.NET6 Ubuntu环境孟加拉字体无法正常显示问题排查

• 问题现象：同一PDF文件在Windows系统中孟加拉字体显示正常，在Ubuntu系统中显示为方块（□）
• 对应截图：
  1. Windows正常显示效果：
     
  2. Ubuntu异常显示效果：
     

当前使用iTextSharp生成PDF，地址内容通过转换为图片的方式嵌入PDF，核心代码如下：

主逻辑代码 #

if (!string.IsNullOrEmpty(shippingAddressData.Address1))
{
    if (String.IsNullOrEmpty(shippingAddressData.Address2))
    {
        var customercityStateZipCountry = await FormatAddressTextAsync(shippingAddressData);
        shippingAddress1 = shippingAddress1 + indent + "Address: " + shippingAddressData.Address1 + customercityStateZipCountry;
    }
    var customerAddress1Split = Split(shippingAddress1, 43);
    int i = 0;
    foreach (var customerAddress1BreakDown in customerAddress1Split)
    {
        if (i == 0)
        {
            var customerAddress1InBitMap = ConvertToBitMapDefault(customerAddress1BreakDown, 22f);
            Image customerAddress1InImage = Image.GetInstance(customerAddress1InBitMap, System.Drawing.Imaging.ImageFormat.Jpeg);

            shippingAddressPDF.AddCell(customerAddress1InImage);
        }
        else
        {
            var secondLine = indent + customerAddress1BreakDown;
            var customerAddress1InBitMap = ConvertToBitMapDefault(secondLine, 22f);
            Image customerAddress1InImage = Image.GetInstance(customerAddress1InBitMap, System.Drawing.Imaging.ImageFormat.Jpeg);

            shippingAddressPDF.AddCell(customerAddress1InImage);
        }
        i++;
    }
}

辅助转换方法代码 #

public System.Drawing.Bitmap ConvertToBitMapDefault(string Text, float fontSize = 22f, int widthPoint = 0)
{
    //string familyName = _fileProvider.Combine(_fileProvider.MapPath("~/App_Data/Pdf/"), "ARIALUNI.ttf");
    //Path.Combine(CommonHelper.MapPath("~/App_Data/Pdf/"), "ARIALUNI.ttf");
    string familyName = _fileProvider.Combine(_fileProvider.MapPath("~/App_Data/Pdf/"), _pdfSettings.FontFileName);

    System.Drawing.Bitmap bitmap = new System.Drawing.Bitmap(850, 40, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
    bitmap.SetResolution(500f, 200f);
    System.Drawing.Graphics graphics = System.Drawing.Graphics.FromImage((System.Drawing.Image)bitmap);
    graphics.Clear(System.Drawing.Color.White);
    graphics.DrawString(Text ?? "", new System.Drawing.Font(familyName, fontSize, System.Drawing.FontStyle.Regular), System.Drawing.SystemBrushes.InfoText,
        (System.Drawing.PointF)new System.Drawing.Point(widthPoint, 3));

    return bitmap;
}

内容的提问来源于stack exchange，提问作者sina_Islam