Mirror

How to obtain a list of all published property names and types defined in a component (Views: 100)


Problem/Question/Abstract:

How to obtain a list of all published property names and types defined in a component

Answer:

Solve 1:

function GetComponentProperties(Instance: TPersistent; AList: TStrings): Integer;
var
  I, Count: Integer;
  PropInfo: PPropInfo;
  PropList: PPropList;
begin
  Result := 0;
  Count := GetTypeData(Instance.ClassInfo)^.PropCount;
  if Count > 0 then
  begin
    GetMem(PropList, Count * SizeOf(Pointer));
    try
      GetPropInfos(Instance.ClassInfo, PropList);
      for I := 0 to Count - 1 do
      begin
        PropInfo := PropList^[I];
        if PropInfo = nil then
          Break;
        if IsStoredProp(Instance, PropInfo) then
        begin
          {
          case PropInfo^.PropType^.Kind of
            tkInteger:
            tkMethod:
            tkClass:
            ...
          end;
          }
        end;
        Result := AList.Add(PropInfo^.Name);
      end;
    finally
      FreeMem(PropList, Count * SizeOf(Pointer));
    end;
  end;
end;


Solve 2:

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;

And calling this code by:

ListProperties(TProject(treeview1.items[0].data), memo3.lines);

My tProject is defined as

type
  TProject = class(tComponent)
  private
    FNaam: string;
    procedure SetNaam(const Value: string);
  public
    constructor Create(AOwner: tComponent);
    destructor Destroy;
  published
    property Naam: string read FNaam write SetNaam;
  end;

Also note the output, there seem to be 2 standard properties (Name and Tag) !

Memo3
Class name: TProject

3 Properties
-------------------
Name: TComponentName
Tag: Integer
Naam: String

<< Back to main page