在kivy中创建一个无限的滚动视图图像。

Question

我想用kivy创建一个数字笔记本应用。我有了我的基本屏幕和一个我想使用的一排工作表的ScrollView。它似乎很好，但我现在希望这个工作表是无限的--这意味着你能够继续向下滚动，并拥有更多的行数（比如让图像垂直复制自己）。我怎样才能做到这一点呢？

我真的很感激任何帮助:)

Python代码。

import kivy
from kivy.lang import Builder
from kivy.app import App
from kivy.uix.gridlayout import GridLayout
from kivy.uix.scrollview import ScrollView
from kivy.uix.label import Label
from kivy.uix.button import Button
from kivy.uix.widget import Widget
from kivy.core.window import Window
from kivy.uix.boxlayout import BoxLayout
from kivy.properties import ObjectProperty
from PIL import Image as Image1
from kivy.uix.image import Image

GUI = Builder.load_file('style.kv')
img_size = Image1.open("images/notebook.png").size


class NotebookScreen(GridLayout):

    def __init__(self, **kwargs):
        self.rows = 1
        super(NotebookScreen, self).__init__(**kwargs)

    def get_size_for_notebook(self, **kwargs):
        global img_size
        width, height = Window.size
        return width, (img_size[0] * height / width)


class MainApp(App):

    def build(self):
        return NotebookScreen()


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

kv文件：

<NotebookScreen>
    FloatLayout:
        rows: 2
        GridLayout:
            size_hint: 1, .05
            pos_hint: {"top": 1, "left": 1}
            id: tool_bar
            cols: 1
            canvas:
                Color:
                    rgba: 0, 0, 1, 1
                Rectangle:
                    pos: self.pos
                    size: self.size
        GridLayout:
            id: notebook_grid
            size_hint: 1, .95
            pos_hint: {"top": .95, "left": .97}
            cols: 1


            ScrollView:
                do_scroll: (False, True)  # up and down

                Image:
                    id: notebook_image
                    source: 'images/notebook.png'
                    allow_stretch: True
                    keep_ratio: False
                    pos: self.pos
                    size: root.get_size_for_notebook()
                    size_hint: 1, None

Answer 1

你可以通过使用 BoxLayout 衬纸 Image. 然后你就可以添加更多的相同的 Image 至 BoxLayout 根据需要。这里是你的代码的一个版本，可以做到这一点。

from kivy.lang import Builder
from kivy.app import App
from kivy.properties import ObjectProperty
from kivy.uix.gridlayout import GridLayout
from kivy.uix.scrollview import ScrollView
from kivy.core.window import Window
from PIL import Image as Image1
from kivy.uix.image import Image

#GUI = Builder.load_file('style.kv')
Builder.load_string('''
<NotebookScreen>
    FloatLayout:
        GridLayout:
            size_hint: 1, .05
            pos_hint: {"top": 1, "left": 1}
            id: tool_bar
            cols: 1
            canvas:
                Color:
                    rgba: 0, 0, 1, 1
                Rectangle:
                    pos: self.pos
                    size: self.size
        GridLayout:
            id: notebook_grid
            size_hint: 1, .95
            pos_hint: {"top": .95, "left": 0}
            cols: 1

            MyScrollView:
                do_scroll: (False, True)  # up and down

                BoxLayout:
                    id: notebook_images
                    orientation: 'vertical'
                    size_hint: 1, None
                    height: self.minimum_height
                    MyImage:
<MyImage>:
    source: 'images/notebook.png'
    allow_stretch: True
    keep_ratio: True
    size_hint: None, None
    size: self.get_size_for_notebook()
''')

Window.size = (1000, 200)
img_size =Image1.open("images/notebook.png").size


class MyImage(Image):
    def get_size_for_notebook(self, **kwargs):
        global img_size
        width, height = Window.size
        return width, (img_size[0] * height / width)


class MyScrollView(ScrollView):
    def on_scroll_y(self, instance, scroll_val):
        if scroll_val < 0.05:  # no logic for this number
            box = App.get_running_app().root.ids.notebook_images
            new_image = MyImage()
            box.add_widget(new_image)
            self.scroll_y = new_image.height / box.height  # a more careful calculation may provide smoother operation


class NotebookScreen(GridLayout):
    def __init__(self, **kwargs):
        self.rows = 1
        super(NotebookScreen, self).__init__(**kwargs)


class MainApp(App):

    def build(self):
        return NotebookScreen()


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

使用 Builder.load_string() 而不是 load_file() 只是为了我自己的方便。