public static Point GetEdgeEndpointOnTriangle(Point oVertexLocation, double mDHalfWidth, Point otherEndpoint)
{
// Instead of doing geometry calculations similar to what is done in
// VertexDrawingHistory.GetEdgePointOnRectangle(), make use of that
// method by making the triangle look like a rectangle. First, figure
// out how to rotate the triangle about the vertex location so that the
// side containing the endpoint is vertical and to the right of the
// vertex location.
var dEdgeAngle = MathHelper.GetAngleBetweenPointsRadians(
oVertexLocation, otherEndpoint);
var dEdgeAngleDegrees = MathHelper.RadiansToDegrees(dEdgeAngle);
double dAngleToRotateDegrees;
if (dEdgeAngleDegrees >= -30.0 && dEdgeAngleDegrees < 90.0)
{
dAngleToRotateDegrees = 30.0;
}
else if (dEdgeAngleDegrees >= -150.0 && dEdgeAngleDegrees < -30.0)
{
dAngleToRotateDegrees = 270.0;
}
else
{
dAngleToRotateDegrees = 150.0;
}
// Now create a rotated rectangle that is centered on the vertex
// location and that has the vertical, endpoint-containing triangle
// side as the rectangle's right edge.
var dWidth = 2.0 * mDHalfWidth;
var oRotatedRectangle = new Rect(
oVertexLocation.X,
oVertexLocation.Y - mDHalfWidth,
dWidth * MathHelper.Tangent30Degrees,
dWidth
);
var oMatrix = GetRotatedMatrix(oVertexLocation,
dAngleToRotateDegrees);
// Rotate the other vertex location.
var oRotatedOtherVertexLocation = oMatrix.Transform(otherEndpoint);
// GetEdgeEndpointOnRectangle will compute an endpoint on the
// rectangle's right edge.
var oRotatedEdgeEndpoint = GetEdgeEndpointOnRectangle(oVertexLocation, oRotatedRectangle,
oRotatedOtherVertexLocation);
// Now rotate the edge endpoint in the other direction.
oMatrix = GetRotatedMatrix(oVertexLocation,
-dAngleToRotateDegrees);
return(oMatrix.Transform(oRotatedEdgeEndpoint));
}
public static PathFigure GenerateArrow(Point oArrowTipLocation, Point start, Point end, double customAngle = 0.1)
{
//Debug.Assert(dEdgeWidth > 0);
// Compute the arrow's dimensions. The width factor is arbitrary and
// was determined experimentally.
//const Double WidthFactor = 1.5;
var dArrowAngle = customAngle == 0.1 ? MathHelper.GetAngleBetweenPointsRadians(start, end) : customAngle;
var dArrowTipX = oArrowTipLocation.X;
var dArrowTipY = oArrowTipLocation.Y;
const double dArrowWidth = 3.0; //TODO dynamic width
const double dArrowHalfHeight = dArrowWidth / 2.0;
var dX = dArrowTipX - dArrowWidth;
// Compute the arrow's three points as if the arrow were at an angle of
// zero degrees, then use a rotated transform to adjust for the actual
// specified angle.
var aoPoints = new[] {
// Index 0: Arrow tip.
oArrowTipLocation,
// Index 1: Arrow bottom.
new Point(dX, dArrowTipY - dArrowHalfHeight),
// Index 2: Arrow top.
new Point(dX, dArrowTipY + dArrowHalfHeight),
// Index 3: Center of the flat end of the arrow.
//
// Note: The 0.2 is to avoid a gap between the edge endcap and the
// flat end of the arrow, but it sometimes causes the two to
// overlap slightly, and that can show if the edge isn't opaque.
// What is the correct way to get the endcap to merge invisibly
// with the arrow?
new Point(dX + 0.2, dArrowTipY)
};
var oMatrix = GetRotatedMatrix(oArrowTipLocation,
-MathHelper.RadiansToDegrees(dArrowAngle));
#if WPF
oMatrix.Transform(aoPoints);
#elif METRO
foreach (var item in aoPoints)
{
oMatrix.Transform(item);
}
#endif
return(GetPathFigureFromPoints(aoPoints[0], aoPoints[1], aoPoints[2]));
}