From 578c226278f37427b50692dd10f59c9e495bf367 Mon Sep 17 00:00:00 2001
From: pierre <pierre.curto@gmail.com>
Date: Tue, 15 Dec 2020 12:45:16 +0100
Subject: [PATCH] io/pointer: CursorNameOp no longer needs an InputOp with
 Leave and Enter events

Signed-off-by: pierre <pierre.curto@gmail.com>
---
 io/router/pointer.go      | 18 +++++++-------
 io/router/pointer_test.go | 49 +++++++++++++++++++++++++++++++++++++++
 widget/editor.go          |  6 ++---
 3 files changed, 60 insertions(+), 13 deletions(-)

diff --git a/io/router/pointer.go b/io/router/pointer.go
index bd8a9e89..ea70dc14 100644
--- a/io/router/pointer.go
+++ b/io/router/pointer.go
@@ -177,6 +177,7 @@ func (q *pointerQueue) init() {
 	if q.handlers == nil {
 		q.handlers = make(map[event.Tag]*pointerHandler)
 	}
+	q.cursor = pointer.CursorDefault
 }
 
 func (q *pointerQueue) Frame(root *op.Ops, events *handlerEvents) {
@@ -289,6 +290,11 @@ func (q *pointerQueue) Push(e pointer.Event, events *handlerEvents) {
 		// No longer need to track pointer.
 		q.pointers = append(q.pointers[:pidx], q.pointers[pidx+1:]...)
 	}
+
+	for _, k := range p.entered {
+		h := q.handlers[k]
+		q.hitCursor(h.area)
+	}
 }
 
 func (q *pointerQueue) deliverEvent(p *pointerInfo, events *handlerEvents, e pointer.Event) {
@@ -327,7 +333,6 @@ func (q *pointerQueue) deliverEnterLeaveEvents(p *pointerInfo, hits []event.Tag,
 
 		if e.Type&h.types == e.Type {
 			events.Add(k, e)
-			q.cursor = pointer.CursorDefault
 		}
 	}
 	// Deliver Enter events.
@@ -341,7 +346,6 @@ func (q *pointerQueue) deliverEnterLeaveEvents(p *pointerInfo, hits []event.Tag,
 
 		if e.Type&h.types == e.Type {
 			events.Add(k, e)
-			q.hitCursor(h.area)
 		}
 	}
 	p.entered = append(p.entered[:0], hits...)
@@ -349,13 +353,9 @@ func (q *pointerQueue) deliverEnterLeaveEvents(p *pointerInfo, hits []event.Tag,
 
 func (q *pointerQueue) hitCursor(want int) {
 	for _, c := range q.cursors {
-		idx := c.area
-		for idx != -1 {
-			if idx == want {
-				q.cursor = c.name
-				return
-			}
-			idx = q.areas[idx].next
+		if c.area == want {
+			q.cursor = c.name
+			return
 		}
 	}
 }
diff --git a/io/router/pointer_test.go b/io/router/pointer_test.go
index 03c78a22..e8638578 100644
--- a/io/router/pointer_test.go
+++ b/io/router/pointer_test.go
@@ -11,6 +11,7 @@ import (
 	"gioui.org/f32"
 	"gioui.org/io/event"
 	"gioui.org/io/pointer"
+	"gioui.org/layout"
 	"gioui.org/op"
 )
 
@@ -416,6 +417,54 @@ func TestMultitouch(t *testing.T) {
 	assertEventSequence(t, r.Events(h2), pointer.Cancel, pointer.Enter, pointer.Press, pointer.Release)
 }
 
+func TestCursorNameOp(t *testing.T) {
+	for _, tc := range []struct {
+		label string
+		pt    image.Point
+		want  pointer.CursorName
+	}{
+		{label: "inside", pt: image.Pt(50, 50), want: pointer.CursorPointer},
+		{label: "outside", pt: image.Pt(200, 200), want: pointer.CursorDefault},
+	} {
+		t.Run(tc.label, func(t *testing.T) {
+			ops := new(op.Ops)
+			var r Router
+			var h int
+			widget := func() {
+				// This is the area where the cursor is changed to CursorPointer.
+				pointer.Rect(image.Rectangle{Max: image.Pt(100, 100)}).Add(ops)
+				// The cursor is checked and changed upon cursor movement.
+				pointer.InputOp{
+					Tag:   &h,
+					Types: pointer.Move,
+				}.Add(ops)
+				pointer.CursorNameOp{Name: pointer.CursorPointer}.Add(ops)
+			}
+			// Register the handlers.
+			widget()
+			// No cursor change as the mouse has not moved yet.
+			if got, want := r.Cursor(), pointer.CursorDefault; got != want {
+				t.Errorf("got %q; want %q", got, want)
+			}
+			// Add a mouse move event.
+			r.Frame(ops)
+			r.Add(
+				pointer.Event{
+					Source:   pointer.Mouse,
+					Type:     pointer.Move,
+					Position: layout.FPt(tc.pt),
+				},
+			)
+			// Make the widget process the new event.
+			widget()
+			// The cursor should now have been changed if the mouse moved over the declared area.
+			if got, want := r.Cursor(), tc.want; got != want {
+				t.Errorf("got %q; want %q", got, want)
+			}
+		})
+	}
+}
+
 // addPointerHandler adds a pointer.InputOp for the tag in a
 // rectangular area.
 func addPointerHandler(ops *op.Ops, tag event.Tag, area image.Rectangle) {
diff --git a/widget/editor.go b/widget/editor.go
index 75709679..f7bbe9a3 100644
--- a/widget/editor.go
+++ b/widget/editor.go
@@ -379,10 +379,7 @@ func (e *Editor) Layout(gtx layout.Context, sh text.Shaper, font text.Font, size
 	}
 	e.makeValid()
 
-	dims := e.layout(gtx)
-	pointer.Rect(image.Rectangle{Max: dims.Size}).Add(gtx.Ops)
-	pointer.CursorNameOp{Name: pointer.CursorText}.Add(gtx.Ops)
-	return dims
+	return e.layout(gtx)
 }
 
 func (e *Editor) layout(gtx layout.Context) layout.Dimensions {
@@ -430,6 +427,7 @@ func (e *Editor) layout(gtx layout.Context) layout.Dimensions {
 	r.Max.X += pointerPadding
 	r.Max.X += pointerPadding
 	pointer.Rect(r).Add(gtx.Ops)
+	pointer.CursorNameOp{Name: pointer.CursorText}.Add(gtx.Ops)
 	e.scroller.Add(gtx.Ops)
 	e.clicker.Add(gtx.Ops)
 	e.caret.on = false