！！用webbrowser控件对网页截图是空白的~急！！
这两天要对一个网页进行后台截图，相当于网页快照，后台保存图片即可。
目前想到的方法是添加一个webbrowser控件，然后对控件抓图进行保存。
新建的wpf工程默认界面是mainwindow，这个上边用toolbox添加的webbrowser是从windows.control中继承来的，没有documentcompletted事件（想通过这个事件判断网页是否加载完毕）；
所以新建了一个form1类，在form界面上用toolbox添加了webbrowser控件，这次是从weindows.form中继承来的。有上述事件。
用了以下两种类似的方法截图，不知道为什么截图保存的图片都是空白的，没有网页内容，请教！
1 通过以下函数进行截图（这个貌似只能在mainwindow里用，form1里不知道对其第一个参数设什么）
private void SaveToImage(FrameworkElement p_FrameworkElement, string p_FileName)
{
System.IO.FileStream fs = new System.IO.FileStream(p_FileName, System.IO.FileMode.Create);
RenderTargetBitmap bmp = new RenderTargetBitmap((int)p_FrameworkElement.ActualWidth, (int)p_FrameworkElement.ActualHeight, 96.0, 96.0, PixelFormats.Pbgra32);
bmp.Render(p_FrameworkElement);
BitmapEncoder encoder = new PngBitmapEncoder();
encoder.Frames.Add(BitmapFrame.Create(bmp));
encoder.Save(fs);
fs.Close();
fs.Dispose();
2 还尝试了在form1代码中用如下代码截图：
private void webBrowser1_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
{
System.Drawing.Size mySize = webBrowser1.Document.Window.Size;
Bitmap myPic = new Bitmap(mySize.Width, mySize.Height);
Rectangle myRec = new Rectangle(0, 0, mySize.Width, mySize.Height);
webBrowser1.Size = mySize;
webBrowser1.DrawToBitmap(myPic, myRec);
myPic.Save("E:\\aaaaaa.jpg");
System.Windows.Forms.MessageBox.Show("Ok");
}
新手，分不多，请大家多多帮忙
如果有不用webbrowser控件就可以后台截图的方法，也请告诉我，谢谢
[解决办法]
使用
Bitmap MyImage = Test.GetControlScrollImage(new Uri(@"http://www.sina.com.cn"), 1024);
MyImage.Save(@"C:/1.BMP");
MyImage.Dispose();
使用到的类
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;
using System.Security;
namespace Print
{
public class Test
{
public static Bitmap GetHtmlImage(Uri UrlString,int Width)
{
WebBrowser MyControl = new WebBrowser();
MyControl.Size = new Size(Width, 10);
MyControl.Url = UrlString;
while (MyControl.ReadyState != WebBrowserReadyState.Complete)
{
Application.DoEvents();
}
MyControl.Height= MyControl.Document.Body.ScrollRectangle.Height+20;
MyControl.Url = UrlString;
WebControlImage.Snapshot snap = new WebControlImage.Snapshot();
Bitmap MyImage= snap.TakeSnapshot(MyControl.ActiveXInstance, new Rectangle(0, 0, MyControl.Width, MyControl.Height));
MyControl.Dispose();
return MyImage;
}
/// <summary>
/// WebBrowser获取图形
/// </summary>
private class WebControlImage
{
internal static class NativeMethods
{
[StructLayout(LayoutKind.Sequential)]
public sealed class tagDVTARGETDEVICE
{
[MarshalAs(UnmanagedType.U4)]
public int tdSize;
[MarshalAs(UnmanagedType.U2)]
public short tdDriverNameOffset;
[MarshalAs(UnmanagedType.U2)]
public short tdDeviceNameOffset;
[MarshalAs(UnmanagedType.U2)]
public short tdPortNameOffset;
[MarshalAs(UnmanagedType.U2)]
public short tdExtDevmodeOffset;
}
[StructLayout(LayoutKind.Sequential)]
public class COMRECT
{
public int left;
public int top;
public int right;
public int bottom;
public COMRECT()
{
}
public COMRECT(Rectangle r)
{
this.left = r.X;
this.top = r.Y;
this.right = r.Right;
this.bottom = r.Bottom;
}
public COMRECT(int left, int top, int right, int bottom)
{
this.left = left;
this.top = top;
this.right = right;
this.bottom = bottom;
}
public static NativeMethods.COMRECT FromXYWH(int x, int y, int width, int height)
{
return new NativeMethods.COMRECT(x, y, x + width, y + height);
}
public override string ToString()
{
return string.Concat(new object[] { "Left = ", this.left, " Top ", this.top, " Right = ", this.right, " Bottom = ", this.bottom });
}
}
[StructLayout(LayoutKind.Sequential)]
public sealed class tagLOGPALETTE
{
[MarshalAs(UnmanagedType.U2)]
public short palVersion;
[MarshalAs(UnmanagedType.U2)]
public short palNumEntries;
}
}
public class Snapshot
{
/// <summary>
/// 取快照
/// </summary>
/// <param name="pUnknown">Com 对象</param>
/// <param name="bmpRect">图象大小</param>
/// <returns></returns>
public Bitmap TakeSnapshot(object pUnknown, Rectangle bmpRect)
{
if (pUnknown == null)
return null;
//必须为com对象
if (!Marshal.IsComObject(pUnknown))
return null;
//IViewObject 接口
UnsafeNativeMethods.IViewObject ViewObject = null;
IntPtr pViewObject = IntPtr.Zero;
//内存图
Bitmap pPicture = new Bitmap(bmpRect.Width, bmpRect.Height);
Graphics hDrawDC = Graphics.FromImage(pPicture);
//获取接口
object hret = Marshal.QueryInterface(Marshal.GetIUnknownForObject(pUnknown),
ref UnsafeNativeMethods.IID_IViewObject, out pViewObject);
try
{
ViewObject = Marshal.GetTypedObjectForIUnknown(pViewObject, typeof(UnsafeNativeMethods.IViewObject)) as UnsafeNativeMethods.IViewObject;
//调用Draw方法
ViewObject.Draw((int)System.Runtime.InteropServices.ComTypes.DVASPECT.DVASPECT_CONTENT,
-1,
IntPtr.Zero,
null,
IntPtr.Zero,
hDrawDC.GetHdc(),
new NativeMethods.COMRECT(bmpRect),
null,
IntPtr.Zero,
0);
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
throw ex;
}
//释放
hDrawDC.Dispose();
return pPicture;
}
}
[SuppressUnmanagedCodeSecurity]
internal static class UnsafeNativeMethods
{
public static Guid IID_IViewObject = new Guid("{0000010d-0000-0000-C000-000000000046}");
[ComImport, Guid("0000010d-0000-0000-C000-000000000046"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
public interface IViewObject
{
[PreserveSig]
int Draw([In, MarshalAs(UnmanagedType.U4)] int dwDrawAspect, int lindex, IntPtr pvAspect, [In] NativeMethods.tagDVTARGETDEVICE ptd, IntPtr hdcTargetDev, IntPtr hdcDraw, [In] NativeMethods.COMRECT lprcBounds, [In] NativeMethods.COMRECT lprcWBounds, IntPtr pfnContinue, [In] int dwContinue);
[PreserveSig]
int GetColorSet([In, MarshalAs(UnmanagedType.U4)] int dwDrawAspect, int lindex, IntPtr pvAspect, [In] NativeMethods.tagDVTARGETDEVICE ptd, IntPtr hicTargetDev, [Out] NativeMethods.tagLOGPALETTE ppColorSet);
[PreserveSig]
int Freeze([In, MarshalAs(UnmanagedType.U4)] int dwDrawAspect, int lindex, IntPtr pvAspect, [Out] IntPtr pdwFreeze);
[PreserveSig]
int Unfreeze([In, MarshalAs(UnmanagedType.U4)] int dwFreeze);
void SetAdvise([In, MarshalAs(UnmanagedType.U4)] int aspects, [In, MarshalAs(UnmanagedType.U4)] int advf, [In, MarshalAs(UnmanagedType.Interface)] System.Runtime.InteropServices.ComTypes.IAdviseSink pAdvSink);
void GetAdvise([In, Out, MarshalAs(UnmanagedType.LPArray)] int[] paspects, [In, Out, MarshalAs(UnmanagedType.LPArray)] int[] advf, [In, Out, MarshalAs(UnmanagedType.LPArray)] System.Runtime.InteropServices.ComTypes.IAdviseSink[] pAdvSink);
}
}
}
}
}
