How to remove focus from currently focused component?

问题

I have a DB component which DataLink.UpdateRecord is called when it receives CM_EXIT message. This message is sent when it loses focus. When I click post button, it doesn't lose focus and value is not written to datasource. How can I reach an effect of component losing focus without switching it to other one?

回答1:

You could use:

procedure TCustomForm.DefocusControl(Control: TWinControl; Removing: Boolean);

回答2:

We accomplish this by setting the Self.ActiveControl := nil. That causes all of the exit events to fire. In our case we wanted to also re-focus back to the control after the save took place. That required a few extra checks to ensure we had a good control that could accept focus.

procedure TSaleEditor.SaveCurrentState();
var
  SavedActiveControl: TWinControl;
  AlternateSavedControl: TWinControl;
begin

  // Force the current control to exit and save any state.
  if Self.ActiveControl <> nil then
  begin
    SavedActiveControl := Self.ActiveControl;

    // We may have an inplace grid editor as the current control.  In that case we
    // will not be able to reset it as the active control.  This will cause the
    // Scroll box to scroll to the active control, which will be the lowest tab order
    // control.  Our "real" controls have names, where the dynamic inplace editor do not
    // find an Alternate control to set the focus by walking up the parent list until we
    // find a named control.
    AlternateSavedControl := SavedActiveControl;
    while (AlternateSavedControl.Name = '') and (AlternateSavedControl.Parent <> nil) do
    begin
      AlternateSavedControl := AlternateSavedControl.Parent;
    end;

    Self.ActiveControl := nil;

    // If the control is a radio button then do not re-set focus
    // because if you are un-selecting the radio button this will automatically
    // re-select it again
    if (SavedActiveControl.CanFocus = true) and
      ((SavedActiveControl is TcxRadioButton) = false) then
    begin
      Self.ActiveControl := SavedActiveControl;
    end
    else if (AlternateSavedControl.CanFocus = true) and
      ((AlternateSavedControl is TcxRadioButton) = false) then
    begin
      Self.ActiveControl := AlternateSavedControl;
    end;

  end;

end;

回答3:

Have a look at TCustomForm.FocusControl. You can't make it lose focus without switching focus to something else, but you can switch and then immediately switch back, which would probably work.

回答4:

There is a SetFocus function in windows unit. Try this:

Windows.SetFocus(0);

来源：https://stackoverflow.com/questions/2264354/how-to-remove-focus-from-currently-focused-component