/// <summary>
/// Draws the scale ticks, with an invisible circle with r=MeterRadius bisecting each tick
/// </summary>
/// <param name="tickLength">The length of each tick</param>
/// <param name="group">The geometry group to add each tick to</param>
/// <param name="startAngle">The angle to start drawing ticks at, relative to the negative Y axis</param>
private void DrawScale(double tickLength, GeometryGroup group, double startAngle = 0.0)
{
MeterTickPoints?.Clear();
if (Intervals == null)
{
return;
}
foreach (var interval in Intervals)
{
DrawInterval(interval, tickLength, group, startAngle);
startAngle += (interval.EndDegree - interval.StartDegree) * (Math.PI / 180);
}
}
/// <summary>
/// Draws an interval for the meter
/// </summary>
/// <param name="interval">The MeterRangeInteraval which represents this range of the meter</param>
/// <param name="tickLength">The length of the ticks for this range</param>
/// <param name="group">The geometry group to add this to add this to</param>
/// <param name="startAngle"></param>
private void DrawInterval(MeterRangeInterval interval, double tickLength, GeometryGroup group, double startAngle = 0.0)
{
double startRad = interval.StartDegree * (Math.PI / 180), endRad = interval.EndDegree * (Math.PI / 180);
double radianInterval = (endRad - startRad) * (interval.TickInterval / (interval.EndValue - interval.StartValue));
var tickCount = (uint)((endRad - startRad) / radianInterval);
for (var i = 0; i <= tickCount; i++)
{
var pathGeometry = new PathGeometry();
var figure = new PathFigure();
// draw tick line
double x1 = MeterRadius * Math.Sin(startAngle),
y1 = MeterRadius * Math.Cos(startAngle),
x2 = (MeterRadius + tickLength) * Math.Sin(startAngle),
y2 = (MeterRadius + tickLength) * Math.Cos(startAngle),
labelX = (MeterRadius + LabelOffset + (tickLength / 2)) * Math.Sin(startAngle),
labelY = (MeterRadius + LabelOffset + (tickLength / 2)) * Math.Cos(startAngle);
figure.StartPoint = new Point(Radius + x1, Radius - y1);
var line = new LineSegment
{
Point = new Point(Radius + x2, Radius - y2)
};
MeterTickPoints?.Add(new TickPoint()
{
// midway point in the tick - the point the tick crosses the meter circle
Point = new Point(Radius + (MeterRadius * Math.Sin(startAngle)), Radius - (MeterRadius * Math.Cos(startAngle))),
LabelPoint = new Point(Radius + labelX, Radius - labelY),
Value = i * interval.TickInterval + interval.StartValue
});
figure.Segments.Add(line);
pathGeometry.Figures.Add(figure);
group.Children.Add(pathGeometry);
startAngle += radianInterval;
}
}
