C# 实现IAccessible学习（二）

第一个示例

新建项目，添加引用：

代码：

using System;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Globalization;
using System.Reflection;
namespace TryQq
{
    /// <summary>
    /// Interface definition for Excel.Window interface
    /// </summary>
    [Guid("00020893-0000-0000-C000-000000000046")]
    [InterfaceType(ComInterfaceType.InterfaceIsIDispatch)]
    public interface ExcelWindow
    {
    }

    /// <summary>
    /// This class is needed as a workaround to http://support.microsoft.com/default.aspx?scid=kb;en-us;320369
    /// Excel automation will fail with the follwoing error on systems with non-English regional settings:
    /// "Old format or invalid type library. (Exception from HRESULT: 0x80028018 (TYPE_E_INVDATAREAD))" 
    /// </summary>
    class UILanguageHelper : IDisposable
    {
        private CultureInfo _currentCulture;

        public UILanguageHelper()
        {
            // save current culture and set culture to en-US 
            _currentCulture = System.Threading.Thread.CurrentThread.CurrentCulture;
            System.Threading.Thread.CurrentThread.CurrentCulture = new CultureInfo("en-US");
        }

        public void Dispose()
        {
            // reset to original culture 
            System.Threading.Thread.CurrentThread.CurrentCulture = _currentCulture;
        }
    }

    public partial class Form1 : Form
    {

        [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 ExcelWindow 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() == "EXCEL7")
            {
                lParam = hwndChild;
                return false;
            }
            return true;
        }

        public Form1()
        {
            InitializeComponent();

            // Use the window class name ("XLMAIN") to retrieve a handle to Excel's main window.
            // Alternatively you can get the window handle via the process id:
            // int hwnd = (int)Process.GetProcessById(excelPid).MainWindowHandle;
            //
            int hwnd = (int)FindWindow("XLMAIN", null);

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

                // Search the accessible child window (it has class name "EXCEL7") 
                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}");
                    ExcelWindow ptr;

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

                    if (hr >= 0)
                    {
                        // We successfully got a native OM IDispatch pointer, we can QI this for
                        // an Excel Application using reflection (and using UILanguageHelper to 
                        // fix http://support.microsoft.com/default.aspx?scid=kb;en-us;320369)
                        //
                        using (UILanguageHelper fix = new UILanguageHelper())
                        {
                            object xlApp = ptr.GetType().InvokeMember("Application", BindingFlags.GetProperty, null, ptr, null);

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

    }
}

这个winform程序可以输出excel版本号。
当中AccessibleObjectFromWindow用法还没有搞明白。