v0.2.0 16 colors, default colors, /dev/tty, bracketed paste, themed form controls

tui/style.go

@@ -5,7 +5,9 @@ import (
 	"github.com/lixenwraith/terminal"
 )
 
-// Style bundles foreground, background, and attributes for text rendering
+// Style bundles foreground, background, and attributes for text rendering.
+// Attr's color bits say how to read Fg and Bg: terminal.AttrFg256 a palette
+// index in R, terminal.AttrFgDefault the terminal's own color.
 type Style struct {
 	Fg   color.RGB
 	Bg   color.RGB
@@ -22,3 +24,12 @@ func (s Style) IsZero() bool {
 	return s.Fg == (color.RGB{}) && s.Bg == (color.RGB{}) && s.Attr == terminal.AttrNone
 }
 
+// On returns s drawn on bg: s's foreground, bg's background (s's own where
+// bg's is transparent), and the attributes of both
+func (s Style) On(bg Style) Style {
+	out := Style{Fg: s.Fg, Bg: s.Bg, Attr: s.Attr | bg.Attr&terminal.AttrStyle}
+	if bg.Bg != (color.RGB{}) || bg.Attr&terminal.AttrBgColor != 0 {
+		out.Bg, out.Attr = bg.Bg, out.Attr&^terminal.AttrBgColor|bg.Attr&terminal.AttrBgColor
+	}
+	return out
+}