Add forground options to whitespace generator

whitespace.go

@@ -19,24 +19,50 @@ func (w whitespace) render(width int) string {
 		w.chars = " "
 	}
 
-	charWidth := ansi.PrintableRuneWidth(w.chars)
-	line := strings.Repeat(w.chars, width/charWidth)
+	r := []rune(w.chars)
+	j := 0
+	b := strings.Builder{}
 
-	// Fill in gaps with spaces
-	short := width - ansi.PrintableRuneWidth(line)
-	if short > 0 {
-		line += strings.Repeat(" ", short)
+	// Cycle through runes and print them into the whitespace.
+	for i := 0; i < width; {
+		b.WriteRune(r[j])
+		j++
+		if j >= len(r) {
+			j = 0
+		}
+		i += ansi.PrintableRuneWidth(string(r[j]))
 	}
 
-	return w.style.Styled(line)
+	// Fill any extra gaps white spaces. This might be necessary if any runes
+	// are more than one cell wide, which could leave a one-rune gap.
+	short := width - ansi.PrintableRuneWidth(b.String())
+	if short > 0 {
+		b.WriteString(strings.Repeat(" ", short))
+	}
+
+	return w.style.Styled(b.String())
 }
 
 // WhiteSpaceOption sets a styling rule for rendering whitespace.
 type WhitespaceOption func(*whitespace)
 
+// WithWhitespaceForeground sets the color of the characters in the whitespace.
+func WithWhitespaceForeground(c ColorType) WhitespaceOption {
+	return func(w *whitespace) {
+		w.style = w.style.Foreground(c.color())
+	}
+}
+
 // WithWhiteSpaceBackground sets the background color of the whitespace.
-func WithWhitespaceBackground(c Color) WhitespaceOption {
+func WithWhitespaceBackground(c ColorType) WhitespaceOption {
 	return func(w *whitespace) {
 		w.style = w.style.Background(c.color())
 	}
 }
+
+// WithWhitespaceChars sets the characters to be rendered in the whitespace.
+func WithWhitespaceChars(s string) WhitespaceOption {
+	return func(w *whitespace) {
+		w.chars = s
+	}
+}