layout: add background color option

1 files changed, 34 insertions, 0 deletions

diff --git a/layout/options.go b/layout/options.go
new file mode 100644
index 0000000..2ea0c81
--- /dev/null
+++ b/layout/options.go
@@ -0,0 +1,34 @@
+package layout
+
+import (
+	"image/color"
+)
+
+var (
+	defaultBg = color.Transparent
+)
+
+// Option is a function option for layout constructors.
+type Option func(*options)
+
+type options struct {
+	bg color.Color // background color
+}
+
+// Background sets the background color of a layout.
+func Background(bg color.Color) Option {
+	return func(o *options) {
+		o.bg = bg
+	}
+}
+
+// EvalOptions evaluates a list of option functions, returning the final set.
+func evalOptions(o ...Option) options {
+	opts := options{
+		bg: defaultBg,
+	}
+	for i := range o {
+		o[i](&opts)
+	}
+	return opts
+}