ReceiptRenderer.cs

using System.Drawing.Drawing2D;

namespace FMPReceiptPrinter;

public static class ReceiptRenderer
{
    public const float PageWidth = 850f;   // hundredths of an inch, approximately 216 mm
    public const float PageHeight = 1098f; // approximately 279 mm
    private const float PageSafeMargin = 36f;
    private const float ReceiptPadding = 6f;
    private const float TitleWidthRatio = .55f;
    private const float QuantityColumnRatio = .12f;
    private const float DescriptionColumnRatio = .60f;
    private const float UnitPriceColumnRatio = .80f;
    private const float PreparedSectionRatio = .48f;
    private const float ReceivedSectionStartRatio = .52f;
    private const float LogoOffsetX = 7f;
    private const float LogoSize = 54f;
    private const float HeaderIndent = 64f;

    public static void DrawPage(Graphics g, RectangleF target, ReceiptData receipt, ReceiptTemplate template, IReadOnlySet<ReceiptSlot> slots, bool showCutGuides = true)
    {
        var state = g.Save();
        g.SmoothingMode = SmoothingMode.AntiAlias;
        g.TextRenderingHint = System.Drawing.Text.TextRenderingHint.ClearTypeGridFit;
        g.TranslateTransform(target.Left, target.Top);
        g.ScaleTransform(target.Width / PageWidth, target.Height / PageHeight);
        g.Clear(Color.White);
        // Keep receipt content inside a roughly 9 mm safe area. This small,
        // symmetric inset clears the tested printer's right-hand hardware edge
        // without changing the four-up proportions or header/logo alignment.
        // The print path separately compensates for the printer's hard margin.
        var inner = new RectangleF(PageSafeMargin, PageSafeMargin, PageWidth - PageSafeMargin * 2, PageHeight - PageSafeMargin * 2);
        var halfW = inner.Width / 2f;
        var halfH = inner.Height / 2f;
        var rects = new Dictionary<ReceiptSlot, RectangleF>
        {
            [ReceiptSlot.TopLeft] = new(inner.Left, inner.Top, halfW, halfH),
            [ReceiptSlot.TopRight] = new(inner.Left + halfW, inner.Top, halfW, halfH),
            [ReceiptSlot.BottomLeft] = new(inner.Left, inner.Top + halfH, halfW, halfH),
            [ReceiptSlot.BottomRight] = new(inner.Left + halfW, inner.Top + halfH, halfW, halfH)
        };
        if (showCutGuides)
        {
            using var guide = new Pen(Color.FromArgb(170, 170, 170), 0.6f) { DashStyle = DashStyle.Dash };
            g.DrawLine(guide, inner.Left + halfW, inner.Top, inner.Left + halfW, inner.Bottom);
            g.DrawLine(guide, inner.Left, inner.Top + halfH, inner.Right, inner.Top + halfH);
        }
        foreach (var slot in slots) DrawReceipt(g, RectangleF.Inflate(rects[slot], -ReceiptPadding, -ReceiptPadding), receipt, template);
        g.Restore(state);
    }

    private static void DrawReceipt(Graphics g, RectangleF r, ReceiptData data, ReceiptTemplate t)
    {
        var accent = ParseColor(t.AccentColor, Color.FromArgb(8, 126, 175));
        using var black = new Pen(Color.Black, 0.9f);
        using var lightFill = new SolidBrush(Color.FromArgb(234, 245, 249));
        using var dark = new SolidBrush(Color.Black);
        using var gray = new SolidBrush(Color.DimGray);
        using var accentBrush = new SolidBrush(accent);
        using var red = new SolidBrush(Color.FromArgb(210, 25, 32));
        using var businessFont = new Font("Arial", 11.2f, FontStyle.Bold);
        using var smallFont = new Font("Arial", 6.2f);
        using var labelFont = new Font("Arial", 6.8f, FontStyle.Bold);
        using var bodyFont = new Font("Arial", 6.7f);
        using var titleFont = new Font("Arial", 8.5f, FontStyle.Bold);
        using var numberFont = new Font("Arial", 8.7f, FontStyle.Bold);
        using var headerFont = new Font("Arial", 6.2f, FontStyle.Bold);
        using var totalFont = new Font("Arial", 6.9f, FontStyle.Bold);
        var center = new StringFormat { Alignment = StringAlignment.Center, LineAlignment = StringAlignment.Center };
        var right = new StringFormat { Alignment = StringAlignment.Far, LineAlignment = StringAlignment.Center };
        var left = new StringFormat { Alignment = StringAlignment.Near, LineAlignment = StringAlignment.Center };

        var y = r.Top;
        var logoRect = new RectangleF(r.Left + LogoOffsetX, y - 2, LogoSize, LogoSize);
        var logoPath = Path.Combine(AppContext.BaseDirectory, "Assets", t.LogoFile);
        if (File.Exists(logoPath))
        {
            using var logo = Image.FromFile(logoPath);
            g.DrawImage(logo, logoRect);
        }
        var headerX = r.Left + HeaderIndent;
        var headerW = r.Width - HeaderIndent;
        g.DrawString(t.BusinessName, businessFont, accentBrush, new RectangleF(headerX, y, headerW, 17), center);
        g.DrawString(t.Proprietor, smallFont, gray, new RectangleF(headerX, y + 17, headerW, 9), center);
        g.DrawString(t.Address, smallFont, gray, new RectangleF(headerX, y + 26, headerW, 9), center);
        g.DrawString(t.Contact, smallFont, gray, new RectangleF(headerX, y + 35, headerW, 9), center);
        y += 56;

        g.DrawString("DELIVERY RECEIPT", titleFont, dark, new RectangleF(r.Left, y, r.Width * TitleWidthRatio, 18), left);
        g.DrawString("NO.", labelFont, dark, new RectangleF(r.Right - 95, y, 30, 18), right);
        g.DrawString(data.ReceiptNumber.ToString("00000"), numberFont, red, new RectangleF(r.Right - 64, y, 64, 18), right);
        y += 23;
        DrawLabelLine(g, labelFont, bodyFont, "Customer:", data.Customer, r.Left, y, r.Width - 115);
        DrawLabelLine(g, labelFont, bodyFont, "Date:", data.Date.ToString("yyyy-MM-dd"), r.Right - 105, y, 105);
        y += 20;
        DrawLabelLine(g, labelFont, bodyFont, "Address:", data.Address, r.Left, y, r.Width);
        y += 20;
        g.DrawString($"Terms: {data.Terms}", bodyFont, dark, new RectangleF(r.Left, y, 160, 15), left);
        g.DrawString($"Due: {data.DueDate:yyyy-MM-dd}", bodyFont, dark, new RectangleF(r.Right - 115, y, 115, 15), right);
        y += 20;

        var tableTop = y;
        var col = new[] { r.Left, r.Left + r.Width * QuantityColumnRatio, r.Left + r.Width * DescriptionColumnRatio, r.Left + r.Width * UnitPriceColumnRatio, r.Right };
        const float headH = 26f;
        var itemRows = Math.Max(4, t.ItemRows);
        const float rowH = 35f;
        const float totalH = 22f;
        g.FillRectangle(lightFill, r.Left, tableTop, r.Width, headH);
        var tableBottom = tableTop + headH + itemRows * rowH + totalH * 2;
        for (var i = 0; i < col.Length; i++) g.DrawLine(black, col[i], tableTop, col[i], tableTop + headH + itemRows * rowH);
        g.DrawRectangle(black, r.Left, tableTop, r.Width, tableBottom - tableTop);
        g.DrawString("QTY", headerFont, dark, new RectangleF(col[0], tableTop, col[1]-col[0], headH), center);
        g.DrawString("DESCRIPTION", headerFont, dark, new RectangleF(col[1], tableTop, col[2]-col[1], headH), center);
        g.DrawString("UNIT PRICE", headerFont, dark, new RectangleF(col[2], tableTop, col[3]-col[2], headH), center);
        g.DrawString("AMOUNT", headerFont, dark, new RectangleF(col[3], tableTop, col[4]-col[3], headH), center);
        y = tableTop + headH;
        for (var i = 0; i < itemRows; i++)
        {
            g.DrawLine(black, r.Left, y, r.Right, y);
            var item = i < data.Items.Count ? data.Items[i] : null;
            if (item is not null)
            {
                g.DrawString(FormatNumber(item.Quantity), bodyFont, dark, new RectangleF(col[0]+2, y, col[1]-col[0]-4, rowH), center);
                g.DrawString(item.Description, bodyFont, dark, new RectangleF(col[1]+3, y, col[2]-col[1]-6, rowH), left);
                g.DrawString(FormatMoney(item.UnitPrice), bodyFont, dark, new RectangleF(col[2]+2, y, col[3]-col[2]-4, rowH), right);
                g.DrawString(FormatMoney(item.Amount), bodyFont, dark, new RectangleF(col[3]+2, y, col[4]-col[3]-4, rowH), right);
            }
            y += rowH;
        }
        g.DrawLine(black, r.Left, y, r.Right, y);
        g.DrawLine(black, col[3], y, col[3], tableBottom);
        g.DrawString("DELIVERY FEE", totalFont, dark, new RectangleF(r.Left, y, col[3]-r.Left-6, totalH), right);
        g.DrawString(FormatMoney(data.DeliveryFee), bodyFont, dark, new RectangleF(col[3]+2, y, r.Right-col[3]-4, totalH), right);
        y += totalH; g.DrawLine(black, r.Left, y, r.Right, y);
        g.DrawString("TOTAL", totalFont, dark, new RectangleF(r.Left, y, col[3]-r.Left-6, totalH), right);
        g.DrawString(FormatMoney(data.Total), totalFont, dark, new RectangleF(col[3]+2, y, r.Right-col[3]-4, totalH), right);
        y += totalH + 8;
        g.DrawString($"Prepared by: {data.PreparedBy}", labelFont, dark, new RectangleF(r.Left, y, r.Width * PreparedSectionRatio, 18), left);
        if (data.UseESignature && File.Exists(data.SignatureFile))
        {
            try
            {
                using var signature = Image.FromFile(data.SignatureFile);
                // Keep the signature on the prepared-by side, larger and farther left.
                var signatureRect = new RectangleF(r.Left + 34, y - 28, 118, 43);
                g.DrawImage(signature, signatureRect);
            }
            catch { /* Keep printing usable if a signature image is corrupt. */ }
        }
        g.DrawString("Received by: __________________", labelFont, dark, new RectangleF(r.Left + r.Width * ReceivedSectionStartRatio, y, r.Width * PreparedSectionRatio, 18), right);
    }

    private static void DrawLabelLine(Graphics g, Font labelFont, Font valueFont, string label, string value, float x, float y, float width)
    {
        using var brush = new SolidBrush(Color.Black);
        using var pen = new Pen(Color.Black, .6f);
        var labelWidth = g.MeasureString(label, labelFont).Width + 3;
        g.DrawString(label, labelFont, brush, new RectangleF(x, y, labelWidth, 16));
        g.DrawString(value, valueFont, brush, new RectangleF(x + labelWidth, y, width - labelWidth, 16));
        g.DrawLine(pen, x + labelWidth, y + 15, x + width, y + 15);
    }

    private static string FormatMoney(decimal value) => value == 0 ? "" : value.ToString("N2");
    private static string FormatNumber(decimal value) => value == 0 ? "" : value.ToString("0.##");
    private static Color ParseColor(string value, Color fallback) { try { return ColorTranslator.FromHtml(value); } catch { return fallback; } }
}