Example how to slice a image into a tiles with aws lambda and upload them to S3 with nodejs

This is a example code that I made to test the concept. The function was triggered by a "Put on a bucket"  that means when a image is uploaded to the bucket on S3.

I hope this will help others solve problems

	'use strict';
	console.log('Loading function');
	const aws = require('aws-sdk');
	const s3 = new aws.S3({ apiVersion: '2006-03-01' });
	var async = require('async');
	//http://aheckmann.github.io/gm/docs.html
	var gm = require('gm').subClass({ imageMagick: true }); // Enable ImageMagick integration.
	var util = require('util');
	exports.handler = (event, context, callback) => {
	// Get the object from the event and show its content type
	const bucketName = event.Records[0].s3.bucket.name;
	const keyName = decodeURIComponent(event.Records[0].s3.object.key.replace(/\+/g, ' '));
	const paramsOrigin = {
	Bucket: bucketName,
	Key: keyName,
	};
	var typeMatch = keyName.match(/\.([^.]*)$/);
	var imageType = typeMatch[1]; //"jpg"
	if (!typeMatch) {
	callback("Could not determine the image type.");
	return;
	}
	async.waterfall([
	function download(next) {
	// Download the image from S3 into a buffer.
	s3.getObject(paramsOrigin, next);
	},
	function resize(response, next) { //if you need resize your image
	gm(response.Body).size(function(err,size) {
	if(err) {
	next('Error getting size of image');
	}
	if(size.width != 4096 ) {
	this.resize(4096, 2048, "!").toBuffer(imageType, function(err, buffer) {
	if (err) {
	next('Error resizing image');
	} else {
	next(null, response.ContentType, buffer,{
	width: 4096,
	height: 2048
	});
	}
	});
	} else {
	next( null, response.ContentType,response.Body,{
	width: 4096,
	height: 2048
	});
	}
	});
	},
	function slice (contentType, data,imgDimension, next) {
	var allPromises = [];
	//example tiles to slice
	var positions = [
	[0,0],
	[256,0],
	[512,0],
	];
	function getPromiseCrop(id,positionX,positionY,imageData) {
	return new Promise(function (resolve, reject){
	gm(imageData).crop(256, 256,positionX,positionY)
	.toBuffer(imageType, function(err, buffer) {
	if (err) {
	reject('error promise');
	next(err);
	} else {
	console.log('promise done' + id);
	s3.putObject({
	Bucket: bucketName,
	Key: 'lambda_output/' + id + '.jpg',
	Body: buffer,
	ContentType: contentType
	},function(){
	resolve();
	});
	}
	});
	});
	}
	for (var y = 0; y < positions.length; y++) {
	var currentPromise = getPromiseCrop(y,positions[y][0],positions[y][1],data);
	allPromises.push(currentPromise);
	}
	Promise.all(allPromises).then(function(values) {
	next( null,'done all promises');
	},function(error){
	console.log(error);
	});
	},
	function upload(msg,next) {
	next( null,msg);
	}
	], function (err) {
	if (err) {
	callback(null, err);
	} else {
	callback(null, 'Successfully sliced');
	}
	});
	};

view raw gistfile1.txt hosted with ❤ by GitHub

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