759996 - simplify border-image nsImageLoader code now that border-image doesn't cause border-width changes

Status: NEW

(Core :: Layout, defect)

Description

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

nsFrame::DidSetStyleContext has the following code:

  // For border-images, we can't be as conservative (we need to set the
  // new loaders if there has been any change) since the CalcDifference
  // call depended on the result of GetComputedBorder() and that result
  // depends on whether the image has loaded, start the image load now
  // so that we'll get notified when it completes loading and can do a
  // restyle.  Otherwise, the image might finish loading from the
  // network before we start listening to its notifications, and then
  // we'll never know that it's finished loading.  Likewise, we want to
  // do this for freshly-created frames to prevent a similar race if the
  // image loads between reflow (which can depend on whether the image
  // is loaded) and paint.  We also don't really care about any callers
  // who try to paint borders with a different style context, because
  // they won't have the correct size for the border either.
  if (!EqualImages(oldBorderImage, GetStyleBorder()->GetBorderImage())) {
    // stop and restart the image loading/notification
    PresContext()->SetupBorderImageLoaders(this, GetStyleBorder());
  }

I believe this can be removed or replaced with something more similar to what background-images do now that border-images don't trigger layout changes.  We need to do a bit of poking around to figure out exactly what and think through whether it's ok, though.

Comment 1

[Boris Zbarsky [:bzbarsky]]

Kyle, beware bitrot.  ;)