[foxnne]

Part of fizzyedit/plans#27 (the corner). Follows #555.

What changes

The corner #555 put on every filled place looked wrong on main (seen by the user): "doesn't look like a bubble filling the top right corner, it's got sharp edges, doesn't cover the corner area, and has a weird single corner cut".

The cause: cornerButton runs inside the place's content clip, the card inset by its padding (8 pt). The resting piece and its morph into the button were drawn under that clip, so their top and right 8 pt were cut off. The piece sat inset from the card's edge, and its outer curve, the card's own, never showed. The ring beside it already drew under the card's rect (clipSet(rs.r)) for the same reason. #555's screenshot showed the cut, and it was misread as the shape.

The corner is now what the user asked for after seeing the options: a small round bubble that "moves behind/under the region's rounded corner, peeking out".

• The bubble: 16 pt round, its centre halfway round the card's top-right curve, so half lies over the card and half peeks past the curve.
• Square cards: with no curve, its centre is the corner point itself.
• Clipping: it is drawn, and morphed into the button, under the card's rect outset by half the bubble, not the content clip. It is kept whole inside the window, for a card that runs to the window's edge.
• Hover: the pointer target is the bubble plus 8 pt round it (CornerPiece.hit). The finger's target is unchanged: 44 pt, centred on the card's outer corner.
• Glyph: centred in the bubble, smaller.
• Why not a flush piece: a shape with the card's top and right edges can't be small. Its outer corner has to match the card's radius (24 pt), and a glass corner is held to half its side, so it would be at least 48 pt across.

Prototype by the session working on the history transport (it measured the clip), taken over, checked and finished here.

SDK impact

• None
• Core-only or additive: reaches plugins at the next SDK release
• Fingerprint moved: recorded in sdk/src/version.zig, sdk_version untouched, PR labelled sdk
• SDK release: bumps sdk_version, lists the sdk PRs since the last sdk-v* tag

Verified

• macOS:
  • Gates: scripts/check-fmt.sh, zig build, zig build check-web all pass. zig build test: 107/107 steps. zig build test-integration: 54/54 steps, 605/605 tests.
  • On screen (sandbox fizzy, --profile, captured):
    • default rounding: the bubble on the main view's and the panel's curve, peeking out;
    • corner_roundness = 0: the bubble whole, centred on the square corner at the window's edge;
    • hovered, by the prototype's author: the bubble turning into the button.
  • Explorer: the explorer has no card of its own, so its bubble sits on the place's corner over the window's chrome. It marks the place, but reads more detached than on a card.
  • Not seen: a tap on a touchscreen.
  • Unchanged by this PR, not re-checked: the empty-place path (hatch and button), which this doesn't touch (resting is false there); and the 44 pt touch target.
• Windows:
• Linux:
• Web: check-web only

Follow-ups

• The corner reads dvui.pointerKind() once core: tabs show the hand, and a tapped item is left unlit #563 merges (it already has a follow-up note on layout: a place's corner is glass, and turns into its button #555).
• Whether the explorer, which has no card, should have a corner at all, or one placed differently.

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