C# CGContext.AddArcToPoint方法代码示例

		public void SSDrawRoundedRect(CGContext context, RectangleF rect, float cornerRadius)
		{
			var minx = rect.GetMinX();
			var midx = rect.GetMidX();
			var maxx = rect.GetMaxX();
			var miny = rect.GetMinY();
			var midy = rect.GetMidY();
			var maxy = rect.GetMaxY();
			context.MoveTo(minx, midy);
			context.AddArcToPoint(minx, miny, midx, miny, cornerRadius);
			context.AddArcToPoint(maxx, miny, maxx, midy, cornerRadius);
			context.AddArcToPoint(maxx, maxy, midx, maxy, cornerRadius);
			context.AddArcToPoint(minx, maxy, minx, midy, cornerRadius);
			context.ClosePath();
			context.FillPath();
		}

		public static void AddRoundedRectToPath(CGContext context, RectangleF rect, float ovalWidth, float ovalHeight)
		{
			float fw, fh;
			if (ovalWidth == 0 || ovalHeight == 0)
			{
				context.AddRect(rect);
				return;
			}
			context.SaveState();
			context.TranslateCTM(rect.GetMinX(), rect.GetMinY());
			context.ScaleCTM(ovalWidth, ovalHeight);
			fw = rect.Width / ovalWidth;
			fh = rect.Height / ovalHeight;
			context.MoveTo(fw, fh / 2);
			context.AddArcToPoint(fw, fh, fw / 2, fh, 1);
			context.AddArcToPoint(0, fh, 0, fh / 2, 1);
			context.AddArcToPoint(0, 0, fw / 2, 0, 1);
			context.AddArcToPoint(fw, 0, fw, fh / 2, 1);
			context.ClosePath();
			context.RestoreState();
		}

	public override void DrawInContext (CGContext context)
	{
		// Drawing with a white stroke color
		context.SetStrokeColor (1, 1, 1, 1);
		// And draw with a blue fill color
		context.SetFillColor (0, 0, 1, 1);
		// Draw them with a 2 stroke width so they are a bit more visible.
		context.SetLineWidth (2);

		// Add an ellipse circumscribed in the given rect to the current path, then stroke it
		context.AddEllipseInRect (new CGRect (30, 30, 60, 60));
		context.StrokePath ();

		// Stroke ellipse convenience that is equivalent to AddEllipseInRect(); StrokePath();
		context.StrokeEllipseInRect (new CGRect (30, 120, 60, 60));

		// Fill rect convenience equivalent to AddEllipseInRect(); FillPath();
		context.FillEllipseInRect (new CGRect (30, 210, 60, 60));

		// Stroke 2 seperate arcs
		context.AddArc (150, 60, 30, 0, (float)Math.PI / 2, false);
		context.StrokePath ();
		context.AddArc (150, 60, 30, (float)(3 * Math.PI / 2), (float)Math.PI, true);
		context.StrokePath ();

		// Stroke 2 arcs together going opposite directions.
		context.AddArc (150, 150, 30, 0, (float)Math.PI / 2, false);
		context.AddArc (150, 150, 30, (float)(3 * Math.PI / 2), (float)Math.PI, true);
		context.StrokePath ();

		// Stroke 2 arcs together going the same direction..
		context.AddArc (150, 240, 30, 0, (float)(Math.PI / 2), false);
		context.AddArc (150, 240, 30, (float)Math.PI, (float)(3 * Math.PI / 2), false);
		context.StrokePath ();

		// Stroke an arc using AddArcToPoint
		CGPoint[] p = {
			new CGPoint (210, 30),
			new CGPoint (210, 60),
			new CGPoint (240, 60),
		};
		context.MoveTo (p [0].X, p [0].Y);
		context.AddArcToPoint (p [1].X, p [1].Y, p [2].X, p [2].Y, 30);
		context.StrokePath ();

		// Show the two segments that are used to determine the tangent lines to draw the arc.
		context.SetStrokeColor (1, 0, 0, 1);
		context.AddLines (p);
		context.StrokePath ();

		// As a bonus, we'll combine arcs to create a round rectangle!

		// Drawing with a white stroke color
		context.SetStrokeColor (1, 1, 1, 1);

		// If you were making this as a routine, you would probably accept a rectangle
		// that defines its bounds, and a radius reflecting the "rounded-ness" of the rectangle.
		var rrect = new CGRect (210, 90, 60, 60);
		var radius = 10;
		// NOTE: At this point you may want to verify that your radius is no more than half
		// the width and height of your rectangle, as this technique degenerates for those cases.

		// In order to draw a rounded rectangle, we will take advantage of the fact that
		// context.AddArcToPoint will draw straight lines past the start and end of the arc
		// in order to create the path from the current position and the destination position.

		// In order to create the 4 arcs correctly, we need to know the min, mid and max positions
		// on the x and y lengths of the given rectangle.
		nfloat minx = rrect.X, midx = rrect.X + rrect.Width / 2, maxx = rrect.X + rrect.Width;
		nfloat miny = rrect.Y, midy = rrect.Y + rrect.Height / 2, maxy = rrect.Y + rrect.Height;

		// Next, we will go around the rectangle in the order given by the figure below.
		//       minx    midx    maxx
		// miny    2       3       4
		// midy   1 9              5
		// maxy    8       7       6
		// Which gives us a coincident start and end point, which is incidental to this technique, but still doesn't
		// form a closed path, so we still need to close the path to connect the ends correctly.
		// Thus we start by moving to point 1, then adding arcs through each pair of points that follows.
		// You could use a similar tecgnique to create any shape with rounded corners.

		// Start at 1
		context.MoveTo (minx, midy);
		// Add an arc through 2 to 3
		context.AddArcToPoint (minx, miny, midx, miny, radius);
		// Add an arc through 4 to 5
		context.AddArcToPoint (maxx, miny, maxx, midy, radius);
		// Add an arc through 6 to 7
		context.AddArcToPoint (maxx, maxy, midx, maxy, radius);
		// Add an arc through 8 to 9
		context.AddArcToPoint (minx, maxy, minx, midy, radius);
		// Close the path
		context.ClosePath ();
		// Fill & stroke the path
		context.DrawPath (CGPathDrawingMode.FillStroke);
	}