gotui/border_merge.go at master · metaspartan/gotui · GitHub

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package gotui

const (
	BorderTop    = 1
	BorderRight  = 2
	BorderBottom = 4
	BorderLeft   = 8
)
const (
	CROSS = '┼'
)

var borderMap = map[rune]int{}
var maskToRune = map[int]rune{}

func init() {
	borderMap = map[rune]int{
		HORIZONTAL_LINE: BorderLeft | BorderRight,
		VERTICAL_LINE:   BorderTop | BorderBottom,
		TOP_LEFT:        BorderRight | BorderBottom,
		TOP_RIGHT:       BorderLeft | BorderBottom,
		BOTTOM_LEFT:     BorderRight | BorderTop,
		BOTTOM_RIGHT:    BorderLeft | BorderTop,
		VERTICAL_RIGHT:  BorderTop | BorderBottom | BorderRight,
		VERTICAL_LEFT:   BorderTop | BorderBottom | BorderLeft,
		HORIZONTAL_DOWN: BorderLeft | BorderRight | BorderBottom,
		HORIZONTAL_UP:   BorderLeft | BorderRight | BorderTop,
		CROSS:           BorderTop | BorderBottom | BorderLeft | BorderRight,
		' ':             0,
	}
	maskToRune = map[int]rune{
		(BorderLeft | BorderRight):                            HORIZONTAL_LINE,
		(BorderTop | BorderBottom):                            VERTICAL_LINE,
		(BorderRight | BorderBottom):                          TOP_LEFT,
		(BorderLeft | BorderBottom):                           TOP_RIGHT,
		(BorderRight | BorderTop):                             BOTTOM_LEFT,
		(BorderLeft | BorderTop):                              BOTTOM_RIGHT,
		(BorderTop | BorderBottom | BorderRight):              VERTICAL_RIGHT,
		(BorderTop | BorderBottom | BorderLeft):               VERTICAL_LEFT,
		(BorderLeft | BorderRight | BorderBottom):             HORIZONTAL_DOWN,
		(BorderLeft | BorderRight | BorderTop):                HORIZONTAL_UP,
		(BorderTop | BorderBottom | BorderLeft | BorderRight): CROSS,
		0: ' ',
	}
}
func ResolveBorderRune(existing, newRune rune) rune {
	m1, ok1 := borderMap[existing]
	m2, ok2 := borderMap[newRune]
	if ok1 && ok2 {
		combined := m1 | m2
		if r, found := maskToRune[combined]; found {
			return r
		}
	}
	return newRune
}