在 Delphi 中创建可访问的 UI 组件

问题描述 投票：0回答：3

我正在尝试从标准 VCL TEdit 控件检索可访问的信息。 get_accName() 和 Get_accDescription() 方法返回空字符串，但 get_accValue() 返回输入到 TEdit 中的文本值。

我刚刚开始尝试了解 MSAA，此时我有点迷失。

我的 TEdit 是否需要具有向 MSA 公开的其他已发布属性？如果是这样，是否需要创建一个继承自 TEdit 的新组件并添加其他已发布的属性，例如“AccessibleName”、“AccessibleDescription”等...？

另外，请注意，我已经查看了 VTVirtualTrees 组件，该组件“应该”是可访问的，但即使在该控件上，MS Active Accessibility Object Inspector 仍然看不到 AccessibleName 已发布属性。 此时我不知所措，非常感谢您在此事上的任何建议或帮助。

... interface uses Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.ComCtrls, Vcl.ExtCtrls, oleacc; const WM_GETOBJECT = $003D; // Windows MSAA message identifier OBJID_NATIVEOM = $FFFFFFF0; type TForm1 = class(TForm) lblFirstName: TLabel; edFirstName: TEdit; panel1: TPanel; btnGetAccInfo: TButton; accInfoOutput: TEdit; procedure btnGetAccInfoClick(Sender: TObject); procedure edFirstNameChange(Sender: TObject); private { Private declarations } FFocusedAccessibleObj: IAccessible; FvtChild: Variant; FAccProperties: TStringList; FAccName: string; FAccDesc: string; FAccValue: string; procedure DoGetAccessibleObjectFromPoint(aPoint: TPoint); public { Public declarations } procedure BeforeDestruction; override; property AccName: string read FAccName; property AccDescription: string read FAccName; property AccValue: string read FAccName; end; var Form1: TForm1; const cCRLF = #13#10; implementation {$R *.dfm} function AccessibleObjectFromPoint(ptScreen: TPoint; out ppacc: IAccessible; out pvarChildt: Variant): HRESULT; stdcall; external 'oleacc.dll' ; {------------------------------------------------------------------------------} procedure TForm1.BeforeDestruction; begin VarClear(FvtChild); FFocusedAccessibleObj := nil; end; {------------------------------------------------------------------------------} procedure TForm1.DoGetAccessibleObjectFromPoint(aPoint: TPoint); var pt: TPoint; bsName: WideString; bsDesc: WideString; bsValue: WideString; begin if (SUCCEEDED(AccessibleObjectFromPoint(aPoint, FFocusedAccessibleObj, FvtChild))) then try // get_accName returns an empty string bsName := ''; FFocusedAccessibleObj.get_accName(FvtChild, bsName); FAccName := bsName; FAccProperties.Add('Acc Name: ' + FAccName + ' | ' + cCRLF); // Get_accDescription returns an empty string bsDesc := ''; FFocusedAccessibleObj.Get_accDescription(FvtChild, bsDesc); FAccDesc := bsDesc; FAccProperties.Add('Acc Description: ' + FAccDesc + ' | ' + cCRLF); // this works bsValue := ''; FFocusedAccessibleObj.get_accValue(FvtChild, bsValue); FAccValue := bsValue; FAccProperties.Add('Acc Value: ' + FAccValue + cCRLF); finally VarClear(FvtChild); FFocusedAccessibleObj := nil ; end; end; {------------------------------------------------------------------------------} procedure TForm1.btnGetAccInfoClick(Sender: TObject); begin FAccProperties := TStringList.Create; DoGetAccessibleObjectFromPoint(edFirstName.ClientOrigin); accInfoOutput.Text := FAccProperties.Text; end; end. 




    
    delphi
    
    accessibility
    
    delphi-xe3
    
    delphi-2006
    
    msaa
    
    
3个回答

    

      
      
      

        

          

            

              
44
投票

              
            

          

        

        
IAccessible
 接口，然后让您的控件响应 
WM_GETOBJECT
 消息，以便它可以返回指向您的实现实例的指针.



更新：
 例如，将 MSAA 添加到现有TEdit（如果您不想派生自己的组件）的一种方法可能如下所示：


uses
  ..., oleacc;

type
  TMyAccessibleEdit = class(TInterfacedObject, IAccessible)
  private
    fEdit: TEdit;
    fDefAcc: IAccessible;
  public
    constructor Create(aEdit: TEdit; aDefAcc: IAccessible);

    function QueryInterface(const IID: TGUID; out Obj): HResult; virtual; stdcall;

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

    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;
  end;







constructor TMyAccessibleEdit.Create(aEdit: TEdit; aDefAcc: IAccessible);
begin
  inherited Create;
  fEdit := aEdit;
  fDefAcc := aDefAcc;
end;

function TMyAccessibleEdit.QueryInterface(const IID: TGUID; out Obj): HResult; virtual; stdcall;
begin
  if IID = IID_IAccessible then
    Result := inherited QueryInterface(IID, Obj)
  else
    Result := fDefAcc.QueryInterface(IID, Obj);
end;

function TMyAccessibleEdit.GetTypeInfoCount(out Count: Integer): HResult; stdcall;
begin
  Result := fDefAcc.GetTypeInfoCount(Count);
end;

function TMyAccessibleEdit.GetTypeInfo(Index, LocaleID: Integer; out TypeInfo): HResult; stdcall;
begin
  Result := fDefAcc.GetTypeInfo(Index, LocaleID, TypeInfo);
end;

function TMyAccessibleEdit.GetIDsOfNames(const IID: TGUID; Names: Pointer; NameCount, LocaleID: Integer; DispIDs: Pointer): HResult; stdcall;
begin
  Result := fDefAcc.GetIDsOfNames(IID, Names, NameCount, LocaleID, DispIDs);
end;

function TMyAccessibleEdit.Invoke(DispID: Integer; const IID: TGUID; LocaleID: Integer; Flags: Word; var Params; VarResult, ExcepInfo, ArgErr: Pointer): HResult; stdcall;
begin
  Result := fDefAcc.Invoke(DispID, IID, LocaleID, Flags, Params, VarResult, ExcepInfo, ArgErr);
end;

function TMyAccessibleEdit.Get_accParent(out ppdispParent: IDispatch): HResult; stdcall;
begin
  Result := fDefAcc.Get_accParent(ppdispParent);
end;

function TMyAccessibleEdit.Get_accChildCount(out pcountChildren: Integer): HResult; stdcall;
begin
  Result := fDefAcc.Get_accChildCount(pcountChildren);
end;

function TMyAccessibleEdit.Get_accChild(varChild: OleVariant; out ppdispChild: IDispatch): HResult; stdcall;
begin
  Result := fDefAcc.Get_accChild(varChild, ppdispChild);
end;

function TMyAccessibleEdit.Get_accName(varChild: OleVariant; out pszName: WideString): HResult; stdcall;
begin
  Result := fDefAcc.Get_accName(varChild, pszName);
  if (Result = S_OK) and (pszName <> '') then Exit;
  if Integer(varChild) = CHILDID_SELF then begin
    pszName := fEdit.Name;
    Result := S_OK;
  end else
    Result := S_FALSE;
end;

function TMyAccessibleEdit.Get_accValue(varChild: OleVariant; out pszValue: WideString): HResult; stdcall;
begin
  Result := fDefAcc.Get_accValue(varChild, pszValue);
end;

function TMyAccessibleEdit.Get_accDescription(varChild: OleVariant; out pszDescription: WideString): HResult; stdcall;
begin
  Result := fDefAcc.Get_accDescription(varChild, pszDescription);
  if (Result = S_OK) and (pszDescription <> '') then Exit;
  if Integer(varChild) = CHILDID_SELF then begin
    pszDescription := fEdit.Hint;
    Result := S_OK;
  end else
    Result := S_FALSE;
end;

function TMyAccessibleEdit.Get_accRole(varChild: OleVariant; out pvarRole: OleVariant): HResult; stdcall;
begin
  Result := fDefAcc.Get_accRole(varChild, pvarRole);
end;

function TMyAccessibleEdit.Get_accState(varChild: OleVariant; out pvarState: OleVariant): HResult; stdcall;
begin
  Result := fDefAcc.Get_accState(varChild, pvarState);
end;

function TMyAccessibleEdit.Get_accHelp(varChild: OleVariant; out pszHelp: WideString): HResult; stdcall;
begin
  Result := fDefAcc.Get_accHelp(varChild, pszHelp);
end;

function TMyAccessibleEdit.Get_accHelpTopic(out pszHelpFile: WideString; varChild: OleVariant; out pidTopic: Integer): HResult; stdcall;
begin
  Result := fDefAcc.Get_accHelpTopic(pszHelpFile, varChild, pidTopic);
end;

function TMyAccessibleEdit.Get_accKeyboardShortcut(varChild: OleVariant; out pszKeyboardShortcut: WideString): HResult; stdcall;
begin
  Result := fDefAcc.Get_accKeyboardShortcut(varChild, pszKeyboardShortcut);
end;

function TMyAccessibleEdit.Get_accFocus(out pvarChild: OleVariant): HResult; stdcall;
begin
  Result := fDefAcc.Get_accFocus(pvarChild);
end;

function TMyAccessibleEdit.Get_accSelection(out pvarChildren: OleVariant): HResult; stdcall;
begin
  Result := fDefAcc.Get_accSelection(pvarChildren);
end;

function TMyAccessibleEdit.Get_accDefaultAction(varChild: OleVariant; out pszDefaultAction: WideString): HResult; stdcall;
begin
  Result := fDefAcc.Get_accDefaultAction(varChild, pszDefaultAction);
end;

function TMyAccessibleEdit.accSelect(flagsSelect: Integer; varChild: OleVariant): HResult; stdcall;
begin
  Result := fDefAcc.accSelect(flagsSelect, varChild);
end;

function TMyAccessibleEdit.accLocation(out pxLeft: Integer; out pyTop: Integer; out pcxWidth: Integer; out pcyHeight: Integer; varChild: OleVariant): HResult; stdcall;
 begin
  Result := fDefAcc.accLocation(pxLeft, pyTop, pcxWidth, pcyHeight, varChild);
end;

function TMyAccessibleEdit.accNavigate(navDir: Integer; varStart: OleVariant; out pvarEndUpAt: OleVariant): HResult; stdcall;
begin
  Result := fDefAcc.accNavigate(navDir, varStart, pvarEndUpAt);
end;

function TMyAccessibleEdit.accHitTest(xLeft: Integer; yTop: Integer; out pvarChild: OleVariant): HResult; stdcall;
begin
  Result := fDefAcc.accHitTest(xLeft, yTop, pvarChild);
end;

function TMyAccessibleEdit.accDoDefaultAction(varChild: OleVariant): HResult; stdcall;
begin
  Result := fDefAcc.accDoDefaultAction(varChild);
end;

function TMyAccessibleEdit.Set_accName(varChild: OleVariant; const pszName: WideString): HResult; stdcall;
begin
  Result := fDefAcc.Set_accName(varChild, pszName);
end;

function TMyAccessibleEdit.Set_accValue(varChild: OleVariant; const pszValue: WideString): HResult; stdcall;
begin
  Result := fDefAcc.Set_accValue(varChild, pszValue);
end;







type
  TMyForm = class(TForm)
    procedure FormCreate(Sender: TObject);
    ...
  private
    DefEditWndProc: TWndMethod;
    procedure EditWndProc(var Message: TMessage);
    ...
  end;

procedure TMyForm.FormCreate(Sender: TObject);
begin
  DefEditWndProc := Edit1.WindowProc;
  Edit1.WindowProc := EditWndProc;
end;

procedure TMyForm.EditWndProc(var Message: TMessage);
var
  DefAcc, MyAcc: IAccessible;
  Ret: LRESULT;
begin
  DefEditWndProc(Message);
  if (Message.Msg = WM_GETOBJECT) and (DWORD(Message.LParam) = OBJID_CLIENT) and (Message.Result > 0) then
  begin
    if ObjectFromLresult(Message.Result, IAccessible, Message.WParam, DefAcc) = S_OK then
    begin
      MyAcc := TMyAccessibleEdit.Create(Edit1, DefAcc) as IAccessible;
      Message.Result := LresultFromObject(IAccessible, Message.WParam, MyAcc);
    end;
  end;
end;


    



      

      
      
      

      

        

          

            

              
1
投票

              

            

          

        

        
让这个工作


unit mainAcc;

interface

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

type
    TForm1 = class(TForm)
        lblFirstName: TLabel;
        btnGetAccInfo: TButton;
        accInfoOutput: TEdit;
        procedure btnGetAccInfoClick(Sender: TObject);
        procedure FormCreate(Sender: TObject);
        procedure FormClose(Sender: TObject; var Action: TCloseAction);
    private
        { Private declarations }
        aEdit: TTWEdit;
        FAccProperties: TStringList;
    public
        { Public declarations }
    end;

    TAccessibleEdit = class(TEdit, IAccessible)
    private
        FOwner: TComponent;
        FAccessibleItem: IAccessible;
        FAccessibleName: string;
        FAccessibleDescription: string;
        procedure WMGetMSAAObject(var Message : TMessage); message WM_GETOBJECT;
        // 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;
    protected
        function QueryInterface(const IID: TGUID; out Obj): HResult; override;
    public
        constructor Create(AOwner: TComponent); override;
    published
        property AccessibleItem: IAccessible read FAccessibleItem write FAccessibleItem;
        property AccessibleName: string read FAccessibleName write FAccessibleName;
        property AccessibleDescription: string read FAccessibleDescription write FAccessibleDescription;
    end;

var
    Form1: TForm1;

implementation

{$R *.dfm}

{------------------------------------------------------------------------------}
procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
    inherited;
    FreeAndNil(aEdit);
end;

{------------------------------------------------------------------------------}
procedure TForm1.FormCreate(Sender: TObject);
begin
    aEdit := TAccessibleEdit.Create(self);
    aEdit.Visible := true;
    aEdit.Parent := Form1;
    aEdit.Left := 91;
    aEdit.Top := 17;
    aEdit.Height := 21;
    aEdit.Width := 204;
    aEdit.Hint := 'This is a custom accessible edit control hint';
end;

{------------------------------------------------------------------------------}
procedure TForm1.btnGetAccInfoClick(Sender: TObject);
var
    vWSTemp: WideString;
    vAccObj: IAccessible;
begin
    FAccProperties := TStringList.Create;
    if (AccessibleObjectFromWindow(aEdit.Handle, OBJID_CLIENT, IID_IAccessible, vAccObj) = S_OK) then
    begin
        vAccObj.Get_accName(CHILDID_SELF, vWSTemp);
        FAccProperties.Add('Name: ' + vWSTemp);
        vWSTemp := '';
        vAccObj.Get_accDescription(CHILDID_SELF, vWSTemp);
        FAccProperties.Add('Description: ' + vWSTemp);
        vWSTemp := '';
        vAccObj.Get_accValue(CHILDID_SELF, vWSTemp);
        FAccProperties.Add('Value: ' + vWSTemp);
    end;
    accInfoOutput.Text := FAccProperties.Text;
end;


        { TAccessibleEdit }
    {------------------------------------------------------------------------------}
    constructor TAccessibleEdit.Create(AOwner: TComponent);
    begin
        inherited Create(AOwner);
        FOwner := AOwner;
    end;

    {------------------------------------------------------------------------------}
    function TAccessibleEdit.QueryInterface(const IID: TGUID; out Obj): HResult;
    begin
        if GetInterface(IID, Obj) then
            Result := 0
        else
            Result := E_NOINTERFACE;
    end;

    {------------------------------------------------------------------------------}
    function TAccessibleEdit.accDoDefaultAction(varChild: OleVariant): HResult;
    begin
        Result := DISP_E_MEMBERNOTFOUND;
    end;

    {------------------------------------------------------------------------------}
    function TAccessibleEdit.accHitTest(xLeft, yTop: Integer;
        out pvarChild: OleVariant): HResult;
    begin
        Result := DISP_E_MEMBERNOTFOUND;
    end;

    {------------------------------------------------------------------------------}
    function TAccessibleEdit.accLocation(out pxLeft, pyTop, pcxWidth, pcyHeight: Integer;
        varChild: OleVariant): HResult;
    var
        P: TPoint;
    begin
        Result := S_FALSE;
        pxLeft := 0;
        pyTop := 0;
        pcxWidth := 0;
        pcyHeight := 0;
        if varChild = CHILDID_SELF then
        begin
            P := self.ClientToScreen(self.ClientRect.TopLeft);
            pxLeft := P.X;
            pyTop := P.Y;
            pcxWidth := self.Width;
            pcyHeight := self.Height;
            Result := S_OK;
        end
    end;

    {------------------------------------------------------------------------------}
    function TAccessibleEdit.accNavigate(navDir: Integer; varStart: OleVariant;
        out pvarEndUpAt: OleVariant): HResult;
    begin
        result := DISP_E_MEMBERNOTFOUND;
    end;

    {------------------------------------------------------------------------------}
    function TAccessibleEdit.accSelect(flagsSelect: Integer; varChild: OleVariant): HResult;
    begin
        Result := DISP_E_MEMBERNOTFOUND;
    end;

    {------------------------------------------------------------------------------}
    function TAccessibleEdit.Get_accChild(varChild: OleVariant;
        out ppdispChild: IDispatch): HResult;
    begin
        Result := DISP_E_MEMBERNOTFOUND;
    end;

    {------------------------------------------------------------------------------}
    function TAccessibleEdit.Get_accChildCount(out pcountChildren: Integer): HResult;
    begin
        Result := DISP_E_MEMBERNOTFOUND;
    end;

    {------------------------------------------------------------------------------}
    function TAccessibleEdit.Get_accDefaultAction(varChild: OleVariant;
        out pszDefaultAction: WideString): HResult;
    begin
        Result := DISP_E_MEMBERNOTFOUND;
    end;

    {------------------------------------------------------------------------------}
    function TAccessibleEdit.Get_accDescription(varChild: OleVariant;
        out pszDescription: WideString): HResult;
    begin
        pszDescription := '';
        result := S_FALSE;
        if varChild = CHILDID_SELF then
        begin
            pszDescription := 'TAccessibleEdit_AccessibleDescription';
            Result := S_OK;
        end;
    end;

    {------------------------------------------------------------------------------}
    function TAccessibleEdit.Get_accFocus(out pvarChild: OleVariant): HResult;
    begin
        Result := DISP_E_MEMBERNOTFOUND;
    end;

    {------------------------------------------------------------------------------}
    function TAccessibleEdit.Get_accHelp(varChild: OleVariant;
        out pszHelp: WideString): HResult;
    begin
        Result := DISP_E_MEMBERNOTFOUND;
    end;

    {------------------------------------------------------------------------------}
    function TAccessibleEdit.Get_accHelpTopic(out pszHelpFile: WideString;
        varChild: OleVariant; out pidTopic: Integer): HResult;
    begin
        pszHelpFile := '';
        pidTopic := 0;
        Result := S_FALSE;
        if varChild = CHILDID_SELF then
        begin
            pszHelpFile := '';
            pidTopic := self.HelpContext;
            Result := S_OK;
        end;
    end;

    {------------------------------------------------------------------------------}
    function TAccessibleEdit.Get_accKeyboardShortcut(varChild: OleVariant;
        out pszKeyboardShortcut: WideString): HResult;
    begin
        Result := DISP_E_MEMBERNOTFOUND;
    end;

    {------------------------------------------------------------------------------}
    function TAccessibleEdit.Get_accName(varChild: OleVariant; out pszName: WideString): HResult;
    begin
        pszName := '';
        Result := S_FALSE;
        if varChild = CHILDID_SELF then
        begin
            pszName := 'TAccessibleEdit_AccessibleName';
            result := S_OK;
        end;
    end;

    {------------------------------------------------------------------------------}
    function TAccessibleEdit.Get_accParent(out ppdispParent: IDispatch): HResult;
    begin
        ppdispParent := nil;
        result := AccessibleObjectFromWindow(self.ParentWindow, CHILDID_SELF, IID_IAccessible, Pointer(ppDispParent));
    end;

    {------------------------------------------------------------------------------}
    function TAccessibleEdit.Get_accRole(varChild: OleVariant;
        out pvarRole: OleVariant): HResult;
    begin
        Result := S_OK;
        if varChild = CHILDID_SELF then
            pvarRole := ROLE_SYSTEM_OUTLINE;
    end;

    {------------------------------------------------------------------------------}
    function TAccessibleEdit.Get_accSelection(out pvarChildren: OleVariant): HResult;
    begin
        Result := DISP_E_MEMBERNOTFOUND;
    end;

    {------------------------------------------------------------------------------}
    function TAccessibleEdit.Get_accState(varChild: OleVariant;
        out pvarState: OleVariant): HResult;
    begin
        Result := S_OK;
        if varChild = CHILDID_SELF then
            pvarState := STATE_SYSTEM_FOCUSED;
    end;

    {------------------------------------------------------------------------------}
    function TAccessibleEdit.Get_accValue(varChild: OleVariant;
        out pszValue: WideString): HResult;
    begin
        pszValue := '';
        Result := S_FALSE;
        if varChild = CHILDID_SELF then
        begin
            pszValue := WideString(self.Text);
            result := S_OK;
        end;
    end;

    {------------------------------------------------------------------------------}
    function TAccessibleEdit.Set_accName(varChild: OleVariant;
        const pszName: WideString): HResult;
    begin
        Result := DISP_E_MEMBERNOTFOUND;
    end;

    {------------------------------------------------------------------------------}
    function TAccessibleEdit.Set_accValue(varChild: OleVariant;
        const pszValue: WideString): HResult;
    begin
        Result := DISP_E_MEMBERNOTFOUND;
    end;

    {------------------------------------------------------------------------------}
    procedure TAccessibleEdit.WMGetMSAAObject(var Message : TMessage);
    begin
        if (Message.Msg = WM_GETOBJECT) then
        begin
            QueryInterface(IID_IAccessible, FAccessibleItem);
            Message.Result := LresultFromObject(IID_IAccessible, Message.WParam, FAccessibleItem);
        end
        else
            Message.Result := DefWindowProc(Handle, Message.Msg, Message.WParam, Message.LParam);
    end;

    end. 

end.


    



      

      
      
      

      

        

          

            

              
0
投票

              
            

          

        

        


雷米有以下代码


procedure TMyForm.EditWndProc(var Message: TMessage);
var
  DefAcc, MyAcc: IAccessible;
  Ret: LRESULT;
begin
  DefEditWndProc(Message);
  if (Message.Msg = WM_GETOBJECT) and (DWORD(Message.LParam) = OBJID_CLIENT) and (Message.Result > 0) then
  begin
    if ObjectFromLresult(Message.Result, IAccessible, Message.WParam, DefAcc) = S_OK then
    begin
      MyAcc := TMyAccessibleEdit.Create(Edit1, DefAcc) as IAccessible;
      Message.Result := LresultFromObject(IAccessible, Message.WParam, MyAcc);
    end;
  end;
end;



本代码中的 DefAcc 是什么？它无需创建即可传递给 TMyAccessibleEdit


通过


constructor TMyAccessibleEdit.Create(aEdit: TEdit; aDefAcc: IAccessible);
begin
  inherited Create;
  fEdit := aEdit;
  fDefAcc := aDefAcc;
end;



DefAcc 最终成为 fDefAcc（仍未定义）


此 fDefAcc 用于 TMyAccessibleEdit 的所有例程中


你能解释一下吗？ DefAcc 这里是什么？

    



      

      
    

  

  

    
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