C# WinForms 生成 Code 39 條碼完整教程：從原理到生產級封裝

Code 39 條碼基礎知識

• 字符集：0-9, A-Z, -, ., $, /, +, %, 空格（共 43 個字符）
• 每字符由 9 個元素組成（5 條粗條、4 條細條），起止符為 *
• 無校驗碼，自檢能力弱，不適用高可靠需求場景
• 寬窄比通常 2:1 至 3:1

方案一：使用開源庫 BarcodeLib（推薦新手）

// NuGet: Install-Package BarcodeLib
using BarcodeLib;

public Image GenerateCode39(string data, int width = 300, int height = 150) {
    Barcode barcode = new Barcode();
    barcode.IncludeLabel = true; // 顯示底部文字
    barcode.Alignment = AlignmentPositions.CENTER;
    barcode.RotateFlipType = RotateFlipType.RotateNoneFlipNone;
    barcode.LabelFont = new Font("Consolas", 10, FontStyle.Bold);
    return barcode.Encode(TYPE.CODE39, data, Color.Black, Color.White, width, height);
}

// 在 PictureBox 顯示
pictureBox1.Image = GenerateCode39("HELLO123");

方案二：手寫繪製邏輯（無依賴、教學用）

private static readonly Dictionary Code39Map = new Dictionary {
    {'0',"█ █   ███ █"}, {'1',"███ █   █ █"}, /* ... 完整映射表 ... */
    {'*',"█ █ ███ █ █"} // 起止符
};

public Bitmap DrawCode39(string input, int narrowWidth = 2, int height = 100) {
    string encoded = "*" + input.ToUpper() + "*";
    int wideWidth = narrowWidth * 3;
    int totalWidth = encoded.Length * (narrowWidth * 5 + wideWidth * 4) - narrowWidth; // 間隙
    var bmp = new Bitmap(totalWidth, height);
    using (var g = Graphics.FromImage(bmp)) {
        g.Clear(Color.White);
        int x = 0;
        bool isBar = true;
        foreach (char c in encoded) {
            if (!Code39Map.TryGetValue(c, out string pattern)) continue;
            foreach (char p in pattern) {
                int w = (p == '█') ? wideWidth : narrowWidth;
                if (isBar) g.FillRectangle(Brushes.Black, x, 0, w, height);
                x += w;
                isBar = !isBar;
            }
            x += narrowWidth; // 字符間隙
            isBar = true;
        }
    }
    return bmp;
}

方案三：ZXing.Net 專業級條碼生成與識別

// NuGet: Install-Package ZXing.Net
using ZXing;
using ZXing.Common;
using ZXing.Rendering;

public Bitmap GenerateCode39ZXing(string content, int width, int height) {
    var writer = new BarcodeWriterPixelData {
        Format = BarcodeFormat.CODE_39,
        Options = new EncodingOptions {
            Width = width,
            Height = height,
            Margin = 10,
            PureBarcode = false // 含文字
        },
        Renderer = new PixelDataRenderer()
    };
    var pixelData = writer.Write(content);
    var bmp = new Bitmap(pixelData.Width, pixelData.Height, System.Drawing.Imaging.PixelFormat.Format32bppRgb);
    var bmpData = bmp.LockBits(new Rectangle(0,0,bmp.Width,bmp.Height), System.Drawing.Imaging.ImageLockMode.WriteOnly, bmp.PixelFormat);
    System.Runtime.InteropServices.Marshal.Copy(pixelData.Pixels, 0, bmpData.Scan0, pixelData.Pixels.Length);
    bmp.UnlockBits(bmpData);
    return bmp;
}

生產環境部署檢查清單

• ✅ 輸入驗證：過濾非法字符、長度限制（建議 ≤ 80 字符）
• ✅ 打印測試：不同 DPI 打印機掃描驗證（最小模組寬度 ≥ 0.19mm）
• ✅ 異常處理：捕獲編碼異常、GDI+ 異常、內存不足
• ✅ 資源釋放：Bitmap、Graphics、非托管資源及時 Dispose
• ✅ 單元測試：覆蓋邊界字符、空字串、超長輸入