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在 Mike Lischke 的Virtual Treeview 中，添加了解决方法代码以修复在同一窗体上使用TWebBrowser控件时出现的错误。

问题在于，如果用户尝试与TOleControl（TWebBrowser 从中下降）进行交互，第一次鼠标点击就会被吃掉。然后他们必须再次单击以赋予控制焦点。然后他们可以与控件交互。

他有评论要解释：

派生自的每个控件TOleControl都有潜在的焦点问题。

为了避免包含允许测试类的OleCtrls单元（其中将包含Variants ），该接口用于测试，这是一个很好的指标。TOleControlIOleClientSiteTOleControl

从完整的片段：

procedure TBaseVirtualTree.WMKillFocus(var Msg: TWMKillFocus);
var
  Form: TCustomForm;
  Control: TWinControl;
  Pos: TSmallPoint;
  Unknown: IUnknown;
begin
  inherited;

  [snip]

  {
    Workaround for wrapped non-VCL controls (like TWebBrowser), 
    which do not use VCL mechanisms and 
    leave the ActiveControl property in the wrong state, 
    which causes trouble when the control is refocused.
  }
  Form := GetParentForm(Self);
  if Assigned(Form) and (Form.ActiveControl = Self) then
  begin
    Cardinal(Pos) := GetMessagePos;
    Control := FindVCLWindow(SmallPointToPoint(Pos));
    {
      Every control derived from TOleControl has potentially 
      the focus problem. In order to avoid including 
      the OleCtrls unit (which will, among others, include Variants),  
      which would allow to test for the TOleControl
      class, the IOleClientSite interface is used for the test, 
      which is supported by TOleControl and a good indicator.
    }
    if Assigned(Control) and Control.GetInterface(IOleClientSite, Unknown) then
      Form.ActiveControl := nil;

    // For other classes the active control should not be modified. Otherwise you need two clicks to select it.
  end;
end;

问题是解决方法不再对我有用。老实说，我不知道问题到底是什么，以及他的解决方案是如何解决的。

有没有人知道他的评论理解他在说什么，可以解释问题是什么，以及他应该如何解决问题？

包装的非 VCL 控件（如 TWebBrowser）的解决方法，这些控件不使用 VCL 机制，并使 ActiveControl 属性处于错误状态，这会在控件重新聚焦时引起问题。从 TOleControl 派生的每个控件都有潜在的焦点问题。

代码达到预期

Form.ActiveControl := nil;

声明，但它只是没有做的伎俩。

我会修复它，但我不知道他是如何找到它的，也不知道TOleControl不“使用 VCL 机制并让 ActiveControl 属性处于错误状态”的原因。

奖金阅读

我最初在 2008 年在 新闻组上问过这个问题borland.public.delphi.nativeapi.win32

Soft-Gems 论坛上的问题

Bump 20110515（12 个月后）

Bump 20150401（7 年后）：在 XE6 中仍然不起作用

凹凸20210309（11年后）

4

1 回答 1

3

我通过使用 TEmbeddedWB（比标准的 TWebBrowser 好得多）克服了这个问题，然后我不得不添加这个 OnShowUI 事件：

function THtmlFrame.webBrowserShowUI(const dwID: Cardinal;
  const pActiveObject: IOleInPlaceActiveObject;
  const pCommandTarget: IOleCommandTarget; const pFrame: IOleInPlaceFrame;
  const pDoc: IOleInPlaceUIWindow): HRESULT;
begin
  try
    if WebBrowser.CanFocus then
      WebBrowser.SetFocus; // tell the VCL that the web-browser is focused
  except
    on E: EInvalidOperation do
      ; // ignore "Cannot focus inactive or invisible control"
  end;
  Result := S_FALSE;
end;


但是如果你必须使用 TWebBrowser 你需要编写更多的代码：

type
  IDocHostUIHandler = interface(IUnknown)
    ['{bd3f23c0-d43e-11cf-893b-00aa00bdce1a}']
    function ShowContextMenu(const dwID: DWORD; const ppt: PPOINT;
      const CommandTarget: IUnknown; const Context: IDispatch): HRESULT; stdcall;
    function GetHostInfo(var pInfo: TDOCHOSTUIINFO): HRESULT; stdcall;
    function ShowUI(const dwID: DWORD; const pActiveObject: IOleInPlaceActiveObject;
      const pCommandTarget: IOleCommandTarget; const pFrame: IOleInPlaceFrame;
      const pDoc: IOleInPlaceUIWindow): HRESULT; stdcall;
    function HideUI: HRESULT; stdcall;
    function UpdateUI: HRESULT; stdcall;
    function EnableModeless(const fEnable: BOOL): HRESULT; stdcall;
    function OnDocWindowActivate(const fActivate: BOOL): HRESULT; stdcall;
    function OnFrameWindowActivate(const fActivate: BOOL): HRESULT; stdcall;
    function ResizeBorder(const prcBorder: PRECT; const pUIWindow: IOleInPlaceUIWindow; const fRameWindow: BOOL): HRESULT; stdcall;
    function TranslateAccelerator(const lpMsg: PMSG; const pguidCmdGroup: PGUID; const nCmdID: DWORD): HRESULT; stdcall;
    function GetOptionKeyPath(out pchKey: POLESTR; const dw: DWORD): HRESULT; stdcall;
    function GetDropTarget(const pDropTarget: IDropTarget; out ppDropTarget: IDropTarget): HRESULT; stdcall;
    function GetExternal(out ppDispatch: IDispatch): HRESULT; stdcall;
    function TranslateUrl(const dwTranslate: DWORD; const pchURLIn: POLESTR; out ppchURLOut: POLESTR): HRESULT; stdcall;
    function FilterDataObject(const pDO: IDataObject; out ppDORet: IDataObject): HRESULT; stdcall;
  end; // IDocHostUIHandler

  ICustomDoc = interface(IUnknown)
    ['{3050f3f0-98b5-11cf-bb82-00aa00bdce0b}']
    function SetUIHandler(const pUIHandler: IDocHostUIHandler): HResult; stdcall;
  end;

  TDocHostUIHandler = class(TInterfacedObject, IDocHostUIHandler)
  private
    FWebBrowser: TWebBrowser;
  protected
    function EnableModeless(const fEnable: BOOL): HResult; stdcall;
    function FilterDataObject(const pDO: IDataObject; out ppDORet: IDataObject): HResult; stdcall;
    function GetDropTarget(const pDropTarget: IDropTarget; out ppDropTarget: IDropTarget): HResult; stdcall;
    function GetExternal(out ppDispatch: IDispatch): HResult; stdcall;
    function GetHostInfo(var pInfo: TDocHostUIInfo): HResult; stdcall;
    function GetOptionKeyPath(var pchKey: POLESTR; const dw: DWORD): HResult; stdcall;
    function HideUI: HResult; stdcall;
    function OnDocWindowActivate(const fActivate: BOOL): HResult; stdcall;
    function OnFrameWindowActivate(const fActivate: BOOL): HResult; stdcall;
    function ResizeBorder(const prcBorder: PRECT; const pUIWindow: IOleInPlaceUIWindow;
      const fFrameWindow: BOOL): HResult; stdcall;
    function ShowContextMenu(const dwID: DWORD; const ppt: PPOINT;
      const pcmdtReserved: IInterface; const pdispReserved: IDispatch): HResult; stdcall;
    function ShowUI(const dwID: DWORD; const pActiveObject: IOleInPlaceActiveObject;
      const pCommandTarget: IOleCommandTarget; const pFrame: IOleInPlaceFrame;
      const pDoc: IOleInPlaceUIWindow): HResult; stdcall;
    function TranslateAccelerator(const lpMsg: PMSG; const pguidCmdGroup: PGUID; const nCmdID: DWORD): HResult; stdcall;
    function TranslateUrl(const dwTranslate: DWORD; const pchURLIn: POLESTR; var ppchURLOut: POLESTR): HResult; stdcall;
    function UpdateUI: HResult; stdcall;
  public
    constructor Create(AWebBrowser: TWebBrowser);
    property WebBrowser: TWebBrowser read FWebBrowser;
  end;


{ TDocHostUIHandler }

function TDocHostUIHandler.EnableModeless(const fEnable: BOOL): HResult;
begin
  Result := S_OK;
end;

function TDocHostUIHandler.FilterDataObject(const pDO: IDataObject; out ppDORet: IDataObject): HResult;
begin
  ppDORet := nil;
  Result := S_FALSE;
end;

function TDocHostUIHandler.GetDropTarget(const pDropTarget: IDropTarget; out ppDropTarget: IDropTarget): HResult;
begin
  ppDropTarget := nil;
  Result := E_FAIL;
end;

function TDocHostUIHandler.GetExternal(out ppDispatch: IDispatch): HResult;
begin
  ppDispatch := nil;
  Result := E_FAIL;
end;

function TDocHostUIHandler.GetHostInfo(var pInfo: TDocHostUIInfo): HResult;
begin
  Result := S_OK;
end;

function TDocHostUIHandler.GetOptionKeyPath(var pchKey: POLESTR; const dw: DWORD): HResult;
begin
  Result := E_FAIL;
end;

function TDocHostUIHandler.HideUI: HResult;
begin
  Result := S_OK;
end;

function TDocHostUIHandler.OnDocWindowActivate(const fActivate: BOOL): HResult;
begin
  Result := S_OK;
end;

function TDocHostUIHandler.OnFrameWindowActivate(const fActivate: BOOL): HResult;
begin
  Result := S_OK;
end;

function TDocHostUIHandler.ResizeBorder(const prcBorder: PRECT; const pUIWindow: IOleInPlaceUIWindow; const fFrameWindow: BOOL): HResult;
begin
  Result := S_FALSE;
end;

function TDocHostUIHandler.ShowContextMenu(const dwID: DWORD; const ppt: PPOINT; const pcmdtReserved: IInterface; const pdispReserved: IDispatch): HResult;
begin
  Result := S_FALSE
end;

function TDocHostUIHandler.TranslateAccelerator(const lpMsg: PMSG; const pguidCmdGroup: PGUID; const nCmdID: DWORD): HResult;
begin
  Result := S_FALSE;
end;

function TDocHostUIHandler.TranslateUrl(const dwTranslate: DWORD; const pchURLIn: POLESTR; var ppchURLOut: POLESTR): HResult;
begin
  Result := E_FAIL;
end;

function TDocHostUIHandler.UpdateUI: HResult;
begin
  Result := S_OK;
end;

function TDocHostUIHandler.ShowUI(const dwID: DWORD; const pActiveObject: IOleInPlaceActiveObject; const pCommandTarget: IOleCommandTarget;
  const pFrame: IOleInPlaceFrame; const pDoc: IOleInPlaceUIWindow): HResult;
begin
  try
    if WebBrowser.CanFocus then
      WebBrowser.SetFocus; // tell the VCL that the web-browser is focused
  except
    on E: EInvalidOperation do
      ; // ignore "Cannot focus inactive or invisible control"
  end;
  Result := S_OK;
end;



// install the DocHostUIHandler into the WebBrowser
var
  CustomDoc: ICustomDoc;
begin
  if WebBrowser1.Document.QueryInterface(ICustomDoc, CustomDoc) = S_OK then
    CustomDoc.SetUIHandler(TDocHostUIHandler.Create(WebBrowser1));
end;
于 2009-05-14T05:53:12.357 回答