feat(tracker/gioui): new tab order logic and refactor instrument editor

tracker/gioui/focus.go

@@ -0,0 +1,79 @@
+package gioui
+
+import (
+	"math"
+
+	"gioui.org/io/event"
+	"gioui.org/io/key"
+)
+
+type TagYieldFunc func(level int, tag event.Tag) bool
+
+// FocusNext navigates to the next focusable tag in the tracker. If stepInto is
+// true, it will focus the next tag regardless of its depth; otherwise it will
+// focus the next tag at the current level or shallower.
+func (t *Tracker) FocusNext(gtx C, stepInto bool) {
+	_, next := t.findPrevNext(gtx, stepInto)
+	if next != nil {
+		gtx.Execute(key.FocusCmd{Tag: next})
+	}
+}
+
+// FocusPrev navigates to the previous focusable tag in the tracker. If stepInto
+// is true, it will focus the previous tag regardless of its depth; otherwise it
+// will focus the previous tag at the current level or shallower.
+func (t *Tracker) FocusPrev(gtx C, stepInto bool) {
+	prev, _ := t.findPrevNext(gtx, stepInto)
+	if prev != nil {
+		gtx.Execute(key.FocusCmd{Tag: prev})
+	}
+}
+
+func (t *Tracker) findPrevNext(gtx C, stepInto bool) (prev, next event.Tag) {
+	var first, last event.Tag
+	found := false
+	maxLevel := math.MaxInt
+	if !stepInto {
+		if level, ok := t.findFocusedLevel(gtx); ok {
+			maxLevel = level // limit to the current focused tag's level
+		}
+	}
+	t.Tags(0, func(l int, t event.Tag) bool {
+		if l > maxLevel || t == nil {
+			return true // skip tags that are too deep or nils
+		}
+		if first == nil {
+			first = t
+		}
+		if found && next == nil {
+			next = t
+		}
+		if gtx.Focused(t) {
+			found = true
+		}
+		if !found {
+			prev = t
+		}
+		last = t
+		return true
+	})
+	if next == nil {
+		next = first
+	}
+	if prev == nil {
+		prev = last
+	}
+	return prev, next
+}
+
+func (t *Tracker) findFocusedLevel(gtx C) (level int, ok bool) {
+	t.Tags(0, func(l int, t event.Tag) bool {
+		if gtx.Focused(t) {
+			level = l
+			ok = true
+			return false // stop when we find the focused tag
+		}
+		return true // continue searching
+	})
+	return level, ok
+}