Secure File Deletion in Delphi

Click on the "Delete Files" button and add the following code:

procedure TForm1.SpeedButton1Click(Sender:
TObject);
var
files:integer;
begin
//if no files are selected then show a warning
if listbox1.Items.Count < 1 then
begin
MessageDlg('There are no files selected to
delete. Please try again.', mtWarning,[mbOk],
0);
exit;
end
else  begin
if MessageDlg('You will not be able to recover
the files once shredded.'+#13#10+' Do you want
to continue?', mtInformation,
      [mbYes, mbNo], 0)=mrYes then
for files:=0 to listbox1.Items.Count-1 do
begin
//retrieve dragged files one by one, overwrite
and delete
getridofFile(listbox1.Items[files]);
end;
//update the listbox
 filelistbox1.Update;
//reset progressbar,labels and form
 prog.Position:=0;
 label1.Caption:='0';
 form1.listbox1.Clear;
 label1.Caption:='0';
//Display  a message
 MessageDlg('File(s) deleted', mtInformation,
      [mbOk], 0);
 end;
end;

This is the most important bit of code. It actually executes the two procedures outlined earlier. Let's go through it. First, it checks whether the files have been selected, and displays the appropriate messages. If files have been selected, then it calls the "getridofFile" procedure, and displays a message depending on whether the operation was successful.

Next, click on the listbox, then go to the object inspector’s events tab and double click on the "dragdrop" field and enter the following code:

procedure TForm1.ListBox1DragDrop(Sender,
Source: TObject; X, Y: Integer);
var i,c: integer;
begin

with FileListBox1 do
 if SelCount > 0 then
  for i:=0 to Items.Count-1 do
   if Selected[i] then
     ListBox1.Items.Add(items[i]);
 c:=ListBox1.Items.count;
label1.Caption:=inttostr(c);

end;

Select the listbox and do the same, except double click on dragover field and enter the code below:

procedure TForm1.ListBox1DragOver(Sender,
Source: TObject; X, Y: Integer;
  State: TDragState; var Accept: Boolean);
begin
//where are the files coming from?
 if source is TFilelistbox then
accept:=true;
end;

The above code will handle the drag and drop actions, which are central to the app. Basically, the user will be able to select more than one file at a time and drag and drop them into the listbox.

The last bit of code will deal with setting the directory list box to a default drive and setting the progressbar to 100.

procedure TForm1.FormCreate(Sender: TObject);
begin
//set progressbar max
 prog.Max:=100;
//set directory default
directorylistbox1.Directory:='c:\';
end;

This will enable you to select all files at once…

procedure TForm1.SpeedButton2Click(Sender:
TObject);
begin
filelistbox1.SelectAll;
{MessageDlg('Right Click and drag selected
files', mtInformation,
      [mbOk], 0);}
MessageDlg ('Click and hold down left mouse
button and drag selected files',    mtCustom, [mbOK], 0);
end;

That’s it. Start deleting!