ShrlAlgoToolkit/WPFluent/Controls/Arc/Arc.cs

using System.Windows.Controls;
using System.Windows.Shapes;

using Point = System.Windows.Point;
using Size = System.Windows.Size;

// ReSharper disable CheckNamespace
namespace WPFluent.Controls;

/// <summary>
/// Control that draws a symmetrical arc with rounded edges.
/// </summary>
/// <example>
/// <code lang="xml"> /// &lt;ui:Arc ///     EndAngle="359" ///     StartAngle="0" ///     Stroke="{ui:ThemeResource
/// SystemAccentColorSecondaryBrush}" ///     StrokeThickness="2" ///     Visibility="Visible" /&gt; ///</code>
/// </example>
public class Arc : Shape
{
    /// <summary>
    /// Identifies the <see cref="EndAngle"/> dependency property.
    /// </summary>
    public static readonly DependencyProperty EndAngleProperty = DependencyProperty.Register(
        nameof(EndAngle),
        typeof(double),
        typeof(Arc),
        new PropertyMetadata(0.0d, PropertyChangedCallback));

    /// <summary>
    /// Identifies the <see cref="StartAngle"/> dependency property.
    /// </summary>
    public static readonly DependencyProperty StartAngleProperty = DependencyProperty.Register(
        nameof(StartAngle),
        typeof(double),
        typeof(Arc),
        new PropertyMetadata(0.0d, PropertyChangedCallback));

    /// <summary>
    /// Identifies the <see cref="SweepDirection"/> dependency property.
    /// </summary>
    public static readonly DependencyProperty SweepDirectionProperty = DependencyProperty.Register(
        nameof(SweepDirection),
        typeof(SweepDirection),
        typeof(Arc),
        new PropertyMetadata(SweepDirection.Clockwise, PropertyChangedCallback));
    private Viewbox _rootLayout;

    static Arc()
    {
        // Modify the metadata of the StrokeStartLineCap dependency property.
        StrokeStartLineCapProperty.OverrideMetadata(
            typeof(Arc),
            new FrameworkPropertyMetadata(PenLineCap.Round, PropertyChangedCallback));
    }

    private void EnsureRootLayout()
    {
        if(_rootLayout != null)
        {
            return;
        }

        _rootLayout = new Viewbox { SnapsToDevicePixels = true };
        AddVisualChild(_rootLayout);
    }

    protected override Size ArrangeOverride(Size finalSize)
    {
        EnsureRootLayout();

        _rootLayout!.Arrange(new Rect(default, finalSize));
        return finalSize;
    }

    /// <summary>
    /// Get the geometry that defines this shape. <para><see href="https://stackoverflow.com/a/36756365/13224348">Based
    /// on Mark Feldman implementation.</see></para>
    /// </summary>
    protected Geometry DefinedGeometry()
    {
        var geometryStream = new StreamGeometry();
        var arcSize = new Size(
            Math.Max(0, (RenderSize.Width - StrokeThickness) / 2),
            Math.Max(0, (RenderSize.Height - StrokeThickness) / 2));

        using var context = geometryStream.Open();
        context.BeginFigure(PointAtAngle(Math.Min(StartAngle, EndAngle)), false, false);

        context.ArcTo(PointAtAngle(Math.Max(StartAngle, EndAngle)), arcSize, 0, IsLargeArc, SweepDirection, true, false);

        geometryStream.Transform = new TranslateTransform(StrokeThickness / 2, StrokeThickness / 2);

        return geometryStream;
    }

    protected override Visual GetVisualChild(int index)
    {
        if(index != 0)
        {
            throw new ArgumentOutOfRangeException(nameof(index), "Arc should have only 1 child");
        }

        EnsureRootLayout();

        return _rootLayout;
    }

    protected override Size MeasureOverride(Size availableSize)
    {
        EnsureRootLayout();

        _rootLayout!.Measure(availableSize);
        return _rootLayout.DesiredSize;
    }

    /// <summary>
    /// Overrides the default OnRender method to draw the <see cref="Arc"/> element.
    /// </summary>
    /// <param name="drawingContext">A <see cref="DrawingContext"/> object that is drawn during the rendering pass of this <see cref="Shape"/>.</param>
    protected override void OnRender(DrawingContext drawingContext)
    {
        base.OnRender(drawingContext);
        Pen pen = new(Stroke, StrokeThickness) { StartLineCap = StrokeStartLineCap, EndLineCap = StrokeStartLineCap, };

        drawingContext.DrawGeometry(Stroke, pen, DefinedGeometry());
    }

    /// <summary>
    /// Draws a point on the coordinates of the given angle. <para><see
    /// href="https://stackoverflow.com/a/36756365/13224348">Based on Mark Feldman implementation.</see></para>
    /// </summary>
    /// <param name="angle">The angle at which to create the point.</param>
    protected Point PointAtAngle(double angle)
    {
        if(SweepDirection == SweepDirection.Counterclockwise)
        {
            angle += 90;
            angle %= 360;
            if(angle < 0)
            {
                angle += 360;
            }

            var radAngle = angle * (Math.PI / 180);
            var xRadius = (RenderSize.Width - StrokeThickness) / 2;
            var yRadius = (RenderSize.Height - StrokeThickness) / 2;

            return new Point(xRadius + xRadius * Math.Cos(radAngle), yRadius - yRadius * Math.Sin(radAngle));
        }
        else
        {
            angle -= 90;
            angle %= 360;
            if(angle < 0)
            {
                angle += 360;
            }

            var radAngle = angle * (Math.PI / 180);
            var xRadius = (RenderSize.Width - StrokeThickness) / 2;
            var yRadius = (RenderSize.Height - StrokeThickness) / 2;

            return new Point(xRadius + xRadius * Math.Cos(-radAngle), yRadius - yRadius * Math.Sin(-radAngle));
        }
    }

    /// <summary>
    /// Event triggered when one of the key parameters is changed. Forces the geometry to be redrawn.
    /// </summary>
    protected static void PropertyChangedCallback(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        if(d is not Arc control)
        {
            return;
        }

        control.IsLargeArc = Math.Abs(control.EndAngle - control.StartAngle) > 180;
        control.InvalidateVisual();
    }

    /// <inheritdoc/>
    protected override Geometry DefiningGeometry => DefinedGeometry();

    /// <summary>
    /// Gets or sets the final angle from which the arc will be drawn.
    /// </summary>
    public double EndAngle { get => (double)GetValue(EndAngleProperty); set => SetValue(EndAngleProperty, value); }

    /// <summary>
    /// Gets a value indicating whether one of the two larger arc sweeps is chosen; otherwise, if is <see
    /// langword="false"/>, one of the smaller arc sweeps is chosen.
    /// </summary>
    public bool IsLargeArc { get; internal set; } = false;

    /// <summary>
    /// Gets or sets the initial angle from which the arc will be drawn.
    /// </summary>
    public double StartAngle
    {
        get => (double)GetValue(StartAngleProperty);
        set => SetValue(StartAngleProperty, value);
    }

    /// <summary>
    /// Gets or sets the direction to where the arc will be drawn.
    /// </summary>
    public SweepDirection SweepDirection
    {
        get => (SweepDirection)GetValue(SweepDirectionProperty);
        set => SetValue(SweepDirectionProperty, value);
    }
}