通过WebBrowser网页截图C#源码(抓取完整页面及首屏)

通过WebBrowser+PrintWindow实现了网页截图，内部使用了拼接的方式可以实现保存完整网页，也可保存第一屏，不过这种方式的潜在 bug是窗体不可最小化，否则为黑屏，而且也没有找到webbrowser以内存方式构建截屏和合理方式，无法正确render后通过PrintWindow 方式截获图片，这可能也是通过PrintWindow截取的不完美的地方吧（请大家指点更完美的方式吧），下面看代码吧：

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Text;
using System.Runtime.InteropServices;
using System.Diagnostics;
using System.IO;
using System.Drawing.Imaging;
using SHDocVw;
using mshtml;
using System.Net;

namespace WebBrowserCapture
{
    public class WebBrowserCapture
    {
        #region DLLImport

        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        private static extern IntPtr FindWindowEx(IntPtr parent /*HWND*/, IntPtr next /*HWND*/, string sClassName, IntPtr sWindowTitle);

        [DllImport("user32.dll", ExactSpelling = true, CharSet = CharSet.Auto)]
        private static extern IntPtr GetWindow(IntPtr hWnd, int uCmd);

        [DllImport("user32.dll")]
        private static extern void GetClassName(int h, StringBuilder s, int nMaxCount);

        [DllImport("user32.dll")]
        private static extern bool PrintWindow(IntPtr hwnd, IntPtr hdcBlt, uint nFlags);

        [DllImport("user32.dll", SetLastError = true)]
        private static extern IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, string lpszClass, string lpszWindow);

        public const int GW_CHILD = 5;
        public const int GW_HWNDNEXT = 2;

        #endregion

        public System.Windows.Forms.WebBrowser m_browser;

        //我还抓你第一屏幕
        public bool firstScreen = true;

        //测试网络连通状况
        private bool TestInternet(string url)
        {
            HttpWebRequest req = (HttpWebRequest)WebRequest.Create(new Uri(url));
            req.AllowAutoRedirect = true;
            req.UserAgent = "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; SLCC1; .NET CLR 2.0.50727; .NET CLR 3.0.04506; .NET CLR 3.5.21022; .NET CLR 1.0.3705; .NET CLR 1.1.4322)";
            req.Referer = "http://www.google.com";
            req.ContentType = "text/html";
            req.AllowWriteStreamBuffering = true;
            req.AutomaticDecompression = DecompressionMethods.GZip;
            req.Method = "GET";
            req.Proxy = null;
            req.ReadWriteTimeout = 20;

            HttpStatusCode status;
            using (HttpWebResponse resp = (HttpWebResponse)req.GetResponse())
            {
                status = resp.StatusCode;
            }

            if (status == HttpStatusCode.OK || status == HttpStatusCode.Moved)
            {
                return true;
            }
            return false;
        }

        private static ImageCodecInfo GetEncoderInfo(String mimeType)
        {
            int j;
            ImageCodecInfo[] encoders;
            encoders = ImageCodecInfo.GetImageEncoders();
            for (j = 0; j < encoders.Length; ++j)
            {
                if (encoders[j].MimeType == mimeType)
                    return encoders[j];
            }
            return null;
        }

        public void GetPageImage(string url, string path)
        {
            //Test Is OK
            if (TestInternet(url))
            {
                bool flag = firstScreen;
                m_browser.Navigate(url);
                //浏览器Dom载入完毕
                while (m_browser.ReadyState != WebBrowserReadyState.Complete)
                {
                    Application.DoEvents();
                }
                mshtml.IHTMLDocument2 myDoc = (mshtml.IHTMLDocument2)m_browser.Document.DomDocument;

                //处理由于webbrowser上、左边框阴影带来的拼接bug
                int URLExtraHeight = 3;
                int URLExtraLeft = 3;

                (myDoc as HTMLDocumentClass).documentElement.setAttribute("scroll", "yes", 0);

                //document完整高度
                int heightsize = (int)(myDoc as HTMLDocumentClass).documentElement.getAttribute("scrollHeight", 0);
                int widthsize = (int)(myDoc as HTMLDocumentClass).documentElement.getAttribute("scrollWidth", 0);

                ////Get Screen Height
                int screenHeight = (int)(myDoc as HTMLDocumentClass).documentElement.getAttribute("clientHeight", 0);
                int screenWidth = (int)(myDoc as HTMLDocumentClass).documentElement.getAttribute("clientWidth", 0);

                IntPtr myIntptr = (IntPtr)m_browser.Handle;

                //寻找IE对象句柄
                IntPtr wbHandle = FindWindowEx(myIntptr, IntPtr.Zero, "Shell Embedding", null);
                wbHandle = FindWindowEx(wbHandle, IntPtr.Zero, "Shell DocObject View", null);
                wbHandle = FindWindowEx(wbHandle, IntPtr.Zero, "Internet Explorer_Server", null);
                IntPtr hwnd = wbHandle;

                Bitmap bm = new Bitmap(screenWidth, screenHeight, System.Drawing.Imaging.PixelFormat.Format16bppRgb555);
                Bitmap bm2 = new Bitmap(widthsize, heightsize, System.Drawing.Imaging.PixelFormat.Format16bppRgb555);
                Graphics g = null;
                Graphics g2 = Graphics.FromImage(bm2);
                //切割用的临时对象
                Bitmap tempbm = null;
                Graphics tempg = null;

                IntPtr hdc;
                Image screenfrag = null;
                Image firstScreenfrag = null;

                #region 拼接
                int brwTop = 0;
                int brwLeft = 0;
                int myPage = 0;

                //Get Screen Height (for bottom up screen drawing)
                while ((myPage * screenHeight) < heightsize)
                {
                    (myDoc as HTMLDocumentClass).documentElement.setAttribute("scrollTop", (screenHeight - 5) * myPage, 0);
                    ++myPage;
                }
                //Rollback the page count by one
                --myPage;

                int myPageWidth = 0;
                //screenWidth+ URLExtraLeft
                while ((myPageWidth * screenWidth) < widthsize)
                {
                    (myDoc as HTMLDocumentClass).documentElement.setAttribute("scrollLeft", (screenWidth - 5) * myPageWidth, 0);
                    brwLeft = (int)(myDoc as HTMLDocumentClass).documentElement.getAttribute("scrollLeft", 0);
                    for (int i = myPage; i >= 0; --i)
                    {
                        //Shoot visible window
                        g = Graphics.FromImage(bm);
                        hdc = g.GetHdc();
                        (myDoc as HTMLDocumentClass).documentElement.setAttribute("scrollTop", (screenHeight - 5) * i, 0);
                        brwTop = (int)(myDoc as HTMLDocumentClass).documentElement.getAttribute("scrollTop", 0);
                        PrintWindow(hwnd, hdc, 0);
                        g.ReleaseHdc(hdc);
                        g.Flush();
                        screenfrag = Image.FromHbitmap(bm.GetHbitmap());

                        //切除URLExtraLeft、URLExtraHeight长度的webbrowser带来的bug
                        tempbm = new Bitmap(screenWidth - URLExtraLeft, screenHeight - URLExtraHeight, System.Drawing.Imaging.PixelFormat.Format16bppRgb555);
                        tempg = Graphics.FromImage(tempbm);
                        tempg.DrawImage(screenfrag, -URLExtraLeft, -URLExtraHeight);

                        //拼接到g2
                        g2.DrawImage(tempbm, brwLeft + URLExtraLeft, brwTop + URLExtraLeft);

                    }

                    //是否得到第一屏
                    if (flag)
                    {
                        firstScreenfrag = (Image)tempbm.Clone();
                        flag = false;
                    }

                    ++myPageWidth;
                }

                int finalWidth = (int)widthsize;
                int finalHeight = (int)heightsize;
                Bitmap finalImage = new Bitmap(finalWidth, finalHeight, System.Drawing.Imaging.PixelFormat.Format16bppRgb555);
                Graphics gFinal = Graphics.FromImage((Image)finalImage);
                gFinal.DrawImage(bm2, 0, 0, finalWidth, finalHeight);

                #endregion

                //Get Time Stamp
                DateTime myTime = DateTime.Now;
                String format = "yyyy_MM_dd_hh_mm_ss";

                //Create Directory to save image to.
                Directory.CreateDirectory(path);

                //Write Image.
                EncoderParameters eps = new EncoderParameters(1);
                long myQuality = Convert.ToInt64(100);
                eps.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, myQuality);
                ImageCodecInfo ici = GetEncoderInfo("image/jpeg");
                //保存
                finalImage.Save(path + @"\Img_" + myTime.ToString(format) + ".jpg", ici, eps);

                //保存第一屏
                if (firstScreen)
                {
                    firstScreenfrag.Save(path + @"\Img_FirstScreen_" + myTime.ToString(format) + ".jpg", ici, eps);
                    firstScreenfrag.Dispose();
                }

                //Process.Start("explorer.exe", path);

                #region Clean
                //Clean Up.
                myDoc.close();
                myDoc = null;
                g.Dispose();
                g2.Dispose();
                gFinal.Dispose();
                bm.Dispose();
                bm2.Dispose();
                finalImage.Dispose();
                tempbm.Dispose();
                tempg.Dispose();
                #endregion
            }
        }

    }
}