Question

I hope there will be an easy answer, as often times, something stripped out of Compact Framework has a way of being performed in a seemingly roundabout manner, but works just as well as the full framework (or can be made more efficient).

Simply put, I wish to be able to do a function similar to System.Drawing.Graphics.DrawArc(…) in Compact Framework 2.0.

It is for a UserControl’s OnPaint override, where an arc is being drawn inside an ellipse I already filled.

Essentially (close pseudo code, please ignore imperfections in parameters):

FillEllipse(ellipseFillBrush, largeEllipseRegion);
DrawArc(arcPen, innerEllipseRegion, startAngle, endAngle); //not available in CF

I am only drawing arcs in 90 degree spaces, so the bottom right corner of the ellipse’s arc, or the top left. If the answer for ANY angle is really roundabout, difficult, or inefficient, while there’s an easy solution for just doing just a corner of an ellipse, I’m fine with the latter, though the former would help anyone else who has a similar question.

Answer 1

I use this code, then use FillPolygon or DrawPolygon with the output points:

private Point[] CreateArc(float StartAngle, float SweepAngle, int PointsInArc, int Radius, int xOffset, int yOffset, int LineWidth)
{
    if(PointsInArc < 0)
        PointsInArc = 0;

    if(PointsInArc > 360)
        PointsInArc = 360;

    Point[] points = new Point[PointsInArc * 2];
    int xo;
    int yo;
    int xi;
    int yi;
    float degs;
    double rads;

    for(int p = 0 ; p < PointsInArc ; p++)
    {
        degs = StartAngle + ((SweepAngle / PointsInArc) * p);

        rads = (degs * (Math.PI / 180));

        xo = (int)(Radius * Math.Sin(rads));
        yo = (int)(Radius * Math.Cos(rads));
        xi = (int)((Radius - LineWidth) * Math.Sin(rads));
        yi = (int)((Radius - LineWidth) * Math.Cos(rads));

        xo += (Radius + xOffset);
        yo = Radius - yo + yOffset;
        xi += (Radius + xOffset);
        yi = Radius - yi + yOffset;

        points[p] = new Point(xo, yo);
        points[(PointsInArc * 2) - (p + 1)] = new Point(xi, yi);
    }

    return points;
}