delphi 怎么调用sendmessage获取取其它程序窗口listviewj里的数据内容

这个是我的代码，仿网上的C++版本写的， 但不是知道错在哪里
就是读取不到数据，哪位大神帮我研究一下
procedure TForm1.btn1Click(Sender: TObject);
var
whwnd,hlistview:HWND;
headerhwnd:Integer;
rows,cols:Integer;
ThreadID:DWORD;
ProcessID:DWORD;
hProcess:THandle;
p_lvitem:^TLVItem;
tmplvitem:TLVItem;
i,j:Integer;
pItem:LPTSTR;
ptr:DWORD;
ItemBuf:array [0..511] of Char;
OutSize,WriteSize:DWORD;
s:string;
begin
whwnd:=FindWindow('#32770','Windows 任务管理器');
whwnd:=FindWindowEx(whwnd,0,'#32770',nil);
hlistview:=FindWindowEx(whwnd,0,'SysListView32',nil);
// ShowMessage(IntToStr(hlistview));

//总行数:进程的数量
rows:=SendMessage(hListview,LVM_GETITEMCOUNT,0,0);
//列表列数
headerhwnd := SendMessage(hListview,LVM_GETHEADER, 0, 0); //listview的列头句柄
cols:=SendMessage(headerhwnd, HDM_GETITEMCOUNT,0,0);

ThreadID:=GetWindowThreadProcessId(hListview,@ProcessID);
//打开并插入进程
hProcess:=OpenProcess(PROCESS_VM_OPERATION or PROCESS_VM_READ or PROCESS_VM_WRITE or PROCESS_QUERY_INFORMATION, FALSE,ProcessID);
//申请代码的内存区
p_lvitem:=VirtualAllocEx(hProcess,nil, SizeOf(TLVITEM),MEM_COMMIT, PAGE_READWRITE);
GetMem(p_lvitem,SizeOf(TLVITEM));

for i:=0 to rows-1 do
begin
for j:=0 to cols-1 do
begin
tmplvitem.mask:=LVIF_TEXT;
tmplvitem.iItem:=i;
tmplvitem.iSubItem:=j;
tmplvitem.cchTextMax:=512;

pItem:=nil;
pItem:=LPSTR(VirtualAllocEx(hProcess, nil, 512, MEM_COMMIT, PAGE_READWRITE));
tmplvitem.pszText:=pItem;


WriteProcessMemory(hProcess , p_lvitem,@tmplvitem, sizeof(tmplvitem),WriteSize);
SendMessage(hListview, LVM_GETITEMW,i,Integer(p_lvitem));
ZeroMemory(@ItemBuf,512);
ReadProcessMemory(hProcess, pItem, @ItemBuf, 512, OutSize);
s:= s+ ' ' + ItemBuf;
VirtualFreeEx(hProcess, pItem, 0, MEM_RELEASE);
end;
mmo1.Lines.Add(s);
end;

VirtualFreeEx(hProcess, p_lvitem, 0, MEM_RELEASE)
CloseHandle(hProcess);//关闭打开的进程对象

end;