io/pointer,io/router: make PassOp apply to InputOps, not areas

We're about to make clip.Ops act as pointer areas, in which case we'd
like to contain the effect of PassOp to just pointer InputOps.

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

io/pointer/doc.go

@@ -59,30 +59,29 @@ For example:
 
 implies a tree of two inner nodes, each with one pointer handler attached.
 
-When determining which handlers match an Event, only handlers whose
+The matching proceeds as follows.
-areas contain the event position are considered. The matching
-proceeds as follows.
 
-First, the foremost area that contains the event is found. If no such area
+First, the foremost area that contains the event is found. Only areas whose
-exists, matching stops.
+parent areas all contain the event is considered.
 
-Then, every handler attached to the area or an area in the area stack is
+Then, every handler attached to the area is matched with the event.
-matched with the event.
 
-Third, If the area or any area in the area stack has pass-through enabled,
+If all attached handlers are marked pass-through, the matching repeats with the
-the matching repeats with the next foremost area.
+next foremost (sibling) area. Otherwise the matching repeats with the parent
+area.
 
-In the example above, all events will go to h2 only even though both
+In the example above, all events will go to h2 because it and h1 are siblings
-handlers have the same area (the implicit area that fills the window).
+and none are pass-through.
 
 Pass-through
 
-The PassOp operations controls the pass-through setting. A handler's
+The PassOp operations controls the pass-through setting. All handlers added
-pass-through setting is recorded along with the InputOp.
+inside one or more PassOp scopes are marked pass-through.
 
-Pass-through handlers are useful for overlay widgets such as a hidden
+Pass-through is useful for overlay widgets. Consider a hidden side drawer: when
-side drawer. When the user touches the side, both the (transparent)
+the user touches the side, both the (transparent) drawer handle and the
-drawer handle and the interface below should receive pointer events.
+interface below should receive pointer events. This effect is achieved by
+marking the drawer handle pass-through.
 
 Disambiguation
 

io/router/pointer.go

@@ -28,7 +28,8 @@ type hitNode struct {
 	area int
 
 	// For handler nodes.
-	tag event.Tag
+	tag  event.Tag
+	pass bool
 }
 
 type cursorNode struct {
@@ -66,7 +67,6 @@ type areaNode struct {
 	trans f32.Affine2D
 	next  int
 	area  areaOp
-	pass  bool
 }
 
 type areaKind uint8
@@ -113,11 +113,12 @@ func (c *pointerCollector) area(op areaOp) {
 		n := c.q.hitTree[i]
 		area = n.area
 	}
-	c.q.areas = append(c.q.areas, areaNode{trans: c.state.t, next: area, area: op, pass: c.state.pass > 0})
+	c.q.areas = append(c.q.areas, areaNode{trans: c.state.t, next: area, area: op})
 	c.nodeStack = append(c.nodeStack, c.state.nodePlusOne-1)
 	c.q.hitTree = append(c.q.hitTree, hitNode{
 		next: c.state.nodePlusOne - 1,
 		area: len(c.q.areas) - 1,
+		pass: true,
 	})
 	c.state.nodePlusOne = len(c.q.hitTree) - 1 + 1
 }
@@ -159,6 +160,7 @@ func (c *pointerCollector) inputOp(op pointer.InputOp, events *handlerEvents) {
 		next: c.state.nodePlusOne - 1,
 		area: area,
 		tag:  op.Tag,
+		pass: c.state.pass > 0,
 	})
 	c.state.nodePlusOne = len(c.q.hitTree) - 1 + 1
 	h, ok := c.q.handlers[op.Tag]
@@ -197,12 +199,12 @@ func (q *pointerQueue) opHit(handlers *[]event.Tag, pos f32.Point) {
 	idx := len(q.hitTree) - 1
 	for idx >= 0 {
 		n := &q.hitTree[idx]
-		hit, areaPass := q.hit(n.area, pos)
+		hit := q.hit(n.area, pos, n.pass)
 		if !hit {
 			idx--
 			continue
 		}
-		pass = pass && areaPass
+		pass = pass && n.pass
 		if pass {
 			idx--
 		} else {
@@ -223,18 +225,16 @@ func (q *pointerQueue) invTransform(areaIdx int, p f32.Point) f32.Point {
 	return q.areas[areaIdx].trans.Invert().Transform(p)
 }
 
-func (q *pointerQueue) hit(areaIdx int, p f32.Point) (bool, bool) {
+func (q *pointerQueue) hit(areaIdx int, p f32.Point, pass bool) bool {
-	pass := false
 	for areaIdx != -1 {
 		a := &q.areas[areaIdx]
 		p := a.trans.Invert().Transform(p)
 		if !a.area.Hit(p) {
-			return false, false
+			return false
 		}
 		areaIdx = a.next
-		pass = pass || a.pass
 	}
-	return true, pass
+	return true
 }
 
 func (q *pointerQueue) reset() {

io/router/pointer_test.go

@@ -686,6 +686,53 @@ func TestCursorNameOp(t *testing.T) {
 	}
 }
 
+func TestPassOp(t *testing.T) {
+	var ops op.Ops
+
+	h1, h2, h3, h4 := new(int), new(int), new(int), new(int)
+	area := pointer.Rect(image.Rect(0, 0, 100, 100))
+	root := area.Push(&ops)
+	pointer.InputOp{Tag: h1, Types: pointer.Press}.Add(&ops)
+	child1 := area.Push(&ops)
+	pointer.InputOp{Tag: h2, Types: pointer.Press}.Add(&ops)
+	child1.Pop()
+	child2 := area.Push(&ops)
+	pass := pointer.PassOp{}.Push(&ops)
+	pointer.InputOp{Tag: h3, Types: pointer.Press}.Add(&ops)
+	pointer.InputOp{Tag: h4, Types: pointer.Press}.Add(&ops)
+	pass.Pop()
+	child2.Pop()
+	root.Pop()
+
+	var r Router
+	r.Frame(&ops)
+	r.Queue(
+		pointer.Event{
+			Type: pointer.Press,
+		},
+	)
+	assertEventSequence(t, r.Events(h1), pointer.Cancel, pointer.Press)
+	assertEventSequence(t, r.Events(h2), pointer.Cancel, pointer.Press)
+	assertEventSequence(t, r.Events(h3), pointer.Cancel, pointer.Press)
+	assertEventSequence(t, r.Events(h4), pointer.Cancel, pointer.Press)
+}
+
+func TestAreaPassthrough(t *testing.T) {
+	var ops op.Ops
+
+	h := new(int)
+	pointer.InputOp{Tag: h, Types: pointer.Press}.Add(&ops)
+	pointer.Rect(image.Rect(0, 0, 100, 100)).Push(&ops).Pop()
+	var r Router
+	r.Frame(&ops)
+	r.Queue(
+		pointer.Event{
+			Type: pointer.Press,
+		},
+	)
+	assertEventSequence(t, r.Events(h), pointer.Cancel, pointer.Press)
+}
+
 // addPointerHandler adds a pointer.InputOp for the tag in a
 // rectangular area.
 func addPointerHandler(ops *op.Ops, tag event.Tag, area image.Rectangle) {