# gulp-responsive-config example

[`gulp-responsive-config`](https://www.npmjs.com/package/gulp-responsive-config) helps to generate `gulp-responsive` configuration from existiong HTML and CSS files.

## HTML layout

```html
<img srcset="image-200x300.jpg 1x, image-200x300@2x.jpg 2x" />
```

## CSS markup

```css
.image {
  /* fallback */
  background-image: url('background-image-x200.png');
  /* image-set */
  background-image: image-set(
    'background-image-x200.png' 1x,
    'background-image-x200@2x.png' 2x,
    'background-image-x200@3x.png' 3x
  );
}
```

## gulp-responsive & gulp-responsive-config

```js
var gulp = require('gulp')
var $ = require('gulp-load-plugins')()

gulp.task('images', ['css', 'html'], function () {
  // Make configuration from existing HTML and CSS files
  var config = $.responsiveConfig(['public/**/*.css', 'public/**/*.html'])

  return (
    gulp
      .src('images/*.{png,jpg}')
      // Use configuration
      .pipe(
        $.responsive(config, {
          errorOnEnlargement: false,
          quality: 80,
          withMetadata: false,
          compressionLevel: 7,
          max: true
        })
      )
      .pipe(gulp.dest('public/images'))
  )
})
```

## Supported filename format for dimensions detect

- `-<width>`: `image-100.png`
- `-<width>x`: `image-100x.png`
- `-<width>x<height>`: `image-100x200.png`
- `-x<height>`: `image-x200.png`
- `-<width>x<height>@<scale>x`: `image-100x200@2x.png`
- `@<scale>x`: `image@2x.png`

## More info

- [gulp-responsive-config](https://www.npmjs.com/package/gulp-responsive-config)
- [parse-image-dimensions](https://www.npmjs.com/package/parse-image-dimensions)
- [image-set specification](https://drafts.csswg.org/css-images-3/#image-set-notation)
- [Responsive Images Community Group](https://responsiveimages.org/)
- [Browsers support for `image-set` method form caniuse.com](http://caniuse.com/css-image-set)
- [Browsers support for `<picture>` element form caniuse.com](http://caniuse.com/picture)
- [Browsers support for `srcset` attribute form caniuse.com](http://caniuse.com/srcset)
- [gulp-responsive](https://www.npmjs.com/package/gulp-responsive)