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Re-design clip/spatial API for simplicity

jbonisteel opened this issue · comments

commented

There's a few things I want to try here, and not sure how they'll pan out:

  • Make ClipChain into a single clip, use parenting for all relationships
    • Eliminate ClipChain in favour of direct clip parenting
    • OR remove clip parenting
  • If ClipChain/Clip distinction is to be preserved:
    • Make ClipId only Clips, and not ClipChains
    • Make ClipChains only contain ClipIds
    • Make items only clipped by ClipChainIds
  • Pull image masks out of clips, make them into a kind of Filter (since they're similar to the Opacity filter)
  • Factor out SpatialTree and ClipTree from the display list as explicit seperate structures, so that SceneBuilding doesn't need to untangle them itself
  • Break StackingContexts into FilterItem, BlendItem, and Picture to make a clearer seperation of concerns..?

Properties that are True about the web, which we might be relying on and which we might want to enforce at the API level:

  • All items in the same StackingContext must be part of the same ReferenceFrame (but not necessarily the same ScrollFrame..?)
  • One should only ever be clipped by a clip in an ancestor stacking context
    • One should only ever be clipped by a clip in the same stacking context (ancestor clipping handled by the fact that the stacking context itself will clip you)
commented

via @mstange

maybe rephrase as: "Items in a stacking context (which are always part of the same reference frame) should only be clipped by clips in that same reference frame"

and "When a clip from an ancestor reference frame needs to be applied, this clip needs to be set on an ancestor stacking context, and then the stacking context will clip you."

commented

@Gankra I think a better place to post the technical details would be in the corresponding bugzilla issue, to which we'd link from here.