메모리 할당부터 해야죠...

procedure TfrmMain.Button1Click(Sender: TObject);
var
IMC: HIMC;
KL: HKL;
ErrorCode: LongWord;
Buffer: PByteArray;
BufferSize: Integer;
HanjaList: string;
CandidateList: PCandidateList absolute Buffer;
Index: Integer;
begin
Edit1.Text := '가';

KL := GetKeyboardLayout(0);
Imc := ImmGetDefaultIMEWnd(Edit1.Handle);
BufferSize := ImmGetConversionList(KL, IMC, PChar(Edit1.Text), nil, 0, GCL_CONVERSION);
if BufferSize <> 0 then
begin
GetMem(Buffer, BufferSize);
FillChar(Buffer^, BufferSize, 0);
try
ErrorCode := ImmGetConversionList(KL, IMC, PChar(Edit1.Text), CandidateList, BufferSize, GCL_CONVERSION);
SetLength(HanjaList, BufferSize - CandidateList.dwOffset[1]);
Move(Buffer[CandidateList.dwOffset[1]], HanjaList[1], BufferSize - CandidateList.dwOffset[1]);
for Index := 1 to Length(HanjaList) do
begin
if HanjaList[Index] = #0 then
HanjaList[Index] := #32;
end;
Memo1.Lines.Add(HanjaList);
finally
FreeMem(Buffer, BufferSize)
end;
end;
ImmReleaseContext(Handle, IMC);
end;

답변주셔서 감사합니다.
우찌하다가 아래처럼 만들었더니 괜찮게 실행됩니다.
charBuf를 array of char 로 주니까 에러나네요. 그래서 넉넉하게 512를 할당했는데 동적할당 방법은 어떻게 되나요.

var
hKL,lngRet : LongInt; //signed 4bytes
charBuf: array[0..511] of char;
hImc: THandle;
intLen,iStart,i : integer;
hjList : string;

begin
edtAnswer.Text := '가';

hKL := GetKeyboardLayout(0);
hImc := ImmGetDefaultIMEWnd(edtAnswer.Handle);
intLen := ImmGetConversionList(hKL,hImc,PChar(edtAnswer.Text),nil,0,GCL_CONVERSION);
if intLen > 0 then
begin
FillChar(charBuf, 512, 0);
lngRet := ImmGetConversionList(hKL,hImc,PChar(edtAnswer.Text),@charBuf,intLen,GCL_CONVERSION);
if lngRet > 0 then
begin
//dwOffset 적용(24~27 low->high)
iStart := byte(charBuf[24]) + byte(charBuf[25]) * 256;

for i := iStart to intLen - 1 do
AppendStr(hjList,charBuf[i]);

for i := 1 to (length(hjList) div 3) do
Memo1.Lines.Add(copy(hjList,(i-1)*3+1,2));
end;
ImmReleaseContext(Handle,hImc);
end;
end;

위 코드가 동적할당하는 코드인데요...
array of char로 잡으실려면 FillChar위에 SetLength(charBuf, intLen); 을 추가해 주시면 될것같네요...

거듭 감사드립니다.


charBuf : array of char;

.
.
SetLength(charBuf, intLen);
FillChar(charBuf, intLen, 0);
lngRet := ImmGetConversionList(hKL,hImc,PChar(edtAnswer.Text),@charBuf,intLen,GCL_CONVERSION);
.
하면 lngRet 값은 나오지만 charBuf에 아무것도 담기지 않아 iStart에서 에러가 납니다.
동적할당 때문에 번지수가 잘못되었는지?

FillChar(charBuf[0], intLen, 0);

드디어 해결되어 기쁩니다. 감사합니다.
문제는 @charBuf => @charBuf[0] 으로 변경하니까 오케이.

charBuf : array of char;
.
.
SetLength(charBuf, intLen);
FillChar(charBuf[0], intLen, 0);
lngRet := ImmGetConversionList(hKL,hImc,PChar(edtAnswer.Text),@charBuf[0],intLen,GCL_CONVERSION);