scissors/bin/simple_rasterize.js

PDF manipulation in Node.js, based on PDFTK.

#!/usr/bin/env node

var fs = require('fs');
var spawn = require('child_process').spawn;

require('bufferjs/indexOf');

function debug () {
	//console.error.apply(console, arguments);
}

function rasterizeImage (ins, page, dpi, format, useCropBox) {
	var device;
	if (format == 'png') {
		device = 'png16m';
	}
	else {
		device = 'jpeg';
	}

  var gsArgs = [
		'-q',
		'-sDEVICE=' + device,
		'-sOutputFile=-',
		'-r' + dpi,
		'-dNOPAUSE',
		'-dBATCH',
		'-dFirstPage=' + page,
		'-dLastPage=' + page,
		'-f',
		'-'
	];

	if (useCropBox) {
		gsArgs.unshift('-dUseCropBox');
	}

	var gs = spawn('gs', gsArgs);

	ins.pipe(gs.stdin);

	gs.stderr.on('data', function (data) {
		console.error('gs encountered an error:\n', String(data));
	});

	gs.on('exit', function (code) {
		if (code) {
			console.error('gs exited with failure code:', code);
		}
		debug('Finished writing image.');
	});

	return gs.stdout;
}

if (process.argv.length < 5) {
	console.error('Invalid number of arguments.');
	process.exit(1);
}

var input = process.argv[2];
var format = process.argv[3];
var page = Number(process.argv[4]) || 1;
var dpi = Number(process.argv[5]) || 72;
var useCropBox = process.argv[6] == 'true';

var inputStream = input == '-' ? process.stdin : fs.createReadStream(input);
rasterizeImage(inputStream, page, dpi, format, useCropBox).pipe(process.stdout);