/// <summary>
/// create the path points
/// </summary>
/// <param name="stroke">the stroke</param>
/// <returns>the path points</returns>
public static SKPoint[] CreatePathPoints(XInkStroke stroke)
{
if (stroke == null)
{
throw new ArgumentNullException(nameof(stroke));
}
var inkPoints = stroke.GetInkPoints().ToArray();
if (inkPoints.Length < 2)
{
return(null);
}
var pointCount = inkPoints.Length * 2 + 2;
var allPoints = new SKPoint[pointCount];
double angle = 0.0;
for (var i = 0; i < inkPoints.Length; i++)
{
var point1 = inkPoints[i];
if (i < inkPoints.Length - 1)
{
var point2 = inkPoints[i + 1];
var x = point2.Position.X - point1.Position.X;
var y = point2.Position.Y - point1.Position.Y;
angle = Math.Atan2(y, x) - Math.PI / 2;
}
var h = stroke.DrawingAttributes.Size * 0.5;
if (!stroke.DrawingAttributes.IgnorePressure)
{
h *= point1.Pressure;
}
var leftX = point1.Position.X + (Math.Cos(angle) * h);
var leftY = point1.Position.Y + (Math.Sin(angle) * h);
var rightX = point1.Position.X - (Math.Cos(angle) * h);
var rightY = point1.Position.Y - (Math.Sin(angle) * h);
allPoints[i + 1] = new Point(leftX, leftY).ToSKPoint();
allPoints[pointCount - i - 1] = new Point(rightX, rightY).ToSKPoint();
}
allPoints[0] = GetModifiedFirstPoint(stroke, inkPoints).ToSKPoint();
allPoints[inkPoints.Length + 1] = GetModifiedLastPoint(stroke, inkPoints).ToSKPoint();
return(allPoints);
}
/// <summary>
/// create a path for the stroke
/// </summary>
/// <param name="stroke">the stroke</param>
/// <returns>a new path</returns>
public static SKPath CreatePath(this XInkStroke stroke)
{
if (stroke == null)
{
throw new ArgumentNullException(nameof(stroke));
}
var path = new SKPath();
var inkPoints = stroke.GetInkPoints();
var points = from point in inkPoints
let x = (float)point.Position.X
let y = (float)point.Position.Y
select new SKPoint(x, y);
var count = points.Count();
//path.AddPoly(points.ToArray(), false);
if (count > 1)
{
var firstPoints = new Point[count - 1];
var secondPoints = new Point[count - 1];
var controlPoints = (from item in inkPoints
select item.Position).ToArray();
BezierSpline.GetCurveControlPoints(controlPoints, out firstPoints, out secondPoints);
path.MoveTo(controlPoints.First().ToSKPoint());
for (var i = 1; i < count; i++)
{
path.CubicTo(firstPoints[i - 1].ToSKPoint(), secondPoints[i - 1].ToSKPoint(), points.ElementAt(i));
}
}
return(path);
}
/// <summary>
/// Convert a Xamarin Ink Stroke to a UWP InkStroke
/// </summary>
/// <param name="xInkStroke">a Xamarin Ink Stroke</param>
/// <returns>a UWP Ink Stroke</returns>
public static InkStroke ToInkStroke(this XInkStroke xInkStroke)
{
if (xInkStroke == null)
{
throw new ArgumentNullException(nameof(xInkStroke));
}
var builder = new InkStrokeBuilder();
var inkPoints = from item in xInkStroke.GetInkPoints()
select new InkPoint(new Point(item.Position.X, item.Position.Y), item.Pressure);
if (!inkPoints.Any())
{
return(null);
}
var stroke = builder.CreateStrokeFromInkPoints(inkPoints, Matrix3x2.Identity);
stroke.DrawingAttributes = xInkStroke.DrawingAttributes.ToInkDrawingAttributes();
return(stroke);
}
/// <summary>
/// Draw an ink stroke
/// </summary>
/// <param name="canvas">the canvas</param>
/// <param name="stroke">the stroke</param>
/// <param name="useCache">true to use cached data</param>
public static void Draw(this SKCanvas canvas, XInkStroke stroke, bool useCache)
{
_ = canvas ?? throw new ArgumentNullException(nameof(canvas));
_ = stroke ?? throw new ArgumentNullException(nameof(stroke));
var inkPoints = stroke.GetInkPoints();
if (useCache)
{
if (inkPoints.Count == 1)
{
if (stroke.Paint == null)
{
var paintResult = stroke.CreatePaint(SKPaintStyle.Fill);
stroke.Paint = paintResult.Item1;
stroke.Resources = paintResult.Item2;
}
canvas.DrawCircle(
stroke.GetInkPoints()[0].Position.ToSKPoint(),
stroke.DrawingAttributes.Size / 4.0f,
stroke.Paint);
}
else
{
stroke.Path ??= stroke.DrawingAttributes.IgnorePressure
? stroke.CreatePath()
: stroke.CreateVariableThicknessPath();
if (stroke.Paint == null)
{
var paintResult = stroke.CreatePaint();
stroke.Resources = paintResult.Item2;
stroke.Paint = paintResult.Item1;
}
if (stroke.Path != null)
{
canvas.DrawPath(stroke.Path, stroke.Paint);
}
}
}
else
{
if (inkPoints.Count == 1)
{
var paintResult = stroke.CreatePaint(SKPaintStyle.Fill);
using (var paint = paintResult.Item1)
{
paint.IsStroke = false;
var radius = stroke.DrawingAttributes.Size / 4.0f;
//System.Diagnostics.Debug.WriteLine($"Drawing dot radius {radius}");
canvas.DrawCircle(
inkPoints[0].Position.ToSKPoint(),
radius,
paint);
}
if (paintResult.Item2 != null)
{
foreach (var item in paintResult.Item2)
{
item.Dispose();
}
}
}
else
{
using var path = stroke.DrawingAttributes.IgnorePressure ? stroke.CreatePath() : stroke.CreateVariableThicknessPath();
if (path == null)
{
return;
}
var paintResult = stroke.CreatePaint();
using (var paint = paintResult.Item1)
{
canvas.DrawPath(path, paint);
}
if (paintResult.Item2 != null)
{
foreach (var item in paintResult.Item2)
{
item.Dispose();
}
}
}
}
}
