ReceiptPreviewControl.cs

using System.ComponentModel;

namespace FMPReceiptPrinter;

public sealed class ReceiptPreviewControl : Control
{
    [Browsable(false), DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
    public ReceiptData Receipt { get; set; } = new();
    [Browsable(false), DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
    public ReceiptTemplate Template { get; set; } = new();
    [Browsable(false), DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
    public HashSet<ReceiptSlot> Slots { get; set; } = [ReceiptSlot.TopLeft];

    public ReceiptPreviewControl()
    {
        DoubleBuffered = true;
        BackColor = Color.FromArgb(230, 232, 235);
        ResizeRedraw = true;
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        base.OnPaint(e);
        var available = RectangleF.Inflate(ClientRectangle, -18, -18);
        var ratio = ReceiptRenderer.PageWidth / ReceiptRenderer.PageHeight;
        var width = Math.Min(available.Width, available.Height * ratio);
        var height = width / ratio;
        if (height > available.Height) { height = available.Height; width = height * ratio; }
        var target = new RectangleF((ClientSize.Width-width)/2f, (ClientSize.Height-height)/2f, width, height);
        e.Graphics.FillRectangle(Brushes.White, target);
        e.Graphics.DrawRectangle(Pens.Gray, Rectangle.Round(target));
        ReceiptRenderer.DrawPage(e.Graphics, target, Receipt, Template, Slots);
    }
}