Question

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，组件的值消失...我的代码如下所示：

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.

我知道只有已发布的属性可以流式传输，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()来提供自定义流媒体，但我不知道如何使用数组执行此操作。我认为的其他可能性是将TMyClass修改为TMyComponent可以作为它的父类的类，就像它在TChart中完成的那样，你可以为它添加不同类的系列。但我不知道这应该是什么类

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

有了这个，我可以取出属性MyArray并创建TMyClass并添加到TMyComponent，如下所示：

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

。哪一个是更好的选择？或者还有其他更好的主意吗？

Answer 1

最简单（也是首选）解决方案是将TMyClass更改为从TCollectionItem派生，并将TMyComponent.FMyArray更改为TOwnedCollection。然后，DFM将自动为您流式传输项目，您可以获得本地设计时支持，以创建和操作TMyClass个对象及其属性。

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.

Answer 2

我投票给DefineProperties！必要的代码可能看起来像这样（假设数组中的实例都不是nil）：

procedure TMyComponent.DefineProperties(Filer: TFiler);
begin
  inherited;
  Filer.DefineProperty('MyArray', ReadMyArray, WriteMyArray, true);
end;

procedure TMyComponent.ReadMyArray(Reader: TReader);
var
  N: Integer;
begin
  N := 0;
  Reader.ReadListBegin;
  while not Reader.EndOfList do begin
    Reader.ReadListBegin;
    FMyArray[N].Name := Reader.ReadString;
    FMyArray[N].Value := Reader.ReadFloat;
    Reader.ReadListEnd;
    Inc(N);
  end;
  Reader.ReadListEnd;
end;

procedure TMyComponent.WriteMyArray(Writer: TWriter);
var
  I: Integer;
begin
  Writer.WriteListBegin;
  for I := 0 to High(FMyArray) do begin
    Writer.WriteListBegin;
    Writer.WriteString(FMyArray[I].Name);
    Writer.WriteFloat(FMyArray[I].Value);
    Writer.WriteListEnd;
  end;
  Writer.WriteListEnd;
end;

自定义类的数组作为属性

2 个答案: