Run Revit commands using Win32 API

Win32Api.cs

  /// <summary>
  /// Run Revit commands using Win32 API
  /// </summary>
  public class Win32Api
  {
    [DllImport("user32.dll")]
    private static extern IntPtr GetForegroundWindow();

    [DllImport("user32.dll")]
    static extern bool SetFocus(IntPtr hWnd);

    [DllImport("user32.dll", SetLastError = false)]
    public static extern IntPtr GetDlgItem(IntPtr hDlg, int nIDDlgItem);

    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    private static extern IntPtr SendMessage(IntPtr hwnd, uint Msg, IntPtr wParam, IntPtr lParam);

    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = false)]
    public static extern IntPtr SendMessage(HandleRef hWnd, uint Msg, IntPtr wParam, string lParam);

    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    static extern IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, string lpszClass, string lpszWindow);

    [DllImport("USER32.DLL")]
    public static extern bool PostMessage(IntPtr hWnd, uint msg, uint wParam, uint lParam);

    public const Int32 BM_CLICK = 0x00F5;
    public const Int32 WM_SETTEXT = 0x000C;
    public const Int32 VK_SPACE = 0x20;
    public const Int32 WM_KEYDOWN = 0x100;

    internal static async Task<string> ExportWarinings(UIApplication uiapp)
    {
      //paths stuff
      var tempDir = Path.Combine(Path.GetTempPath(), "RevitWarnings");
      var path = Path.Combine(tempDir, "warning_" + Guid.NewGuid()+".html");
      if (!Directory.Exists(tempDir))
        Directory.CreateDirectory(tempDir);
      
      //get revit command to open the warnings window
      var id = RevitCommandId.LookupPostableCommandId(PostableCommand.ReviewWarnings);
      IntPtr mainWin = GetForegroundWindow();
      uiapp.PostCommand(id);

      //wait until the new window gets in the foreground
      while (GetForegroundWindow()== mainWin)
        await DelayWork(100);
      IntPtr warningsWindow = GetForegroundWindow();

      //must be before the thread-blocking export dialog, and must be without 'await'
      Task.Run(() => TypeSaveFileName(path));
      //click the export button, will show a modal window to Save As
      ClickControl(warningsWindow, "&Export...");
      //after the save dialog is closed, close the warnings window
      ClickControl(warningsWindow, "Close");

      return path;
    }

    /// <summary>
    /// The Save As is shown as modal dialog and it blocks the normal execution of the code
    /// This function is executed on a new thread with a small delay so that it is not blocked and it can
    /// set the file path an then click Save.
    /// </summary>
    /// <param name="text"></param>
   private static async void TypeSaveFileName(string text)
    {
      //wait until the new window gets in the foreground
      IntPtr mainWin = GetForegroundWindow();
      while (GetForegroundWindow() == mainWin)
        await DelayWork(100);
      
      IntPtr exportWindow = GetForegroundWindow();
      IntPtr comboHandle = GetDlgItem(exportWindow, 13006);
      IntPtr editHandle = GetDlgItem(comboHandle, 1001);
      SetControlText(comboHandle, 1001, text);
      SetFocus(editHandle);
      //need to simulate a keystroke or the path won't come throught
      PostMessage(editHandle, WM_KEYDOWN, VK_SPACE, 0);
      await DelayWork(100);
      ClickControl(exportWindow, "&Save");
    }

    /// <summary>
    /// Clicks a button using Win32API
    /// </summary>
    /// <param name="windowHandle">Handle of the windows the control belongs to</param>
    /// <param name="buttonText">Label of the button, to get it correctly use WinSpy</param>
    private static void ClickControl(IntPtr windowHandle, string buttonText)
    {
      IntPtr export = FindWindowEx(windowHandle, IntPtr.Zero, null, buttonText);
      SendMessage(export, BM_CLICK, IntPtr.Zero, IntPtr.Zero);
    }

    /// <summary>
    /// Sets the text value of a control using Win32API
    /// </summary>
    /// <param name="windowHandle">Handle of the windows the control belongs to</param>
    /// <param name="controlId">ID of the control, to get it use WinSpy and convert the value fron Hex to  Decimal</param>
    /// <param name="text">String to be set</param>
    private static void SetControlText(IntPtr windowHandle, int controlId, string text)
    {
      IntPtr iptrHWndControl = GetDlgItem(windowHandle, controlId);
      HandleRef hrefHWndTarget = new HandleRef(null, iptrHWndControl);
      SendMessage(hrefHWndTarget, WM_SETTEXT, IntPtr.Zero, text);
    }

    /// <summary>
    /// Simple function to delay the code async, so that the windows can be loaded
    /// </summary>
    /// <param name="i"></param>
    /// <returns></returns>
    private static async Task DelayWork(int i)
    {
      await Task.Delay(i);
    }
  }