buildSrcSet function

String buildSrcSet(String src, List<int> widths, { ImageUrlBuilder? urlBuilder, })

Builds a standard HTML5 srcset attribute string from a base src and a list of target widths.

Converts each width into an entry formatted as "$url ${w}w", joined by commas. If urlBuilder is omitted, defaultImageUrlBuilder is used by default.

final srcset = buildSrcSet('/assets/photo.jpg', [320, 640, 1024]);
// Returns: '/assets/photo.jpg?w=320 320w, /assets/photo.jpg?w=640 640w, /assets/photo.jpg?w=1024 1024w'

See also:

• ImageUrlBuilder, for custom CDN URL rewriting.
• defaultImageUrlBuilder, the default query-parameter builder.
• bloomImage, which utilizes buildSrcSet when widths is supplied.

Implementation

String buildSrcSet(
  String src,
  List<int> widths, {
  ImageUrlBuilder? urlBuilder,
}) {
  final builder = urlBuilder ?? defaultImageUrlBuilder;
  return widths.map((w) => '${builder(src, w)} ${w}w').join(', ');
}