使用 On_Press 事件更改屏幕，而无需动态创建按钮的 KV 语言
Use On_Press Event to Change Screen without KV Language for Dynamically Created Buttons
问题：
如何在不使用 KV 语言的情况下使用 On-Press 事件为动态创建的按钮更改屏幕 python？
目标：
能够通过单击动态创建的按钮导航到新屏幕，
[无需在 Kivy 中创建按钮，并且仍然可以在 Python 和 Kivy 中使用 Screenmanager（不确定在整个程序中是否必须坚持使用 Python 或 Kivy？ ]
我已经尝试过的事情：
- 使用
button_share.bind(on_press = self.changer)，然后是：
def changer(self,*args):
ScreenManager()
screenmanager.current = 'MainScreen'
但是我收到错误 ScreenManagerException: No Screen with name "MainScreen".
怀疑：
我认为这是因为我正在创建一个新的 ScreenManager 实例，而不是引用现有实例。为了解决这个问题，我考虑在 App class 中实例化 Screenmanager()，然后在我的按钮 def changer(self, *args) 方法中引用该实例化，但如果它与我实际使用的 ScreenManager 不同，那将毫无用处我所有的屏幕。而这些都是用KV语言定义的。如果不付出大量努力，我将无法将它们全部切换过来。
- 使用：
button_share.bind(on_press=partial(app.sm.setter('current'), (app.sm, "MainScreen")))`
但是我得到的错误是ValueError: ScreenManager.current accept only str
下面是一个完全可运行的例子：
注意：在这个例子中，我想点击 'Continue Editing' 按钮，然后点击 'Test 1'、'Test 2' 或 'Test 3' 按钮，让它把我带到另一个屏幕。
Python代码：
from kivy.app import App
# kivy.require("1.10.0")
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen, FadeTransition
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
from kivy.clock import Clock
from kivy.uix.widget import Widget
#from kivy.base import runTouchApp
from kivy.properties import StringProperty, ObjectProperty, NumericProperty
from functools import partial
class ScrollableLabelDataEntryInstructions(BoxLayout):
pass
class NewGarageScreen(Screen):
pass
class ContinueEditingScreen(Screen):
pass
class GarageNameBoxLayout(BoxLayout):
box_share2 = ObjectProperty()
sm = ScreenManager()
def __init__(self, **kwargs):
super(GarageNameBoxLayout, self).__init__(**kwargs)
self.orientation = "vertical"
Clock.schedule_interval(self.create_button, 5)
def create_button(self, *args):
self.box_share2.clear_widgets()
app = App.get_running_app()
#put GarageNameStartList data into app class, then pull from it in this class
top_button_share = 1.1
color = (.4, .4, .4, 1)
for i in range(len(app.GarageNameStartList)):
top_button_share -= .4
id_ = app.GarageNameStartList[i]
button_share = Button(background_normal='',
background_color = color,
id = id_,
pos_hint = {"x": 0, "top": top_button_share},
size_hint_y = None,
height = 60,
font_size = 30,
text = app.GarageNameStartList[i])
button_share.bind(on_press = self.changer)
#button_share.bind(on_press=partial(app.sm.setter('current'), (app.sm, "MainScreen")))
self.box_share2.add_widget(button_share)
def changer(self,*args):
ScreenManager()
#app = App.get_running_app()
screenmanager.current = 'MainScreen'
class BackHomeWidget(Widget):
pass
class MainScreen(Screen):
pass
class AnotherScreen(Screen):
pass
class ScreenManagement(ScreenManager):
pass
presentation = Builder.load_file("example_on_press.kv")
class MainApp(App):
GarageNameStartList = ["Test1", "Test2", "Test3"]
def Update_GarageNameStartList(self, *args):
self.GarageNameStartList = ["Test1", "Test2", "Test3"]
def build(self):
return presentation
if __name__ == "__main__":
MainApp().run()
KV代码：
#: import FadeTransition kivy.uix.screenmanager.FadeTransition
ScreenManagement:
transition: FadeTransition()
MainScreen:
AnotherScreen:
NewGarageScreen:
ContinueEditingScreen:
<SmallNavButton@Button>:
font_size: 32
size: 125, 50
color: 0,1,0,1
<MedButton@Button>:
font_size: 30
size_hint: 0.25, 0.1
color: 0,1,0,1
<BackHomeWidget>:
SmallNavButton:
on_release: app.root.current = "main"
text: "Home"
pos: root.x, root.top - self.height
<MainScreen>:
name: "main"
FloatLayout:
MedButton:
on_release: app.root.current = "edit"
text: "Edit"
pos_hint: {"x":0.3728, "top": 0.4}
<AnotherScreen>:
name: "edit"
BackHomeWidget:
SmallNavButton:
on_release: app.root.current = "main"
text: "Back"
pos: root.x, root.top - (2.25*(self.height))
FloatLayout:
MedButton:
on_release: app.root.current = "continueediting"
text: "Continue Editing"
pos_hint: {"x":0.25, "top": 0.6}
MedButton:
on_release: app.root.current = "newgarage"
text: "Create New"
pos_hint: {"x":0.3728, "top": 0.4}
<NewGarageScreen>:
name: "newgarage"
BackHomeWidget:
SmallNavButton:
on_release: app.root.current = "edit"
text: "Back"
pos: root.x, root.top - (2.25*(self.height))
FloatLayout:
MedButton:
text: "1. Groundfloor"
pos_hint: {"x":0, "top": 0.6}
<GarageNameBoxLayout>:
box_share2: box_share2
ScrollView:
GridLayout:
id: box_share2
cols: 1
size_hint_y: None
size_hint_x: 0.5
spacing: 5
padding: 130
height: self.minimum_height
canvas:
Color:
rgb: 0, 0, 0
Rectangle:
pos: self.pos
size: self.size
<ContinueEditingScreen>:
name: "continueediting"
GarageNameBoxLayout:
BackHomeWidget:
SmallNavButton:
on_release: app.root.current = "edit"
text: "Back"
pos: root.x, root.top - (2.25*(self.height))
您的代码可以在以下方面进行改进：
您不必在 .py 中创建 box_share2，因为您是在 .kv
当您使用 sm = ScreenManager() 时，您正在创建另一个与原始版本不同的 ScreenManager，这是没有必要的。
没有必要使用range和len，让你的代码可读性变差，你只需要迭代。
如果我们查看 .kv 的结构，我们会发现表示对象是 ScreenManager，因此您可以通过 app.root.
获取它
使用上面的代码，解决方案是：
[...]
class GarageNameBoxLayout(BoxLayout):
def __init__(self, **kwargs):
super(GarageNameBoxLayout, self).__init__(**kwargs)
self.orientation = "vertical"
Clock.schedule_interval(self.create_button, 5)
def create_button(self, *args):
self.box_share2.clear_widgets()
app = App.get_running_app()
sm = app.root
#put GarageNameStartList data into app class, then pull from it in this class
top_button_share = 1.1
color = (.4, .4, .4, 1)
for text in app.GarageNameStartList:
top_button_share -= .4
id_ = text
button_share = Button(background_normal='',
background_color = color,
id = id_,
pos_hint = {"x": 0, "top": top_button_share},
size_hint_y = None,
height = 60,
font_size = 30,
text = text)
button_share.bind(on_press=lambda *args: setattr(sm, 'current', "main"))
self.box_share2.add_widget(button_share)
[...]
问题：
如何在不使用 KV 语言的情况下使用 On-Press 事件为动态创建的按钮更改屏幕 python？
目标：
能够通过单击动态创建的按钮导航到新屏幕，
[无需在 Kivy 中创建按钮，并且仍然可以在 Python 和 Kivy 中使用 Screenmanager（不确定在整个程序中是否必须坚持使用 Python 或 Kivy？ ]
我已经尝试过的事情：
- 使用
button_share.bind(on_press = self.changer)，然后是：
def changer(self,*args):
ScreenManager()
screenmanager.current = 'MainScreen'
但是我收到错误 ScreenManagerException: No Screen with name "MainScreen".
怀疑：
我认为这是因为我正在创建一个新的 ScreenManager 实例，而不是引用现有实例。为了解决这个问题，我考虑在 App class 中实例化 Screenmanager()，然后在我的按钮 def changer(self, *args) 方法中引用该实例化，但如果它与我实际使用的 ScreenManager 不同，那将毫无用处我所有的屏幕。而这些都是用KV语言定义的。如果不付出大量努力，我将无法将它们全部切换过来。
- 使用：
button_share.bind(on_press=partial(app.sm.setter('current'), (app.sm, "MainScreen")))`
但是我得到的错误是ValueError: ScreenManager.current accept only str
下面是一个完全可运行的例子：
注意：在这个例子中，我想点击 'Continue Editing' 按钮，然后点击 'Test 1'、'Test 2' 或 'Test 3' 按钮，让它把我带到另一个屏幕。
Python代码：
from kivy.app import App
# kivy.require("1.10.0")
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen, FadeTransition
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
from kivy.clock import Clock
from kivy.uix.widget import Widget
#from kivy.base import runTouchApp
from kivy.properties import StringProperty, ObjectProperty, NumericProperty
from functools import partial
class ScrollableLabelDataEntryInstructions(BoxLayout):
pass
class NewGarageScreen(Screen):
pass
class ContinueEditingScreen(Screen):
pass
class GarageNameBoxLayout(BoxLayout):
box_share2 = ObjectProperty()
sm = ScreenManager()
def __init__(self, **kwargs):
super(GarageNameBoxLayout, self).__init__(**kwargs)
self.orientation = "vertical"
Clock.schedule_interval(self.create_button, 5)
def create_button(self, *args):
self.box_share2.clear_widgets()
app = App.get_running_app()
#put GarageNameStartList data into app class, then pull from it in this class
top_button_share = 1.1
color = (.4, .4, .4, 1)
for i in range(len(app.GarageNameStartList)):
top_button_share -= .4
id_ = app.GarageNameStartList[i]
button_share = Button(background_normal='',
background_color = color,
id = id_,
pos_hint = {"x": 0, "top": top_button_share},
size_hint_y = None,
height = 60,
font_size = 30,
text = app.GarageNameStartList[i])
button_share.bind(on_press = self.changer)
#button_share.bind(on_press=partial(app.sm.setter('current'), (app.sm, "MainScreen")))
self.box_share2.add_widget(button_share)
def changer(self,*args):
ScreenManager()
#app = App.get_running_app()
screenmanager.current = 'MainScreen'
class BackHomeWidget(Widget):
pass
class MainScreen(Screen):
pass
class AnotherScreen(Screen):
pass
class ScreenManagement(ScreenManager):
pass
presentation = Builder.load_file("example_on_press.kv")
class MainApp(App):
GarageNameStartList = ["Test1", "Test2", "Test3"]
def Update_GarageNameStartList(self, *args):
self.GarageNameStartList = ["Test1", "Test2", "Test3"]
def build(self):
return presentation
if __name__ == "__main__":
MainApp().run()
KV代码：
#: import FadeTransition kivy.uix.screenmanager.FadeTransition
ScreenManagement:
transition: FadeTransition()
MainScreen:
AnotherScreen:
NewGarageScreen:
ContinueEditingScreen:
<SmallNavButton@Button>:
font_size: 32
size: 125, 50
color: 0,1,0,1
<MedButton@Button>:
font_size: 30
size_hint: 0.25, 0.1
color: 0,1,0,1
<BackHomeWidget>:
SmallNavButton:
on_release: app.root.current = "main"
text: "Home"
pos: root.x, root.top - self.height
<MainScreen>:
name: "main"
FloatLayout:
MedButton:
on_release: app.root.current = "edit"
text: "Edit"
pos_hint: {"x":0.3728, "top": 0.4}
<AnotherScreen>:
name: "edit"
BackHomeWidget:
SmallNavButton:
on_release: app.root.current = "main"
text: "Back"
pos: root.x, root.top - (2.25*(self.height))
FloatLayout:
MedButton:
on_release: app.root.current = "continueediting"
text: "Continue Editing"
pos_hint: {"x":0.25, "top": 0.6}
MedButton:
on_release: app.root.current = "newgarage"
text: "Create New"
pos_hint: {"x":0.3728, "top": 0.4}
<NewGarageScreen>:
name: "newgarage"
BackHomeWidget:
SmallNavButton:
on_release: app.root.current = "edit"
text: "Back"
pos: root.x, root.top - (2.25*(self.height))
FloatLayout:
MedButton:
text: "1. Groundfloor"
pos_hint: {"x":0, "top": 0.6}
<GarageNameBoxLayout>:
box_share2: box_share2
ScrollView:
GridLayout:
id: box_share2
cols: 1
size_hint_y: None
size_hint_x: 0.5
spacing: 5
padding: 130
height: self.minimum_height
canvas:
Color:
rgb: 0, 0, 0
Rectangle:
pos: self.pos
size: self.size
<ContinueEditingScreen>:
name: "continueediting"
GarageNameBoxLayout:
BackHomeWidget:
SmallNavButton:
on_release: app.root.current = "edit"
text: "Back"
pos: root.x, root.top - (2.25*(self.height))
您的代码可以在以下方面进行改进：
您不必在 .py 中创建 box_share2，因为您是在 .kv
中创建它
当您使用
sm = ScreenManager()时，您正在创建另一个与原始版本不同的ScreenManager，这是没有必要的。没有必要使用
range和len，让你的代码可读性变差，你只需要迭代。如果我们查看 .kv 的结构，我们会发现表示对象是
获取它ScreenManager，因此您可以通过app.root.
使用上面的代码，解决方案是：
[...]
class GarageNameBoxLayout(BoxLayout):
def __init__(self, **kwargs):
super(GarageNameBoxLayout, self).__init__(**kwargs)
self.orientation = "vertical"
Clock.schedule_interval(self.create_button, 5)
def create_button(self, *args):
self.box_share2.clear_widgets()
app = App.get_running_app()
sm = app.root
#put GarageNameStartList data into app class, then pull from it in this class
top_button_share = 1.1
color = (.4, .4, .4, 1)
for text in app.GarageNameStartList:
top_button_share -= .4
id_ = text
button_share = Button(background_normal='',
background_color = color,
id = id_,
pos_hint = {"x": 0, "top": top_button_share},
size_hint_y = None,
height = 60,
font_size = 30,
text = text)
button_share.bind(on_press=lambda *args: setattr(sm, 'current', "main"))
self.box_share2.add_widget(button_share)
[...]