StrAlloc not working after migrating to Delphi XE7 - delphi

Question

I am working on an application which was recently upgraded from Delphi 2007 to XE7. There is one particular scenario where the conversion of TMemoryStream to PChar is failing. Here is the code:
procedure TCReport.CopyToClipboard;
var
CTextStream: TMemoryStream;
PValue: PChar;
begin
CTextStream := TMemoryStream.Create;
//Assume that this code is saving a report column to CTextStream
//Verified that the value in CTextStream is correct
Self.SaveToTextStream(CTextStream);
//The value stored in PValue below is corrupt
PValue := StrAlloc(CTextStream.Size + 1);
CTextStream.Read(PValue^, CTextStream.Size + 1);
PValue[CTextStream.Size] := #0;
{ Copy text stream to clipboard }
Clipboard.Clear;
Clipboard.SetTextBuf(PValue);
CTextStream.Free;
StrDispose(PValue);
end;
Adding the code for SaveToTextStream:
procedure TCReport.SaveToTextStream(CTextStream: TStream);
var
CBinaryMemoryStream: TMemoryStream;
CWriter: TWriter;
begin
CBinaryMemoryStream := TMemoryStream.Create;
CWriter := TWriter.Create(CBinaryMemoryStream, 24);
try
CWriter.Ancestor := nil;
CWriter.WriteRootComponent(Self);
CWriter.Free;
CBinaryMemoryStream.Position := 0;
{ Convert Binary 'WriteComponent' stream to text}
ObjectBinaryToText(CBinaryMemoryStream, CTextStream);
CTextStream.Position := 0;
finally
CBinaryMemoryStream.Free;
end;
end;
I observed that the StrLen(PChar) is also coming out to be half the size of TMemoryStream. But in Delphi 2007 it was coming out to be same as the size of TMemoryStream.
I know that the above code is assuming the size of a char to be 1 byte, and that could be a problem. But I tried multiple approaches, and nothing works.
Could you suggest a better way to go about this conversion?

Answer 1

Yet again, this is the issue of Delphi 2009 and later using Unicode text. In Delphi 2007 and earlier:
Char is an alias to AnsiChar.
PChar is an alias to PAnsiChar.
string is an alias to AnsiString.
In Delphi 2009 and later:
Char is an alias to WideChar.
PChar is an alias to PWideChar.
string is an alias to UnicodeString.
Your code is written assuming that PChar is PAnsiChar. Hence your problems. You need to stop using StrAlloc anyway. You are making life hard for yourself by manually allocating heap memory here. Let the compiler do the work.
You need to obtain your text in a string variable, and then simply do:
Clipboard.AsText := MyStrVariable;
Exactly how best to obtain the string depends on the facilities that TCReport offers. I expect that it will yield a string directly in which case you'll write something like this:
procedure TCReport.CopyToClipboard;
begin
Clipboard.AsText := Self.ReportAsText;
end;
I'm guessing as to what your functionality your TCReport offers, but I'm sure you know.

Answer 2

By reffering to what hvd and David Heffernan wrote above, one possible way is to change CTextStream on CopyToClipboard to TStringStream as follow :
procedure TCReport.CopyToClipboard;
var
CTextStream: TStringStream;
begin
CTextStream := TStringStream.Create;
try
//Assume no error with Self.SaveToTextStream
Self.SaveToTextStream(CTextStream);
{ Copy text stream to clipboard }
Clipboard.AsText := CTextStream.DataString;
finally
CTextStream.Free;
end;
end;
But you should make sure that SaveToTextStream function provides CTextStream with the exact encoding text data.