How to extract strings from RCDATA?

I'm using a RC file with images and strings , like this :

splash RCDATA splash.png
ilogo RCDATA ilogo.png
site RCDATA { "https://www.example.com" }

I then compile this file with BRCC32 and generate a RES file.

I know how to extract the images, using a code like this :

Var
  img: TWICImage;
Begin
  Try
    img := TWICImage.create;
    img.LoadFromResourceName(HInstance, resName);
    im.Picture.Graphic := img;
    Result := true;
  Finally
    img.free;
  End;

But i don't know how to extract the string RCDATA, for instance the 'site' RCDATA ; how can i do this ?

Solution

This depends on the encoding of your RCDATA. The low-level approach is to read the bytes and then interpret them explicitly in the encoding you know is right:

var RS := TResourceStream.Create(HInstance, 'greeting', RT_RCDATA);
try
  var LData := TBytes(nil);
  SetLength(LData, RS.Size);
  RS.ReadData(LData, RS.Size);
  var LStr := TEncoding.ASCII.GetString(LData);
  ShowMessage(LStr);
finally
  RS.Free;
end;

A marginally simpler approach is to use a TStringList, for example:

var List := TStringList.Create;
try
  var RS := TResourceStream.Create(HInstance, 'greeting', RT_RCDATA);
  try
    List.LoadFromStream(RS, TEncoding.ASCII);
    ShowMessage(List.Text);
  finally
    RS.Free;
  end;
finally
  List.Free;
end;

And a very important off-topic remark:

Your code

Var
  img: TWICImage;
Begin
  Try
    img := TWICImage.create;
    img.LoadFromResourceName(HInstance, resName);
    im.Picture.Graphic := img;
    Result := true;
  Finally
    img.free;
  End;

has a serious bug that can cause memory corruption, at least in some contexts. Specifically, if this is the code of a procedure or function, then img is a local variable of a non-managed type, and so it is not initialized. Hence, initially, img is a "random" pointer. Its value is the native-sized integer that happens to be there in your computer's RAM.

So if the TWICImage.Create constructor raises an exception (which is very much a possibility), then you'll do img.Free on a random pointer img. Then anything can happen. If you are lucky, you get an access violation almost immediately.

Always write

var LFrog := TFrog.Create;
try
  { use LFrog }
finally
  LFrog.Free;
end

and never write

try
  LFrog := TFrog.Create;
  { use LFrog }
finally
  LFrog.Free; // wrong!
end