I am trying to modify the visibility of an ActionButton accordingly to the current screen (using Screen Manager). I could not find a Visible property or something like that that can simply toggle visibility (neither for ActionButton nor for Widgets in general) .
A post from 2013 suggests changing the texture of the button, but I don't want to rely on such a hack to accomplish such a simple task, besides, the background of my app will be variable.
Another post suggest removing the widget and adding it again as needed. Despite its unnecessary complexity. I modified to work in my case (ActionBar and ActionButton), so I clear the widgets from the ActionView and then try to add the ActionButton. I tried storing both a weakref and the self member, with both I got the following error:
WidgetException: Cannot add <kivy.uix.actionbar.ActionButton object at 0x7fcd3fe22ce8>, it already has a parent <kivy.uix.actionbar.ActionView object at 0x7fcd3fe22870>
Any idea would be greatly appreciated. I am working with the dev version, but it neither work with 1.8.
EDIT
I tried the following code:
<AppActionBar>:
ActionView:
id: av
ActionButton:
id: btn_next
text: 'Next screen'
icon: 'data/icons/next_dark.png'
important: True
on_release: app.go_next()
This function is run after the scene is loaded:
def _initialize(self):
self.next = self.ids.btn_next.__self__ # same result if I don't use .__self__
This code raises the exception posted above:
self.ids.av.clear_widgets()
self.ids.av.add_widget(self.next)
Here is the full exception trace:
self._mainloop()
File "/usr/local/lib/python2.7/dist-packages/kivy/core/window/window_pygame.py", line 266, in _mainloop
EventLoop.idle()
File "/usr/local/lib/python2.7/dist-packages/kivy/base.py", line 330, in idle
Clock.tick_draw()
File "/usr/local/lib/python2.7/dist-packages/kivy/clock.py", line 429, in tick_draw
self._process_events_before_frame()
File "/usr/local/lib/python2.7/dist-packages/kivy/clock.py", line 562, in _process_events_before_frame
if event.tick(self._last_tick) is False:
File "/usr/local/lib/python2.7/dist-packages/kivy/clock.py", line 309, in tick
ret = callback(self._dt)
File "/usr/local/lib/python2.7/dist-packages/kivy/uix/boxlayout.py", line 174, in do_layout
c.width = w
File "properties.pyx", line 345, in kivy.properties.Property.__set__ (kivy/properties.c:3589)
File "properties.pyx", line 377, in kivy.properties.Property.set (kivy/properties.c:4064)
File "properties.pyx", line 431, in kivy.properties.Property.dispatch (kivy/properties.c:4657)
File "/usr/local/lib/python2.7/dist-packages/kivy/uix/actionbar.py", line 552, in on_width
self._layout_all()
File "/usr/local/lib/python2.7/dist-packages/kivy/uix/actionbar.py", line 441, in _layout_all
super_add(child)
File "/usr/local/lib/python2.7/dist-packages/kivy/uix/boxlayout.py", line 212, in add_widget
return super(BoxLayout, self).add_widget(widget, index)
File "/usr/local/lib/python2.7/dist-packages/kivy/uix/layout.py", line 78, in add_widget
return super(Layout, self).add_widget(widget, index)
File "/usr/local/lib/python2.7/dist-packages/kivy/uix/widget.py", line 466, in add_widget
% (widget, parent))
WidgetException: Cannot add <kivy.uix.actionbar.ActionButton object at 0x7fecb5d6ed50>, it already has a parent <kivy.uix.actionbar.ActionView object at 0x7fecb5d6e8d8>
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