update Width to report in physical pixels #61
Merged
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We originally defined
Width
to report in CSS px because the same header was responsible for reporting both the "intended image display width", or the "layout viewport size" for resources that don't have a "display width". However, we've since split these use cases (see #48) into separate headers:Viewport-Width
andWidth
.This update changes the definition of
Width
to report image display width (when it's known) in physical pixels, instead of CSS pixels. This offers a couple of important benefits:w descriptor
used for viewport-based selection.Vary: DPR, Width
) which leads to unnecessary fragmentation (see viewport-based selection use case and caching #59).Closes #59.