Complete application works fine. But when I change the screen transition effect from slide or NO to FadeTransition(and similar which uses shader effects) I see the following issue.
Transition to new screens happens without any issue. But transition to any previous screens gives an error saying that the screen is not found. To be more clear, suppose I have 3 screens 1, 2 & 3. FadeTransitions works from 1 to 2, or 2 to 3 but never from 2 to 1 or 3 to 1.
I'm posting the error message below.
[INFO ] [Base ] Leaving application in progress...
Traceback (most recent call last):
File "example.py", line 1229, in <module>
ShamarApp().run()
File "/usr/local/lib/python2.7/dist-packages/kivy/app.py", line 855, in run
runTouchApp()
File "/usr/local/lib/python2.7/dist-packages/kivy/base.py", line 504, in runTouchApp
EventLoop.window.mainloop()
File "/usr/local/lib/python2.7/dist-packages/kivy/core/window/window_egl_rpi.py", line 92, in mainloop
self._mainloop()
File "/usr/local/lib/python2.7/dist-packages/kivy/core/window/window_egl_rpi.py", line 87, in _mainloop
EventLoop.idle()
File "/usr/local/lib/python2.7/dist-packages/kivy/base.py", line 339, in idle
Clock.tick()
File "/usr/local/lib/python2.7/dist-packages/kivy/clock.py", line 591, in tick
self._process_events()
File "kivy/_clock.pyx", line 384, in kivy._clock.CyClockBase._process_events
File "kivy/_clock.pyx", line 414, in kivy._clock.CyClockBase._process_events
File "kivy/_clock.pyx", line 412, in kivy._clock.CyClockBase._process_events
File "kivy/_clock.pyx", line 167, in kivy._clock.ClockEvent.tick
File "shamar.py", line 248, in <lambda>
event = Clock.schedule_interval(lambda dt: self.update_time(), 1)
File "shamar.py", line 315, in update_time
self.root.current = 'main'
File "kivy/properties.pyx", line 497, in kivy.properties.Property.__set__
File "kivy/properties.pyx", line 544, in kivy.properties.Property.set
File "kivy/properties.pyx", line 599, in kivy.properties.Property.dispatch
File "kivy/_event.pyx", line 1214, in kivy._event.EventObservers.dispatch
File "kivy/_event.pyx", line 1120, in kivy._event.EventObservers._dispatch
File "/usr/local/lib/python2.7/dist-packages/kivy/uix/screenmanager.py", line 1039, in on_current
screen = self.get_screen(value)
File "/usr/local/lib/python2.7/dist-packages/kivy/uix/screenmanager.py", line 1065, in get_screen
raise ScreenManagerException('No Screen with name "%s".' % name)
kivy.uix.screenmanager.ScreenManagerException: No Screen with name "main".
------------------
(program exited with code: 1)
Press return to continue
Here the screen with name 'main' is there and works well when I remove this transition effect. Please help.
I am adding a sample code below to further explain this scenario.
screenmanager_test.py
import kivy
kivy.require('1.11.0')
import os
os.environ['KIVY_GL_BACKEND'] = 'gl'
from kivy.app import App
from kivy.uix.popup import Popup
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.screenmanager import Screen, ScreenManager, NoTransition,\
FadeTransition
from kivy.clock import Clock
class MainScreen(Screen):
def setName(self,*args):
FirstPopup().open()
class SecondScreen(Screen):
pass
class FirstPopup(Popup):
pass
class MyScreenManager(ScreenManager):
pass
class SmTestApp(App):
def build(self):
sm = MyScreenManager()
sm.transition = FadeTransition()
sm.add_widget(MainScreen(name="main_scr"))
sm.add_widget(SecondScreen(name="second_scr"))
return sm
SmTestApp().run()
smtest.kv
#: kivy 1.11.0
<MainScreen>:
name: 'main_scr'
BoxLayout:
orientation: 'vertical'
padding: 100,100
spacing: 50
Label:
text: 'Welcome to Main Screen'
font_size: 35
Button:
text: 'Options'
font_size: 15
on_release: root.setName(*args)
Button:
text: 'Next Screen'
font_size: 15
on_release: app.root.current = 'second_scr'
<SecondScreen>:
name: 'second_scr'
BoxLayout:
orientation:'vertical'
padding:100,100
spacing:50
Label:
text: 'This is your second screen'
font_size: 35
Button:
text: 'Back'
font_size: 25
on_release: app.root.current = 'main_scr'
<FirstPopup>:
title: 'Options Window'
size_hint: None, None
size: 400,370
BoxLayout:
orientation : 'vertical'
Label:
text : "Checkbox options listed here"
Button:
text: "OK"
on_release: root.dismiss()
And following is the error message while trying to switch back from second screen to first.
[INFO ] [Base ] Leaving application in progress...
Traceback (most recent call last):
File "screenmanager_test.py", line 34, in <module>
SmTestApp().run()
File "/usr/local/lib/python2.7/dist-packages/kivy/app.py", line 855, in run
runTouchApp()
File "/usr/local/lib/python2.7/dist-packages/kivy/base.py", line 504, in runTouchApp
EventLoop.window.mainloop()
File "/usr/local/lib/python2.7/dist-packages/kivy/core/window/window_egl_rpi.py", line 92, in mainloop
self._mainloop()
File "/usr/local/lib/python2.7/dist-packages/kivy/core/window/window_egl_rpi.py", line 87, in _mainloop
EventLoop.idle()
File "/usr/local/lib/python2.7/dist-packages/kivy/base.py", line 342, in idle
self.dispatch_input()
File "/usr/local/lib/python2.7/dist-packages/kivy/base.py", line 327, in dispatch_input
post_dispatch_input(*pop(0))
File "/usr/local/lib/python2.7/dist-packages/kivy/base.py", line 293, in post_dispatch_input
wid.dispatch('on_touch_up', me)
File "kivy/_event.pyx", line 707, in kivy._event.EventDispatcher.dispatch
File "/usr/local/lib/python2.7/dist-packages/kivy/uix/behaviors/button.py", line 179, in on_touch_up
self.dispatch('on_release')
File "kivy/_event.pyx", line 703, in kivy._event.EventDispatcher.dispatch
File "kivy/_event.pyx", line 1214, in kivy._event.EventObservers.dispatch
File "kivy/_event.pyx", line 1098, in kivy._event.EventObservers._dispatch
File "/usr/local/lib/python2.7/dist-packages/kivy/lang/builder.py", line 64, in custom_callback
exec(__kvlang__.co_value, idmap)
File "/home/pi/Toller_Rpi/training_prgms/smtest.kv", line 37, in <module>
on_release: app.root.current = 'main_scr'
File "kivy/properties.pyx", line 497, in kivy.properties.Property.__set__
File "kivy/properties.pyx", line 544, in kivy.properties.Property.set
File "kivy/properties.pyx", line 599, in kivy.properties.Property.dispatch
File "kivy/_event.pyx", line 1214, in kivy._event.EventObservers.dispatch
File "kivy/_event.pyx", line 1120, in kivy._event.EventObservers._dispatch
File "/usr/local/lib/python2.7/dist-packages/kivy/uix/screenmanager.py", line 1039, in on_current
screen = self.get_screen(value)
File "/usr/local/lib/python2.7/dist-packages/kivy/uix/screenmanager.py", line 1065, in get_screen
raise ScreenManagerException('No Screen with name "%s".' % name)
kivy.uix.screenmanager.ScreenManagerException: No Screen with name "main_scr".
------------------
(program exited with code: 1)
Press return to continue
