private FollowingTitle getFollowingTitle(Graphics g, LinePath part, double length, string label, TitleStyle titleStyle, BoundingRectangle viewBox, double scaleFactor)
{
StringFormat format = StringFormat.GenericTypographic;
SizeF sizeF;
PointF zeroPoint = new PointF(0, 0);
using (Font f = titleStyle.GetFont())
{
sizeF = g.MeasureString(label, f, zeroPoint, format);
// label length must be less than the length of the line
if (sizeF.Width / scaleFactor < length)
{
LinePath tempPart = new LinePath();
foreach (ICoordinate p in part.Vertices)
tempPart.Vertices.Add(p);
int vertexNumber = 0;
ICoordinate centerPoint = getDistantPoint(tempPart.Vertices, length / 2, out vertexNumber);
// if the point of the proposed mid-label misses the display area of the map, the inscription does not appear
if (!viewBox.ContainsPoint(centerPoint))
return null;
// simplify the line
tempPart.Weed(sizeF.Height / scaleFactor / 2);
//get the center point of the simplified line
centerPoint = getDistantPoint(tempPart.Vertices, length / 2, out vertexNumber);
List<double> leftPointsRotationDeltas = new List<double>();
List<double> rightPointsRotationDeltas = new List<double>();
// coordinates of points on the left of the middle of the inscription
IList<ICoordinate> leftPoints =
getLeftPoints(tempPart.Vertices,
centerPoint,
sizeF.Width / 2 / scaleFactor,
vertexNumber,
sizeF.Height / 2 / scaleFactor,
leftPointsRotationDeltas);
// coordinates of the points to the right of the middle of the inscription
IList<ICoordinate> rightPoints =
getRightPoints(tempPart.Vertices,
centerPoint,
sizeF.Width / 2 / scaleFactor,
vertexNumber,
sizeF.Height / 2 / scaleFactor,
rightPointsRotationDeltas);
//coordinates of the vertices of the broken line, which will be located along the inscription
List<ICoordinate> points = leftPoints.ToList();
points.AddRange(rightPoints);
// shifts of the inscriptions associated with break lines
List<double> rotationDeltas = leftPointsRotationDeltas;
rotationDeltas.AddRange(rightPointsRotationDeltas);
for (int i = 0; i < points.Count; i++)
points[i] = PlanimetryEnvironment.NewCoordinate((points[i].X - viewBox.MinX) * scaleFactor,
(viewBox.MaxY - points[i].Y) * scaleFactor);
for (int i = 0; i < rotationDeltas.Count; i++)
rotationDeltas[i] = rotationDeltas[i] * scaleFactor;
//determine the direction of following labels (direct or reverse)
double forwardWeight = 0;
double backwardWeight = 0;
for (int i = 1; i < points.Count; i++)
{
Segment s = new Segment(PlanimetryEnvironment.NewCoordinate(points[i].X, points[i].Y),
PlanimetryEnvironment.NewCoordinate(points[i - 1].X, points[i - 1].Y));
int quadNumber = pointQuadrantNumber(PlanimetryEnvironment.NewCoordinate(s.V1.X - s.V2.X, s.V1.Y - s.V2.Y));
if (quadNumber == 1 || quadNumber == 4)
forwardWeight += s.Length();
else
backwardWeight += s.Length();
}
if (backwardWeight > forwardWeight)
{
points.Reverse();
rotationDeltas.Reverse();
}
// inscriptions along the route should not be a large number of points
if (label.Length > points.Count - 2)
{
List<int> subStringLengths = new List<int>();
List<double> deltas = new List<double>();
LinePath p1 = new LinePath(points.ToArray());
double l = p1.Length();
// partition of the inscription on the straight parts, the calculation of displacement
int startIndex = 0;
for (int i = 1; i < points.Count; i++)
{
double currentDistance = PlanimetryAlgorithms.Distance(points[i - 1], points[i]);
if (deltas.Count > 0)
if (deltas[deltas.Count - 1] < currentDistance)
currentDistance -= deltas[deltas.Count - 1];
//subtract the offset associated with line breaks
currentDistance -= rotationDeltas[i - 1];
if (i < rotationDeltas.Count)
currentDistance -= rotationDeltas[i];
int currentLength = (int)(currentDistance / l * label.Length);
if (startIndex + currentLength > label.Length)
currentLength = label.Length - startIndex;
subStringLengths.Add(currentLength > 0 ? currentLength : 0);
string subString;
if (subStringLengths[i - 1] > 0)
subString = label.Substring(startIndex, subStringLengths[i - 1]);
else
subString = string.Empty;
float width1, width2, width3;
width1 = width2 = width3 = g.MeasureString(subString, f, zeroPoint, format).Width;
if (!string.IsNullOrEmpty(subString))
{
if (subStringLengths[i - 1] > 1)
{
width2 = g.MeasureString(label.Substring(startIndex, subStringLengths[i - 1] - 1), f, zeroPoint, format).Width;
if (Math.Abs(width2 - currentDistance) < Math.Abs(width1 - currentDistance))
{
subStringLengths[i - 1] = subStringLengths[i - 1] - 1;
width1 = width2;
}
}
if (label.Length > subStringLengths[i - 1] + startIndex)
{
width3 = g.MeasureString(label.Substring(startIndex, subStringLengths[i - 1] + 1), f, zeroPoint, format).Width;
if (Math.Abs(width3 - currentDistance) < Math.Abs(width1 - currentDistance) &&
Math.Abs(width3 - currentDistance) < sizeF.Width / label.Length / 6)
{
subStringLengths[i - 1] = subStringLengths[i - 1] + 1;
width1 = width3;
}
}
}
deltas.Add(0.5 * (width1 - currentDistance));
if (currentLength > 0)
startIndex += currentLength;
}
int sum = 0;
int maxZeroLengths = 0;
int zeroLengthsCount = 0;
foreach (int k in subStringLengths)
{
if (k <= 0)
{
zeroLengthsCount++;
if (maxZeroLengths < zeroLengthsCount)
maxZeroLengths = zeroLengthsCount;
}
else
zeroLengthsCount = 0;
sum += k;
}
if (maxZeroLengths > 1)
return null;
int lastIndex = subStringLengths.Count() - 1;
if (lastIndex >= 0)
{
subStringLengths[lastIndex] += label.Length - sum;
if (subStringLengths[lastIndex] < 0)
{
subStringLengths[lastIndex - 1] -= subStringLengths[lastIndex];
subStringLengths[lastIndex] = 0;
}
}
FollowingTitle followingTitle = new FollowingTitle();
startIndex = 0;
double? previousAngle = null;
for (int i = 0; i < subStringLengths.Count(); i++)
{
if (subStringLengths[i] <= 0)
continue;
if (startIndex + subStringLengths[i] > label.Length)
return null;
SizeF size;
size = g.MeasureString(label.Substring(startIndex, subStringLengths[i]), f, zeroPoint, format);
int x0 = (i == 0 ? 0 : (int)Math.Round(deltas[i - 1] + rotationDeltas[i - 1]));
PointF[] v = new PointF[4];
v[0].X = x0;
v[0].Y = -size.Height / 2;
v[1].X = size.Width + x0;
v[1].Y = -size.Height / 2;
v[2].X = size.Width + x0;
v[2].Y = size.Height / 2;
v[3].X = x0;
v[3].Y = size.Height / 2;
float angle = (float)(180 / Math.PI * getAngle(PlanimetryEnvironment.NewCoordinate(Math.Abs(points[i].X * 2), points[i].Y),
points[i],
points[i + 1],
false));
if (previousAngle != null)
{
double angleDelta = Math.Abs(angle - previousAngle.Value);
if (angleDelta > 45 && 360 - angleDelta > 45)
return null;
}
previousAngle = angle;
g.TranslateTransform((float)points[i].X, (float)points[i].Y);
g.RotateTransform(-(angle % 360));
g.Transform.TransformPoints(v);
for (int j = 0; j < 4; j++)
{
v[j].X = (float)(v[j].X / scaleFactor + viewBox.MinX);
v[j].Y = (float)(viewBox.MaxY - v[j].Y / scaleFactor);
}
FollowingTitleElement element =
new FollowingTitleElement(new PointF((float)points[i].X, (float)points[i].Y),
-(angle % 360),
new PointF(x0, -size.Height / 2),
label.Substring(startIndex, subStringLengths[i]),
v[0], v[1], v[2], v[3]);
startIndex += subStringLengths[i];
followingTitle.AddElement(element);
g.ResetTransform();
}
return followingTitle.EnvelopePolygon == null ? null : followingTitle;
}
}
}
return null;
}