tui/utils.go

package tui

import (
	"strings"

	"golang.org/x/text/width"
)

// WriteString writes a whole string to the buffer at position (x,y)
// no word wrap is applied at all. If the string does not fit, it will be truncated
func WriteString(b *ViewBuffer, str string, style Style, x, y int) (width int) {
	dx := x
	for _, r := range str {
		if dx >= b.Width() {
			return
		}

		b.Set(dx, y, Rune{r, style})
		dx += runeWidth(r)
	}
	return dx - x
}

// WriteMultiLineString writes a multi-line string to the buffer at position (x,y)
// no word wrap is applied at all. If a line does not fit horizontally, it will be truncated
// All lines which do not fit vertically will be truncated as well
func WriteMultiLineString(b *ViewBuffer, str string, style Style, x, y int) (maxLineWidth, lineCount int) {
	lines := strings.Split(str, "\n")
	for dy, line := range lines {
		if dy >= b.Height() {
			return
		}
		lineWidth := WriteString(b, line, style, x, y+dy)
		maxLineWidth = max(maxLineWidth, lineWidth)
	}
	return maxLineWidth, len(lines)
}

// MeasureString measures how much horizontal space str consumes when drawn to a buffer
func MeasureString(str string) (width int) {
	dx := 0
	for _, r := range str {
		dx += runeWidth(r)
	}
	return dx
}

// MeasureString measures how much horizontal and vertical space str consumes when drawn to a buffer
func MeasureMultiLineString(str string) (maxLineWidth, lineCount int) {
	lines := strings.Split(str, "\n")
	for _, line := range lines {
		lineWidth := MeasureString(line)
		maxLineWidth = max(maxLineWidth, lineWidth)
	}
	return maxLineWidth, len(lines)
}

func runeWidth(r rune) int {
	//fmt.Println(r, width.LookupRune(r).Kind())
	switch width.LookupRune(r).Kind() {
	case width.EastAsianFullwidth:
		fallthrough
	case width.EastAsianWide:
		return 2
	default:
		return 1
	}
}

func min(x, y int) int {
	if x < y {
		return x
	}
	return y
}

func max(x, y int) int {
	if x > y {
		return x
	}
	return y
}

func iff[T any](condition bool, trueValue, falseValue T) T {
	if condition {
		return trueValue
	}
	return falseValue
}

func ConstrainBufferToAnchor(buf *ViewBuffer, anchor Anchor, width, height int) *ViewBuffer {
	switch anchor {
	default:
		fallthrough
	case AnchorTopLeft:
		return buf.Sub(0, 0, width, height)
	case AnchorTop:
		return buf.Sub(buf.Width()/2-width/2, 0, width, height)
	case AnchorTopRight:
		return buf.Sub(buf.Width()-width, 0, width, height)
	case AnchorLeft:
		return buf.Sub(0, buf.Height()/2-height/2, width, height)
	case AnchorCenter:
		return buf.Sub(buf.Width()/2-width/2, buf.Height()/2-height/2, width, height)
	case AnchorRight:
		return buf.Sub(buf.Width()-width, buf.Height()/2-height/2, width, height)
	case AnchorBottomLeft:
		return buf.Sub(0, buf.Height()-height, width, height)
	case AnchorBottom:
		return buf.Sub(buf.Width()/2-width/2, buf.Height()-height, width, height)
	case AnchorBottomRight:
		return buf.Sub(buf.Width()-width, buf.Height()-height, width, height)
	}
}