SlideTransition in Kivy - slide direction fails - python-3.x

Question

I am having issues with the slide direction using SlideTransition in Kivy. When implementing a button-specific slide direction, the direction seems to work fine only occasionally. However, it fails in other circumstances.
To reproduce the problem, please feel free to use the following code:
main.py:
from kivy.app import App # Use of fields and methods of Kivy
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen, FadeTransition
class Screen1(Screen):
pass
class Screen2(Screen):
pass
class Screen3(Screen):
pass
class ScreenManagement(ScreenManager):
pass
presentation = Builder.load_file("style.kv")
class MyApp(App):
def build(self):
return presentation
myApp = MyApp()
myApp.run()
style.kv:
#: import SlideTransition kivy.uix.screenmanager.SlideTransition
ScreenManagement:
transition: SlideTransition()
Screen1:
Screen2:
Screen3:
<Screen1>:
name: "screen1"
FloatLayout:
Label:
text: "Screen 1"
pos_hint: {"top": 1.0}
Button:
on_release:
app.root.current = "screen2"
app.root.transition = SlideTransition(direction="left")
size_hint: 0.5, 0.8/3
pos_hint: {"bottom": 0.8, "left": 1}
text: "Screen 2 (slide left)"
font_size: 30
<Screen2>:
name: "screen2"
FloatLayout:
Label:
text: "Screen 2"
pos_hint: {"top": 1.0}
Button:
on_release:
app.root.current = "screen1"
app.root.transition = SlideTransition(direction="right")
size_hint: 0.5, 0.8/3
pos_hint: {"top": 0.8, "right": 1}
text: "Screen 1 (slide right)"
font_size: 30
Button:
on_release:
app.root.current = "screen3"
app.root.transition = SlideTransition(direction="left")
size_hint: 0.5, 0.8/3
pos_hint: {"top": 0.8, "left": 1}
text: "Screen 3 (slide left)"
font_size: 30
<Screen3>:
name: "screen3"
FloatLayout:
Label:
text: "Screen 3"
pos_hint: {"top": 1.0}
Button:
on_release:
app.root.current = "screen1"
app.root.transition = SlideTransition(direction="right")
size_hint: 0.5, 0.8/3
pos_hint: {"top": 0.8, "left": 1}
text: "Screen 1 (slide right)"
font_size: 30
I am experiencing the following problem: Upon clicking on "Slide 2" in the first slide and "Slide 3" in the second slide, both disappearing to the left as specified, clicking "Slide 1" in the third slide results in slide direction "left", although the specified direction is "right". Something seems to override the slide direction?
Did anyone experience similar problems and does know how to solve them? Thanks in advance!

Answer 1

Problem
The screen was displayed before the given direction. Therefore, it used the previous Slide Transition direction i.e. left. You have the same problem in a couple of places.
Button:
on_release:
app.root.current = "screen1"
app.root.transition = SlideTransition(direction="right")
Solution
Set the Slide Transition direction first, and then set current to the desire screen name. Please refer to the example for details.
Button:
on_release:
app.root.transition = SlideTransition(direction="right")
app.root.current = "screen1"
Example
style.kv
#:import SlideTransition kivy.uix.screenmanager.SlideTransition
ScreenManagement:
transition: SlideTransition()
Screen1:
Screen2:
Screen3:
<Screen1>:
name: "screen1"
FloatLayout:
Label:
text: "Screen 1"
pos_hint: {"top": 1.0}
Button:
on_release:
app.root.transition = SlideTransition(direction="left")
app.root.current = "screen2"
size_hint: 0.5, 0.8/3
pos_hint: {"bottom": 0.8, "left": 1}
text: "Screen 2 (slide left)"
font_size: 30
<Screen2>:
name: "screen2"
FloatLayout:
Label:
text: "Screen 2"
pos_hint: {"top": 1.0}
Button:
on_release:
app.root.transition = SlideTransition(direction="right")
app.root.current = "screen1"
size_hint: 0.5, 0.8/3
pos_hint: {"top": 0.8, "right": 1}
text: "Screen 1 (slide right)"
font_size: 30
Button:
on_release:
app.root.transition = SlideTransition(direction="left")
app.root.current = "screen3"
size_hint: 0.5, 0.8/3
pos_hint: {"top": 0.8, "left": 1}
text: "Screen 3 (slide left)"
font_size: 30
<Screen3>:
name: "screen3"
FloatLayout:
Label:
text: "Screen 3"
pos_hint: {"top": 1.0}
Button:
on_release:
app.root.transition = SlideTransition(direction="right")
app.root.current = "screen1"
size_hint: 0.5, 0.8/3
pos_hint: {"top": 0.8, "left": 1}
text: "Screen 1 (slide right)"
font_size: 30