pngStream End Before File is writen

[pyromanci]

Issue or Feature

I'm currently working on a script that takes the output from a roll20 API wrote and merge the map data down to a single image. This was due to the fact that a couple of my maps are so big that a few of my maps were so large with so many different elements it was crashing a few of my players.

So i wrote this to rebuild the map in a canvas and save it off as a single PNG. The problem is when i do this. I seem to get the 'saved png' message far before the actually file is finished being written.

The Final PNG size in my tests was almost 300MB in size.

Steps to Reproduce

var fs = require('fs')
, out = fs.createWriteStream(__dirname + '/text.png')
, stream = canvas.pngStream();

stream.on('data', function(chunk){
out.write(chunk);
});

stream.on('end', function(){
console.log('saved png');
});

Your Environment

• Version of node-canvas (e.g. 1.4.0): 1.4.0
• Environment: Centos 6 Linux 3.10.101-1.el6.elrepo.x86_64 Expose cairo version #1 SMP Wed Mar 16 20:55:27 EDT 2016 x86_64 x86_64 x86_64 GNU/Linux

[LinusU]

This is expected, end only mean that the data has ended from the stream. If you want to know when the file is written, you'll have to listen to the finish event on the file writer.

out.on('finish', () => console.log('saved png'))

[mathiasbynens]

@LinusU In that case, we may want to update this README example: https://github.com/Automattic/node-canvas#canvaspngstreamoptions

[LinusU]

Great catch! I’m on mobile now so can’t do it myself, PR welcome or I’ll fix it after the weekend :)