isDpr method
Implementation
bool isDpr(Map<String, String> params) {
var width = params['w'];
var hasWidth = width != null && isNotBlank(params['w']);
var height = params['h'];
var hasHeight = (height != null) && height.isNotEmpty;
var aspectRatio = params['ar'];
var hasAspectRatio = (aspectRatio != null) && aspectRatio.isNotEmpty;
// If `params` have a width param or _both_ height and aspect
// ratio parameters then the srcset to be constructed with
// these params _is dpr based_.
return hasWidth || (hasHeight && hasAspectRatio);
}