attributes.go

package hexes

// Type representing the style of the text being written (e.g. color, font weight).
// Internally, just command sequences (a.k.a. ANSI escape codes).
type Attribute []byte

// Create an attribute joining the given.
func Join(attributes... Attribute) Attribute {
	size := len(attributes)
	for _, attribute := range attributes {
		size += len(attribute)
	}

	out := make(Attribute, size)
	index := 0

	for _, attribute := range attributes {
		index += copy(out[index:], attribute)
	}

	return out
}

var (
	NORMAL     = Attribute("\033[0m")
	BOLD       = Attribute("\033[1m")
	FAINT      = Attribute("\033[2m")
	ITALIC     = Attribute("\033[3m")
	UNDERLINE  = Attribute("\033[4m")
	SLOW_BLINK = Attribute("\033[5m")
	FAST_BLINK = Attribute("\033[6m")
	REVERSE    = Attribute("\033[7m")
	STRIKE     = Attribute("\033[8m")

	BLACK   = Attribute("\033[30m")
	RED     = Attribute("\033[31m")
	GREEN   = Attribute("\033[32m")
	YELLOW  = Attribute("\033[33m")
	BLUE    = Attribute("\033[34m")
	MAGENTA = Attribute("\033[35m")
	CYAN    = Attribute("\033[36m")
	WHITE   = Attribute("\033[37m")

	BG_BLACK   = Attribute("\033[40m")
	BG_RED     = Attribute("\033[41m")
	BG_GREEN   = Attribute("\033[42m")
	BG_YELLOW  = Attribute("\033[43m")
	BG_BLUE    = Attribute("\033[44m")
	BG_MAGENTA = Attribute("\033[45m")
	BG_CYAN    = Attribute("\033[46m")
	BG_WHITE   = Attribute("\033[47m")
)

func byteToAscii(dest []byte, num byte) {
	dest[0] = (num / 100) + '0'
	dest[1] = ((num % 100) / 10) + '0'
	dest[2] = (num % 10) + '0'
}

// Creates an attribute that sets the foreground to the RGB value.
func TrueColor(red, green, blue int) Attribute {
	//                 0    1    2    3    4    5    6   7  8  9  10   11 12 13  14  15 16 17  18
	//                Esc                                   RED         GREEN         BLUE
	sequence := []byte{27, '[', '3', '8', ';', '2', ';', 0, 0, 0, ';', 0, 0, 0, ';', 0, 0, 0, 'm'}
	byteToAscii(sequence[7:], byte(red))
	byteToAscii(sequence[11:], byte(green))
	byteToAscii(sequence[15:], byte(blue))

	return sequence
	// return fmt.Sprintf("\033[38;2;%v;%v;%vm", red, green, blue) // This version is way slower
}

// Creates an attribute that sets the background to the RGB value.
func TrueColorBg(red, green, blue int) Attribute {
	//                 0    1    2    3    4    5    6   7  8  9  10   11 12 13  14  15 16 17  18
	//                Esc                                   RED         GREEN         BLUE
	sequence := []byte{27, '[', '4', '8', ';', '2', ';', 0, 0, 0, ';', 0, 0, 0, ';', 0, 0, 0, 'm'}
	byteToAscii(sequence[7:], byte(red))
	byteToAscii(sequence[11:], byte(green))
	byteToAscii(sequence[15:], byte(blue))

	return sequence
	// return fmt.Sprintf("\033[48;2;%v;%v;%vm", red, green, blue)
}