io/pointer: unify area ops into a single AreaOp

Make Rect and Ellipse constructors of AreaOp.

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

io/pointer/doc.go

@@ -19,7 +19,7 @@ For example, to set up a rectangular hit area:
 	var h *Handler = ...
 
 	r := image.Rectangle{...}
-	pointer.RectAreaOp{Rect: r}.Add(ops)
+	pointer.Rect().Add(ops)
 	pointer.InputOp{Key: h}.Add(ops)
 
 Note that areas compound: the effective area of multiple area

io/pointer/pointer.go

@@ -42,24 +42,10 @@ type Event struct {
 	Scroll f32.Point
 }
 
-// RectAreaOp updates the hit area to the intersection
-// of the current hit area with a rectangular area.
-type RectAreaOp struct {
-	// Rect defines the rectangle. The current transform
-	// is applied to it.
-	Rect image.Rectangle
-}
-
-// EllipseAreaOp updates the hit area to the intersection
-// of the current hit area with an elliptical area.
-type EllipseAreaOp struct {
-	// Rect is the bounds for the ellipse. The current transform
-	// is applied to the rectangle.
-	Rect image.Rectangle
-}
-
-// Must match the structure in input.areaOp
-type areaOp struct {
+// AreaOp updates the hit area to the intersection of the current
+// hit area and the area. The area is transformed before applying
+// it.
+type AreaOp struct {
 	kind areaKind
 	rect image.Rectangle
 }
@@ -133,21 +119,23 @@ const (
 	areaEllipse
 )
 
-func (op RectAreaOp) Add(ops *op.Ops) {
-	areaOp{
+// Rect constructs a rectangular hit area.
+func Rect(size image.Rectangle) AreaOp {
+	return AreaOp{
 		kind: areaRect,
-		rect: op.Rect,
-	}.add(ops)
+		rect: size,
+	}
 }
 
-func (op EllipseAreaOp) Add(ops *op.Ops) {
-	areaOp{
+// Ellipse constructs an ellipsoid hit area.
+func Ellipse(size image.Rectangle) AreaOp {
+	return AreaOp{
 		kind: areaEllipse,
-		rect: op.Rect,
-	}.add(ops)
+		rect: size,
+	}
 }
 
-func (op areaOp) add(o *op.Ops) {
+func (op AreaOp) Add(o *op.Ops) {
 	data := o.Write(opconst.TypeAreaLen)
 	data[0] = byte(opconst.TypeArea)
 	data[1] = byte(op.kind)

layout/list.go

@@ -263,7 +263,7 @@ func (l *List) layout() Dimensions {
 	l.beforeEnd = !atEnd
 	dims := axisPoint(l.Axis, mainc.Constrain(pos), maxCross)
 	l.macro.Stop()
-	pointer.RectAreaOp{Rect: image.Rectangle{Max: dims}}.Add(ops)
+	pointer.Rect(image.Rectangle{Max: dims}).Add(ops)
 	l.scroll.Add(ops)
 	l.macro.Add(ops)
 	return Dimensions{Size: dims}

widget/editor.go

@@ -258,7 +258,7 @@ func (e *Editor) layout(gtx *layout.Context, sh *text.Shaper) {
 	r.Min.Y -= pointerPadding
 	r.Max.X += pointerPadding
 	r.Max.X += pointerPadding
-	pointer.RectAreaOp{Rect: r}.Add(gtx.Ops)
+	pointer.Rect(r).Add(gtx.Ops)
 	e.scroller.Add(gtx.Ops)
 	e.clicker.Add(gtx.Ops)
 	e.caretOn = false

widget/material/button.go

@@ -72,7 +72,7 @@ func (b Button) Layout(gtx *layout.Context, button *widget.Button) {
 				widget.Label{}.Layout(gtx, b.shaper, b.Font, b.Text)
 			})
 		})
-		pointer.RectAreaOp{Rect: image.Rectangle{Max: gtx.Dimensions.Size}}.Add(gtx.Ops)
+		pointer.Rect(image.Rectangle{Max: gtx.Dimensions.Size}).Add(gtx.Ops)
 		button.Layout(gtx)
 	})
 	bg := st.Expand(gtx, func() {
@@ -105,7 +105,7 @@ func (b IconButton) Layout(gtx *layout.Context, button *widget.Button) {
 				Size: image.Point{X: size, Y: size},
 			}
 		})
-		pointer.EllipseAreaOp{Rect: image.Rectangle{Max: gtx.Dimensions.Size}}.Add(gtx.Ops)
+		pointer.Ellipse(image.Rectangle{Max: gtx.Dimensions.Size}).Add(gtx.Ops)
 		button.Layout(gtx)
 	})
 	bgcol := b.Background

widget/material/checkable.go

@@ -63,5 +63,5 @@ func (c *checkable) layout(gtx *layout.Context, checked bool) {
 	})
 
 	flex.Layout(gtx, ico, lbl)
-	pointer.RectAreaOp{Rect: image.Rectangle{Max: gtx.Dimensions.Size}}.Add(gtx.Ops)
+	pointer.Rect(image.Rectangle{Max: gtx.Dimensions.Size}).Add(gtx.Ops)
 }