Add borderFocusStyle to box

box.go

@@ -36,6 +36,9 @@ type Box struct {
 	// The border style.
 	borderStyle tcell.Style
 
+	// The border focus style.
+	borderFocusStyle tcell.Style
+
 	// The title. Only visible if there is a border, too.
 	title string
 
@@ -76,6 +79,7 @@ func NewBox() *Box {
 		innerX:           -1, // Mark as uninitialized.
 		backgroundColor:  Styles.PrimitiveBackgroundColor,
 		borderStyle:      tcell.StyleDefault.Foreground(Styles.BorderColor).Background(Styles.PrimitiveBackgroundColor),
+		borderFocusStyle: tcell.StyleDefault.Foreground(Styles.BorderColor).Background(Styles.PrimitiveBackgroundColor),
 		titleColor:       Styles.TitleColor,
 		titleAlign:       AlignCenter,
 	}
@@ -253,10 +257,11 @@ func (b *Box) GetMouseCapture() func(action MouseAction, event *tcell.EventMouse
 func (b *Box) SetBackgroundColor(color tcell.Color) *Box {
 	b.backgroundColor = color
 	b.borderStyle = b.borderStyle.Background(color)
+	b.borderFocusStyle = b.borderFocusStyle.Background(color)
 	return b
 }
 
-// SetBorder sets the flag indicating whether or not the box should have a
+// SetBorder sets the flag indicating whether the box should have a
 // border.
 func (b *Box) SetBorder(show bool) *Box {
 	b.border = show
@@ -290,6 +295,33 @@ func (b *Box) GetBorderColor() tcell.Color {
 	return color
 }
 
+// SetBorderFocusColor sets the box's border focus color.
+func (b *Box) SetBorderFocusColor(color tcell.Color) *Box {
+	b.borderFocusStyle = b.borderFocusStyle.Foreground(color)
+	return b
+}
+
+// SetBorderFocusAttributes sets the border's focus style attributes. You can combine
+// different attributes using bitmask operations:
+//
+//   box.SetBorderFocusAttributes(tcell.AttrUnderline | tcell.AttrBold)
+func (b *Box) SetBorderFocusAttributes(attr tcell.AttrMask) *Box {
+	b.borderFocusStyle = b.borderFocusStyle.Attributes(attr)
+	return b
+}
+
+// GetBorderFocusAttributes returns the border's focus style attributes.
+func (b *Box) GetBorderFocusAttributes() tcell.AttrMask {
+	_, _, attr := b.borderFocusStyle.Decompose()
+	return attr
+}
+
+// GetBorderFocusColor returns the box's border focus color.
+func (b *Box) GetBorderFocusColor() tcell.Color {
+	color, _, _ := b.borderFocusStyle.Decompose()
+	return color
+}
+
 // GetBackgroundColor returns the box's background color.
 func (b *Box) GetBackgroundColor() tcell.Color {
 	return b.backgroundColor
@@ -351,7 +383,9 @@ func (b *Box) DrawForSubclass(screen tcell.Screen, p Primitive) {
 	// Draw border.
 	if b.border && b.width >= 2 && b.height >= 2 {
 		var vertical, horizontal, topLeft, topRight, bottomLeft, bottomRight rune
+		var borderStyle tcell.Style
 		if p.HasFocus() {
+			borderStyle = b.borderFocusStyle
 			horizontal = Borders.HorizontalFocus
 			vertical = Borders.VerticalFocus
 			topLeft = Borders.TopLeftFocus
@@ -359,6 +393,7 @@ func (b *Box) DrawForSubclass(screen tcell.Screen, p Primitive) {
 			bottomLeft = Borders.BottomLeftFocus
 			bottomRight = Borders.BottomRightFocus
 		} else {
+			borderStyle = b.borderStyle
 			horizontal = Borders.Horizontal
 			vertical = Borders.Vertical
 			topLeft = Borders.TopLeft
@@ -367,17 +402,17 @@ func (b *Box) DrawForSubclass(screen tcell.Screen, p Primitive) {
 			bottomRight = Borders.BottomRight
 		}
 		for x := b.x + 1; x < b.x+b.width-1; x++ {
-			screen.SetContent(x, b.y, horizontal, nil, b.borderStyle)
-			screen.SetContent(x, b.y+b.height-1, horizontal, nil, b.borderStyle)
+			screen.SetContent(x, b.y, horizontal, nil, borderStyle)
+			screen.SetContent(x, b.y+b.height-1, horizontal, nil, borderStyle)
 		}
 		for y := b.y + 1; y < b.y+b.height-1; y++ {
-			screen.SetContent(b.x, y, vertical, nil, b.borderStyle)
-			screen.SetContent(b.x+b.width-1, y, vertical, nil, b.borderStyle)
+			screen.SetContent(b.x, y, vertical, nil, borderStyle)
+			screen.SetContent(b.x+b.width-1, y, vertical, nil, borderStyle)
 		}
-		screen.SetContent(b.x, b.y, topLeft, nil, b.borderStyle)
-		screen.SetContent(b.x+b.width-1, b.y, topRight, nil, b.borderStyle)
-		screen.SetContent(b.x, b.y+b.height-1, bottomLeft, nil, b.borderStyle)
-		screen.SetContent(b.x+b.width-1, b.y+b.height-1, bottomRight, nil, b.borderStyle)
+		screen.SetContent(b.x, b.y, topLeft, nil, borderStyle)
+		screen.SetContent(b.x+b.width-1, b.y, topRight, nil, borderStyle)
+		screen.SetContent(b.x, b.y+b.height-1, bottomLeft, nil, borderStyle)
+		screen.SetContent(b.x+b.width-1, b.y+b.height-1, bottomRight, nil, borderStyle)
 
 		// Draw title.
 		if b.title != "" && b.width >= 4 {