all: initial import

Signed-off-by: Elias Naur <mail@eliasnaur.com>

ui/key/queue.go

@@ -0,0 +1,109 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package key
+
+import (
+	"gioui.org/ui"
+)
+
+type Queue struct {
+	focus    Key
+	events   []Event
+	handlers map[Key]bool
+}
+
+type listenerPriority uint8
+
+const (
+	priNone listenerPriority = iota
+	priDefault
+	priCurrentFocus
+	priNewFocus
+)
+
+func (q *Queue) Frame(op ui.Op) TextInputState {
+	q.events = q.events[:0]
+	f, pri, hide := resolveFocus(op, q.focus)
+	changed := f != nil && f != q.focus
+	for k, active := range q.handlers {
+		if !active || changed {
+			delete(q.handlers, k)
+		} else {
+			q.handlers[k] = false
+		}
+	}
+	q.focus = f
+	switch {
+	case pri == priNewFocus:
+		return TextInputOpen
+	case hide:
+		return TextInputClosed
+	case changed:
+		return TextInputFocus
+	default:
+		return TextInputKeep
+	}
+}
+
+func (q *Queue) Push(e Event) {
+	q.events = append(q.events, e)
+}
+
+func (q *Queue) For(k Key) []Event {
+	if q.handlers == nil {
+		q.handlers = make(map[Key]bool)
+	}
+	_, exists := q.handlers[k]
+	q.handlers[k] = true
+	if !exists {
+		if k == q.focus {
+			// Prepend focus event.
+			q.events = append(q.events, nil)
+			copy(q.events[1:], q.events)
+			q.events[0] = Focus{Focus: true}
+		} else {
+			return []Event{Focus{Focus: false}}
+		}
+	}
+	if k != q.focus {
+		return nil
+	}
+	return q.events
+}
+
+func resolveFocus(op ui.Op, focus Key) (Key, listenerPriority, bool) {
+	type childOp interface {
+		ChildOp() ui.Op
+	}
+	var k Key
+	var pri listenerPriority
+	var hide bool
+	switch op := op.(type) {
+	case ui.Ops:
+		for i := len(op) - 1; i >= 0; i-- {
+			newK, newPri, h := resolveFocus(op[i], focus)
+			hide = hide || h
+			if newPri > pri {
+				k, pri = newK, newPri
+			}
+		}
+	case OpHandler:
+		var newPri listenerPriority
+		switch {
+		case op.Focus:
+			newPri = priNewFocus
+		case op.Key == focus:
+			newPri = priCurrentFocus
+		default:
+			newPri = priDefault
+		}
+		if newPri > pri {
+			k, pri = op.Key, newPri
+		}
+	case OpHideInput:
+		hide = true
+	case childOp:
+		return resolveFocus(op.ChildOp(), focus)
+	}
+	return k, pri, hide
+}