ludic/packages/ludic.ui/popover_anchor.ludic
2026-09-24 21:48:58 +03:00

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# popover_anchor.ludic - `<div popover anchor="cell">` sits beside the element with that id (the
# nearest), a bare `anchor` beside the one before it: `placement` right, left, bottom or top (its margin
# is the gap), `align` start, center or end along that side, flipped and kept within its bounds.
function pp_anchor_all(n: UiNode) -> void {
if n.children == null { return }
for i in 0 .. len(n.children) {
let c = n.children[i]
if c.popover and Value.kind(ui_attr(c, "anchor")) != 0 { pp_anchor(c, pp_anchor_of(n, i)) }
pp_anchor_all(c)
}
}
# the element a popover (the i-th child of `parent`) is anchored to, or null
function pp_anchor_of(parent: UiNode, i: int) -> UiNode {
let pop = parent.children[i]
let id = ui_attr_text(pop, "anchor")
if id == "" or id == "true" {
var k = i - 1
while k >= 0 and parent.children[k].popover { k -= 1 }
if k < 0 { return null }
return parent.children[k]
}
var at = parent
while at != null {
let f = pp_by_id(at, id, pop)
if f != null { return f }
at = at.parent
}
ui_err(`anchor="{id}": no element has that id`)
return null
}
function pp_by_id(n: UiNode, id: string, skip: UiNode) -> UiNode {
if n == skip { return null }
if n.id == id { return n }
if n.children == null { return null }
for i in 0 .. len(n.children) {
let f = pp_by_id(n.children[i], id, skip)
if f != null { return f }
}
return null
}
function pp_anchor(p: UiNode, a: UiNode) -> void {
if a == null { return }
let side = ui_attr_text(p, "placement")
let align = ui_attr_text(p, "align")
pp_bounds(p)
let w = p.cw
let h = p.ch
var x = a.x
var y = a.y
if side == "top" or side == "bottom" {
let below = a.y + a.ch + p.mt
let above = a.y - h - p.mb
y = pp_side(side == "top", above, below, h, pp_by, pp_bh)
x = pp_along(align, a.x, a.cw, w) + p.ml
} else {
let right = a.x + a.cw + p.ml
let left = a.x - w - p.mr
x = pp_side(side == "left", left, right, w, pp_bx, pp_bw)
y = pp_along(align, a.y, a.ch, h) + p.mt
}
x = Math.max(pp_bx, Math.min(x, pp_bx + pp_bw - w))
y = Math.max(pp_by, Math.min(y, pp_by + pp_bh - h))
ly_place(p, x, y, w, h)
sc_apply(p)
}
# where along one axis: the side asked for (`low` first when `first_low`), else the other when the
# first leaves the screen and the other does not
function pp_side(first_low: bool, low: float, high: float, size: float, v0: float, vsize: float) -> float {
let low_fits = low >= v0
let high_fits = high + size <= v0 + vsize
if first_low {
if low_fits or not high_fits { return low }
return high
}
if high_fits or not low_fits { return high }
return low
}