canvas-object-fit

Easily draw images in your canvas with object-type contraints.

• Works with node-canvas on the server.
• Supports EXIF orientation values to handle mobile pictures.

Usage

Quickstart

1. Draw an image with a cover object-fit:

   import Canvas from 'canvas';
   import {drawImage} from 'canvas-object-fit';
    
   const [width, height] = [200, 200];
   const canvas = new Canvas(width, height);
   const context = canvas.getContext('2d');
   const image = new Canvas.Image();
   image.src = await fs.readFileAsync(`${fixturesPath}/image.jpg`);
   drawImage(context, image, 0, 0, canvas.width, canvas.height, {objectFit: 'cover'});
   const buffer = canvas.toBuffer('png');

2. Draw an image with a contain object-fit and 90-CW exif orientation:

   import Canvas from 'canvas';
   import {drawImage} from 'canvas-object-fit';
    
   const [width, height] = [200, 200];
   const canvas = new Canvas(width, height);
   const context = canvas.getContext('2d');
   const image = new Canvas.Image();
   image.src = await fs.readFileAsync(`${fixturesPath}/image-rotated.jpg`);
   drawImage(context, image, 0, 0, canvas.width, canvas.height, {objectFit: 'contain', orientation: 6});
   const buffer = canvas.toBuffer('png');

Exif orientations

//   1        2       3      4         5            6           7          8
//  888888  888888      88  88      8888888888  88                  88  8888888888
//  88          88      88  88      88  88      88  88          88  88      88  88
//  8888      8888    8888  8888    88          8888888888  8888888888          88
//  88          88      88  88
//  88          88  888888  888888
export const EXIF_ORIENTATIONS = [
  {op: 'none', radians: 0},
  {op: 'none', radians: 0},
  {op: 'flip-x', radians: 0},
  {op: 'none', radians: Math.PI},
  {op: 'flip-y', radians: 0},
  {op: 'flip-x', radians: Math.PI / 2},
  {op: 'none', radians: Math.PI / 2},
  {op: 'flip-x', radians: -Math.PI / 2},
  {op: 'none', radians: -Math.PI / 2}
];

Available scripts

Script	Description
test	Run mocha unit tests
lint	Run eslint static tests
test:watch	Run and watch mocha unit tests
compile	Compile the library

Authors

Olivier Louvignes

• http://olouv.com
• http://github.com/mgcrea

License

The MIT License

Copyright (c) 2016 Olivier Louvignes

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.