Files
MujicaUI/core/overlay_layers.go
T

116 lines
3.2 KiB
Go

package core
import (
"log/slog"
"time"
"github.com/egoist/mygo/ui"
)
// overlayLayers is the window's open MujicaUI layers, oldest first.
type overlayLayers struct {
frame, prev time.Time
keys []any
seen []time.Time
}
type overlayLayersKey struct{}
// OverlayLayer marks the layer key open in this frame and reports whether it is on top.
func OverlayLayer(c *ui.Context, key any) bool {
s := ui.Local(c.Root(), overlayLayersKey{}, func() overlayLayers { return overlayLayers{} })
if now := c.Now(); now != s.frame {
s.prev, s.frame = s.frame, now
n := 0
for i, k := range s.keys {
if !s.seen[i].Before(s.prev) { // drop layers the last frame did not build
s.keys[n], s.seen[n] = k, s.seen[i]
n++
}
}
clear(s.keys[n:])
s.keys, s.seen = s.keys[:n], s.seen[:n]
}
at := -1
for i, k := range s.keys {
if k == key {
at = i
}
}
if at < 0 {
s.keys, s.seen = append(s.keys, key), append(s.seen, s.frame)
at = len(s.keys) - 1
}
s.seen[at] = s.frame
return at == len(s.keys)-1
}
// OverlayEscape reports Escape for a window-level layer, delivered only while it is on top.
func OverlayEscape(c *ui.Context, key any) bool {
if !OverlayLayer(c, key) {
return false
}
// The root is around every focus, so it takes Escape before MyGo's overlays.
byFocus := c.Root().Shortcut(0, ui.KeyEscape)
byWindow := c.Shortcut(0, ui.KeyEscape)
if byFocus || byWindow {
s := ui.Local(c.Root(), overlayLayersKey{}, func() overlayLayers { return overlayLayers{} })
for i, k := range s.keys {
if k == key {
s.keys = append(s.keys[:i], s.keys[i+1:]...)
s.seen = append(s.seen[:i], s.seen[i+1:]...)
break
}
}
c.Invalidate()
return true
}
return false
}
// overlaySiteState follows the focus of a layer after it closes.
type overlaySiteState struct {
focusIn bool // the focus was inside the layer when it last showed
wait int // frames left to check the focus after a close
holding bool // the site holds the fallback focus
}
// OverlaySite builds the invisible focus fallback at a layer's call site.
func OverlaySite(c *ui.Context) (*ui.Element, *overlaySiteState) {
site := ui.Box(c).Size(0, 0).FocusRing(false)
st := ui.Local(site, "mujica.overlay.site", func() overlaySiteState { return overlaySiteState{} })
st.holding = st.holding && site.FocusWithin()
if st.holding {
site.Focusable() // in flow, so Tab goes on from the layer's place
} else {
site.Absolute()
}
return site, st
}
// Shown records whether the focus is in the open layer's panel.
func (st *overlaySiteState) Shown(panel *ui.Element) {
st.focusIn, st.wait = panel != nil && panel.FocusWithin(), 0
}
// Closed moves a lost focus to the site once MyGo has had its chance to restore it.
func (st *overlaySiteState) Closed(c *ui.Context, site *ui.Element) {
if st.focusIn {
st.focusIn, st.wait = false, 2 // MyGo prunes the panel at the end of the next frame
}
if st.wait == 0 {
return
}
st.wait--
if st.wait > 0 {
c.AnimationFrame()
return
}
// The site itself counts as lost: it may inherit a vanished opener's positional ID.
if !c.Root().FocusWithin() || site.FocusWithin() {
slog.Debug("mujica: overlay focus fallback")
site.Focus()
st.holding = true
}
}