CircleArcTo.cs

using System.Threading.Tasks;
using System.Xml;
using SkiaSharp;
using Waher.Layout.Layout2D.Model.Attributes;
 
namespace Waher.Layout.Layout2D.Model.Figures.SegmentNodes
{
    public class CircleArcTo : Point, ISegment
    {
        private LengthAttribute radius;
        private BooleanAttribute clockwise;
 
        public CircleArcTo(Layout2DDocument Document, ILayoutElement Parent)
            : base(Document, Parent)
        {
        }
 
        public override string LocalName => "CircleArcTo";
 
        public LengthAttribute RadiusAttribute
        {
            get => this.radius;
            set => this.radius = value;
        }
 
        public BooleanAttribute ClockwiseAttribute
        {
            get => this.clockwise;
            set => this.clockwise = value;
        }
 
        public override Task FromXml(XmlElement Input)
        {
            this.radius = new LengthAttribute(Input, "radius", this.Document);
            this.clockwise = new BooleanAttribute(Input, "clockwise", this.Document);
 
            return base.FromXml(Input);
        }
 
        public override void ExportAttributes(XmlWriter Output)
        {
            base.ExportAttributes(Output);
 
            this.radius?.Export(Output);
            this.clockwise?.Export(Output);
        }
 
        public override ILayoutElement Create(Layout2DDocument Document, ILayoutElement Parent)
        {
            return new CircleArcTo(Document, Parent);
        }
 
        public override void CopyContents(ILayoutElement Destination)
        {
            base.CopyContents(Destination);
 
            if (Destination is CircleArcTo Dest)
            {
                Dest.radius = this.radius?.CopyIfNotPreset(Destination.Document);
                Dest.clockwise = this.clockwise?.CopyIfNotPreset(Destination.Document);
            }
        }
 
        public override async Task DoMeasureDimensions(DrawingState State)
        {
            await base.DoMeasureDimensions(State);
 
            EvaluationResult<Length> RadiusLength = await this.radius.TryEvaluate(State.Session);
            if (RadiusLength.Ok)
                State.CalcDrawingSize(RadiusLength.Result, ref this.r, true, (ILayoutElement)this);
            else
                this.defined = false;
 
            EvaluationResult<bool> Clockwise = await this.clockwise.TryEvaluate(State.Session);
            if (Clockwise.Ok)
                this.clockDir = Clockwise.Result;
            else
                this.defined = false;
        }
 
        public virtual Task Measure(DrawingState State, PathState PathState)
        {
            if (this.defined)
                PathState.Set(this.xCoordinate, this.yCoordinate);
        
            return Task.CompletedTask;
        }
 
        protected float r;
 
        protected bool clockDir;
 
        public virtual Task Draw(DrawingState State, PathState PathState, SKPath Path)
        {
            if (this.defined)
            {
                PathState.Set(this.xCoordinate, this.yCoordinate);
                Path.ArcTo(this.r, this.r, 0, SKPathArcSize.Small, 
                    this.clockDir ? SKPathDirection.Clockwise : SKPathDirection.CounterClockwise,
                    this.xCoordinate, this.yCoordinate);
            }
    
            return Task.CompletedTask;
        }
 
        public override void ExportStateAttributes(XmlWriter Output)
        {
            base.ExportStateAttributes(Output);
 
            this.radius?.ExportState(Output);
            this.clockwise?.ExportState(Output);
        }
 
        // TODO: IDirectedElement
    }
}