layout: add background color option

1 files changed, 9 insertions, 4 deletions

diff --git a/layout/region.go b/layout/region.go
index 1e92455..4e3a791 100644
--- a/layout/region.go
+++ b/layout/region.go
@@ -15,7 +15,9 @@ type Region struct {
 
 // NewRegion creates a region layout that occupies part of the parent env's area, as determined by the resize function.
 // Resize takes the area of the parent and returns the area of the region.
-func NewRegion(env gui.Env, resize func(image.Rectangle) image.Rectangle) gui.Env {
+func NewRegion(env gui.Env, resize func(image.Rectangle) image.Rectangle, o ...Option) gui.Env {
+	opts := evalOptions(o...)
+
 	events := make(chan gui.Event)                     // to child
 	drw := make(chan func(draw.Image) image.Rectangle) // from child
 
@@ -25,17 +27,20 @@ func NewRegion(env gui.Env, resize func(image.Rectangle) image.Rectangle) gui.En
 		area := resize(event.(gui.Resize).Rectangle) // first event guaranteed to be Resize
 		events <- gui.Resize{area}
 
+		env.Draw() <- drawBackground(opts.bg)
+
 		for {
 			select {
-			case event := <-env.Events():
+			case event := <-env.Events(): // event from parent
 				switch event := event.(type) {
 				case gui.Resize:
+					env.Draw() <- drawBackground(opts.bg)
 					area = resize(event.Rectangle)
-					events <- gui.Resize{area}
+					events <- gui.Resize{area} // forward to child
 				default:
 					events <- event
 				}
-			case f, ok := <-drw:
+			case f, ok := <-drw: // draw call from child
 				if !ok {
 					close(events)
 					close(env.Draw())