自作コンポーネントの順序型と集合型のプロパティの初期化の仕方

unit PropUtil;

interface

procedure InitPropWithDefault(obj: TObject; PropName: string);

implementation
uses 
  SysUtils, TypInfo;

procedure InitPropWithDefault(Obj: TObject; PropName: string);
var
  ppi: PPropInfo;
begin
  ppi := GetPropInfo(obj.ClassInfo, PropName);
  if ppi = nil then Exception.Create('プロパティが有りません');
  if not (ppi.PropType^.Kind in [tkInteger, tkChar, tkWChar, tkSet, tkEnumeration]) then
    raise Exception.Create('プロパティはデフォルト値を持てない型です');

  SetOrdProp(obj, ppi, ppi.Default);
end;

end.

type
  TGaugeEx = class(TGraphicControl)

  （略）

  public
    constructor Create(AOwner: TComponent); override;
  published
    { Published 宣言 }
    property BackColor: TColor
             read FBackColor write SetBackColor default clWhite;
    property Color: TColor read FColor write SetColor default clBlack;
    property Style: TGaugeExStyle
             read FStyle write SetStyle default gesRectangle;
    property OVNormalColor: TColor
             read FOVNormalColor write SetOVNormalColor default clPurple;
    property OVHiliteColor: TColor
             read FOVHiliteColor write SetOvHiliteColor default clYellow;
    property ZeroCenter: Boolean
             read FZeroCenter write SetZeroCenter default False;
  end;

procedure Register;

implementation

uses PropUtil;

constructor TGaugeEx.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);

  Width := 100;
  Height := 65;

  InitPropWithDefault(Self, 'BackColor');
  InitPropWithDefault(Self, 'Color');
  InitPropWithDefault(Self, 'Style');
  InitPropWithDefault(Self, 'OVNormalColor');
  InitPropWithDefault(Self, 'OVHiliteColor');
  InitPropWithDefault(Self, 'ZeroCenter');
end;

type
  TBarEnum = (e0, e1, e2, e3, e4, e5, e6, e7,
              e8, e9, e10, e11, e12, e13, e14, e15,
              e16, e17, e18, e19, e20, e21, e22, e23,
              e24, e25, e26, e27, e28, e29, e30, e31);
　TBarSet = set of TBarEnum;