c#根据网址抓取网页截屏生成图片的示例

using system.drawing;
using system.drawing.imaging;
using system.io;
using system.threading;
using system.windows.forms;

public class websitetoimage
{
private bitmap m_bitmap;
private string m_url;
private string m_filename = string.empty;

public websitetoimage(string url)
{
// without file
m_url = url;
}

public websitetoimage(string url, string filename)
{
// with file
m_url = url;
m_filename = filename;
}

public bitmap generate()
{
// thread
var m_thread = new thread(_generate);
m_thread.setapartmentstate(apartmentstate.sta);
m_thread.start();
m_thread.join();
return m_bitmap;
}

private void _generate()
{
var browser = new webbrowser { scrollbarsenabled = false };
browser.navigate(m_url);
browser.documentcompleted += webbrowser_documentcompleted;

while (browser.readystate != webbrowserreadystate.complete)
{
application.doevents();
}

browser.dispose();
}

private void webbrowser_documentcompleted(object sender, webbrowserdocumentcompletedeventargs e)
{
// capture
var browser = (webbrowser)sender;
browser.clientsize = new size(browser.document.body.scrollrectangle.width, browser.document.body.scrollrectangle.bottom);
browser.scrollbarsenabled = false;
m_bitmap = new bitmap(browser.document.body.scrollrectangle.width, browser.document.body.scrollrectangle.bottom);
browser.bringtofront();
browser.drawtobitmap(m_bitmap, browser.bounds);

// save as file?
if (m_filename.length > 0)
{
// save
m_bitmap.savejpg100(m_filename);
}
}
}

public static class bitmapextensions
{
public static void savejpg100(this bitmap bmp, string filename)
{
var encoderparameters = new encoderparameters(1);
encoderparameters.param[0] = new encoderparameter(system.drawing.imaging.encoder.quality, 100l);
bmp.save(filename, getencoder(imageformat.jpeg), encoderparameters);
}

public static void savejpg100(this bitmap bmp, stream stream)
{
var encoderparameters = new encoderparameters(1);
encoderparameters.param[0] = new encoderparameter(system.drawing.imaging.encoder.quality, 100l);
bmp.save(stream, getencoder(imageformat.jpeg), encoderparameters);
}

public static imagecodecinfo getencoder(imageformat format)
{
var codecs = imagecodecinfo.getimagedecoders();

foreach (var codec in codecs)
{
if (codec.formatid == format.guid)
{
return codec;
}
}

// return
return null;
}
}

调用方式如下：

websitetoimage websitetoimage = new websitetoimage( "//www.jb51.net", @"d:\some folder\keleyi.jpg");
websitetoimage.generate();

这种方式使用了webbrowser控件，所以必须引用 system.windows.forms 命名空间。