0.9.1-alpha.39

Patch Changes

• 4eda62d: Popover — Trigger · Overlay · Content · Title · Description · Close

  A panel anchored to whatever opened it, and the component the Select was written before.

  Four sides, where the Select has two. A select's list is as wide as the field it drops out of, and one hanging off the side of that field reads as a menu; a popover belongs to nothing, so placement takes start and end as well. width defaults to content-fit rather than trigger for the same reason — matching the width of a word or an icon would give the panel no room at all.

  No variant. A popover is the theme's floating surface: no emphasis to report, no intent to carry, so a variant would name a decision nobody makes.

  Four things move out of the Select and become shared

  §2 bis, at the second use rather than by anticipation:

  moved	to
  the placement arithmetic	utils/placement.ts
  the trigger's measurement	hooks/use-anchor-ref.ts
  the measuring pass and the origin	hooks/use-anchored-position.ts
  the entrance and exit keyframes	system/anchored/

  The arithmetic gained the two horizontal sides on the way, which is a real generalisation rather than a rename: on a vertical side the room bounds the panel's height, on a horizontal one it bounds its width and the height is bounded by the screen instead. A panel beside its trigger can be as tall as the window allows. Seven more tests cover it, on top of the twelve the vertical sides already had.

  Two of the four exist because of bugs rather than tidiness, and both would have been rewritten wrong in Menu, SubMenu and Tooltip. The trigger measures again on every open, because onLayout never fires on scroll and a trigger inside a ScrollView otherwise reports where it used to be. And the position is computed in the host's coordinates rather than the window's, because the trigger reports itself against the window while the panel is laid out inside the PortalHost.

  The Select's chevron spring moves to system/anchored too, where the Accordion already reads it.

  One bug the Select was hiding

  The measuring pass laid the panel out at the anchor's width. That is right for width: 'trigger' — the content then wraps during the measurement exactly as it will afterwards, so the measured height is the real one — and it is exactly wrong for content-fit, which is the question "how wide does this want to be" asked while imposing an answer.

  Against a small trigger it measured a paragraph as a column one character wide, and held the panel at that width forever. The Select never showed it, because its default width is the trigger's anyway.

  content-fit now measures unconstrained, bounded by two things in this order: the component's own measure, and the screen.

  The measure is what stops "as wide as its content wants" from meaning the width of the screen — a paragraph always wants more, so a panel bounded only by the edges is a full-width panel the moment it holds a sentence, and a popover is an aside rather than a sheet. Thirteen ems of the body size, about twenty-six characters a line — narrow on purpose. A popover is read at a glance, and a glance is two or three short lines rather than a paragraph; past that it stops being an aside and starts being a sheet with a tail. It is where the reference implementation's own panels land too, measured off their placement demos. A multiple of the type rather than a number of points, so a theme that scales its type scales the panel with it.

  Both axes are clamped, not only the cross one

  The side decides where the panel wants to go; the insets decide where it is allowed to be. The main axis was in the first half and not the second, so a panel beside a trigger with no room for it went off the screen entirely — start and end were unusable and nothing said so until one was opened.

  The panel may now overlap its own trigger. That is the right trade, and the one the reference implementation's useRelativePosition makes too: a panel covering the button that opened it is legible, and a panel past the edge of the screen is not.

  width gains 'full' for the case the measure exists to refuse — the screen less its insets, said out loud. Nothing else in the union can say it: a number is a guess at the screen's width, and content-fit declines by design.