Как получить контекст свойства по его целочисленному значению



Автор: Ralph Friedman
WEB-сайт: http://www.lmc-mediaagentur.de

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.

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