grunt-responsive-images

Produces images at different sizes

Getting Started

This plugin requires Grunt ~0.4.0

If you haven't used Grunt before, be sure to check out the Getting Started guide, as it explains how to create a Gruntfile as well as install and use Grunt plugins. Once you're familiar with that process, you may install this plugin with this command:

npm install grunt-responsive-images --save-dev

You'll also need to install Imagemagick CLI Tools.

brew install ImageMagick

Once both the plugin and ImageMagick have been installed, it may be enabled inside your Gruntfile with this line of JavaScript:

grunt.loadNpmTasks('grunt-responsive-images');

The "responsive_images" task

Overview

The responsive_images task will take your source image and create images at different resolutions for use with PictureFill or with srcset.

A demo of both srcset and PictureFill using Grunt Responsive Images is available here.

Some slides about the plugin are available here.

In your project's Gruntfile, add a section named responsive_images to the data object passed into grunt.initConfig().

grunt.initConfig({
  responsive_images: {
    options: {
      // Task-specific options go here.
    },
    your_target: {
      // Target-specific file lists and/or options go here.
    },
  },
})

Options

options.sizes

Type: Array

Default value:

[{
  name: "small",
  width: 320,
  height: 240,
  quality: 1
},{
  name: "medium",
  width: 640,
  height: 480,
  quality: 1
},{
  name: "large",
  width: 1024,
  height: 768,
  quality: 1
}]

An array of objects containing the sizes we want to resize our image to.

If both width and height are specified, then the image will be resized and cropped.

If a name is specified, then the file will be suffixed with this name. e.g. my-image-small.jpg

If a name is not specified, then the file will be suffixed with the width and/or height. e.g. my-image-320x240.jpg

Use suffix for retina graphic filenames. e.g. my-image-320x240_x2.jpg

Use quality to change the quality of an image (0.1, 0.2 ... 0.9, 1).

options.separator

Type: String Default value: -

The character used to separate the image filename from the size name.

Usage Examples

Default Options

Using the default options will produce 3 responsive images - one at 320px wide, one at 640px wide and one at 1024px wide.

grunt.initConfig({
  responsive_images: {
    myTask: {
      options: {},
      files: {
        'dest/mario-yoshi.jpg': 'test/assets/mario-yoshi.jpg'
      }
    }
  }
})

Custom Options

In this example, we specify our own image sizes, including a retina graphic. We also specify our files with a wildcard.

grunt.initConfig({
  responsive_images: {
    myTask: {
      options: {
        sizes: [{
          width: 320,
          height: 240
        },{
          name: 'large',
          width: 640
        },{
          name: "large",
          width: 1024,
          suffix: "_x2",
          quality: 0.6
        }]
      },
      files: [{
        expand: true,
        src: ['assets/**.{jpg,gif,png}'],
        cwd: 'test/',
        dest: 'tmp/'
      }]
    }
  },
})

Custom Destination

If you would like to output each image size to a different directory, you can do so with custom_dest. For example:

grunt.initConfig({
  responsive_images: {
    myTask: {
      options: {
        sizes: [{
          width: 320,
        },{
          width: 640,
        },{
          width: 1024,
        }]
      },
      files: [{
        expand: true,
        src: ['**.{jpg,gif,png}'],
        cwd: 'test/assets/custom_dest/',
        custom_dest: 'tmp/custom_dest/{%= width %}/'
      }]
    }
  },
})

FAQ

• Receiving a fatal error: spawn ENOENT - Ensure Imagemagick CLI tools are installed. Try uninstalling and reinstalling them if you are having issues.

Contributing

In lieu of a formal styleguide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code using Grunt.

Release History

0.0.4

• Fixed issue with quality setting not producing correct quality output. (thanks to pdud).
• Reduced the amount of logging when running the task (thanks to tnguyen).
• Allowed images of different sizes to be uploaded to different directories with custom_dest (thanks to maslen and oncletom).

0.0.3

• Bug fixes for Srcset and PictureFill demos

0.0.2

• Added srcset and PictureFill demo

0.0.1

• Initial Commit

Roadmap

• The ability to resize images by a percentage of their original size.