// parsePolygon parses a polygon.
func (p *Parser) parsePolygon(
parent elem,
lines [][]byte,
x, y int,
) error {
var pg Polygon
pg.X = append(pg.X, float64(x))
pg.Y = append(pg.Y, float64(y))
startX := x
startY := y
outEdges := outgoingEdges(lines, x, y)
switch bit.Count(outEdges) {
case 0:
return &ParseError{X: x, Y: y, Err: ErrPolyCornerNoEdge}
case 1:
return &ParseError{X: x, Y: y, Err: ErrPolyCornerOneEdge}
case 2:
// nothing
default:
return &ParseError{X: x, Y: y, Err: ErrPolyCornerTooManyEdges}
}
var edge byte
if outEdges&eEdge > 0 {
edge = wEdge
x++
} else if outEdges&seEdge > 0 {
edge = nwEdge
x++
y++
} else if outEdges&sEdge > 0 {
edge = nEdge
y++
}
endX, endY, arrowEnd, dotted, endCorner, err := followLine(&pg, lines, x, y,
edgeState, edge, false, true)
if err != nil {
return err
}
// check final point
if endCorner {
if endX != startX || endY != startY {
return &ParseError{X: startX, Y: startY, Err: ErrPolygonNotClosed}
}
pg.Dotted = append(pg.Dotted, dotted)
// scale
pg.scale(p)
// add polygon to parent
parent.addElem(&pg)
} else {
// we got a polyline and not a polygon, this is the end
var (
pls Polyline // start
ple Polyline // end
pl Polyline // final
)
ple.X = pg.X
ple.Y = pg.Y
ple.X = append(ple.X, float64(endX))
ple.Y = append(ple.Y, float64(endY))
ple.ArrowEnd = arrowEnd
ple.Dotted = pg.Dotted
ple.Dotted = append(ple.Dotted, dotted)
// go into other direction to get start
x, y, arrowEnd, dotted, _, err := followLine(&pls, lines, startX,
startY, cornerState, 0, false, false)
if err != nil {
return err
}
pls.ArrowEnd = arrowEnd
pls.X = append(pls.X, float64(x))
pls.Y = append(pls.Y, float64(y))
pls.Dotted = append(pls.Dotted, dotted)
pl.ArrowStart = pls.ArrowEnd
pl.ArrowEnd = ple.ArrowEnd
for i := len(pls.X) - 1; i >= 0; i-- {
pl.X = append(pl.X, pls.X[i])
pl.Y = append(pl.Y, pls.Y[i])
}
for i := len(pls.Dotted) - 1; i >= 0; i-- {
pl.Dotted = append(pl.Dotted, pls.Dotted[i])
}
for i := 0; i < len(ple.X); i++ {
pl.X = append(pl.X, ple.X[i])
pl.Y = append(pl.Y, ple.Y[i])
}
for i := 0; i < len(ple.Dotted); i++ {
pl.Dotted = append(pl.Dotted, ple.Dotted[i])
}
// scale
pl.scale(p)
// add polygon to parent
parent.addElem(&pl)
}
return nil
}
func followLine(
poly appender,
lines [][]byte,
x, y int,
state, edge byte,
dotted, endEmptyCorner bool,
) (outX, outY int, arrowEnd, outDotted, endCorner bool, err error) {
for {
switch state {
case cornerState:
lines[y][x] = ' ' // nom nom nom
// process corner (+)
outEdges := outgoingEdges(lines, x, y)
switch bit.Count(outEdges) {
case 0:
if !endEmptyCorner {
return 0, 0, false, false, false,
&ParseError{X: x, Y: y, Err: ErrPolyCornerOneEdge}
}
endCorner = true
state = endState
case 1:
// add segement
poly.appendPoint(float64(x), float64(y), dotted)
dotted = false
// follow edge
switch {
case outEdges&nEdge > 0:
edge = sEdge
y--
case outEdges&neEdge > 0:
edge = swEdge
x++
y--
case outEdges&eEdge > 0:
edge = wEdge
x++
case outEdges&seEdge > 0:
edge = nwEdge
x++
y++
case outEdges&sEdge > 0:
edge = nEdge
y++
case outEdges&swEdge > 0:
edge = neEdge
x--
y++
case outEdges&wEdge > 0:
edge = eEdge
x--
case outEdges&nwEdge > 0:
edge = seEdge
x--
y--
}
dotted = startsDotted(lines, x, y, edge)
state = edgeState
default:
// TODO: split
return 0, 0, false, false, false,
errors.New("poly split not implemented")
}
case edgeState:
next, a, d := procEdge(lines, &x, &y, edge)
if a {
arrowEnd = true
}
if d {
dotted = true
}
state = next
case endState:
lines[y][x] = ' ' // nom nom nom
outX = x
outY = y
outDotted = dotted
return
}
}
}
