From f18f6b6d6df2aad02cd6045a78f9d84f9bc1ad80 Mon Sep 17 00:00:00 2001
From: Brady James Garvin <bgarvin@cse.unl.edu>
Date: Sun, 18 Jul 2021 12:12:40 -0500
Subject: [PATCH] Used model properties to control the ScreenManager, moving
presentation logic to the Kv.
---
main.py | 15 +++++++++++----
twoscreen.kv | 9 +++++++--
2 files changed, 18 insertions(+), 6 deletions(-)
diff --git a/main.py b/main.py
index b7ebfae..2781354 100644
--- a/main.py
+++ b/main.py
@@ -1,4 +1,5 @@
from kivy.app import App
+from kivy.properties import BooleanProperty, StringProperty
# The following lines ensure that FirstScreen and SecondScreen are available for when the Kv code is loaded.
@@ -12,13 +13,19 @@ from second_screen import SecondScreen # pylint: disable=unused-import
class TwoScreenApp(App):
+ advancing = BooleanProperty(True)
+ current_screen_name = StringProperty() # We must wait to select a screen until the app starts.
+
def open_first_screen(self):
- self.root.transition.direction = 'right'
- self.root.current = 'first'
+ self.advancing = True
+ self.current_screen_name = 'first'
def open_second_screen(self):
- self.root.transition.direction = 'left'
- self.root.current = 'second'
+ self.advancing = False
+ self.current_screen_name = 'second'
+
+ def on_start(self):
+ self.open_first_screen() # Once the app starts, we can select the starting screen.
if __name__ == '__main__':
diff --git a/twoscreen.kv b/twoscreen.kv
index ca47926..331e111 100644
--- a/twoscreen.kv
+++ b/twoscreen.kv
@@ -1,8 +1,13 @@
+# We import the type of transition we want so that we can use it in the `transition` property below.
+# Imports have three parts: #:import, the name we want to use in our code, and the fully qualified name.
+
+#:import SlideTransition kivy.uix.screenmanager.SlideTransition
+
ScreenManager:
+ transition: SlideTransition(direction='right' if app.advancing else 'left')
+ current: app.current_screen_name
FirstScreen:
- id: first
name: 'first'
SecondScreen:
- id: second
name: 'second'
message: 'This is a message!' # The app sends information to the custom widgets by setting their properties.
--
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