Как получить контекст свойства по его целочисленному значению

Автор: Ralph Friedman

unit PropertyList;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
    StdCtrls, Buttons;

type
  TMyStream = class(TFileStream)
  private
    FFred: integer;
  published
    property Fred: integer read FFred write FFred;
  end;
type
  TFrmPropertyList = class(TForm)
    SpeedButton1: TSpeedButton;
    ListBox1: TListBox;
    procedure SpeedButton1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  FrmPropertyList: TFrmPropertyList;

implementation

{$R *.DFM}

uses
  TypInfo;

procedure ListProperties(AInstance: TPersistent; AList: TStrings);
var
  i: integer;
  pInfo: PTypeInfo;
  pType: PTypeData;
  propList: PPropList;
  propCnt: integer;
  tmpStr: string;
begin
  pInfo := AInstance.ClassInfo;
  if (pInfo = nil) or (pInfo^.Kind <> tkClass) then
    raise Exception.Create('Invalid type information');
  pType := GetTypeData(pInfo); {Pointer to TTypeData}
  AList.Add('Class name: ' + pInfo^.Name);
  {If any properties, add them to the list}
  propCnt := pType^.PropCount;
  if propCnt > 0 then
  begin
    AList.Add(EmptyStr);
    tmpStr := IntToStr(propCnt) + ' Propert';
    if propCnt > 1 then
      tmpStr := tmpStr + 'ies'
    else
      tmpStr := tmpStr + 'y';
    AList.Add(tmpStr);
    FillChar(tmpStr[1], Length(tmpStr), '-');
    AList.Add(tmpStr);
    {Get memory for the property list}
    GetMem(propList, sizeOf(PPropInfo) * propCnt);
    try
      {Fill in the property list}
      GetPropInfos(pInfo, propList);
      {Fill in info for each property}
      for i := 0 to propCnt - 1 do
        AList.Add(propList[i].Name + ': ' + propList[i].PropType^.Name);
    finally
      FreeMem(propList, sizeOf(PPropInfo) * propCnt);
    end;
  end;
end;

function GetPropertyList(AControl: TPersistent; AProperty: string): PPropInfo;
var
  i: integer;
  props: PPropList;
  typeData: PTypeData;
begin
  Result := nil;
  if (AControl = nil) or (AControl.ClassInfo = nil) then
    Exit;
  typeData := GetTypeData(AControl.ClassInfo);
  if (typeData = nil) or (typeData^.PropCount = 0) then
    Exit;
  GetMem(props, typeData^.PropCount * SizeOf(Pointer));
  try
    GetPropInfos(AControl.ClassInfo, props);
    for i := 0 to typeData^.PropCount - 1 do
    begin
      with Props^[i]^ do
        if (Name = AProperty) then
          result := Props^[i];
    end;
  finally
    FreeMem(props);
  end;
end;

procedure TFrmPropertyList.SpeedButton1Click(Sender: TObject);
var
  c: integer;
begin
  ListProperties(self, ListBox1.Items);
  for c := 0 to ComponentCount - 1 do
  begin
    ListBox1.Items.Add(EmptyStr);
    ListProperties(Components[c], ListBox1.Items);
  end;
end;

end.