io/router: avoid a decode round for key ops

Like a previous change for pointer ops, process key ops during the
router decode of ops. This is a performance optimization and preparation
for processing future accessibility ops without without another decode
loop.

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

io/router/key.go

@@ -6,7 +6,6 @@ import (
 	"gioui.org/internal/ops"
 	"gioui.org/io/event"
 	"gioui.org/io/key"
-	"gioui.org/op"
 )
 
 type TextInputState uint8
@@ -14,7 +13,6 @@ type TextInputState uint8
 type keyQueue struct {
 	focus    event.Tag
 	handlers map[event.Tag]*keyHandler
-	reader   ops.Reader
 	state    TextInputState
 	hint     key.InputHint
 }
@@ -27,6 +25,14 @@ type keyHandler struct {
 	hint    key.InputHint
 }
 
+// keyCollector tracks state required to update a keyQueue
+// from key ops.
+type keyCollector struct {
+	q       *keyQueue
+	focus   event.Tag
+	changed bool
+}
+
 const (
 	TextInputKeep TextInputState = iota
 	TextInputClose
@@ -53,46 +59,46 @@ func (q *keyQueue) InputHint() (key.InputHint, bool) {
 	return q.hint, old != q.hint
 }
 
-func (q *keyQueue) Frame(root *op.Ops, events *handlerEvents) {
+func (q *keyQueue) Reset() {
 	if q.handlers == nil {
 		q.handlers = make(map[event.Tag]*keyHandler)
 	}
 	for _, h := range q.handlers {
 		h.visible, h.new = false, false
 	}
-	q.reader.Reset(&root.Internal)
+	q.state = TextInputKeep
+}
 
-	focus, changed, state := q.resolveFocus(events)
+func (q *keyQueue) Frame(events *handlerEvents, collector keyCollector) {
 	for k, h := range q.handlers {
 		if !h.visible {
 			delete(q.handlers, k)
 			if q.focus == k {
 				// Remove the focus from the handler that is no longer visible.
 				q.focus = nil
-				state = TextInputClose
+				q.state = TextInputClose
 			}
-		} else if h.new && k != focus {
+		} else if h.new && k != collector.focus {
 			// Reset the handler on (each) first appearance, but don't trigger redraw.
 			events.AddNoRedraw(k, key.FocusEvent{Focus: false})
 		}
 	}
-	if changed && focus != nil {
-		if _, exists := q.handlers[focus]; !exists {
-			focus = nil
+	if collector.changed && collector.focus != nil {
+		if _, exists := q.handlers[collector.focus]; !exists {
+			collector.focus = nil
 		}
 	}
-	if changed && focus != q.focus {
+	if collector.changed && collector.focus != q.focus {
 		if q.focus != nil {
 			events.Add(q.focus, key.FocusEvent{Focus: false})
 		}
-		q.focus = focus
+		q.focus = collector.focus
 		if q.focus != nil {
 			events.Add(q.focus, key.FocusEvent{Focus: true})
 		} else {
-			state = TextInputClose
+			q.state = TextInputClose
 		}
 	}
-	q.state = state
 }
 
 func (q *keyQueue) Push(e event.Event, events *handlerEvents) {
@@ -101,32 +107,27 @@ func (q *keyQueue) Push(e event.Event, events *handlerEvents) {
 	}
 }
 
-func (q *keyQueue) resolveFocus(events *handlerEvents) (focus event.Tag, changed bool, state TextInputState) {
-	for encOp, ok := q.reader.Decode(); ok; encOp, ok = q.reader.Decode() {
-		switch ops.OpType(encOp.Data[0]) {
-		case ops.TypeKeyFocus:
-			op := decodeFocusOp(encOp.Data, encOp.Refs)
-			changed = true
-			focus = op.Tag
-		case ops.TypeKeySoftKeyboard:
-			op := decodeSoftKeyboardOp(encOp.Data, encOp.Refs)
-			if op.Show {
-				state = TextInputOpen
-			} else {
-				state = TextInputClose
-			}
-		case ops.TypeKeyInput:
-			op := decodeKeyInputOp(encOp.Data, encOp.Refs)
-			h, ok := q.handlers[op.Tag]
-			if !ok {
-				h = &keyHandler{new: true}
-				q.handlers[op.Tag] = h
-			}
-			h.visible = true
-			h.hint = op.Hint
-		}
+func (k *keyCollector) focusOp(tag event.Tag) {
+	k.focus = tag
+	k.changed = true
+}
+
+func (k *keyCollector) softKeyboard(show bool) {
+	if show {
+		k.q.state = TextInputOpen
+	} else {
+		k.q.state = TextInputClose
 	}
-	return
+}
+
+func (k *keyCollector) inputOp(op key.InputOp) {
+	h, ok := k.q.handlers[op.Tag]
+	if !ok {
+		h = &keyHandler{new: true}
+		k.q.handlers[op.Tag] = h
+	}
+	h.visible = true
+	h.hint = op.Hint
 }
 
 func decodeKeyInputOp(d []byte, refs []interface{}) key.InputOp {
@@ -156,3 +157,16 @@ func decodeFocusOp(d []byte, refs []interface{}) key.FocusOp {
 		Tag: refs[0],
 	}
 }
+
+func (t TextInputState) String() string {
+	switch t {
+	case TextInputKeep:
+		return "Keep"
+	case TextInputClose:
+		return "Close"
+	case TextInputOpen:
+		return "Open"
+	default:
+		panic("unexpected value")
+	}
+}