Как прочитать свойство напрямую из его ресурса

Delphi , Компоненты и Классы , RTTI

Автор: Michael Duerig
WEB-сайт: http://www.lmc-mediaagentur.de

Does anyone know if there is an easy way to load the value of a component's property directly from its resource without creating the component? Something like:

if ReadPropertyValue('Form1.Button1', 'width') > 1000 then
  ShowMessage('You are about to create a big button!');

function TForm1.ReadProp(r: TReader): string;
begin
  result := '';
  {Determine the value type of the property, read it with the appropriate method of TReader
  and convert it to string. Not all value types are implemented here but you get the idea.}
  case r.NextValue of
    vaInt8, vaInt16, vaInt32:
      result := IntToStr(r.ReadInteger);
    vaExtended:
      result := FloatToStr(r.ReadFloat);
    vaString:
      result := r.ReadString;
  else
    r.SkipValue; {Not implemented}
  end;
end;

procedure TForm1.ReadRes(PropPath: string; r: TReader);
var
  p: string;
begin
  {Skip the class name}
  r.ReadStr;
  {Construct the property path}
  if PropPath = '' then
    p := r.ReadStr
  else
    p := PropPath + '.' + r.ReadStr;
  {Read all properties and its values and fill them into the memo}
  while not r.EndOfList do
    Memo1.Lines.Add(p + '.' + r.ReadStr + ' = ' + ReadProp(r));
  {Skip over the end of the list of the properties of this component}
  r.CheckValue(vaNull);
  {Recursively read the properties of all sub-components}
  while not r.EndOfList do
  begin
    ReadRes(p, r);
    r.CheckValue(vaNull);
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  strm: TResourceStream;
  Reader: TReader;
begin
  strm := TResourceStream.Create(HInstance, 'TForm1', RT_RCDATA);
  Reader := TReader.Create(strm, 1024);
  try
    Memo1.Clear;
    Reader.ReadSignature;
    ReadRes('', Reader);
  finally
    Reader.Free;
    strm.Free;
  end;
end;

Only one small problem. r.SkipValue was protected (in D5) but I hacked that out with the following code:

type
  THackReader = class(TReader);
  { ... }
  THackReader(r).SkipValue;

And now it works like a charm.

Статья Как прочитать свойство напрямую из его ресурса раздела Компоненты и Классы RTTI может быть полезна для разработчиков на Delphi и FreePascal.

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