web端生成pdf

背景：之前生成pdf一直是直接把html代码通过iTextSharp.text.pdf转成pdf,但是一旦html样式稍微复杂就会错乱，比如input标签不会展示，边框也不会展示，只能展示table这些，所以需要通过其它办法。

一开始是直接搞了个窗体程序做尝试，思路是通过WebBrowser打开html截取图片，注意html需要设置好宽高，否则会以很小的窗口打开，截图会不全。

但是后面想迁移到web项目上发现，web项目没法引用using System.Windows.Forms;从而无法使用WebBrowser。我是直接的把这个dll文件拷到web项目，然后强制引用，最后可以了，一开始虽然可以用WebBrowser，但是运行会报错，看网上通过把WebBrowser另起一个线程，并做一些设置就可以了。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using iTextSharp.text;
using iTextSharp.text.pdf;
using System.IO;
using System.Windows.Forms;
using System.Drawing;
using System.Threading;

namespace ISPR.Common
{
    public class PDFConvert
    {
        public WebBrowser webBrowser = null;
        public string PDFPath = "";

        /// <summary>
        /// 将含有特殊样式的html(例如含有input标签)先转成图片，再从图片转成pdf,注意html宽高需要设置好，否则WebBrowser打开后转成图片会显示不全
        /// </summary>
        /// <param name="html"></param>
        /// <param name="pdfFilePath"></param>
        public void ConvertImgToPDF(String html, String pdfFilePath)
        {
            var t = new Thread(()=>
            {
                PDFPath = pdfFilePath;
                webBrowser = new WebBrowser();

                webBrowser.ScriptErrorsSuppressed = true;  //防止脚本异常跳出弹窗
                //是否显式滚动条
                webBrowser.ScrollBarsEnabled = false;

                //加载 html
                webBrowser.DocumentText = html;

                //页面加载完成执行事件
                webBrowser.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(webBrowser_DocumentCompleted);
                while (webBrowser.ReadyState != System.Windows.Forms.WebBrowserReadyState.Complete)
                {
                    System.Windows.Forms.Application.DoEvents(); //避免假死，若去掉则可能无法触发 DocumentCompleted 事件。
                }
            });
            t.SetApartmentState(ApartmentState.STA);
            t.Start();
            //t.Join(); //阻塞当前线程，等待子线程执行完成 
            //while(t.IsAlive)
            //{

            //}
        }
        public void webBrowser_DocumentCompleted(object sender, EventArgs e)//这个就是当网页载入完毕后要进行的操作
        {
            //获取解析后HTML的大小
            System.Drawing.Rectangle rectangle = webBrowser.Document.Body.ScrollRectangle;
            int width = rectangle.Width;
            int height = rectangle.Height;

            //设置解析后HTML的可视区域
            webBrowser.Width = width;//宽高可能需要针对每个html css写好宽高，不然WebBrowser获取的宽高可能会很小
            webBrowser.Height = height;

            Bitmap bitmap = new System.Drawing.Bitmap(width, height);
            webBrowser.DrawToBitmap(bitmap, new System.Drawing.Rectangle(0, 0, width, height));

            //设置图片文件保存路径和图片格式，格式可以自定义
            //string filePath = AppDomain.CurrentDomain.BaseDirectory + DateTime.Now.ToString("yyyyMMddHHmmssfff") + ".png";
            //bitmap.Save(filePath, System.Drawing.Imaging.ImageFormat.Png);
            if (System.IO.File.Exists(PDFPath))
            {
                File.Delete(PDFPath);
            }
            //创建PDF
            FileStream fileStream = new FileStream(PDFPath, FileMode.Create);

            byte[] result = CreatePDF(bitmap, width, height);

            fileStream.Write(result, 0, result.Length);

            fileStream.Close();
            fileStream.Dispose();
            webBrowser = null;
        }


        public byte[] CreatePDF(Bitmap bitmap, int width, int height)
        {
            using (MemoryStream ms = new MemoryStream())
            {
                Document doc = new Document(new iTextSharp.text.Rectangle(0, 0, width, height), 3, 3, 3, 3);    // 左右上下

                PdfWriter writer = PdfWriter.GetInstance(doc, ms);

                writer.CloseStream = false;

                doc.Open();

                iTextSharp.text.Image img = iTextSharp.text.Image.GetInstance(bitmap, System.Drawing.Imaging.ImageFormat.Png);

                img.ScalePercent(100);      // 放缩比例

                doc.Add(img);       // 添加图片对像
                doc.Close();

                return ms.ToArray();
            }
        }
        /// <summary>
        /// 将html转成pdf,复杂样式或者含有input等标签无法渲染出效果
        /// </summary>
        /// <param name="html"></param>
        /// <param name="pdfFilePath"></param>
        /// <param name="rotate"></param>
        public void ConvertToPDF(String html, String pdfFilePath, bool rotate = false)
        {
            //Create a byte array that will eventually hold our final PDF
            Byte[] bytes;

            //Boilerplate iTextSharp setup here
            //Create a stream that we can write to, in this case a MemoryStream
            using (var ms = new MemoryStream())
            {

                //Create an iTextSharp Document which is an abstraction of a PDF but **NOT** a PDF
                using (var doc = new Document())
                {
                    //Create a writer that's bound to our PDF abstraction and our stream
                    if(rotate)
                        doc.SetPageSize(iTextSharp.text.PageSize.A4.Rotate());
                    using (var writer = PdfWriter.GetInstance(doc, ms))
                    {

                        //Open the document for writing
                        doc.Open();

                        /**************************************************
                         * Example #2                                     *
                         *                                                *
                         * Use the XMLWorker to parse the HTML.           *
                         * Only inline CSS and absolutely linked          *
                         * CSS is supported                               *
                         * ************************************************/

                        //XMLWorker also reads from a TextReader and not directly from a string
                        //using (var srHtml = new StringReader(html))
                        //{

                        //    //Parse the HTML
                        //    iTextSharp.tool.xml.XMLWorkerHelper.GetInstance().ParseXHtml(writer, doc, srHtml);
                        //}

                        byte[] data = Encoding.UTF8.GetBytes(html);//字串轉成byte[]
                        MemoryStream msInput = new MemoryStream(data);
                        iTextSharp.tool.xml.XMLWorkerHelper.GetInstance().ParseXHtml(writer, doc, msInput, null, Encoding.UTF8, new UnicodeFontFactory());
                        doc.Close();
                    }
                }

                //After all of the PDF "stuff" above is done and closed but **before** we
                //close the MemoryStream, grab all of the active bytes from the stream
                bytes = ms.ToArray();
            }

            //Now we just need to do something with those bytes.
            //Here I'm writing them to disk but if you were in ASP.Net you might Response.BinaryWrite() them.
            //You could also write the bytes to a database in a varbinary() column (but please don't) or you
            //could pass them to another function for further PDF processing.

            System.IO.File.WriteAllBytes(pdfFilePath, bytes);
        }
    }
    public class UnicodeFontFactory : FontFactoryImp
    {
        private static readonly string arialFontPath = Path.Combine(System.AppDomain.CurrentDomain.BaseDirectory,
            "Template/Font/arialuni.ttf");//arial unicode MS是完整的unicode字型。
        private static readonly string bkt_Path = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Fonts),
          "KAIU.TTF");//標楷體


        public override iTextSharp.text.Font GetFont(string fontname, string encoding, bool embedded, float size, int style, BaseColor color,
            bool cached)
        {
            //可用Arial或標楷體，自己選一個
            BaseFont baseFont = BaseFont.CreateFont(arialFontPath, BaseFont.IDENTITY_H, BaseFont.EMBEDDED);
            return new iTextSharp.text.Font(baseFont, size, style, color);
        }
    }
}