Question

例如，像Font一样。谁能举一个非常简单的例子？也许只是一个有两个子属性的属性

编辑：我的意思是当我在对象检查器中查看Font时，它有一个小加号，我可以单击以设置字体名称“times new roman”，字体大小为“10”等。如果我使用的话，Sorrry错误的条款，这就是我所谓的“子属性”。

Answer 1

您所要做的就是创建一个新的已发布属性，该属性指向已发布属性的类型。

检查此代码

  type
    TCustomType = class(TPersistent) //this type has 3 published properties
    private
      FColor : TColor;
      FHeight: Integer;
      FWidth : Integer;
    public
      procedure Assign(Source: TPersistent); override;
    published
      property Color: TColor read FColor write FColor;
      property Height: Integer read FHeight write FHeight;
      property Width : Integer read FWidth write FWidth;
    end;

    TMyControl = class(TWinControl) 
    private
      FMyProp : TCustomType;
      FColor1 : TColor;
      FColor2 : TColor;
      procedure SetMyProp(AValue: TCustomType);
    public
      constructor Create(AOwner: TComponent); override;
      destructor Destroy; override;
    published
      property MyProp : TCustomType read FMyProp write SetMyProp; //now this property has 3 "sub-properties" (this term does not exist in delphi)
      property Color1 : TColor read FColor1 write FColor1;
      property Color2 : TColor read FColor2 write FColor2;
    end;

  procedure TCustomType.Assign(Source: TPersistent);
  var
    Src: TCustomType;
  begin
    if Source is TCustomType then
    begin
      Src := TCustomType(Source);
      FColor := Src.Color;
      Height := Src.Height;
      FWidth := Src.Width;
    end else
      inherited;
  end;

  constructor TMyControl.Create(AOwner: TComponent);
  begin
    inherited;
    FMyProp := TCustomType.Create;
  end;

  destructor TMyControl.Destroy;
  begin
    FMyProp.Free;
    inherited;
  end;

  procedure TMyControl.SetMyProp(AValue: TCustomType);
  begin
    FMyProp.Assign(AValue);
  end;

Answer 2

你是什么意思，子属性？德尔福没有这样的东西。

也许你的意思是对象组合，其中一个对象包含对另一个对象的引用，例如 -

interface

type
TObj1 = class
private
  FFont: TFont;  
  property Font: TFont read FFont;
end;

...

implementation

var
  MyObj: TObj1;
begin
  MyObj1 := TObj1.Create;
  MyObj1.Font.Name := 'Arial';

如何使用子属性编写属性？

2 个答案: