/// <summary>
/// Determine what ratio amounts to a given pixel distance
/// </summary>
/// <param name="p_points">
/// A <see cref="Point"/> array of 4 points specifying the Bezier curve to analyze
/// </param>
/// <param name="p_pixels">
/// A <see cref="System.Int32"/> indicating how many pixels the returned ratio should indicate
/// </param>
/// <returns>
/// A <see cref="System.Double"/> representing the ratio on the curve that amounts to p_pixels distance
/// </returns>
static public double CalculateRatioSizeToPixelAccuracy(Point [] p_points, int p_pixels)
{
if (p_points.Length != 4)
{
throw new Exception("p_points array passed to GetRatioSizeToPixelAccuracy must have exactly 4 items, this one has " + p_points.Length);
}
double testRatio = 1.0d;
PointF prevPoint = BezierSprite.CalculatePoint(p_points, 0.0d);
// first cut test ratio in half repeatedly until we fall below the requested
// pixel threshold, then increment the ratio back up by .01 until we hit the
// threshold again.
while (true)
{
testRatio /= 2.0d;
PointF nextPoint = BezierSprite.CalculatePoint(p_points, testRatio);
if (BezierSprite.Hypot(prevPoint, nextPoint) < p_pixels)
{
while (true)
{
testRatio += 0.01d;
PointF nextPoint2 = BezierSprite.CalculatePoint(p_points, testRatio);
if (BezierSprite.Hypot(prevPoint, nextPoint2) > p_pixels)
{
break;
}
}
break;
}
}
return(testRatio);
}
