Sử dụng hậu duệ TownedCollection trong Delphi

Question

Tôi đang cố tạo một thành phần tùy chỉnh với thuộc tính bộ sưu tập. Tuy nhiên, nếu tôi cố gắng mở trình chỉnh sửa bộ sưu tập trong thời gian thiết kế bằng cách nhấp vào nút "..." trong trình kiểm tra đối tượng, thì không có gì xảy ra. Những gì tôi đang mất tích?

Dưới đây là hậu duệ của tôi TCollection:

TMyCollection = class(TOwnedCollection) 
    private 
    function GetItem(Index: Integer): TMyCollectionItem; 
    procedure SetItem(Index: Integer; const Value: TMyCollectionItem); 
    public 
    function Add : TMyCollectionItem; 
    property Items[Index: Integer]: TMyCollectionItem read GetItem write SetItem; 
    end; 

Và mục:

TMyCollectionItem = class(TCollectionItem) 
    private 
    FValue: integer; 
    protected 
    function GetDisplayName: string; override; 
    public 
    procedure Assign(Source: TPersistent); override; 
    constructor Create(Collection: TCollection); override; 
    destructor Destroy; override; 
    published 
    property Value : integer read FValue write FValue; 
    end; 

Answer 1

định nghĩa lớp của bạn trông đúng như vậy với ra khi nhìn thấy toàn bộ thi tôi không biết vấn đề là gì.

Đây là đơn vị đơn giản mà tôi đã viết sử dụng TOwnedCollection, TCollectionItem và TComponent.

Tôi biết đơn vị này hoạt động. Sử dụng nó làm cơ sở để kiểm tra mã của bạn.

Ryan.

unit rmMultiStrings; 

interface 

uses classes, sysutils; 

type 
    ErmMultiStringNameException = Exception; 
    TrmMultiStringsCollection = class; 

    TrmMultiStringCollectionItem = class(TCollectionItem) 
    private 
    fItemDesc: string; 
    fItemName: string; 
    fData : TStringList; 
    fMultiStrings : TrmMultiStringsCollection; 
    function GetStrings: TStringList; 
    function GetStringText: String; 
    procedure SetItemName(const Value: string); 
    procedure SetStrings(const Value: TStringList); 
    procedure SetStringText(const Value: String); 
    public 
    constructor Create(Collection: TCollection); override; 
    destructor Destroy; override; 

    procedure Assign(Source: TPersistent); override; 
    published 
    property ItemName : string read fItemName write SetItemName; 
    property Description : string read fItemDesc write fItemDesc; 
    property Strings : TStringList read GetStrings write SetStrings stored false; 
    property Text : String read GetStringText write SetStringText; 
    end; 

    TrmMultiStringsCollection = class(TOwnedCollection) 
    private 
    function GetItem(AIndex: integer): TrmMultiStringCollectionItem; 
    procedure SetItem(AIndex: integer; const Value: TrmMultiStringCollectionItem); 
    public 

    function Add: TrmMultiStringCollectionItem; 

    function IndexOf(ItemName:string):integer; 
    function ValueOf(ItemName:string):String; 
    function ValueOfIndex(aIndex:integer):string; 

    procedure Assign(Source: TPersistent); override; 

    property Items[AIndex: integer] : TrmMultiStringCollectionItem read GetItem write SetItem; 
    end; 

    TrmMultiStrings = class(TComponent) 
    private 
    fData : TrmMultiStringsCollection; 
    procedure SetData(const Value: TrmMultiStringsCollection); 
    public 
    constructor Create(AOwner: TComponent); override; 
    destructor Destroy; override; 

    function IndexOf(ItemName:string):integer; 
    function ValueOf(ItemName:string):String; 
    function ValueOfIndex(aIndex:integer):string; 
    published 
    property Data : TrmMultiStringsCollection read fData write SetData; 
    end; 

procedure Register; 

implementation 

procedure Register; 
begin 
    RegisterClass(TrmMultiStringsCollection); 
    RegisterClass(TrmMultiStringCollectionItem); 
    RegisterComponents('rmConcordia', [TrmMultiStrings]); 
end; 


{ TrmMultiStringCollectionItem } 

procedure TrmMultiStringCollectionItem.Assign(Source: TPersistent); 
var 
    wSrc : TrmMultiStringCollectionItem; 
begin 
    if Source is TrmMultiStringCollectionItem then 
    begin 
    wSrc := TrmMultiStringCollectionItem(Source); 
    ItemName := wSrc.ItemName; 
    Description := wSrc.Description; 
    Text := wSrc.Text; 
    end 
    else 
    inherited; 
end; 

constructor TrmMultiStringCollectionItem.Create(Collection: TCollection); 
begin 
    inherited; 
    fMultiStrings := TrmMultiStringsCollection(Collection); 
    fData := TStringList.create; 
end; 

destructor TrmMultiStringCollectionItem.Destroy; 
begin 
    fData.free; 
    inherited; 
end; 

function TrmMultiStringCollectionItem.GetStrings: TStringList; 
begin 
    result := fData; 
end; 

function TrmMultiStringCollectionItem.GetStringText: String; 
begin 
    result := fData.Text; 
end; 

procedure TrmMultiStringCollectionItem.SetItemName(const Value: string); 
begin 
    if (fItemName <> Value) then 
    begin 
    if fMultiStrings.IndexOf(Value) = -1 then 
     fItemName := Value 
    else 
     raise ErmMultiStringNameException.Create('Item name already exists'); 
    end; 
end; 

procedure TrmMultiStringCollectionItem.SetStrings(
    const Value: TStringList); 
begin 
    fData.Assign(Value); 
end; 

procedure TrmMultiStringCollectionItem.SetStringText(const Value: String); 
begin 
    fData.Text := Value; 
end; 

{ TrmMultiStringsCollection } 

function TrmMultiStringsCollection.Add: TrmMultiStringCollectionItem; 
begin 
    result := TrmMultiStringCollectionItem(inherited Add); 
    result.ItemName := 'Item_'+inttostr(NextID); 
end; 

procedure TrmMultiStringsCollection.Assign(Source: TPersistent); 
var 
    wSrc : TrmMultiStringsCollection; 
    loop : integer; 
begin 
    if (source is TrmMultiStringsCollection) then 
    begin 
    wSrc := TrmMultiStringsCollection(Source); 
    Clear; 
    for loop := 0 to wSrc.Count - 1 do 
     Add.Assign(wSrc.Items[loop]); 
    end 
    else 
    inherited; 
end; 

function TrmMultiStringsCollection.GetItem(
    AIndex: integer): TrmMultiStringCollectionItem; 
begin 
    result := TrmMultiStringCollectionItem(inherited Items[AIndex]); 
end; 

function TrmMultiStringsCollection.IndexOf(ItemName: string): integer; 
var 
    loop : integer; 
begin 
    result := -1; 
    loop := 0; 
    while (result = -1) and (loop < Count) do 
    begin 
     if (CompareText(Items[loop].ItemName, ItemName) = 0) then 
     result := loop 
     else 
     inc(loop); 
    end; 
end; 

procedure TrmMultiStringsCollection.SetItem(AIndex: integer; const Value: TrmMultiStringCollectionItem); 
begin 
    inherited SetItem(AIndex, Value) 
end; 

function TrmMultiStringsCollection.ValueOf(ItemName: string): String; 
begin 
    result := ValueOfIndex(IndexOf(ItemName)); 
end; 

function TrmMultiStringsCollection.ValueOfIndex(aIndex: integer): string; 
begin 
    if (aIndex >= 0) and (aIndex < Count) then 
    result := Items[aIndex].Text 
    else 
    result := ''; 
end; 

{ TrmMultiStrings } 

constructor TrmMultiStrings.Create(AOwner: TComponent); 
begin 
    inherited; 
    fData := TrmMultiStringsCollection.Create(self, TrmMultiStringCollectionItem); 
end; 

destructor TrmMultiStrings.Destroy; 
begin 
    fData.Free; 
    inherited; 
end; 

function TrmMultiStrings.IndexOf(ItemName: string): integer; 
begin 
    result := Data.IndexOf(ItemName); 
end; 

procedure TrmMultiStrings.SetData(const Value: TrmMultiStringsCollection); 
begin 
    fData.Assign(Value); 
end; 

function TrmMultiStrings.ValueOf(ItemName: string): String; 
begin 
    result := Data.ValueOf(ItemName); 
end; 

function TrmMultiStrings.ValueOfIndex(aIndex: integer): string; 
begin 
    result := Data.ValueOfIndex(aIndex); 
end; 

end.