Method PixelToCursor

texteditor/render.go:551–609

PixelToCursor finds the cursor position that corresponds to the given pixel location (e.g., from mouse click) which has had ScBBox.Min subtracted from it (i.e, relative to upper left of text area)

(pt image.Point)

// location (e.g., from mouse click) which has had ScBBox.Min subtracted from
// it (i.e, relative to upper left of text area)
func (ed *Editor) PixelToCursor(pt image.Point) lexer.Pos {
	if ed.NumLines == 0 {
		return lexer.PosZero
	}
	bb := ed.renderBBox()
	sty := &ed.Styles
	yoff := float32(bb.Min.Y)
	xoff := float32(bb.Min.X)
	stln := ed.firstVisibleLine(0)
	cln := stln
	fls := ed.charStartPos(lexer.Pos{Ln: stln}).Y - yoff
	if pt.Y < int(math32.Floor(fls)) {
		cln = stln
	} else if pt.Y > bb.Max.Y {
		cln = ed.NumLines - 1
	} else {
		got := false
		for ln := stln; ln < ed.NumLines; ln++ {
			ls := ed.charStartPos(lexer.Pos{Ln: ln}).Y - yoff
			es := ls
			es += math32.Max(ed.renders[ln].BBox.Size().Y, ed.lineHeight)
			if pt.Y >= int(math32.Floor(ls)) && pt.Y < int(math32.Ceil(es)) {
				got = true
				cln = ln
				break
			}
		}
		if !got {
			cln = ed.NumLines - 1
		}
	}
	// fmt.Printf("cln: %v  pt: %v\n", cln, pt)
	if cln >= len(ed.renders) {
		return lexer.Pos{Ln: cln, Ch: 0}
	}
	lnsz := ed.Buffer.LineLen(cln)
	if lnsz == 0 || sty.Font.Face == nil {
		return lexer.Pos{Ln: cln, Ch: 0}
	}
	scrl := ed.Geom.Scroll.Y
	nolno := float32(pt.X - int(ed.LineNumberOffset))
	sc := int((nolno + scrl) / sty.Font.Face.Metrics.Ch)
	sc -= sc / 4
	sc = max(0, sc)
	cch := sc

	lnst := ed.charStartPos(lexer.Pos{Ln: cln})
	lnst.Y -= yoff
	lnst.X -= xoff
	rpt := math32.Vector2FromPoint(pt).Sub(lnst)

	si, ri, ok := ed.renders[cln].PosToRune(rpt)
	if ok {
		cch, _ := ed.renders[cln].SpanPosToRuneIndex(si, ri)
		return lexer.Pos{Ln: cln, Ch: cch}
	}

	return lexer.Pos{Ln: cln, Ch: cch}