Title: Changing the ZOrder of you controls
Question: How could one change the order of the controls in Delphi (viewed front to back)
Answer:
Sometimes you want to change the order of your controls during runtime. Usually you only can send them all the way to the front (Control.BringToFront) or send them all the way back (Control.SendToBack).
The following procedure will help you moving a control just one position for or back. This is especially useful when using vector graphis or similar applications.
The procedure takes the control to be moved as the first parameter. The direction is the second parameter (True brings the control one step up, False sends it one step back).
Internally, this procedure works with SendToBack and BringToFront too, however, it creates an order list first and pushes the other controls as well.
procedure ChangeControlZOrder(Sender: TObject; MoveUp: Boolean = True);
var
I, Curr: Integer;
Control: TControl;
List: TList;
begin
if Sender is TControl then
begin
// only components of type TControl and descendends
// work
Control := Sender as TControl;
// has no parent, cannot move ;-)
if Control.Parent = nil then
// quit
Exit;
// determine position in z-order
Curr := -1;
for I := 0 to Pred(Control.Parent.ControlCount) do
if Control.Parent.Controls[I] = Sender then
begin
Curr := I;
Break;
end;
if Curr // position not found, quit
Exit;
List := TList.Create;
try
if MoveUp then
begin
for I := Curr + 2 to Pred(Control.Parent.ControlCount) do
// load other controls in group
List.Add(Control.Parent.Controls[I]);
Control.BringToFront;
for I := 0 to Pred(List.Count) do
// move other controls to front, too
TControl(List[I]).BringToFront;
end else begin
for I := 0 to Curr - 2 do
// load other controls in group
List.Add(Control.Parent.Controls[I]);
Control.SendToBack;
for I := Pred(List.Count) downto 0 do
// move other controls to back, too
TControl(List[I]).SendToBack;
end;
finally
List.Free;
end;
end;
end;