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Implement Readable instead of Stream #740

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Merged
merged 1 commit into from
May 3, 2017
Merged

Implement Readable instead of Stream #740

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45 changes: 30 additions & 15 deletions lib/jpegstream.js
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,8 @@
* Module dependencies.
*/

var Stream = require('stream').Stream;
var Readable = require('stream').Readable;
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You should depend from readable-stream, it is better practice and yields more stability across node versions.

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It does require pulling in another dependency though...

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Considering the fact that most of the stream utilities depends on readable-stream, it's not really problematic (the users will do depend on it anyway). The only issue might be in the browser, but I don't think this can be used there.

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(in browserify the stream module is based on readable-stream so it's no big deal)

var util = require('util');

/**
* Initialize a `JPEGStream` with the given `canvas`.
Expand All @@ -30,33 +31,47 @@ var Stream = require('stream').Stream;
*/

var JPEGStream = module.exports = function JPEGStream(canvas, options, sync) {
var self = this
, method = sync
if (!(this instanceof JPEGStream)) {
throw new TypeError("Class constructors cannot be invoked without 'new'");
}

Readable.call(this);

var self = this;
var method = sync
? 'streamJPEGSync'
: 'streamJPEG';
this.options = options;
this.sync = sync;
this.canvas = canvas;
this.readable = true;

// TODO: implement async
if ('streamJPEG' == method) method = 'streamJPEGSync';
this.method = method;
};

util.inherits(JPEGStream, Readable);

function noop() {}

JPEGStream.prototype._read = function _read() {
// For now we're not controlling the c++ code's data emission, so we only
// call canvas.streamJPEGSync once and let it emit data at will.
this._read = noop;
var self = this;
var method = this.method;
var bufsize = this.options.bufsize;
var quality = this.options.quality;
var progressive = this.options.progressive;
process.nextTick(function(){
canvas[method](options.bufsize, options.quality, options.progressive, function(err, chunk){
self.canvas[method](bufsize, quality, progressive, function(err, chunk){
if (err) {
self.emit('error', err);
self.readable = false;
} else if (chunk) {
self.emit('data', chunk);
self.push(chunk);
} else {
self.emit('end');
self.readable = false;
self.push(null);
}
});
});
};

/**
* Inherit from `EventEmitter`.
*/

JPEGStream.prototype.__proto__ = Stream.prototype;
37 changes: 24 additions & 13 deletions lib/pdfstream.js
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,8 @@
* Module dependencies.
*/

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

/**
* Initialize a `PDFStream` with the given `canvas`.
Expand All @@ -28,32 +29,42 @@ var Stream = require('stream').Stream;
*/

var PDFStream = module.exports = function PDFStream(canvas, sync) {
if (!(this instanceof PDFStream)) {
throw new TypeError("Class constructors cannot be invoked without 'new'");
}

Readable.call(this);

var self = this
, method = sync
? 'streamPDFSync'
: 'streamPDF';
this.sync = sync;
this.canvas = canvas;
this.readable = true;

// TODO: implement async
if ('streamPDF' == method) method = 'streamPDFSync';
this.method = method;
};

util.inherits(PDFStream, Readable);

function noop() {}

PDFStream.prototype._read = function _read() {
// For now we're not controlling the c++ code's data emission, so we only
// call canvas.streamPDFSync once and let it emit data at will.
this._read = noop;
var self = this;
process.nextTick(function(){
canvas[method](function(err, chunk, len){
self.canvas[self.method](function(err, chunk, len){
if (err) {
self.emit('error', err);
self.readable = false;
} else if (len) {
self.emit('data', chunk, len);
self.push(chunk);
} else {
self.emit('end');
self.readable = false;
self.push(null);
}
});
});
};

/**
* Inherit from `EventEmitter`.
*/

PDFStream.prototype.__proto__ = Stream.prototype;
60 changes: 44 additions & 16 deletions lib/pngstream.js
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,8 @@
* Module dependencies.
*/

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

/**
* Initialize a `PNGStream` with the given `canvas`.
Expand All @@ -30,32 +31,59 @@ var Stream = require('stream').Stream;
*/

var PNGStream = module.exports = function PNGStream(canvas, sync) {
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I would add a:

if (!(this instanceof PNGStream)) {
  return new PNGStream(canvas, sync)
}

To avoid pollution of the global namespace if invoked without new.

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I would prefer throwing an error since this is the default behaviour with ES6 classes which we probably will want to upgrade the code base to at some point. Also, you can always stop throwing an exception without a major bump but going the other way is more complicated.

This is the exact error the Node throws:

throw new TypeError("Class constructors cannot be invoked without 'new'")

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(Addressed. GitHub isn't hiding this because the diff is below the comment.)

var self = this
, method = sync
if (!(this instanceof PNGStream)) {
throw new TypeError("Class constructors cannot be invoked without 'new'");
}

Readable.call(this);

var self = this;
var method = sync
? 'streamPNGSync'
: 'streamPNG';
this.sync = sync;
this.canvas = canvas;

// TODO: implement async
if ('streamPNG' === method) method = 'streamPNGSync';
this.method = method;
};

util.inherits(PNGStream, Readable);

var PNGStream = module.exports = function PNGStream(canvas, sync) {
Readable.call(this);

var self = this;
var method = sync
? 'streamPNGSync'
: 'streamPNG';
this.sync = sync;
this.canvas = canvas;
this.readable = true;

// TODO: implement async
if ('streamPNG' == method) method = 'streamPNGSync';
if ('streamPNG' === method) method = 'streamPNGSync';
this.method = method;
};

util.inherits(PNGStream, Readable);

function noop() {}

PNGStream.prototype._read = function _read() {
// For now we're not controlling the c++ code's data emission, so we only
// call canvas.streamPNGSync once and let it emit data at will.
this._read = noop;
var self = this;
process.nextTick(function(){
canvas[method](function(err, chunk, len){
self.canvas[self.method](function(err, chunk, len){
if (err) {
self.emit('error', err);
self.readable = false;
} else if (len) {
self.emit('data', chunk, len);
self.push(chunk);
} else {
self.emit('end');
self.readable = false;
self.push(null);
}
});
});
};

/**
* Inherit from `EventEmitter`.
*/

PNGStream.prototype.__proto__ = Stream.prototype;
2 changes: 1 addition & 1 deletion src/Canvas.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -460,7 +460,7 @@ NAN_METHOD(Canvas::StreamPNGSync) {
Nan::Null()
, Nan::Null()
, Nan::New<Uint32>(0) };
Nan::MakeCallback(Nan::GetCurrentContext()->Global(), (v8::Local<v8::Function>)closure.fn, 1, argv);
Nan::MakeCallback(Nan::GetCurrentContext()->Global(), (v8::Local<v8::Function>)closure.fn, 3, argv);
}
return;
}
Expand Down
6 changes: 5 additions & 1 deletion test/canvas.test.js
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,8 @@ var Canvas = require('../')
, assert = require('assert')
, parseFont = Canvas.Context2d.parseFont
, fs = require('fs')
, os = require('os');
, os = require('os')
, Readable = require('stream').Readable;

console.log();
console.log(' canvas: %s', Canvas.version);
Expand Down Expand Up @@ -878,6 +879,7 @@ describe('Canvas', function () {
it('Canvas#createSyncPNGStream()', function (done) {
var canvas = new Canvas(20, 20);
var stream = canvas.createSyncPNGStream();
assert(stream instanceof Readable);
var firstChunk = true;
stream.on('data', function(chunk){
if (firstChunk) {
Expand All @@ -896,6 +898,7 @@ describe('Canvas', function () {
it('Canvas#createSyncPDFStream()', function (done) {
var canvas = new Canvas(20, 20, 'pdf');
var stream = canvas.createSyncPDFStream();
assert(stream instanceof Readable);
var firstChunk = true;
stream.on('data', function (chunk) {
if (firstChunk) {
Expand All @@ -914,6 +917,7 @@ describe('Canvas', function () {
it('Canvas#jpegStream()', function (done) {
var canvas = new Canvas(640, 480);
var stream = canvas.jpegStream();
assert(stream instanceof Readable);
var firstChunk = true;
var bytes = 0;
stream.on('data', function(chunk){
Expand Down