Kivy 中的 SlideTransition - 滑动方向失败

Question

我在 Kivy 中使用 SlideTransition 时遇到了滑动方向问题。在实现特定于按钮的滑动方向时，方向似乎只是偶尔正常工作。但是，在其他情况下它会失败。

要重现问题，请随意使用以下代码：

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

我遇到了以下问题：单击第一张幻灯片中的“幻灯片 2”和第二张幻灯片中的“幻灯片 3”后，两者都按指定向左消失，单击第三张幻灯片中的“幻灯片 1”会导致滑动方向“左”，虽然指定的方向是“右”。似乎有什么东西覆盖了滑动方向？

有没有人遇到过类似的问题并且知道如何解决？提前致谢！

Answer 1

问题

屏幕在给定方向之前显示。因此，它使用了之前的幻灯片过渡方向，即向左。你在几个地方有同样的问题。

Button:
    on_release: 
        app.root.current = "screen1"
        app.root.transition = SlideTransition(direction="right")

解决方案

先设置Slide Transition方向，再设置current为想要的屏幕名称。详情请参考示例。

Button:
    on_release:
        app.root.transition = SlideTransition(direction="right")
        app.root.current = "screen1"

示例

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