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public DrawPoints ( SKPointMode mode, |
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| mode | SKPointMode | |
| points | ||
| paint | ||
| return | void | |
void DrawArcFromTo (SKCanvas canvas, SKPaint paint, int xc, int yc, int radius,
float startAngleInDegrees, float endAngleInDegrees)
{
if (radius <= 0)
return;
int x = radius;
int y = 0;
int cd2 = 0;
// convert degrees to radians
var startAngleRadians = startAngleInDegrees * Math.PI / 180;
var endAngleRadians = endAngleInDegrees * Math.PI / 180;
// find x,y coordinates for start and end points
var startx = xc + radius * (float)Math.Cos (startAngleRadians);
var starty = yc + radius * (float)Math.Sin (startAngleRadians);
var startPoint = new SKPoint (startx, starty);
var endx = xc + radius * (float)Math.Cos (endAngleRadians);
var endy = yc + radius * (float)Math.Sin (endAngleRadians);
var endPoint = new SKPoint (endx, endy);
// build the path
var points = new List<SKPoint> ();
// 4 cardinal points
var p00 = new SKPoint (xc - radius, yc);
var ap00 = Math.Atan2 (p00.Y - yc, p00.X - xc) * 180 / Math.PI;
if (IsAngleBetween ((int)ap00, (int)startAngleInDegrees, (int)endAngleInDegrees))
points.Add (p00);
var p01 = new SKPoint (xc + radius, yc);
var ap01 = Math.Atan2 (p01.Y - yc, p01.X - xc) * 180 / Math.PI;
if (IsAngleBetween ((int)ap01, (int)startAngleInDegrees, (int)endAngleInDegrees))
points.Add (p01);
var p02 = new SKPoint (xc, yc - radius);
var ap02 = Math.Atan2 (p02.Y - yc, p02.X - xc) * 180 / Math.PI;
if (IsAngleBetween ((int)ap02, (int)startAngleInDegrees, (int)endAngleInDegrees))
points.Add (p02);
var p03 = new SKPoint (xc, yc + radius);
var ap03 = Math.Atan2 (p03.Y - yc, p03.X - xc) * 180 / Math.PI;
if (IsAngleBetween ((int)ap03, (int)startAngleInDegrees, (int)endAngleInDegrees))
points.Add (p03);
while (x > y)
{
x--;
y++;
cd2 -= x - y;
if (cd2 < 0)
cd2 += x++;
// 8 octants - listed clockwise
// right hemisphere, starting at the top
var p0 = new SKPoint (xc + y, yc - x);
var arp0 = Math.Atan2 (p0.Y - yc, p0.X - xc) * 180 / Math.PI;
if (IsAngleBetween ((int)arp0, (int)startAngleInDegrees, (int)endAngleInDegrees))
points.Add (p0);
var p1 = new SKPoint (xc + x, yc - y);
var arp1 = Math.Atan2 (p1.Y - yc, p1.X - xc) * 180 / Math.PI;
if (IsAngleBetween ((int)arp1, (int)startAngleInDegrees, (int)endAngleInDegrees))
points.Add (p1);
var p2 = new SKPoint (xc + x, yc + y);
var arp2 = Math.Atan2 (p2.Y - yc, p2.X - xc) * 180 / Math.PI;
if (IsAngleBetween ((int)arp2, (int)startAngleInDegrees, (int)endAngleInDegrees))
points.Add (p2);
var p3 = new SKPoint (xc + y, yc + x);
var arp3 = Math.Atan2 (p3.Y - yc, p3.X - xc) * 180 / Math.PI;
if (IsAngleBetween ((int)arp3, (int)startAngleInDegrees, (int)endAngleInDegrees))
points.Add (p3);
// left hemisphere, continuing around from the bottom
var p4 = new SKPoint (xc - y, yc + x);
var arp4 = Math.Atan2 (p4.Y - yc, p4.X - xc) * 180 / Math.PI;
if (IsAngleBetween ((int)arp4, (int)startAngleInDegrees, (int)endAngleInDegrees))
points.Add (p4);
var p5 = new SKPoint (xc - x, yc + y);
var arp5 = Math.Atan2 (p5.Y - yc, p5.X - xc) * 180 / Math.PI;
if (IsAngleBetween ((int)arp5, (int)startAngleInDegrees, (int)endAngleInDegrees))
points.Add (p5);
var p6 = new SKPoint (xc - x, yc - y);
var arp6 = Math.Atan2 (p6.Y - yc, p6.X - xc) * 180 / Math.PI;
if (IsAngleBetween ((int)arp6, (int)startAngleInDegrees, (int)endAngleInDegrees))
points.Add (p6);
var p7 = new SKPoint (xc - y, yc - x);
var arp7 = Math.Atan2 (p7.Y - yc, p7.X - xc) * 180 / Math.PI;
if (IsAngleBetween ((int)arp7, (int)startAngleInDegrees, (int)endAngleInDegrees))
points.Add (p7);
}
canvas.DrawPoints (SKPointMode.Points, points.ToArray (), paint);
}
void DrawCircle (SKCanvas canvas, SKPaint paint, int xc, int yc, int radius)
{
if (radius <= 0)
return;
int x = radius;
int y = 0;
int cd2 = 0;
var points = new List<SKPoint> ();
points.Add (new SKPoint (xc - radius, yc));
points.Add (new SKPoint (xc + radius, yc));
points.Add (new SKPoint (xc, yc - radius));
points.Add (new SKPoint (xc, yc + radius));
while (x > y)
{
cd2 -= (--x) - (++y);
if (cd2 < 0)
cd2 += x++;
// 8 octants - listed clockwise
// right hemisphere, starting at the top
points.Add (new SKPoint (xc + y, yc - x));
points.Add (new SKPoint (xc + x, yc - y));
points.Add (new SKPoint (xc + x, yc + y));
points.Add (new SKPoint (xc + y, yc + x));
// left hemisphere, continuing around from the bottom
points.Add (new SKPoint (xc - y, yc + x));
points.Add (new SKPoint (xc - x, yc + y));
points.Add (new SKPoint (xc - x, yc - y));
points.Add (new SKPoint (xc - y, yc - x));
}
canvas.DrawPoints (SKPointMode.Points, points.ToArray (), paint);
}
