Problemas al guardar componentes con TStream!!

[rounin]

Procedures Stream.WriteComponent and ReadComponent are
purposed for deal mainly with Root components (Form, DataModule, ...).

Somewhen I was experimenting with components
and wrote procedures for read/write
non-root components from stream:

Código Delphi [-]
 
 
{*******************************************************************************
* *
* Reonid sources *
* Categoty: other *
* (c) [email protected] *
* *
*******************************************************************************}
unit Comp2Stm;
interface
uses
Classes, Controls;
 
function LoadComponentFromStream(ARoot, AOwner: TComponent; AParent: TWinControl;
SrcTxtStream: TStream; AComp: TComponent = nil): TComponent;
 
procedure SaveComponentToStream(AComp, ARoot: TComponent; DestTxtStream: TStream);
 
implementation
 
type
TDummy = class
class procedure ReaderSetName(Reader: TReader; Component: TComponent; var Name: string);
end;
 
class procedure TDummy.ReaderSetName(Reader: TReader; Component: TComponent; var Name: string);
begin
if (Reader.Owner <> nil) and
(Reader.Owner.FindComponent(Name) <> nil) then Name := '';
// The simplest way to resolve the name conflicts
end;
 
function LoadComponentFromStream(ARoot, AOwner: TComponent; AParent: TWinControl;
SrcTxtStream: TStream; AComp: TComponent = nil): TComponent;
var
BinStream: TStream;
Reader: TReader;
Comp: TComponent;
begin
BinStream := TMemoryStream.Create;
try
Reader := TReader.Create(BinStream, 4096);
 
//SrcTxtStream.Position := 0;
ObjectTextToBinary(SrcTxtStream, BinStream);
try
Reader.Position := 0;
Reader.Owner := AOwner;
Reader.Parent := AParent;
Reader.Root := ARoot;
// Owner, Parent and Root for new Component
// Reader will search in RTTI-tables of the Root component 
// classes and event handlers etc.
 
Reader.OnSetName := TDummy.ReaderSetName;
// Äëÿ ðàçðåøåíèÿ êîíôëèêòîâ èì¸í
// For the name conflicts resolution
 
//Reader.OnFindMethod := ;
//Reader.OnFindComponentClass := ;
 
Reader.BeginReferences;
try
Reader.ReadSignature;
Comp := Reader.ReadComponent(AComp);
Result := Comp;
Reader.FixupReferences;
// Initializes references on other components,
// that saved in DFM as names.
finally
Reader.EndReferences;
end;
finally
Reader.Free;
end;
finally
BinStream.Free;
end;
end;
 
procedure SaveComponentToStream(AComp, ARoot: TComponent; DestTxtStream: TStream);
var BinStream: TStream;
Writer: TWriter;
begin
BinStream := TMemoryStream.Create();
try
Writer := TWriter.Create(BinStream, 4096);
try
Writer.Root := ARoot;
Writer.WriteSignature;
Writer.WriteComponent(AComp);
Writer.WriteListEnd;
finally
Writer.Free;
end;
BinStream.Position := 0;
ObjectBinaryToText(BinStream, DestTxtStream);
finally
BinStream.Free;
end;
end;
 
end.

PS: When Reader reads a component from stream,
initially it reads the Class Name of the component.
Then (if the component has not been created before reading)
Reader tries to find the Class Reference by Class Name.

First, it searches the class in the RTTI-table of Root component.
If there is any component of the same class in the Root,
then success.

Second, the Reader searches the class in the
registered classes. If the class have been registered by
RegisterClass (RegisterClasses), then success.

Third, the Reader let user to resolve the Class Name
to the Class Reference by himself
(it calls OnFindComponentClass event handler).

If all this attempts have failed, the Reader raise EClassNotFound
"class <Class Name> not found".
Use RegisterClasses to solve it.

[OzzyzzO]

Thanks! Rounin. I think that your solution will help me. Very good explanation. Thanks again!

Saludos

[vtdeleon]

Saludos

Rounin, Sabes escribir en español?, Lo digo porque en este foro la gran mayoría hablamos(o escribimos) en español. Entonces los forista que consulten este hilo y tenga pocos conocimiento del ingles estarán despistado.

Ante todo, Es muy grata y muy buena tu ayuda (hasta a mi me has ayudado). Espero seguir viendote por aqui

[rounin]

Saludos,

Estoy estudiando español,
(yo periodicamente voy en comisiones de servicio a España)
pero mi nivel de español no es bastante alto,
y lo escribir en español todavía es dificil para mi.
Lo siento.

[vtdeleon]

Saludos

Empezado por rounin

pero mi nivel de español no es bastante alto,

Cómo va ser. Se entiende perfectamente

Empezado por rounin

y lo escribir en español todavía es dificil para mi.

Aquí te serviría de práctica

[rounin]

Saludos,

pienso que en tu caso necesita incluir flag csSubcomponent
en tus subcomponentes:

  TDigitalDisplay = class(TCustomPanel)
  private
	FImage1: TImage;
	FStaticText1: TStaticText;
	FPopupMenu1: TPopupMenu;
	{...}
  published
	property StaticText1: TStaticText read FStaticText1; {r/o}
	property Image1: TImage read FImage1;
	property PopupMenu1: TPopupMenu read FPopupMenu1;
	{...}
  end;
 
 
constructor TDigitalDisplay.Create(AOwner: TComponent);
 
   function CreateSubComponent(AClass: TComponentClass): TComponent;
   begin
	 Result := AClass.Create(Self);
	 Result.SetSubComponent(True); {!!!!!!!!}
	 Result.FreeNotification(Self); 
	 if Result is TControl then TControl(Result).Parent := Self;
   end;
 
var
  MenuItem: TMenuItem;
begin
  inherited;
  {...}
  FStaticText1 := CreateSubComponent(TStaticText) as TStaticText;
  FStaticText2 := CreateSubComponent(TStaticText) as TStaticText;
  FStaticText3 := CreateSubComponent(TStaticText) as TStaticText;
  FImage1	  := CreateSubComponent(TImage) as TImage;
  FPopupMenu1  := CreateSubComponent(TPopupMenu) as TPopupMenu;
 
  MenuItem := TMenuItem.Create(PopupMenu1);
  FPopupMenu1.Items.Add(MenuItem);

  with MenuItem do
  begin
	Caption := 'Configurar';
	OnClick := PopupConfigurar;
  end;

end;
 
procedure TDigitalDisplay.Notification(AComponent: TComponent; Operation: TOperation);
begin
  inherited;
  if (AComponent = FStaticText1) and (Operation = opRemove) then FStaticText1 := nil;
  if (AComponent = FStaticText2) and (Operation = opRemove) then FStaticText2 := nil;
  if (AComponent = FStaticText3) and (Operation = opRemove) then FStaticText3 := nil;
  if (AComponent = FPopupMenu1) and (Operation = opRemove) then FPopupMenu1 := nil;
  if (AComponent = FImage1)	 and (Operation = opRemove) then FImage1	 := nil;
end;

PS Porque creas subcomponentes en AfterConstruction?
Porque no en Create?

[OzzyzzO]

Empezado por rounin

PS Porque creas subcomponentes en AfterConstruction?
Porque no en Create?

Perdón por no contestar , estuve con mucho trabajo.

Los subcomponentes los creo en el metodo AfterConstruction porque en el constructor Create el componente aun no está creado y no puedo asignarle la variable Self a la propiedad Parent del subcomponente, ni tampoco pasarlo como Owner en la creación del subcomponente. O almenos eso entendí.

Saludos y éxitos con el español.