagick/gm.exe", // the relative path to the graphics-magick executable
"-composite",
"-gravity",
"center",
__dirname + "/data/images/qr/logo-small.png", // relative paths to the images you want to composite
__dirname + "/data/images/qr/qr-webpage.png",
__dirname + "/data/images/qr/qr-webpage-logo.png" // relative path to the result
];
var returnValue = exec(commandArray.join(" "));
For windows I think this is the correct portable way to do it.