我在这里找到了一个winform的代码:http://www.wincustomize.com/articles.aspx?aid=136426&c=1
而且它作为 winform 工作正常。但我想在网络应用程序中运行代码。
我将 C:\Program Files\Microsoft.NET\Primary Interop Assemblies\中的 System.Windows.Forms 和 Microsoft.mshtml.dll 的引用添加到我的 Web 应用中。
<我将 WebPageBitmap.cs 复制到我的网络应用中。
我将 Program.cs 的 Main() 作为 Button_Click() 复制到我的 Web 应用。
当我点击网络应用程序中的按钮时。出现错误:
ActiveX 控件 '8856f961-340a-11d0-a96b-00c04fd705a2' 无法实例化，因为当前线程不在单线程单元中。
如何在 Web 应用程序中使用 System.Windows.Forms.WebBrowser 来获取网站缩略图？
public partial class Capture01 : System.Web.UI.Page
{
public delegate void WebBrowserDocumentCompletedEventHandler(object sender, WebBrowserDocumentCompletedEventArgs e);
[STAThread]
protected void Button1_Click(object sender, EventArgs e)
{
int width = 1024;
int height = 900;
int thumbwidth = width;
int thumbheight = height;
string fileName = "image01.jpg";
string url = "http://www.iweixtest.cn/WE/Site/1647/index.aspx";
thumbwidth = 150;
thumbheight = 100;
//WebPageBitmap webBitmap = new WebPageBitmap(args[0], width, height, false, 10000);
WebPageBitmap webBitmap = new WebPageBitmap(url, width, height, false, 10000);
if (webBitmap.IsOk)
{
webBitmap.Fetch();
Bitmap thumbnail = webBitmap.GetBitmap(thumbwidth, thumbheight);
//thumbnail.Save(args[1], ImageFormat.Jpeg);
thumbnail.Save(fileName, ImageFormat.Jpeg);
thumbnail.Dispose();
}
else
{
MessageBox.Show(webBitmap.ErrorMessage);
}
}
}
WebPageBitmap.cs
namespace GetSiteThumbnail
{
/// <summary>
/// Thanks for the solution to the "sometimes not painting sites to Piers Lawson
/// Who performed some extensive research regarding the origianl implementation.
/// You can find his codeproject profile here:
/// http://www.codeproject.com/script/Articles/MemberArticles.aspx?amid=39324
/// </summary>
[InterfaceType(1)]
[Guid("3050F669-98B5-11CF-BB82-00AA00BDCE0B")]
public interface IHTMLElementRender2
{
void DrawToDC(IntPtr hdc);
void SetDocumentPrinter(string bstrPrinterName, ref _RemotableHandle hdc);
}
/// <summary>
/// Code by Adam Najmanowicz
/// http://www.codeproject.com/script/Membership/Profiles.aspx?mid=923432
/// http://blog.najmanowicz.com/
/// Some improvements suggested by Frank Herget
/// http://www.artviper.net/
/// </summary>
class WebPageBitmap
{
private WebBrowser webBrowser;
private string url;
private int width;
private int height;
private bool isOk;
private string errorMessage;
public string ErrorMessage
{
get { return errorMessage; }
}
public bool IsOk
{
get { return isOk; }
set { isOk = value; }
}
public WebPageBitmap(string url, int width, int height, bool scrollBarsEnabled, int wait)
{
this.width = width;
this.height = height;
this.url =
url.StartsWith("http://", StringComparison.InvariantCultureIgnoreCase) ?
url : this.url = "http://" + url;
try
// needed as the script throws an exeception if the host is not found
{
HttpWebRequest req = (HttpWebRequest)WebRequest.Create(this.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)"; //成功
req.UserAgent = "Mozilla/4.0 (Compatible; Windows NT 5.1; MSIE 6.0) (compatible; MSIE 6.0; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)";
//req.Referer = "http://www.cognifide.com";
req.ContentType = "text/html";
req.Accept = "*/*";
req.KeepAlive = false;
using (HttpWebResponse resp = (HttpWebResponse)req.GetResponse())
{
string x = resp.StatusDescription;
}
}
catch (Exception ex)
{
errorMessage = ex.Message;
isOk = false;
return;
}
isOk = true; // public, to check in program.cs if the domain is found, so the image can be saved
webBrowser = new WebBrowser();
webBrowser.DocumentCompleted +=
new WebBrowserDocumentCompletedEventHandler(documentCompletedEventHandler);
webBrowser.Size = new Size(width, height);
webBrowser.ScrollBarsEnabled = false;
}
/// <summary>
/// Fetches the image
/// </summary>
/// <returns>true is the operation ended with a success</returns>
public bool Fetch()
{
HttpWebRequest req = (HttpWebRequest)WebRequest.Create(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.UserAgent = "Mozilla/4.0 (Compatible; Windows NT 5.1; MSIE 6.0) (compatible; MSIE 6.0; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)";
//req.Referer = "http://www.cognifide.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)
{
webBrowser.Navigate(url);
while (webBrowser.ReadyState != WebBrowserReadyState.Complete)
{
Application.DoEvents();
}
return true;
}
else
{
return false;
}
}
private void documentCompletedEventHandler(object sender, WebBrowserDocumentCompletedEventArgs e)
{
((WebBrowser)sender).Document.Window.Error +=
new HtmlElementErrorEventHandler(SuppressScriptErrorsHandler);
}
public void SuppressScriptErrorsHandler(object sender, HtmlElementErrorEventArgs e)
{
e.Handled = true;
MessageBox.Show("Error!");
}
internal Bitmap GetBitmap(int thumbwidth, int thumbheight)
{
IHTMLDocument2 rawDoc = (IHTMLDocument2)webBrowser.Document.DomDocument;
IHTMLElement rawBody = rawDoc.body;
IHTMLElementRender2 render = (IHTMLElementRender2)rawBody;
Bitmap bitmap = new Bitmap(width, height);
Rectangle bitmapRect = new Rectangle(0, 0, width, height);
// Interesting thing that despite using the renderer later
// this following line is still necessary or
// the background may not be painted on some websites.
webBrowser.DrawToBitmap(bitmap, bitmapRect);
using (Graphics graphics = Graphics.FromImage(bitmap))
{
IntPtr graphicshdc = graphics.GetHdc();
render.DrawToDC(graphicshdc);
graphics.ReleaseHdc(graphicshdc);
graphics.Dispose();
if (thumbheight == height && thumbwidth == width)
{
return bitmap;
}
else
{
Bitmap thumbnail = new Bitmap(thumbwidth, thumbheight);
using (Graphics gfx = Graphics.FromImage(thumbnail))
{
// high quality image sizing
gfx.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
gfx.InterpolationMode = InterpolationMode.HighQualityBicubic; // make it look pretty
gfx.DrawImage(bitmap, new Rectangle(0, 0, thumbwidth, thumbheight), bitmapRect, GraphicsUnit.Pixel);
}
bitmap.Dispose();
return thumbnail;
}
}
}
}
}
请您参考如下方法:
您可以创建自己的工作线程并调用 SetApartmentState将其更改为 STA 线程；该线程可以完成呈现网页的工作。但是，将需要大量的线程间通信，而且正如 R. Bemrose 所说，System.Windows 类并非真正设计用于 Web 应用程序内部。
另一种方法是重写示例应用程序(作为 .EXE)以采用两个参数:(1) 要下载的 URL，以及 (2) 屏幕截图图像的输出位置。您的网络应用程序可以创建一个临时路径(用于输出文件)，启动此程序(使用 Process.Start )，等待它完成，加载它创建的输出文件，然后在将临时文件发送到客户端或以其他方式不再需要。 (当然，如果出现问题，它需要有与显示消息框不同的错误处理。)
