CalculateArrowhead Method

In This Topic

Modify an array of points to hold the four points of a polygon outlining an arrowhead

Syntax

public virtual void CalculateArrowhead( 
   PointF anchor,
   PointF endPoint,
   bool atEnd,
   PointF[] poly
)

Parameters

anchor: The arrowhead anchor position, giving the spot the arrow is coming from
endPoint: The arrowhead end point
atEnd: true if for the "To" end, false if for the "From" end
poly: An array of PointF of at least length four to hold the results

Remarks

By default the four points are as follows:

[0] the inner point on the shaft, arrow shaft length from the end point
[1] and [3] the barbs of the arrowhead, arrow width apart
[2] the tip of the arrowhead, at the end point

If necessary, the length of the arrowhead is actually scaled down to fit in the distance between the and the .

This method is normally called by Paint to produce a point array to be passed to DrawArrowhead in the following fashion:


              if (this.ToArrow && this.PointsCount >= 2) {
                PointF[] toPoly = new PointF[GetArrowheadPointsCount(true)];
                PointF anchor = this.ToArrowAnchorPoint;
                PointF end = this.ToArrowEndPoint;
                CalculateArrowhead(anchor, end, true, toPoly);
                ... now use the toPoly array ...
              }

Reference

GoStroke Class
GoStroke Members

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