//
// Summary:
// Translates the specified System.Windows.Point by the specified System.Windows.Vector
// and returns the result.
//
// Parameters:
// point:
// The point to translate.
//
// vector:
// The amount by which to translate point.
//
// Returns:
// The result of translating the specified point by the specified vector.
public static PointHelper operator +(PointHelper point, Vector vector)
{
var result = new PointHelper();
result._value.X = vector.X + point.Value.X;
result._value.Y = vector.Y + point.Value.Y;
return result;
}
private void FlattenArc(List<Point> points, Point pt1, Point pt2,
double radiusX, double radiusY, double angleRotation,
bool isLargeArc, bool isCounterclockwise,
double tolerance)
{
// Adjust for different radii and rotation angle
#if SILVERLIGHT
var matx = new MatrixHelper();
matx.Rotate(-angleRotation);
matx.Scale(radiusY / radiusX, 1);
pt1 = matx.Value.Transform(pt1);
pt2 = matx.Value.Transform(pt2);
#else
Matrix matx = new Matrix();
matx.Rotate(-angleRotation);
matx.Scale(radiusY / radiusX, 1);
pt1 = matx.Transform(pt1);
pt2 = matx.Transform(pt2);
#endif
// Get info about chord that connects both points
var midPoint = new Point((pt1.X + pt2.X) / 2, (pt1.Y + pt2.Y) / 2);
#if SILVERLIGHT
Vector vect = new PointHelper(pt2) - new PointHelper(pt1);
#else
Vector vect = pt2 - pt1;
#endif
double halfChord = vect.Length / 2;
// Get vector from chord to center
Vector vectRotated;
// (comparing two Booleans here!)
vectRotated = isLargeArc == isCounterclockwise ? new Vector(-vect.Y, vect.X) : new Vector(vect.Y, -vect.X);
vectRotated.Normalize();
// Distance from chord to center
double centerDistance = Math.Sqrt(radiusY * radiusY - halfChord * halfChord);
// Calculate two center points
Point center = midPoint + centerDistance * vectRotated;
// Get angles from center to the two points
double angle1 = Math.Atan2(pt1.Y - center.Y, pt1.X - center.X);
double angle2 = Math.Atan2(pt2.Y - center.Y, pt2.X - center.X);
// (another comparison of two Booleans!)
if (isLargeArc == (Math.Abs(angle2 - angle1) < Math.PI))
{
if (angle1 < angle2)
angle1 += 2 * Math.PI;
else
angle2 += 2 * Math.PI;
}
// Invert matrix for final point calculation
matx.Invert();
// Calculate number of points for polyline approximation
var max = (int)((4 * (radiusX + radiusY) * Math.Abs(angle2 - angle1) / (2 * Math.PI)) / tolerance);
// Loop through the points
for (int i = 0; i <= max; i++)
{
double angle = ((max - i) * angle1 + i * angle2) / max;
double x = center.X + radiusY * Math.Cos(angle);
double y = center.Y + radiusY * Math.Sin(angle);
// Transform the point back
Point pt = matx.Transform(new Point(x, y));
points.Add(pt);
}
}