Method FindWrapPosLR

paint/span.go:523–568

FindWrapPosLR finds a position to do word wrapping to fit within trgSize. RelPos positions must have already been set (e.g., SetRunePosLR)

(trgSize, curSize float32)

// FindWrapPosLR finds a position to do word wrapping to fit within trgSize.
// RelPos positions must have already been set (e.g., SetRunePosLR)
func (sr *Span) FindWrapPosLR(trgSize, curSize float32) int {
	sz := len(sr.Text)
	if sz == 0 {
		return -1
	}
	idx := int(float32(sz) * (trgSize / curSize))
	if idx >= sz {
		idx = sz - 1
	}
	// find starting index that is just within size
	csz := sr.RelPos.X + sr.Render[idx].RelPosAfterLR()
	if csz > trgSize {
		for idx > 0 {
			csz = sr.RelPos.X + sr.Render[idx].RelPosAfterLR()
			if csz <= trgSize {
				break
			}
			idx--
		}
	} else {
		for idx < sz-1 {
			nsz := sr.RelPos.X + sr.Render[idx+1].RelPosAfterLR()
			if nsz > trgSize {
				break
			}
			idx++
		}
	}
	fitIdx := idx
	if unicode.IsSpace(sr.Text[idx]) {
		idx++
		for idx < sz && unicode.IsSpace(sr.Text[idx]) { // break at END of whitespace
			idx++
		}
		return idx
	}
	// find earlier space
	for idx > 0 && !unicode.IsSpace(sr.Text[idx-1]) {
		idx--
	}
	if idx > 0 {
		return idx
	}
	// no spaces within size: do a hard break at point
	return fitIdx
}

// ZeroPos ensures that the positions start at 0, for LR direction
func (sr *Span) ZeroPosLR() {