node-canvas

Node canvas is a Cairo backed Canvas implementation for NodeJS.

Authors

• TJ Holowaychuk (visionmedia)

Installation

$ npm install canvas

Example

var Canvas = require('canvas')
  , canvas = new Canvas(200,200)
  , ctx = canvas.getContext('2d');


  ctx.font = '30px Impact';
  ctx.rotate(.1);
  ctx.fillText("Awesome!", 50, 100);

  var te = ctx.measureText('Awesome!');
  ctx.strokeStyle = 'rgba(0,0,0,0.5)';
  ctx.beginPath();
  ctx.lineTo(50, 102);
  ctx.lineTo(50 + te.width, 102);
  ctx.stroke();
  
  console.log('<img src="' + canvas.toDataURL() + '" />');

Non-Standard API

Due to interfacing with existing node internals such as I/O node-canvas includes a non-standard API which is shown below.

Canvas#createPNGStream()

To create a PNGStream simple call canvas.createPNGStream(), and the stream will start to emit data events, finally emitting end when finished. If an exception occurs the error event is emitted.

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

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

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

Canvas#toBuffer()

A call to Canvas#toBuffer() will return a node Buffer instance containing all of the PNG data.

Contribute

Want to contribute to node-canvas? patches for features, bug fixes, documentation, examples and others are certainly welcome. Take a look at the issue queue for existing issues.

Testing

Visual tests utilize md5 checksums in order to assert integrity.

Build:

$ node-waf configure build

Test:

$ make test

License

(The MIT License)

Copyright (c) 2010 LearnBoost <dev@learnboost.ca>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.