Delphi XE中未声明的标识符AccessibleObjectFromEvent

Question

How can I resolve the following error, it seems he can not find the function AccessibleObjectFromEvent. I am using version Delphi XE6.

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Image

http://i.imgur.com/2JbiIR7.png

Here is my code:

unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;

type
  TForm1 = class(TForm)
    Memo1: TMemo;
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
  private
    { Private declarations }
    procedure AddUrlToMemo;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

uses
  { MSAAIntf, } Oleacc, ActiveX;

{$R *.dfm}

type
  HWINEVENTHOOK = THandle;

var
  UrlVelha: WideString;
  Thread: THandle = 0;
  ThreadId: DWORD = 0;

procedure WinEventProc(hWinEventHook: HWINEVENTHOOK; event: DWORD; hwnd: HWND;
  idObject, idChild: Longint; idEventThread, dwmsEventTime: DWORD); stdcall;
var
  vAccObj: IAccessible;
  varChild: OleVariant;
  vWSName, vWSValue: WideString;
  ClassName: String;
  Acesso: HResult;
begin
  SetLength(ClassName, 255);
  SetLength(ClassName, GetClassName(hwnd, PChar(ClassName), 255));

  if (ClassName = 'Chrome_WidgetWin_1') then
  begin
    Acesso := AccessibleObjectFromEvent(hwnd, idObject, idChild, vAccObj, varChild);
    If (Acesso = S_OK) and (vAccObj <> nil) then
    begin
      vAccObj.Get_accName( { CHILDID_SELF } varChild, vWSName);
      if (vWSName = 'Address and search bar') then
      begin
        vAccObj.Get_accValue( { CHILDID_SELF } varChild, vWSValue);
        if (vWSValue <> '') and (vWSValue <> '<null>') and (UrlVelha <> vWSValue) then
        begin
          UrlVelha := vWSValue;
          TThread.Synchronize(nil, Form1.AddUrlToMemo);
        end;
      end;
    end;
  end;
end;

function Thread_Infinite(param: Pointer): DWORD; stdcall;
var
  Msg: TMSG;
  vHook: HWINEVENTHOOK;
begin
  CoInitialize(nil);

  vHook := SetWinEventHook(EVENT_OBJECT_FOCUS, EVENT_OBJECT_VALUECHANGE, 0,
    @WinEventProc, 0, 0, WINEVENT_SKIPOWNPROCESS);

  while GetMessage(Msg, 0, 0, 0) do
  begin
    TranslateMessage(Msg);
    DispatchMessage(Msg);
  end;

  if (vHook <> 0) then
    UnhookWinEvent(vHook);

  CoUninitialize;
  Result := 0;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
 Thread := CreateThread(nil, 0, @Thread_Infinite, nil, 0, ThreadId);
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  if (ThreadId <> 0) then
    PostThreadMessage(ThreadId, WM_QUIT, 0, 0);
  if (Thread <> 0) then
  begin
    repeat
      if (WaitForSingleObject(Thread, 5000) <> WAIT_TIMEOUT) then
        Break;
      CheckSynchronize;
    until False;
    CloseHandle(Thread);
  end;
end;

procedure TForm1.AddUrlToMemo;
begin
  if (Memo1 <> nil) and (not (csDestroying in ComponentState)) then
    Memo1.Lines.Add(UrlVelha);
end;

end.

Answer 1

The function AccessibleObjectFromEvent is part of Oleacc.dll , to use it add the definition to your declarations.

function AccessibleObjectFromEvent( hWnd            :HWND;
                                    dwObjewctID     :DWORD;
                                    dwChildID       :DWORD;
                                    out pAcc        :IAccessible;
                                    out pVarChild   :OleVariant
                                   ):HResult;  stdcall; external 'OLEACC.DLL';