ui/layout: make Align a Direction

Removes the stutter by simplifying

	layout.Align{Alignment: layout.NE}

to

	layout.Align(layout.NE)

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

ui/layout/doc.go

@@ -38,7 +38,7 @@ This example both aligns and insets a child:
 
 	inset := layout.Inset{...}
 	inset.Layout(..., ctx, func() {
-		align := layout.Align{...}
+		align := layout.Align(...)
 		align.Layout(..., ctx, func() {
 			widget.Layout(..., ctx)
 		})

ui/layout/layout.go

@@ -113,9 +113,7 @@ type Inset struct {
 }
 
 // Align aligns a widget in the available space.
-type Align struct {
+type Align Direction
-	Alignment Direction
-}
 
 // Layout a widget.
 func (in Inset) Layout(c ui.Config, ops *ui.Ops, ctx *Context, w Widget) {
@@ -175,13 +173,13 @@ func (a Align) Layout(ops *ui.Ops, st *Context, w Widget) {
 		sz.Y = cs.Height.Min
 	}
 	var p image.Point
-	switch a.Alignment {
+	switch Direction(a) {
 	case N, S, Center:
 		p.X = (sz.X - dims.Size.X) / 2
 	case NE, SE, E:
 		p.X = sz.X - dims.Size.X
 	}
-	switch a.Alignment {
+	switch Direction(a) {
 	case W, Center, E:
 		p.Y = (sz.Y - dims.Size.Y) / 2
 	case SW, S, SE:

ui/layout/layout_test.go

@@ -47,7 +47,7 @@ func ExampleAlign() {
 	// Rigid constraints with both minimum and maximum set.
 	ctx.Constraints = layout.RigidConstraints(image.Point{X: 100, Y: 100})
 
-	align := layout.Align{Alignment: layout.Center}
+	align := layout.Align(layout.Center)
 	align.Layout(ops, ctx, func() {
 		// Lay out a 50x50 sized widget.
 		layoutWidget(ctx, 50, 50)