个人认为DELPHI实现activex控件的限制存在于DELPHI的activex控件的基类派生于TAutoObject如下:
TActiveXControl = class(TAutoObject, IConnectionPointContainer, IDataObject, IObjectSafety, IOleControl, IOleInPlaceActiveObject, IOleInPlaceObject, IOleObject, IPerPropertyBrowsing, IPersistPropertyBag, IPersistStorage, IPersistStreamInit, IQuickActivate, ISimpleFrameSite, ISpecifyPropertyPages, IViewObject, IViewObject2)
....
....
end;
用DELPHI制作过activex控件的人都知道DELPHI的activex控件向导中必须指明控件包含的VCL窗体控件(从TWinControl派生的VCL控件),这样就使得它的实现必须包含一个VCL窗体控件,而为了让这个VCL窗体控件随时可用DELPHI还要为该控件提供一个父窗口。看下面代码:
procedure TActiveXControl.Initialize;
begin
inherited Initialize;
FConnectionPoints := TConnectionPoints.Create(Self);
FControlFactory := Factory as TActiveXControlFactory;
if FControlFactory.EventTypeInfo <> nil then
FConnectionPoints.CreateConnectionPoint(FControlFactory.EventIID,
ckSingle, EventConnect);
FPropertySinks := FConnectionPoints.CreateConnectionPoint(IPropertyNotifySink,
ckMulti, nil);
FControl := FControlFactory.WinControlClass.CreateParented(ParkingWindow);
if csReflector in FControl.ControlStyle then
FWinControl := TReflectorWindow.Create(ParkingWindow, FControl) else
FWinControl := FControl;
FControlWndProc := FControl.WindowProc;
FControl.WindowProc := WndProc;
InitializeControl;
end;
这就是DELPHI实现activex控件的限制,我们如何去控制这个ParkingWindow,就算能够控制整个activex控件的体积以及膨胀了很多了,在internet上的activex控件越小越好,至少现在的DELPHI要实现类似vc轻量级控件(只实现IPersistStreamInit,IOleControl,IOleObject,IOleInPlaceActiveObject,IViewObjectEx,IOleInPlaceObjectWindowless这些接口的COM对象)非常困难,更不要说要按需(根据activex控件的使用范围是IE还是word或者其他)实现接口了。一种解决方案就是不从TAutoObject派生而是直接从窗体控件派生如下:
TMyActiveXControl=class(TMyControl,
//TMyControl是一般的类也可以是VCL窗体控件类.
//下面的接口并不总是需要派生和实现。可按需派生和实现
IConnectionPointContainer, IDataObject, IObjectSafety, IOleControl, IOleInPlaceActiveObject, IOleInPlaceObject, IOleObject, IPerPropertyBrowsing, IPersistPropertyBag, IPersistStorage, IPersistStreamInit, IQuickActivate, ISimpleFrameSite, ISpecifyPropertyPages, IViewObject, IViewObject2)
....
....
end;
但是如果这样,新的问题又产生了,如何注册这个activex控件呢?因为没有合适的类厂对象,DELPHI的类厂是如下关系:
TComObjectFactory-->TTypedComObjectFactory-->TAutoObjectFactory
-->TActiveXControlFactory-->TActiveFormFactory
而TComObjectFactory是这样实现的,
TComObject = class(TObject, IUnknown, ISupportErrorInfo)
。。。。
End;
TComClass = class of TComObject;
TComObjectFactory = class(TObject, IUnknown, IClassFactory, IClassFactory2)
…..
constructor Create(ComServer: TComServerObject; ComClass: TComClass;
const ClassID: TGUID; const ClassName, Description: string;
Instancing: TClassInstancing; ThreadingModel: TThreadingModel = tmSingle);
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