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Better streams that support being returned asynchronously. #765

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50 changes: 50 additions & 0 deletions lib/imagestream.js
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Original file line number Diff line number Diff line change
@@ -0,0 +1,50 @@
'use strict';

/*!
* Canvas - ImageStream
* Copyright (c) 2010 LearnBoost <[email protected]>
* MIT Licensed
*/

/**
* Module dependencies.
*/

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

if (typeof Readable === 'undefined') {
throw new Error('Node versions <0.10 are no longer supported.');
}

/**
* A base class for a stream of compressed image data.
*
* @api public
*/

var ImageStream = module.exports = function ImageStream() {

Readable.call(this, {});

this._started = false;
};

util.inherits(ImageStream, Readable);

function noop() {}

ImageStream.prototype._read = function () {
// 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 () {
self._stream_method(self._handle_chunk.bind(self));
});
};

ImageStream.prototype._stream_method = noop;

ImageStream.prototype._handle_chunk = noop;
38 changes: 13 additions & 25 deletions lib/jpegstream.js
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Expand Up @@ -10,7 +10,7 @@
* Module dependencies.
*/

var Readable = require('stream').Readable;
var ImageStream = require('./imagestream');
var util = require('util');

/**
Expand All @@ -26,6 +26,7 @@ var util = require('util');
* stream.pipe(out);
*
* @param {Canvas} canvas
* @param {Object} options options passed to the JPEG encoder.
* @param {Boolean} sync
* @api public
*/
Expand All @@ -35,7 +36,7 @@ var JPEGStream = module.exports = function JPEGStream(canvas, options, sync) {
throw new TypeError("Class constructors cannot be invoked without 'new'");
}

Readable.call(this);
ImageStream.call(this);

var self = this;
var method = sync
Expand All @@ -48,30 +49,17 @@ var JPEGStream = module.exports = function JPEGStream(canvas, options, sync) {
// TODO: implement async
if ('streamJPEG' == method) method = 'streamJPEGSync';
this.method = method;
this._stream_method = canvas[method].bind(canvas, options.bufsize, options.quality, options.progressive);
};

util.inherits(JPEGStream, Readable);
util.inherits(JPEGStream, ImageStream);

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(){
self.canvas[method](bufsize, quality, progressive, function(err, chunk){
if (err) {
self.emit('error', err);
} else if (chunk) {
self.push(chunk);
} else {
self.push(null);
}
});
});
JPEGStream.prototype._handle_chunk = function (err, chunk) {
if (err) {
this.emit('error', err);
} else if(chunk) {
this.push(chunk);
} else {
this.push(null);
}
};
34 changes: 13 additions & 21 deletions lib/pdfstream.js
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@
* Module dependencies.
*/

var Readable = require('stream').Readable;
var ImageStream = require('./imagestream');
var util = require('util');

/**
Expand All @@ -33,7 +33,7 @@ var PDFStream = module.exports = function PDFStream(canvas, sync) {
throw new TypeError("Class constructors cannot be invoked without 'new'");
}

Readable.call(this);
ImageStream.call(this);

var self = this
, method = sync
Expand All @@ -45,26 +45,18 @@ var PDFStream = module.exports = function PDFStream(canvas, sync) {
// TODO: implement async
if ('streamPDF' == method) method = 'streamPDFSync';
this.method = method;
};

util.inherits(PDFStream, Readable);
this._stream_method = canvas[method].bind(canvas);
};

function noop() {}
util.inherits(PDFStream, ImageStream);

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(){
self.canvas[self.method](function(err, chunk, len){
if (err) {
self.emit('error', err);
} else if (len) {
self.push(chunk);
} else {
self.push(null);
}
});
});
PDFStream.prototype._handle_chunk = function (err, chunk, len) {
if (err) {
this.emit('error', err);
} else if(len) {
this.push(chunk);
} else {
this.push(null);
}
};
49 changes: 12 additions & 37 deletions lib/pngstream.js
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,7 @@
* Module dependencies.
*/

var Readable = require('stream').Readable;
var ImageStream = require('./imagestream');
var util = require('util');

/**
Expand All @@ -35,7 +35,7 @@ var PNGStream = module.exports = function PNGStream(canvas, sync) {
throw new TypeError("Class constructors cannot be invoked without 'new'");
}

Readable.call(this);
ImageStream.call(this);

var self = this;
var method = sync
Expand All @@ -47,43 +47,18 @@ var PNGStream = module.exports = function PNGStream(canvas, sync) {
// 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;

// TODO: implement async
if ('streamPNG' === method) method = 'streamPNGSync';
this.method = method;
this._stream_method = canvas[method].bind(canvas);
};

util.inherits(PNGStream, Readable);

function noop() {}
util.inherits(PNGStream, ImageStream);

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(){
self.canvas[self.method](function(err, chunk, len){
if (err) {
self.emit('error', err);
} else if (len) {
self.push(chunk);
} else {
self.push(null);
}
});
});
PNGStream.prototype._handle_chunk = function (err, chunk, len) {
if (err) {
this.emit('error', err);
} else if(len) {
this.push(chunk);
} else {
this.push(null);
}
};
90 changes: 90 additions & 0 deletions test/canvas.test.js
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Expand Up @@ -956,6 +956,96 @@ describe('Canvas', function () {
s.on('end', done);
});

it('should handle PNG streams returned asynchronously, (AKA in a Promise)', function (done) {

function build_stream(funk) {
var canvas = new Canvas(20, 20)
, stream = canvas.createSyncPNGStream();

process.nextTick(function () {
funk(stream);
});
}

build_stream(function (stream) {
var firstChunk = true;
stream.on('data', function(chunk){
if (firstChunk) {
firstChunk = false;
assert.equal('PNG', chunk.slice(1,4).toString());
}
});
stream.on('end', function(){
done();
});
stream.on('error', function(err) {
done(err);
});
})
});

it('should handle JPEG streams returned asynchronously, (AKA in a Promise)', function (done) {

function build_stream(funk) {
var canvas = new Canvas(640, 480)
, stream = canvas.jpegStream();

process.nextTick(function () {
funk(stream);
});
}

build_stream(function (stream) {
var firstChunk = true;
var bytes = 0;
stream.on('data', function(chunk){
if (firstChunk) {
firstChunk = false;
assert.equal(0xFF, chunk[0]);
assert.equal(0xD8, chunk[1]);
assert.equal(0xFF, chunk[2]);
}
bytes += chunk.length;
});
stream.on('end', function(){
assert.equal(bytes, 5427);
done();
});
stream.on('error', function(err) {
done(err);
});
})
});

it('should handle PDF streams returned asynchronously, (AKA in a Promise)', function (done) {

function build_stream(funk) {
var canvas = new Canvas(640, 480, 'pdf')
, stream = canvas.createSyncPDFStream();

process.nextTick(function () {
funk(stream);
});
}

build_stream(function (stream) {
var firstChunk = true;
var bytes = 0;
stream.on('data', function (chunk) {
if (firstChunk) {
firstChunk = false;
assert.equal(chunk.slice(1, 4).toString(), 'PDF');
}
});
stream.on('end', function () {
done();
});
stream.on('error', function (err) {
done(err);
});
})
});

it('Context2d#fill()', function() {
var canvas = new Canvas(2, 2);
var ctx = canvas.getContext('2d');
Expand Down