仔细查看RTL决定是否需要流传TPersistent
属性的要求列表:
if (PropInfo^.GetProc <> nil) and
((PropInfo^.SetProc <> nil) or
((PropInfo^.PropType^.Kind = tkClass) and
(TObject(GetOrdProp(Instance, PropInfo)) is TComponent) and
(csSubComponent in TComponent(GetOrdProp(Instance, PropInfo)).ComponentStyle))) then
您的ChildObj
属性是只读属性,因此它不满足PropInfo^.SetProc <> nil
的要求,也不是TComponent
派生的子组件,因此它也不符合is TComponent
和csSubComponent
的要求。这就是为什么您的属性在DFM中缺失的原因。
最简单的解决方案是将您的ChildObj
属性改为读/写属性(在这种情况下,除非必须使用TComponent
,否则不要使用它)。
您的TTest
中也缺少一个析构函数来释放TChildObj
对象。为了保险起见,您应该给TChildObj
添加一个OnChange
事件,以便TTest
可以分配一个处理程序来响应对TChildObj
子属性的更改。
请尝试以下内容:
type
TChildObj = class(TPersistent)
private
FVisible : Boolean;
FColor : TColor;
FOnChange : TNotifyEvent;
procedure Changed;
procedure SetVisible(Value : Boolean);
procedure SetColor(Value : TColor);
public
procedure Assign(Source : TPersistent); override;
property OnChange : TNotifyEvent read FOnChange write FOnChange;
published
property Visible : Boolean read FVisible write SetVisible;
property Color : TColor read FColor write SetColor;
end;
TTest = class(TComponent)
private
FChildObj : TChildObj;
FOne : integer;
procedure ChildObjChanged(Sender : TObject);
procedure SetChildObj(Value : TChildObj);
protected
procedure Loaded; override;
public
constructor Create(AOwner : TComponent); override;
destructor Destroy; override;
published
property One : integer read FOne write FOne;
property ChildObj : TChildObj read FChildObj write SetChildObj;
end;
.
procedure TChildObj.Assign(Source: TPersistent);
begin
if Source is TChildObj then
begin
FVisible := TChildObj(Source).Visible;
FColor := TChildObj(Source).Color;
Changed;
end else
inherited;
end;
procedure TChildObj.Changed;
begin
if Assigned(FOnChange) then
FOnChange(Self);
end;
procedure TChildObj.SetVisible(Value : Boolean);
begin
if FVisible <> Value then
begin
FVisible := Value;
Changed;
end;
end;
procedure TChildObj.SetColor(Value : TColor);
begin
if FColor <> Value then
begin
FColor := Value;
Changed;
end;
end;
constructor TTest.Create(AOwner : TComponent);
begin
inherited;
FChildObj := TChildObj.Create;
FChildObj.OnChange := ChildObjChanged;
end;
destructor TTest.Destroy;
begin
FChildObj.Free;
inherited;
end;
procedure TTest.ChildObjChanged(Sender : TObject);
begin
if csLoading in ComponentState then Exit;
end;
procedure TTest.Loaded;
begin
inherited;
ChildObjChanged(nil);
end;
procedure TTest.SetChildObj(Value : TChildObj);
begin
if FChildObj <> Value then
FChildObj.Assign(Value);
end;
如果你采用 TComponent
的方式,那么尝试使用以下方法:
type
TChildObj = class(TComponent)
private
FVisible : Boolean;
FColor : TColor;
FOnChange : TNotifyEvent;
procedure Changed;
procedure SetVisible(Value : Boolean);
procedure SetColor(Value : TColor);
public
procedure Assign(Source : TPersistent); override;
property OnChange : TNotifyEvent read FOnChange write FOnChange;
published
property Visible : Boolean read FVisible write SetVisible;
property Color : TColor read FColor write SetColor;
end;
TTest = class(TComponent)
private
FChildObj : TChildObj;
FOne : integer;
procedure ChildObjChanged(Sender : TObject);
procedure SetChildObj(Value : TChildObj);
protected
procedure Loaded; override;
public
constructor Create(AOwner : TComponent); override;
published
property One : integer read FOne write FOne;
property ChildObj : TChildObj read FChildObj write SetChildObj;
end;
.
procedure TChildObj.Assign(Source: TPersistent);
begin
if Source is TChildObj then
begin
FVisible := TChildObj(Source).Visible;
FColor := TChildObj(Source).Color;
Changed;
end else
inherited;
end;
procedure TChildObj.Changed;
begin
if Assigned(FOnChange) then
FOnChange(Self);
end;
procedure TChildObj.SetVisible(Value : Boolean);
begin
if FVisible <> Value then
begin
FVisible := Value;
Changed;
end;
end;
procedure TChildObj.SetColor(Value : TColor);
begin
if FColor <> Value then
begin
FColor := Value;
Changed;
end;
end;
constructor TTest.Create(AOwner : TComponent);
begin
inherited;
FChildObj := TChildObj.Create(Self);
FChildObj.SetSubComponent(True);
FChildObj.OnChange := ChildObjChanged;
end;
procedure TTest.ChildObjChanged(Sender : TObject);
begin
if csLoading in ComponentState then Exit;
end;
procedure TTest.Loaded;
begin
inherited;
ChildObjChanged(nil);
end;
procedure TTest.SetChildObj(Value : TChildObj);
begin
if FChildObj <> Value then
FChildObj.Assign(Value);
end;
SetSubComponent(True)
。 - Sertac Akyuz