public RenderContext(ResourceManager resourceManager, Selector selector, RectangleF tileRect,
double scale, MapOptions options, Stylesheet styles, Size tileSize)
{
this.resourceManager = resourceManager;
this.selector = selector;
this.tileRect = tileRect;
this.scale = scale;
this.options = options;
this.styles = styles;
this.tileSize = tileSize;
XMatrix m = new XMatrix();
m.TranslatePrepend((float)(-tileRect.Left * scale * Astrometrics.ParsecScaleX), (float)(-tileRect.Top * scale * Astrometrics.ParsecScaleY));
m.ScalePrepend((float)scale * Astrometrics.ParsecScaleX, (float)scale * Astrometrics.ParsecScaleY);
imageSpaceToWorldSpace = m;
m.Invert();
worldSpaceToImageSpace = m;
}
/// <summary>
/// Creates between 1 and 5 Béziers curves from parameters specified like in WPF.
/// </summary>
public static List<XPoint> BezierCurveFromArc(XPoint point1, XPoint point2, XSize size,
double rotationAngle, bool isLargeArc, bool clockwise, PathStart pathStart)
{
// See also http://www.charlespetzold.com/blog/blog.xml from January 2, 2008:
// http://www.charlespetzold.com/blog/2008/01/Mathematics-of-ArcSegment.html
double δx = size.Width;
double δy = size.Height;
Debug.Assert(δx * δy > 0);
double factor = δy / δx;
bool isCounterclockwise = !clockwise;
// Adjust for different radii and rotation angle.
XMatrix matrix = new XMatrix();
matrix.RotateAppend(-rotationAngle);
matrix.ScaleAppend(δy / δx, 1);
XPoint pt1 = matrix.Transform(point1);
XPoint pt2 = matrix.Transform(point2);
// Get info about chord that connects both points.
XPoint midPoint = new XPoint((pt1.X + pt2.X) / 2, (pt1.Y + pt2.Y) / 2);
XVector vect = pt2 - pt1;
double halfChord = vect.Length / 2;
// Get vector from chord to center.
XVector vectRotated;
// (comparing two Booleans here!)
if (isLargeArc == isCounterclockwise)
vectRotated = new XVector(-vect.Y, vect.X);
else
vectRotated = new XVector(vect.Y, -vect.X);
vectRotated.Normalize();
// Distance from chord to center.
double centerDistance = Math.Sqrt(δy * δy - halfChord * halfChord);
if (double.IsNaN(centerDistance))
centerDistance = 0;
// Calculate center point.
XPoint center = midPoint + centerDistance * vectRotated;
// Get angles from center to the two points.
double α = Math.Atan2(pt1.Y - center.Y, pt1.X - center.X);
double β = Math.Atan2(pt2.Y - center.Y, pt2.X - center.X);
// (another comparison of two Booleans!)
if (isLargeArc == (Math.Abs(β - α) < Math.PI))
{
if (α < β)
α += 2 * Math.PI;
else
β += 2 * Math.PI;
}
// Invert matrix for final point calculation.
matrix.Invert();
double sweepAngle = β - α;
// Let the algorithm of GDI+ DrawArc to Bézier curves do the rest of the job
return BezierCurveFromArc(center.X - δx * factor, center.Y - δy, 2 * δx * factor, 2 * δy,
α / Calc.Deg2Rad, sweepAngle / Calc.Deg2Rad, pathStart, ref matrix);
}
/// <summary>
/// Some test code to check that there are no typing errors in the formulars.
/// </summary>
public static void Test()
{
XMatrix xm1 = new XMatrix(23, -35, 837, 332, -3, 12);
Matrix m1 = new Matrix(23, -35, 837, 332, -3, 12);
DumpMatrix(xm1, m1);
XMatrix xm2 = new XMatrix(12, 235, 245, 42, 33, -56);
Matrix m2 = xm2.ToMatrix();
DumpMatrix(xm2, m2);
// xm1.Multiply(xm2, XMatrixOrder.Prepend);
// m1.Multiply(m2, MatrixOrder.Append);
xm1.Multiply(xm2, XMatrixOrder.Append);
m1.Multiply(m2, MatrixOrder.Append);
DumpMatrix(xm1, m1);
xm1.Translate(-243, 342, XMatrixOrder.Append);
m1.Translate(-243, 342, MatrixOrder.Append);
DumpMatrix(xm1, m1);
xm1.Scale(-5.66, 7.87);
m1.Scale(-5.66f, 7.87f);
// xm1.Scale(-5.66, 7.87, XMatrixOrder.Prepend);
// m1.Scale(-5.66f, 7.87f, MatrixOrder.Prepend);
DumpMatrix(xm1, m1);
xm1.Rotate(135, XMatrixOrder.Append);
m1.Rotate(135, MatrixOrder.Append);
// xm1.Scale(-5.66, 7.87, XMatrixOrder.Prepend);
// m1.Scale(-5.66f, 7.87f, MatrixOrder.Prepend);
DumpMatrix(xm1, m1);
xm1.RotateAt(177, new XPoint(-3456, 654), XMatrixOrder.Append);
m1.RotateAt(177, new PointF(-3456, 654), MatrixOrder.Append);
DumpMatrix(xm1, m1);
xm1.Shear(0.76, -0.87, XMatrixOrder.Prepend);
m1.Shear(0.76f, -0.87f, MatrixOrder.Prepend);
DumpMatrix(xm1, m1);
xm1 = new XMatrix(23, -35, 837, 332, -3, 12);
m1 = new Matrix(23, -35, 837, 332, -3, 12);
XPoint[] xpoints = new XPoint[3]{new XPoint(23, 10), new XPoint(-27, 120), new XPoint(-87, -55)};
PointF[] points = new PointF[3]{new PointF(23, 10), new PointF(-27, 120), new PointF(-87, -55)};
xm1.TransformPoints(xpoints);
m1.TransformPoints(points);
xm1.Invert();
m1.Invert();
DumpMatrix(xm1, m1);
}
