通过IViewObject接口,取浏览器的图象,实现SNAP
今天又见到snap实现的文章,看来对此感兴趣的人挺多的.实现这个功能确实很'眩',我也来做一个把玩一下.
我的做法不是 Control.DrawToBitmap ,而是直接QueryInterface 浏览器Com对象的 IViewObject 接口,用它实现的Draw方法,画到图象上.
首先定义IViewObject的接口声名,如下:
using System;
using System.Collections.Generic;
using System.Text;
using System.Security;
using System.Runtime.InteropServices;
using System.Runtime.InteropServices.ComTypes;
namespace SnapLibrary
{
/// <summary>
/// 从 .Net 2.0 的 System.Windows.Forms.Dll 库提取
/// 版权所有:微软公司
/// </summary>
[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)] IAdviseSink pAdvSink);
void GetAdvise([In, Out, MarshalAs(UnmanagedType.LPArray)] int[] paspects, [In, Out, MarshalAs(UnmanagedType.LPArray)] int[] advf, [In, Out, MarshalAs(UnmanagedType.LPArray)] IAdviseSink[] pAdvSink);
}
}
}
该接口.net 自己带了,只是internal形式,所以只有想办法用Reflector 将它弄出来,相关的还有几个类,分别是tagLOGPALETTE,COMRECT,tagDVTARGETDEVICE.
定义如下:
现在可以通过 Marshal.QueryInterface 将浏览器COM实例的IViewObject接口取出:
将IViewObject 指针对象 pViewObject 转化为接口对象.
调用draw方法,绘制到图象上,以下是TakeSnapshot方法的完整代码:
到此既完成了对Com对象的图象抓取.那么现在给它提供一个浏览器的实例,让它实现对 web page 的快照吧.
.net 2.0提供了webbrowser对象,它是对activex对象的包装,它的使用很简单,这里就不详细说明.
WebBrowser 对象的实例的属性ActiveXInstance就是它的原生COM对象,获取它的IVewObject接口,即可调用它实现的Draw方法把网页绘制到指定的DC上.
以下是对webbrowser对象的包装类,结合Snapshot 类的类代码:
这里提供一个测试用的代码:
工程原始代码下载:
/Files/Chinasf/SnapLibrary.rar
当然,这样做可能太复杂了,因为.net 为我们简化了所有的工作,简单到任意的contrl对象都支持DrawToBitmap 方法.不过想要了解机制的朋友们,可以研究一下.
2006年12月26日 8:55:14 修正:请到Snapshot类中增加一句释放引用接口的代码.
Snapshot..
红色加粗位置.
我的做法不是 Control.DrawToBitmap ,而是直接QueryInterface 浏览器Com对象的 IViewObject 接口,用它实现的Draw方法,画到图象上.
首先定义IViewObject的接口声名,如下:
using System;
using System.Collections.Generic;
using System.Text;
using System.Security;
using System.Runtime.InteropServices;
using System.Runtime.InteropServices.ComTypes;
namespace SnapLibrary
{
/// <summary>
/// 从 .Net 2.0 的 System.Windows.Forms.Dll 库提取
/// 版权所有:微软公司
/// </summary>
[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)] IAdviseSink pAdvSink);
void GetAdvise([In, Out, MarshalAs(UnmanagedType.LPArray)] int[] paspects, [In, Out, MarshalAs(UnmanagedType.LPArray)] int[] advf, [In, Out, MarshalAs(UnmanagedType.LPArray)] IAdviseSink[] pAdvSink);
}
}
}
该接口.net 自己带了,只是internal形式,所以只有想办法用Reflector 将它弄出来,相关的还有几个类,分别是tagLOGPALETTE,COMRECT,tagDVTARGETDEVICE.
定义如下:
相关定义
现在可以通过 Marshal.QueryInterface 将浏览器COM实例的IViewObject接口取出:
//获取接口
object hret = Marshal.QueryInterface(Marshal.GetIUnknownForObject(pUnknown),ref UnsafeNativeMethods.IID_IViewObject, out pViewObject);
pUnknown为 com对象实例.object hret = Marshal.QueryInterface(Marshal.GetIUnknownForObject(pUnknown),ref UnsafeNativeMethods.IID_IViewObject, out pViewObject);
将IViewObject 指针对象 pViewObject 转化为接口对象.
ViewObject = Marshal.GetTypedObjectForIUnknown(pViewObject, typeof(SnapLibrary.UnsafeNativeMethods.IViewObject)) as SnapLibrary.UnsafeNativeMethods.IViewObject;
调用draw方法,绘制到图象上,以下是TakeSnapshot方法的完整代码:
Snapshot类
到此既完成了对Com对象的图象抓取.那么现在给它提供一个浏览器的实例,让它实现对 web page 的快照吧.
.net 2.0提供了webbrowser对象,它是对activex对象的包装,它的使用很简单,这里就不详细说明.
WebBrowser 对象的实例的属性ActiveXInstance就是它的原生COM对象,获取它的IVewObject接口,即可调用它实现的Draw方法把网页绘制到指定的DC上.
以下是对webbrowser对象的包装类,结合Snapshot 类的类代码:
web 页面快照类
这里提供一个测试用的代码:
class Program
{
/// <summary>
/// 测试
/// </summary>
/// <param name="args"></param>
[STAThread]
static void Main(string[] args)
{
//web 页面快照
WebPageSnapshot wps = new WebPageSnapshot();
if (args != null && args.Length > 1)
wps.Url = args[0];
else
wps.Url = "http://www.cnblogs.com";
try
{
//保存到文件
wps.TakeSnapshot().Save("1.bmp");
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
Console.ReadLine();
}
wps.Dispose();
}
}
{
/// <summary>
/// 测试
/// </summary>
/// <param name="args"></param>
[STAThread]
static void Main(string[] args)
{
//web 页面快照
WebPageSnapshot wps = new WebPageSnapshot();
if (args != null && args.Length > 1)
wps.Url = args[0];
else
wps.Url = "http://www.cnblogs.com";
try
{
//保存到文件
wps.TakeSnapshot().Save("1.bmp");
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
Console.ReadLine();
}
wps.Dispose();
}
}
工程原始代码下载:
/Files/Chinasf/SnapLibrary.rar
当然,这样做可能太复杂了,因为.net 为我们简化了所有的工作,简单到任意的contrl对象都支持DrawToBitmap 方法.不过想要了解机制的朋友们,可以研究一下.
2006年12月26日 8:55:14 修正:请到Snapshot类中增加一句释放引用接口的代码.
Snapshot..
try
{
//ViewObject = Marshal.GetObjectForIUnknown(pViewObject) as SnapLibrary.UnsafeNativeMethods.IViewObject;
ViewObject = Marshal.GetTypedObjectForIUnknown(pViewObject, typeof(SnapLibrary.UnsafeNativeMethods.IViewObject)) as SnapLibrary.UnsafeNativeMethods.IViewObject;
//调用Draw方法
ViewObject.Draw((int)DVASPECT.DVASPECT_CONTENT,
-1,
IntPtr.Zero,
null,
IntPtr.Zero,
hDrawDC.GetHdc(),
new NativeMethods.COMRECT(bmpRect),
null,
IntPtr.Zero,
0);
Marshal.Release(pViewObject);
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
throw ex;
}
{
//ViewObject = Marshal.GetObjectForIUnknown(pViewObject) as SnapLibrary.UnsafeNativeMethods.IViewObject;
ViewObject = Marshal.GetTypedObjectForIUnknown(pViewObject, typeof(SnapLibrary.UnsafeNativeMethods.IViewObject)) as SnapLibrary.UnsafeNativeMethods.IViewObject;
//调用Draw方法
ViewObject.Draw((int)DVASPECT.DVASPECT_CONTENT,
-1,
IntPtr.Zero,
null,
IntPtr.Zero,
hDrawDC.GetHdc(),
new NativeMethods.COMRECT(bmpRect),
null,
IntPtr.Zero,
0);
Marshal.Release(pViewObject);
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
throw ex;
}
红色加粗位置.
本文转自suifei博客园博客,原文链接:http://www.cnblogs.com/Chinasf/archive/2006/12/25/603294.html,如需转载请自行联系原作者