gulp-responsive

Generates images at different sizes

Installation

gulp-responsive depends on sharp. Sharp is one of the fastest Node.js modules for resizing JPEG, PNG, WebP and TIFF images.

If you are using Mac OS then before installing gulp-responsive you should install the libvips library. Further information and instructions can be found in the sharp installation guide.

$ npm install --save-dev gulp-responsive

Usage

var gulp = require('gulp');
var responsive = require('gulp-responsive');

gulp.task('default', function () {
  return gulp.src('src/*.{png,jpg}')
    .pipe(responsive({
      'background-*.jpg': {
        width: 700,
        quality: 50
      },
      'cover.png': {
        width: '50%',
        // convert to jpeg format
        format: 'jpeg',
        rename: 'cover.jpg'
      },
      // produce multiple images from one source
      'logo.png': [
        {
          width: 200
        },{
          width: 200 * 2,
          rename: 'logo@2x.png'
        }
      ]
    }))
    .pipe(gulp.dest('dist'));
});

Examples

• Simple example
• Multiple resolutions
• Advanced example

Integration

• HTML srcset attribute
• HTML <picture> element
• CSS image-set method

All together 🎆

• gulp-responsive config generation example

API

responsive(config, options)

config

Configuration can be provided in one of the following formats:

1. Array of unique configurations

[{
  name: 'logo.png',
  width: 200,
  height: 100
},{
  name: 'banner.png',
  width: 500
}]

2. Object of unique configurations. Keys are filenames.

{
  'logo.png': {
    width: 300,
    height: 200,
    rename: 'logo@2x.png'
  },
  'background-*.png': {
    width: 1400,
    withoutEnlargement: true
  }
}

3. Object of arrays of unique configurations. Keys are filenames.

{
  'logo.png': [{
      width: 200,
      rename: 'logo@1x.png'
    },{
      width: 400,
      rename: 'logo@2x.png'
    }],
  'background-*': [{
    height: 400
  }]
}

Configuration unit

Configuration unit is an object:

• name: String — filename glob pattern.
• width: Number or String — width in pixels or percentage of the original, not set by default.
• height: Number or String — height in pixels or percentage of the original, not set by default.
• withoutEnlargement: Boolean — do not enlarge the output image, default true.
• skipOnEnlargement: Boolean — do not write an output image at all if the original image is smaller than the configured width or height, default false.
• min: Boolean — preserving aspect ratio, resize the image to be as small as possible while ensuring its dimensions are greater than or equal to the width and height specified.
• max: Boolean — resize to the max width or height the preserving aspect ratio (both width and height have to be defined), default false.
• quality: Number — output quality for JPEG, WebP and TIFF, default 80.
• progressive: Boolean — progressive (interlace) scan for JPEG and PNG output, default false.
• withMetadata: Boolean — include image metadata, default false.
• compressionLevel: Number — zlib compression level for PNG, default 6.
• rename: String, Object or Function — renaming options, file will not be renamed by default. When extname is specified, output format is parsed from extension. You can override this autodetection with format option.
• format: String — output format jpeg, png, webp or raw, default is null.
• crop: Crop the resized image to the exact size specified, default is false.
• embed: Preserving aspect ratio, resize the image to the maximum width or height specified then embed on a background of the exact width and height specified, default is false.
• ignoreAspectRatio: Boolean — Ignoring the aspect ratio of the input, stretch the image to the exact width and/or height provided via resize, default is false.
• kernel: String — The kernel to use for image reduction, defaulting to lanczos3.
• background: Color — Set the background for the embed and flatten operations, '#default is fff'.
• flatten: Boolean — Merge alpha transparency channel, if any, with background, default is false.
• negate: Boolean — Produces the "negative" of the image, default is false.
• rotate: Boolean — Rotate the output image by either an explicit angle or auto-orient based on the EXIF Orientation tag, default is false.
• flip: Boolean — Flip the image about the vertical Y axis. This always occurs after rotation, if any. The use of flip implies the removal of the EXIF Orientation tag, if any. Default is false.
• flop: Boolean — Flop the image about the horizontal X axis. This always occurs after rotation, if any. The use of flop implies the removal of the EXIF Orientation tag, if any. Default is false.
• blur: Boolean — When used without parameters, performs a fast, mild blur of the output image. This typically reduces performance by 10%. Default is false.
• sharpen: Boolean — When used without parameters, performs a fast, mild sharpen of the output image. This typically reduces performance by 10%. Default is false.
• threshold: Number or Boolean — Converts all pixels in the image to greyscale white or black, default is false.
• gamma: Boolean — Apply a gamma correction by reducing the encoding (darken) pre-resize at a factor of 1/gamma then increasing the encoding (brighten) post-resize at a factor of gamma. Default is false.
• grayscale: Boolean — Convert to 8-bit greyscale; 256 shades of grey, default is false.
• normalize: Boolean — Enhance output image contrast by stretching its luminance to cover the full dynamic range. This typically reduces performance by 30%. Default is false.
• trim: Boolean or Number — Trim "boring" pixels from all edges that contain values within a percentage similarity of the top-left pixel. Default is false.
• tile: Boolean or Object — The size and overlap, in pixels, of square Deep Zoom image pyramid tiles, default is false.
• withoutChromaSubsampling: Boolean — Disable the use of chroma subsampling with JPEG output (4:4:4), default is false.

Detailed description of each option can be found in the sharp API documentation.

Renaming

Renaming is implemented by the rename module. Options correspond with options of gulp-rename.

options

errorOnUnusedConfig

Type: Boolean
Default: true

Emit the error when configuration is not used.

errorOnUnusedImage

Type: Boolean
Default: true

Emit the error when image is not used.

passThroughUnused

Type: Boolean
Default: false

Keep unmatched images in the stream. To use this option errorOnUnusedImage should be false.

errorOnEnlargement

Type: Boolean
Default: true

Emit the error when image is enlarged.

stats

Type: Boolean
Default: true

Show statistics after the run — how many images were created, how many were matched and how many were in the run in total.

silent

Type: Boolean
Default: false

Silence messages and stats if 0 images were created. If you wish to supress all messages and stats, set the options.stats to false as well.

You can specify global default value for any of the configuration options.

gulp.task('default', function () {
  return gulp.src('src/*.png')
    .pipe(responsive(config, {
      // global quality for all images
      quality: 50,
      errorOnUnusedImage: false
    }))
    .pipe(gulp.dest('dist'));
});

License

MIT © Evgeny Vlasenko