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feat(streams): refactor streams and buffer usage #1

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feat(streams): refactor streams and buffer usage #1

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100 changes: 58 additions & 42 deletions index.js
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Original file line number Diff line number Diff line change
@@ -1,44 +1,60 @@
var PNG = require('png-js');
var charm = require('charm');
var x256 = require('x256');
var buffers = require('buffers');
var es = require('event-stream');

var Stream = require('stream').Stream;

module.exports = function (opts) {
if (!opts) opts = {};
if (!opts.cols) opts.cols = 80;

var c = charm();
var bufs = buffers();

var ws = es.writeArray(function (err, bufs) {
var data = buffers(bufs).slice();
var png = new PNG(data);

png.decode(function (pixels) {
var dx = png.width / opts.cols;
var dy = 2 * dx;

for (var y = 0; y < png.height; y += dy) {
for (var x = 0; x < png.width; x += dx) {
var i = (Math.floor(y) * png.width + Math.floor(x)) * 4;

var ix = x256([ pixels[i], pixels[i+1], pixels[i+2] ]);
if (pixels[i+3] > 0) {
c.background(ix).write(' ');
}
else {
c.display('reset').write(' ');
}
}
c.display('reset').write('\r\n');
}

c.display('reset').end();
});
var PNG = require("png-js");
var charm = require("charm");
var x256 = require("x256");

var { Duplex } = require("stream");
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You should really use readable-stream.


class PictureTube extends Duplex {
constructor(opts = {}) {
super();
this.data = [];
this.cols = opts.cols || 80;

this.c = charm();

this.c.on("data", chunk => {
this.push(chunk);
});

return es.duplex(ws, c);

this.c.on("end", () => {
this.emit("end");
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this should be this.push(null) to correctly end the stream.

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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:

image

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

});
}

_read() {}

_write(chunk, encoding, callback) {
this.data.push(chunk);
callback();
}

_final(callback) {
var png = new PNG(Buffer.concat(this.data));

png.decode(pixels => {
var dx = png.width / this.cols;
var dy = 2 * dx;

for (var y = 0; y < png.height; y += dy) {
for (var x = 0; x < png.width; x += dx) {
var i = (Math.floor(y) * png.width + Math.floor(x)) * 4;

var ix = x256([pixels[i], pixels[i + 1], pixels[i + 2]]);
if (pixels[i + 3] > 0) {
this.c.background(ix).write(" ");
} else {
this.c.display("reset").write(" ");
}
}
this.c.display("reset").write("\r\n");
}

this.c.display("reset").end();
callback();
});
}
}

module.exports = opts => {
return new PictureTube(opts);
};