Artemis/src/Artemis.Core/Plugins/LayerBrushes/PerLedLayerBrush.cs

using SkiaSharp;

namespace Artemis.Core.LayerBrushes;

/// <summary>
///     Represents a brush that renders on a per-layer basis
/// </summary>
/// <typeparam name="T">The type of brush properties</typeparam>
public abstract class PerLedLayerBrush<T> : PropertiesLayerBrush<T> where T : LayerPropertyGroup, new()
{
    /// <summary>
    ///     Creates a new instance of the <see cref="PerLedLayerBrush{T}" /> class
    /// </summary>
    protected PerLedLayerBrush()
    {
        BrushType = LayerBrushType.Regular;
    }

    /// <summary>
    ///     The main method of rendering for this type of brush. Called once per frame for each LED in the layer
    ///     <para>
    ///         Note: Due to transformations, the render point may not match the position of the LED, always use the render
    ///         point to determine where the color will go.
    ///     </para>
    /// </summary>
    /// <param name="led">The LED that will receive the color</param>
    /// <param name="renderPoint">The point at which the color is located</param>
    /// <returns>The color the LED will receive</returns>
    public abstract SKColor GetColor(ArtemisLed led, SKPoint renderPoint);

    private readonly SKPoint[] _points = new SKPoint[2];
    
    internal override void InternalRender(SKCanvas canvas, SKRect bounds, SKPaint paint)
    {
        // We don't want rotation on this canvas because that'll displace the LEDs, translations are applied to the points of each LED instead
        if (Layer.General.TransformMode.CurrentValue == LayerTransformMode.Normal && SupportsTransformation)
            canvas.SetMatrix(canvas.TotalMatrix.PreConcat(Layer.GetTransformMatrix(true, false, false, true).Invert()));

        using SKPath pointsPath = new();
        foreach (ArtemisLed artemisLed in Layer.Leds)
        {
            _points[0] = new SKPoint(0, 0);
            _points[1] = new SKPoint(artemisLed.AbsoluteRectangle.Left - Layer.Bounds.Left, artemisLed.AbsoluteRectangle.Top - Layer.Bounds.Top);
            pointsPath.AddPoly(_points);
        }

        // Apply the translation to the points of each LED instead
        if (Layer.General.TransformMode.CurrentValue == LayerTransformMode.Normal && SupportsTransformation)
            pointsPath.Transform(Layer.GetTransformMatrix(true, true, true, true).Invert());

        TryOrBreak(() =>
        {
            for (int index = 0; index < Layer.Leds.Count; index++)
            {
                ArtemisLed artemisLed = Layer.Leds[index];
                SKPoint renderPoint = pointsPath.GetPoint(index * 2 + 1);
                if (!float.IsFinite(renderPoint.X) || !float.IsFinite(renderPoint.Y))
                    continue;

                // Let the brush determine the color
                paint.Color = GetColor(artemisLed, renderPoint);
                SKRect ledRectangle = SKRect.Create(
                    artemisLed.AbsoluteRectangle.Left - Layer.Bounds.Left,
                    artemisLed.AbsoluteRectangle.Top - Layer.Bounds.Top,
                    artemisLed.AbsoluteRectangle.Width,
                    artemisLed.AbsoluteRectangle.Height
                );

                canvas.DrawRect(ledRectangle, paint);
            }
        }, "Failed to render");
    }

    internal override void Initialize()
    {
        TryOrBreak(InitializeProperties, "Failed to initialize");
    }
}