Kivy Scrollview 自动滚动到新文本和行消失

Posted 2023-04-01

【中文标题】Kivy Scrollview 自动滚动到新文本和行消失

【英文标题】：Kivy Scrollview autoscroll to new text and lines disappear

【发布时间】：2021-09-04 00:39:15

【问题描述】：

我有一个 Kivy 滚动视图，想通过单击按钮添加一些文本。每次单击后，滚动视图应自动滚动到最新的文本行。但由于某种原因，它只能每秒钟一次，并且只有一行。当有多行时（参见示例），一些行会消失在滚动视图的边缘后面。文本在跳到顶部和跳到底部边缘之间切换。当文本位于底部并且您手动滚动（或只需单击滚动视图字段）时，文本会跳到顶部。我希望能够手动滚动，但是如果不单击“添加文本”，文本不应该跳转。但是，当单击“添加文本”时，它应该按照描述滚动到新的底部文本行。

import kivy
from kivy.config import Config
from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.gridlayout import GridLayout
from kivy.uix.button import Button
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.core.window import Window
from kivy.uix.scrollview import ScrollView
from kivy.clock import mainthread
import threading

kivy.require("2.0.0")
Config.set('kivy', 'keyboard_mode', 'systemandmulti')

class MainMenu(GridLayout):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.cols = 1
        self.rows = 3
        
        self.infowindow = ScrollableInfo(height=Window.size[1]*0.8, size_hint_y=None)
        self.add_widget(self.infowindow)

        self.addtextbutton = Button(text="Add Text")
        self.addtextbutton.bind(on_press=self.add_text_thread)
        self.add_widget(self.addtextbutton)

    def addtext(self, *_):
        self.infowindow.update_scrollview(f"This is some new Text \n and even more \n and more")
     

    def add_text_thread(self, *args):
        threading.Thread(target=self.addtext, daemon=True).start()



class ScrollableInfo(ScrollView):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.layout = GridLayout(cols=1, size_hint=(1, None))
        self.add_widget(self.layout)

        self.text_history = Label(size_hint_y=None, markup=True)
        self.scrolllabel = Label()

        self.layout.add_widget(self.text_history)
        self.layout.add_widget(self.scrolllabel)

    @mainthread
    def update_scrollview(self, newinfo):
        self.text_history.text += '\n' + newinfo
        
        self.layout.height = self.text_history.texture_size[1]+15
        self.text_history.height = self.text_history.texture_size[1]
        self.text_history.text_size = (self.text_history.width*0.98, None)

        self.scroll_y = 0

class Textadding(App):
    def build(self):
        self.screen_manager = ScreenManager()

        self.mainmenu_page = MainMenu()
        screen = Screen(name="MainMenu")
        screen.add_widget(self.mainmenu_page)
        self.screen_manager.add_widget(screen)

        return self.screen_manager

if __name__ == "__main__":
    counting_app = Textadding()
    counting_app.run()

提前谢谢你！

【参考方案1】：

您可以通过使用更多绑定来做到这一点。首先，将GridLayout 的高度绑定到它自己计算的minimum_size。然后将其size绑定到调整scroll_y属性的方法：

    self.layout = GridLayout(cols=1, size_hint=(1, None))
    self.layout.bind(minimum_height=self.layout.setter('height'))
    self.layout.bind(size=self.on_size)

和ScrollableInfo的on_size()方法：

def on_size(self, *args):
    self.scroll_y = 0

现在，您不必在 update_scrollview() 方法中进行大小计算，所以它变成了：

@mainthread
def update_scrollview(self, newinfo):
    self.text_history.text += '\n' + newinfo