Rotate.cs

using System.Threading.Tasks;
using System.Xml;
using SkiaSharp;
using Waher.Layout.Layout2D.Model.Attributes;
 
namespace Waher.Layout.Layout2D.Model.Transforms
{
    public class Rotate : PivotTrasformation
    {
        private FloatAttribute degrees;
 
        public Rotate(Layout2DDocument Document, ILayoutElement Parent)
            : base(Document, Parent)
        {
        }
 
        public override string LocalName => "Rotate";
 
        public FloatAttribute DegreesAttribute
        {
            get => this.degrees;
            set => this.degrees = value;
        }
 
        public override Task FromXml(XmlElement Input)
        {
            this.degrees = new FloatAttribute(Input, "degrees", this.Document);
            return base.FromXml(Input);
        }
 
        public override void ExportAttributes(XmlWriter Output)
        {
            base.ExportAttributes(Output);
 
            this.degrees?.Export(Output);
        }
 
        public override ILayoutElement Create(Layout2DDocument Document, ILayoutElement Parent)
        {
            return new Rotate(Document, Parent);
        }
 
        public override void CopyContents(ILayoutElement Destination)
        {
            base.CopyContents(Destination);
 
            if (Destination is Rotate Dest)
                Dest.degrees = this.degrees?.CopyIfNotPreset(Destination.Document);
        }
 
        public override async Task AfterMeasureDimensions(DrawingState State)
        {
            await base.AfterMeasureDimensions(State);
 
            this.angle = await this.degrees.Evaluate(State.Session, 0);
 
            SKMatrix M = SKMatrix.CreateRotationDegrees(this.angle, this.xCoordinate, this.yCoordinate);
            this.TransformBoundingBox(M);
        }
 
        private float angle;
 
        public override async Task Draw(DrawingState State)
        {
            SKMatrix M = State.Canvas.TotalMatrix;
            State.Canvas.RotateDegrees(this.angle, this.xCoordinate, this.yCoordinate);
            
            await base.Draw(State);
 
            State.Canvas.SetMatrix(M);
        }
 
        public override void ExportStateAttributes(XmlWriter Output)
        {
            base.ExportStateAttributes(Output);
 
            this.degrees?.ExportState(Output);
        }
    }
}