using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
using System.Runtime.InteropServices.ComTypes;
using System.Drawing;
using System.Windows.Forms;
namespace SnapLibrary
{
  /// <summary>
  /// ActiveX 組件快照類，用于網(wǎng)頁(yè)拍照，將網(wǎng)頁(yè)保存成圖片
  /// AcitveX 必須實(shí)現(xiàn) IViewObject 接口
  /// 作者:隨飛
  /// </summary>
  public class Snapshot
  {
    /// <summary>
    /// 取快照
    /// </summary>
    /// <param name="pUnknown">Com 對(duì)象</param>
    /// <param name="bmpRect">圖象大小</param>
    /// <returns></returns>
    public Bitmap TakeSnapshot(object pUnknown, Rectangle bmpRect)
    {
      if (pUnknown == null)
        return null;
      //必須為com對(duì)象
      if (!Marshal.IsComObject(pUnknown))
        return null;
      //IViewObject 接口
      SnapLibrary.UnsafeNativeMethods.IViewObject ViewObject = null;
      IntPtr pViewObject = IntPtr.Zero;
      //內(nèi)存圖
      Bitmap pPicture = new Bitmap(bmpRect.Width, bmpRect.Height);
      Graphics hDrawDC = Graphics.FromImage(pPicture);
      //獲取接口
      object hret = Marshal.QueryInterface(Marshal.GetIUnknownForObject(pUnknown),
        ref UnsafeNativeMethods.IID_IViewObject, out pViewObject);
      try
      {
        ViewObject = Marshal.GetTypedObjectForIUnknown(pViewObject, typeof(SnapLibrary.UnsafeNativeMethods.IViewObject)) as SnapLibrary.UnsafeNativeMethods.IViewObject;
        //調(diào)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;
      }
      //釋放
      hDrawDC.Dispose();
      return pPicture;
    }
  }
}