How to write a custom TAction to control the visibility of a TStatusBar (Views: 712)
Problem/Question/Abstract: I am trying to write a custom action that will set the visible property of a TStatusBar on and off. I assigned this action to a menu item and when I select this menu item at runtime the status bar is hidden. The problem is that the menu item (connected to the action) is disabled, so I can't view the statusbar again. I think that it's a matter of how the TMenuActionLink behaves (the action controls the enabled property of the menu ). I tried to set the enabled property in the action to true , but no avail. The menu is still disabled. Is there any way to do this? Answer: I think that the best solution would be to write an action, which will have a StatusBar property and, in case this property was assigned, set the statusbar's visibility in the overridden Execute method. Here's an example: { ... } TMyAction = class(TAction) protected FStatusBar: TStatusBar; procedure Notification(AComponent: TComponent; Operation: TOperation); override; procedure SetStatusBar(AValue: TStatusBar); public constructor Create(AOwner: TComponent); override; function Execute: Boolean; override; published property StatusBar: TStatusBar read FStatusBar write SetStatusBar; end; { ... } constructor TMyAction.Create(AOwner: TComponent); begin inherited Create(AOwner); DisableIfNoHandler := false; FStatusBar := nil; Caption := 'Turn On/ Off Status Bar'; end; function TMyAction.Execute: Boolean; begin Result := inherited Execute; if Assigned(FStatusBar) then begin FStatusBar.Visible := not FStatusBar.Visible; Checked := FStatusBar.Visible; end; end; procedure TMyAction.Notification(AComponent: TComponent; Operation: TOperation); begin inherited Notification(AComponent, Operation); if (Operation = opRemove) and (AComponent = StatusBar) then StatusBar := nil; end; procedure TMyAction.SetStatusBar(AValue: TStatusBar); begin if FStatusBar <> AValue then begin FStatusBar := AValue; if Assigned(FStatusBar) then begin FStatusBar.FreeNotification(Self); Checked := FStatusBar.Visible; end else Checked := false; end; end; |