feat(streams): refactor streams and buffer usage

[lirantal]

Refactoring the original picture-tube code to minimize the use of external modules (event-stream, buffers) and use built-in Streams and Buffers support in Node.js

Would be happy if someone more experienced with terminal emulation and streams could review this. Perhaps you could help @waldyrious, @J-Cat, @reconbot, @larsonjj ?

Context: this is in follow-up of a blessed-contrib change to use a thinner picture-tube package with no vulnerabilities: yaronn/blessed-contrib#162

[reconbot]

This is alright, there’s probably another way to make charm the read part of the duplex but I don’t see any issues doing it this way.

One note is that _final is only node 8 and above.

[lirantal]

I could perhaps have the 1.x version of this new replacement use older streams syntax to be compatible with <=8 and then we could release 2.x with the new class and _final syntax.

I linked a local development version of this branch to blessed-contrib and when I run it with the default cols: 95 I get this:

var blessed = require('blessed')
  , contrib = require('../')
  , screen = blessed.screen()
    
var pic = contrib.picture(
   { file: './media/flower.png'
   , cols: 95
   , onReady: ready})
function ready() { screen.render() }

screen.append(pic)

Only when I change the cols value to something smaller like 60 I get the full picture:

Any ideas why this happens?

[lirantal]

@cancerberoSgx tagged you here due to recent activity in blessed-contrib in hope that you might be able to help with the outstanding issue here?

[cancerberoSgx]

@lirantal thanks for including me. I'm not familiar with the library or PNG library but it sounds like the stream is not flushed entirely? will try to research when I have more time, thanks again. Cool lib!

[mcollina]

You should really use readable-stream.

[mcollina]

this should be this.push(null) to correctly end the stream.

[lirantal]

Thanks for jumping in Matteo!

I saw that in the docs as well for a readable stream implementation and had tried this.push(null); when c streams ends but that just doesn't draw anything at all.

To add context:
Both variations of this.push(null) and this.emit('end') work well with this picture-tuber branch if you test it out with the CLI util: node bin/tube.js /Users/lirantal/projects/forks/blessed-contrib/examples/media/flower.png:

The issue is when I use this branch of picture-tuber in blessed-contrib (its used in the picture widget). To re-construct that setup:

• cd picture-tuber
• git checkout feat/refactor-streams-use
• npm link
• cd blessed-contrib
• npm link picture-tuber
• cd examples
• node picture.js