I'm a french user of Delphi 2010 so please excuse my bad english.
I've created a control from a TCustomControl. This control have a TOwnedCollection populated by TCollectionItem descendant. Those Items have a published custom list property. This list is a list of couples of integers made by me. I've written a custom designtime editor for this property and it works perfectly. So now, I want to write the list data into the dfm and it becomes a bit harder.
Here is what I've done:
TPedroGraphLineCollectionIem = class(TCollectionItem)
published
property PointList: TPedroIntegerCoupleList read FList write SetList
stored GetStored;
...
procedure TPedroGraphLineCollectionIem.DefineProperties(Filer: TFiler);
begin
inherited;
//'PointList' : the property name
//FList.Count > 0 : Is the list empty ?
Filer.DefineProperty('PointList', ReadListData, WriteListData,
(FList.Count > 0));
end;
...
procedure TPedroGraphLineCollectionIem.ReadListData(Reader: TReader);
var
Val1, Val2: Integer;
begin
with Reader do
begin
ReadListBegin;
while not EndOfList do
begin
Val1 := ReadInteger;
Val2 := ReadInteger;
FList.AddCouple(Val1, Val2);
end;
ReadListEnd;
end;
end;
...
procedure TPedroGraphLineCollectionIem.WriteListData(Writer: TWriter);
var
I: Integer;
begin
with Writer do
begin
WriteListBegin;
for I := 0 to Count - 1 do
begin
WriteInteger(FList[I].Value1);
WriteInteger(FList[I].Value2);
end;
WriteListEnd;
end;
end;
The WriteListData procedure works perfectly and writes the values into the dfm. But when I try to load the Form, it always crashes and a dialog box tell me that there is an reading flow error on this property.
FList is created inside the constructor of the class.
Here is the .dfm :
object MainFrm: TMainFrm
Left = 0
Top = 0
Caption = 'MainFrm'
ClientHeight = 425
ClientWidth = 689
Color = clBtnFace
ParentFont = True
OldCreateOrder = False
Position = poScreenCenter
OnCreate = FormCreate
OnDestroy = FormDestroy
PixelsPerInch = 96
TextHeight = 13
object PedroGraph1: TPedroGraph
Left = 120
Top = 136
Width = 313
Height = 209
TitleFont.Charset = DEFAULT_CHARSET
TitleFont.Color = clWindowText
TitleFont.Height = -11
TitleFont.Name = 'Tahoma'
TitleFont.Style = []
Lines = <
item
LinePen.Color = clRed
PointList = (
1
2
3
4)
end>
MarksFont.Charset = DEFAULT_CHARSET
MarksFont.Color = clWindowText
MarksFont.Height = -11
MarksFont.Name = 'Tahoma'
MarksFont.Style = []
end
end
Error Messages (in french) :
1
Erreur lors de la lecture de TPedroGraphLineCollectionItem.PointList: Valeur de propriété incorrecte. Ignorer l'erreur et continuer ?Remarque: ceci peut provoquer la suppression de composants ou la perte de valeurs de propriété
2
Erreur lors de la lecture de TPedroGraphLineCollectionItem.□□: la propriété □□ n'existe pas. Ignorer l'erreur et continuer ?Remarque: ceci peut provoquer la suppression de composants ou la perte de valeurs de propriété
Note: the '□' char is really displayed as this.
3
Erreur lors de la lecture de TPedroGraphLineCollectionItem.□□
4
Erreur lors de la lecture de PedroGraphLines1.Lines: Valeur de propriété incorrecte. Ignorer l'erreur et continuer ?Remarque: ceci peut provoquer la suppression de composants ou la perte de valeurs de propriété
5
Erreur à la création de la fiche : Erreur de lecture du flux.
Declaration of TPedroIntegerCoupleList:
TPedroIntegerCouple = record
Value1: Integer;
Value2: Integer;
end;
TPedroGenericList<T> = class(TList<T>)
private
FOnChange: TNotifyEvent;
FUpdating: Boolean;
protected
procedure Notify(const Item: T; Action: TCollectionNotification); override;
procedure DoChange;
published
public
constructor Create;
procedure SortCustom; virtual; abstract;
procedure Assign(const Source: TPedroGenericList<T>);
property OnChange: TNotifyEvent read FOnChange write FOnChange;
end;
TPedroIntegerCoupleList = class(TPedroGenericList<TPedroIntegerCouple>)
private
function GetString: String;
procedure SetString(const Value: String);
public
procedure SortCustom; override;
function AddCouple(const Value1, Value2: Integer): Integer;
procedure InsertCouple(const Index, Value1, Value2: Integer);
property AsString: String read GetString write SetString;
end;
Where am I wrong ?
