Kivy 无法通过单击更改图像位置

Question

我的代码有一个大问题。单击按钮时，我想更改屏幕背景图像的 x 位置。其实我认为我正在正确地改变位置。因为我用其他按钮检查图像的当前位置。但是屏幕上什么都没有。图像没有移动到任何地方。我的错是什么，或者我不应该使用小部件在屏幕上显示图像？有什么办法可以做这个小游戏。

我的 .py 文件：

from kivy.app import App
from kivy.uix.screenmanager import ScreenManager, Screen, NoTransition , FadeTransition
from kivy.properties import ObjectProperty, NumericProperty
from kivy.lang import Builder
from kivy.uix.gridlayout import GridLayout
from kivy.uix.layout import Layout
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
from kivy.uix.label import Label
from kivy.uix.image import Image
from kivy.core.window import Window

Builder.load_file('jumpergame.kv')



class MainMenu(Screen):
    pass

class Dark(Screen):
    pass


class SettingsMenu(Screen):
    pass

class Game(Screen):

    first_image_py = ObjectProperty(None)

    def test(self):
        print(self.first_image_py.pos)

    def swipe(self):
        print(self.first_image_py.pos[0])
        self.first_image_py.pos[0] -= 100
        print(self.first_image_py.pos[0])


    def show_bg_first_pos(self):
        print('*******************')
        print('First Background [X] Position ==>',self.first_image_py.pos[0])
        print('First Background [Y] Position ==>',self.first_image_py.pos[1])
        return self.bg_first_pos_x,self.bg_first_pos_y

    def show_screen_size(self):
        print('*******************')
        print('Screen [X] Size ==>',self.width)
        print('Screen [Y] Size ==>',self.height)


    def show_bg_second_pos(self):
        print('*******************')


sm = ScreenManager()
sm.add_widget(MainMenu(name='mainmenu'))
sm.add_widget(SettingsMenu(name='settings'))
sm.add_widget(Game(name='game'))
sm.add_widget(Dark(name='dark'))

class JumperGame(App):
    def build(self):
        return sm

if __name__ == "__main__":
    JumperGame().run()

我的 .kv 文件：

<MainMenu>:

    BoxLayout:
        orientation : 'vertical'

        Label:
            text: 'JumperGame v1.00 \n          by 320V'
        Button:
            text: 'Start'
            on_press: root.manager.current = 'game'
        Button:
            text: 'Settings'
            on_press: root.manager.current = 'settings'

<SettingsMenu>:
    Button:
        text: 'BACK to MENU'
        on_press: root.manager.current = 'mainmenu'

<Game>:
    first_image_py : first_image_kv

    Widget:
        id: first_image_kv
        pos: 0,0

        canvas.before:
            Color:
                rgb: (1,1,1)
            Rectangle:

                source: 'bg.png'
                size: self.width  , self.height



    AnchorLayout:
        anchor_x : 'right'
        anchor_y : 'top'

        Button:
            text: 'Check image 1 pos'
            size_hint: .25,.1
            on_press: root.show_bg_first_pos()

    AnchorLayout:
        anchor_x : 'left'
        anchor_y : 'top'

        Button:
            text: 'Check Image 2 Pos'
            size_hint:.25,.1
            on_press: root.show_bg_second_pos()


    AnchorLayout:
        anchor_x : 'center'
        anchor_y : 'bottom'

        Button:
            text: 'Check Window Size'
            size_hint: .25 , .1
            on_press: root.show_screen_size()

    FloatLayout:
        canvas:
            Color:
                rgb: (1,1,1)
            Rectangle:
                id: bg_Image_Second
                source: 'bg.png'
                size: self.width  , self.height
                pos: root.width,root.height
        Button:
            text: 'Swipe Images'
            size_hint: .1,.1
            on_press: root.swipe()

        Button:
            text: 'TEST'
            size_hint: .1 , .1
            on_press: root.test()
            pos: 50,0

Answer 1

您的 swipe 方法正在更改小部件的位置，但您的图像在 Rectangle canvas 指令中。由于您没有将 Rectangle 的位置绑定到 Widget 的位置，因此图像永远不会移动。您只需要通过在kv 文件中添加pos: self.pos 来添加该绑定：

<Game>:
    first_image_py : first_image_kv

    Widget:
        id: first_image_kv
        pos: 0,0

        canvas.before:
            Color:
                rgb: (1,1,1)
            Rectangle:
                source: 'bg.png'
                size: self.width  , self.height
                pos: self.pos