EnvelopeGenerator/EnvelopeGenerator.API/Models/PsPdfKitAnnotation/Background.cs

using System.Text.Json.Serialization;

namespace EnvelopeGenerator.API.Models.PsPdfKitAnnotation;

/// <summary>
/// The Background is an annotation for the PSPDF Kit. However, it has no function.
/// It is only the first annotation as a background for other annotations.
/// </summary>
public record Background : IAnnotation
{
    [JsonIgnore]
    public double Margin { get; init; }

    public string Name { get; } = "Background";

    public double? Width { get; set; }

    public double? Height { get; set; }

    public double Left { get; set; }

    public double Top { get; set; }

    public Color? BackgroundColor { get; init; }

    #region Border
    public Color? BorderColor { get; init; }

    public string? BorderStyle { get; init; }

    public int? BorderWidth { get; set; }
    #endregion

    public void Locate(IEnumerable<IAnnotation> annotations)
    {
        // set Top
        if (annotations.MinBy(a => a.Top)?.Top is double minTop)
            Top = minTop;

        // set Left
        if (annotations.MinBy(a => a.Left)?.Left is double minLeft)
            Left = minLeft;

        // set Width
        if(annotations.MaxBy(a => a.GetRight())?.GetRight() is double maxRight)
            Width = maxRight - Left;

        // set Height
        if (annotations.MaxBy(a => a.GetBottom())?.GetBottom() is double maxBottom)
            Height = maxBottom - Top;

        // add margins
        Top -= Margin;
        Left -= Margin;
        Width += Margin * 2;
        Height += Margin * 2;
    }
}