C# 实现IAccessible学习（三）

示例：获取word版本

using System;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Text;

namespace TryWord
{
    [ComImport, InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("00020400-0000-0000-C000-000000000046")]
    public interface IDispatch
    {
    }

    class Program
    {
        [DllImport("user32.dll", SetLastError = true)]
        static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

        [DllImport("Oleacc.dll")]
        static extern int AccessibleObjectFromWindow(int hwnd, uint dwObjectID, byte[] riid, out IDispatch ptr);

        public delegate bool EnumChildCallback(int hwnd, ref int lParam);

        [DllImport("User32.dll")]
        public static extern bool EnumChildWindows(int hWndParent, EnumChildCallback lpEnumFunc, ref int lParam);

        [DllImport("User32.dll")]
        public static extern int GetClassName(int hWnd, StringBuilder lpClassName, int nMaxCount);

        public static bool EnumChildProc(int hwndChild, ref int lParam)
        {
            StringBuilder buf = new StringBuilder(128);
            GetClassName(hwndChild, buf, 128);
            if (buf.ToString() == "_WwG")
            {
                lParam = hwndChild;
                return false;
            }
            return true;
        }

        static void Main(string[] args)
        {
            // Use the window class name ("OpusApp") to retrieve a handle to Word's main window.
            // Alternatively you can get the window handle via the process id:
            // int hwnd = (int)Process.GetProcessById(wordPid).MainWindowHandle;
            //
            int hwnd = (int)FindWindow("OpusApp", null);

            if (hwnd != 0)
            {
                int hwndChild = 0;

                // Search the accessible child window (it has class name "_WwG") 
                // as described in http://msdn.microsoft.com/en-us/library/dd317978%28VS.85%29.aspx
                //
                EnumChildCallback cb = new EnumChildCallback(EnumChildProc);
                EnumChildWindows(hwnd, cb, ref hwndChild);

                if (hwndChild != 0)
                {
                    // We call AccessibleObjectFromWindow, passing the constant OBJID_NATIVEOM (defined in winuser.h) 
                    // and IID_IDispatch - we want an IDispatch pointer into the native object model.
                    //
                    const uint OBJID_NATIVEOM = 0xFFFFFFF0;
                    Guid IID_IDispatch = new Guid("{00020400-0000-0000-C000-000000000046}");
                    IDispatch ptr;

                    int hr = AccessibleObjectFromWindow(hwndChild, OBJID_NATIVEOM, IID_IDispatch.ToByteArray(), out ptr);

                    if (hr >= 0)
                    {
                        object wordApp = ptr.GetType().InvokeMember("Application", BindingFlags.GetProperty, null, ptr, null);

                        object version = wordApp.GetType().InvokeMember("Version", BindingFlags.GetField | BindingFlags.InvokeMethod | BindingFlags.GetProperty, null, wordApp, null);
                        Console.WriteLine(string.Format("Word version is: {0}", version));
                    }
                }
            }
        }
    }
}