自定义类的数组作为属性 [英] Array of a custom class as a property

问题描述

我正在尝试使用自定义类的数组作为我的组件的属性，但问题是这些值没有保存到组件中，这意味着如果我设置了值，请保存所有内容并再次打开项目中，组件的值消失了...我的代码如下所示:

I am trying to use an array of a custom class as a property for my component, but the problem is that the values are not been saved to the component, that means that if I set the values, save everything and open again the project, the values for the component disappears... My code looks like the following:

unit Unit1;

interface

uses  Windows, ExtCtrls,Classes,Controls;

type

  TMyClass=class(TPersistent)
  private
    FName: string;
    FValue: double;
  public
    property Name: string read FName write FName;
    property Value: double read FValue write FValue;
  end;

  TMyComponent= class(TCustomPanel)
  private
    FMyArray: array[0..200] of TMyClass;

    function GetmyArray(Index: Integer): TMyClass;

    procedure SetMyArray(index: Integer; Value: TMyClass);
  public
    property myArray[index: Integer]: TMyClass read GetMyArray write SetMyArray;
  end;

implementation

function TMyComponent.GetmyArray(Index: Integer): TMyClass;
begin
  result:= FmyArray[Index];
end;

procedure TMyComponent.SetMyArray(index: Integer; Value: TMyClass);
begin
  FMyArray[index].FName:= Value.FName;
  FMyArray[index].FValue:= Value.FValue;
end;

end.

我知道只能流式传输已发布的属性，但问题是我的属性是一个数组，无法发布...我的建议是使用 DefineProperties() 来提供自定义流，但我不知道如何使用数组执行此操作.我认为的另一种可能性是将 TMyClass 修改为一种 TMyComponent 可能是它的父类的类，就像在 TChart 中所做的那样，您可以向其中添加不同的系列类.但我不知道这应该是什么类

I know that that only published properties can be streamed, but the problem is that my property is an array and it can not be published... A suggestion that I had was to use DefineProperties() to provide a custom streaming but I don't see how to do this with an array. Other possibility that I thought was to modify TMyClass to a kind of class that TMyComponent could be the parent of it, like it is done in TChart, which you can add different classes of series to it. But I don't know What class this should be

TMyClass=class(T???????????)

这样我就可以取出属性 MyArray 并创建 TMyClass 并添加到 TMyComponent 中，如下所示:

With that I could take out the property MyArray and create TMyClass and add to TMyComponent as the following:

MyArray1.parent:= MyComponent1;
MyArray2.parent:= MyComponent2;
...

.哪一个是更好的选择?或者还有什么更好的办法吗?

. Which one is the better option? Or is there any other better idea?

推荐答案

最简单(也是首选)的解决方案是将 TMyClass 更改为从 TCollectionItem 派生并更改 TMyComponent.FMyArray 到 TOwnedCollection.然后，DFM 会自动为您流式传输项目，并且您获得用于创建和操作 TMyClass 对象及其属性的原生设计时支持.

The simpliest (and preferred) solution is to change TMyClass to derive from TCollectionItem and change TMyComponent.FMyArray to TOwnedCollection. Then the DFM will stream the items automatically for you, and you gain native design-time support for creating and manipulating TMyClass objects and their properties.

试试这个:

unit Unit1;

interface

uses
  Windows, ExtCtrls, Classes, Controls;

type
  TMyClass = class(TCollectionItem)
  private
    FName: string;
    FValue: double;

    procedure SetName(const AValue: string);
    procedure SetValue(AValue: double);
  public
    procedure Assign(ASource: TPersistent); override;
  published
    property Name: string read FName write SetName;
    property Value: double read FValue write SetValue;
  end;

  TMyArray = class(TOwnedCollection)
  private
    function  GetItem(Index: Integer): TMyClass;
    procedure SetItem(Index: Integer; const Value: TMyClass);
  public
    constructor Create(AOwner: TPersistent);
    function  Add: TMyClass; reintroduce;
    function  Insert(Index: Integer): TMyClass; reintroduce;
    property  Items[Index: Integer]: TMyClass read GetItem write SetItem; default;
  end;

  TMyComponent = class(TCustomPanel)
  private
    FMyArray: TMyArray;

    procedure SetMyArray(Value: TMyArray);
  public
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
  published
    property myArray: TMyArray read FMyArray write SetMyArray;
  end;

implementation

procedure TMyClass.Assign(ASource: TPersistent);
begin
  if ASource is TMyClass then
  begin
    with TMyClass(ASource) do
    begin
      Self.FName := Name;
      Self.FValue := Value;
    end;
    Changed(False);
  end else
    inherited;
end;

procedure TMyClass.SetName(const AValue: string);
begin
  if FName <> AValue then
  begin
    FName := AValue;
    Changed(False);
  end;
end;

procedure TMyClass.SetValue(AValue: double);
begin
  if FValue <> AValue then
  begin
    FValue := AValue;
    Changed(False);
  end;
end;

constructor TMyArray.Create(AOwner: TPersistent);
begin
  inherited Create(AOwner, TMyClass);
end;

function TMyArray.GetItem(Index: Integer): TMyClass;
begin
  Result := TMyClass(inherited GetItem(Index));
end;

procedure TMyArray.SetItem(Index: Integer; const Value: TMyClass);
begin
  inherited SetItem(Index, Value);
end;

function TMyArray.Add: TMyClass;
begin
  Result := TMyClass(inherited Add);
end;

function TMyArray.Insert(Index: Integer): TMyClass;
begin
  Result := TMyClass(inherited Insert(Index));
end;

constructor TMyComponent.Create(AOwner: TComponent);
begin
  inherited;
  FMyArray := TMyArray.Create(Self);
end;

destructor TMyComponent.Destroy;
begin
  FMyArray.Free;
  inherited;
end;

procedure TMyComponent.SetMyArray(Value: TMyArray);
begin
  FMyArray.Assign(Value);
end;

end.

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