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This question refers to the given solution in Creating Accessible UI components in Delphi

I tried to solve my problem described in the last question (here) using the solution from the question above. After implementing the IAccessible Interface as shown, I debugged and was happy too see that the interface is accessed when I try to read the WinForm-Properties via an external program (in this case the Coded UI-Test Recording-Tool of Visual Studio).

The accessible name was set like i wanted, but it got lost somehow, because the name was still not defined in the WinForm properties.

Here the code:

Declaration:

TXControlEigenschaften = class (TInterfacedObject, IAccessible)
strict private
  FControl: IXControl;

  FAccessibleName: string;
  FAccessibleDescription: string;
  // IAccessible
  function Get_accParent(out ppdispParent: IDispatch): HResult; stdcall;
  function Get_accChildCount(out pcountChildren: Integer): HResult; stdcall;
  function Get_accChild(varChild: OleVariant; out ppdispChild: IDispatch): HResult; stdcall;
  function Get_accName(varChild: OleVariant; out pszName: WideString): HResult; stdcall;
  function Get_accValue(varChild: OleVariant; out pszValue: WideString): HResult; stdcall;
  function Get_accDescription(varChild: OleVariant; out pszDescription: WideString): HResult; stdcall;
  function Get_accRole(varChild: OleVariant; out pvarRole: OleVariant): HResult; stdcall;
  function Get_accState(varChild: OleVariant; out pvarState: OleVariant): HResult; stdcall;
  function Get_accHelp(varChild: OleVariant; out pszHelp: WideString): HResult; stdcall;
  function Get_accHelpTopic(out pszHelpFile: WideString; varChild: OleVariant;
                                                      out pidTopic: Integer): HResult; stdcall;
  function Get_accKeyboardShortcut(varChild: OleVariant; out pszKeyboardShortcut: WideString): HResult; stdcall;
  function Get_accFocus(out pvarChild: OleVariant): HResult; stdcall;
  function Get_accSelection(out pvarChildren: OleVariant): HResult; stdcall;
  function Get_accDefaultAction(varChild: OleVariant; out pszDefaultAction: WideString): HResult; stdcall;
  function accSelect(flagsSelect: Integer; varChild: OleVariant): HResult; stdcall;
  function accLocation(out pxLeft: Integer; out pyTop: Integer; out pcxWidth: Integer;
                                           out pcyHeight: Integer; varChild: OleVariant): HResult; stdcall;
  function accNavigate(navDir: Integer; varStart: OleVariant; out pvarEndUpAt: OleVariant): HResult; stdcall;
  function accHitTest(xLeft: Integer; yTop: Integer; out pvarChild: OleVariant): HResult; stdcall;
  function accDoDefaultAction(varChild: OleVariant): HResult; stdcall;
  function Set_accName(varChild: OleVariant; const pszName: WideString): HResult; stdcall;
  function Set_accValue(varChild: OleVariant; const pszValue: WideString): HResult; stdcall;

  function GetIDsOfNames(const IID: TGUID; Names: Pointer;
    NameCount, LocaleID: Integer; DispIDs: Pointer): HResult; stdcall;
  function GetTypeInfo(Index, LocaleID: Integer; out TypeInfo): HResult; stdcall;
  function GetTypeInfoCount(out Count: Integer): HResult; stdcall;
  function Invoke(DispID: Integer; const IID: TGUID; LocaleID: Integer;
    Flags: Word; var Params; VarResult, ExcepInfo, ArgErr: Pointer): HResult; stdcall;

public
  constructor Create(aControl: IXControl);

  procedure WMGetMSAAObject(var Message : TMessage); message WM_GETOBJECT;

  property AccessibleName: string read FAccessibleName write FAccessibleName;
  property AccessibleDescription: string read FAccessibleDescription write FAccessibleDescription;

end;

Implementation of the important ones:

procedure TXControlEigenschaften.WMGetMSAAObject(var Message: TMessage);
begin
    Message.Result := LresultFromObject(IID_IAccessible, Message.WParam, Self);
end;

function TXControlEigenschaften.Get_accName(varChild: OleVariant; out pszName: WideString): HResult;
begin
  pszName := '';
  Result := S_FALSE;
  if varChild = CHILDID_SELF then
  begin
    if AccessibleName <> '' then
      pszName := AccessibleName
    else
      pszName := FControl.Name;
    result := S_OK;
  end;
end;

The Interface created is used by a derivation of TEdit, here the regarding code:

TXCustomEdit = class(TCustomMaskEdit, IAccessible, IXControl, IXCtrlInterface, ITBXValidate, IXReadOnly, IXChange,
                   IXDelete, IXCut, IXPaste, IXSelectAll, IXVisible, IComboEdit
                   {$IFNDEF PACKAGE}, IXDPISkalierung, IExtrafeldControl{$ENDIF PACKAGE})

strict private
  procedure WMGetMSAAObject(var Message : TMessage); message WM_GETOBJECT;
  FAccessible: IAccessible;
...

implementation

constructor TXCustomEdit.Create(AOwner: TComponent);
var
  ce: TXControlEigenschaften;
begin
  ...
  FSkalierungsZustand := TSkalierungsZustand.Create(Self);
end;

...

procedure TXCustomEdit.WMGetMSAAObject(var Message: TMessage);
begin
  (FAccessible as TXControlEigenschaften).WMGetMSAAObject(Message);
end;

Btw, this is just a debug solution, so I will change things like the message handling later.

Does someone have an idea, why I still get an empty Name in the WinForms-Properties?

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  • Does `TXCustomEdit.WMGetMSAAObject` execute? – David Heffernan Feb 20 '14 at 03:56
  • yeah it does, and i can also debug into the get_accname of TXControlEigenschaften and the name is set – Florian Koch Feb 20 '14 at 06:13
  • Something strange just occured: when i debug through every call on the `TXControlEigenschaften.WMGetMSAAObject` after trying to read the Objects properties, the name appears in my Property-List. When i disable the breakpoints, it doesn't show the name. Now its getting ridiculous... – Florian Koch Feb 20 '14 at 06:57
  • and another thing: this just works once, when i already read out the properties in this instance of the application, there are much less calls of the WMGetMSAAObject and even with breakpoints the names does not appear, after restarting the application it works again – Florian Koch Feb 20 '14 at 07:05
  • just simplified the thing by putting the implemenatation for IAccessible in a own class, because I suspected the usage of one class for two interfaces as the problem, but it didnt change anything – Florian Koch Feb 20 '14 at 08:07
  • Now working through [this Article](http://msdn.microsoft.com/en-us/library/windows/desktop/cc307844.aspx) maybe this could help. I'll update the Code when I finished – Florian Koch Feb 20 '14 at 08:50

1 Answers1

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I solved the problem by just returning DISP_E_MEMBERNOTFOUND in Get_accState instead of taking the Code provided in this article. This works for the name, but the selection of Components via Tools like AutoIt or the Visual Studio Test-Generator for coded UI will be much more diffcult then.

So its more a workaround then a real solution.

I opened a new question regarding this problem here, because the original problem is solved.

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