Delphi: hook ToggleSwitch manual State change to avoid a Click call

Question

Delphi Rio 10.3.2

With the TToggleSwitch component, when you manually change the State property, i.e

ToggleSwitch1.State := tssOff 

the OnClick event is called. How can I prevent this?

Answer 1

You have a few choices:

• set the OnClick property to nil before setting the State, then restore the event handler afterwards.

  ToggleSwitch1.OnClick := nil;
  try
    ToggleSwitch1.State := ...;
  finally
    ToggleSwitch1.OnClick := ToggleSwitch1Click;
  end;
  

• set a flag before setting the State, then clear the flag afterwards, and have the OnClick event handler check the flag before doing anything.

  ToggleSwitch1.Tag := 1;
  try
    ToggleSwitch1.State := ...;
  finally
    ToggleSwitch1.Tag := 0;
  end;
  
  procedure TMyForm.ToggleSwitch1Click(Sender: TObject);
  begin
    if ToggleSwitch1.Tag <> 0 then Exit;
    ...
  end;
  

• use an accessor class to reach the protected FClicksDisabled member so you can temporarily set it to True while changing the State:

  type
    TToggleSwitchAccess = class(TToggleSwitch)
    end;
  
  TToggleSwitchAccess(ToggleSwitch1).FClicksDisabled := True;
  try
    ToggleSwitch1.State := ...;
  finally
    TToggleSwitchAccess(ToggleSwitch1).FClicksDisabled := False;
  end;