Kivy：如何将画布放置在特定布局中

Question

我正在尝试将图像放置在每秒自动更新的画布上。画布有一个特定的图像来源，每当图像文件被替换时，我都会更新它并在 GUI 上重新加载。无需用户输入，也无需退出 GUI。

我能够让图像重新加载，但现在我无法将图像放置在我想要的位置。我希望能够把它放在一个布局中，最好位于屏幕的右上角

我的以下主要python文件如下

import kivy
import os

kivy.require('1.10.0')

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.image import Image
from kivy.properties import StringProperty
from kivy.clock import Clock
from kivy.uix.anchorlayout import AnchorLayout
from kivy.uix.widget import Widget
from kivy.graphics.instructions import InstructionGroup
from sshtest import ssh #import the ssh class from the ssh python file


class ScreenOne(Screen):
    def login(self): #define login using ssh as a function

        #Make a Class Variable called connection. This allows for other
        #classes to call on it without passing it as an argument

        ScreenOne.connection = ssh("192.168.1.3", "pi", "seniordesign")
                #ScreenOne.connection.sendCommand("ls")
        #ScreenOne.connection.sendCommand("mkdir thisistest")
        print("Logging in") #For error checking

    def gpioSet(self): #allows for gpio pins to trigger image capture
        ScreenOne.connection.sendCommand("echo '18' > /sys/class/gpio/export")
        ScreenOne.connection.sendCommand("echo 'out' > /sys/class/gpio/gpio18/direction")

class ScreenTwo(Screen): #This is where all the functions are

    def command(self, input): #create a function that sends command through ssh
        ScreenOne.connection.sendCommand(input) #Call on connection made before to send command




class MyScreenManager(ScreenManager):
    pass

class MyPicture(Widget):

    def __init__(self,**kwargs):
        super(MyPicture,self).__init__(**kwargs)
        with self.canvas:
            MyPicture.picture = Image(source = 'C:/Users/Jason/Desktop/RaspberryPiTransferred/TEST.jpg',
                                      size_hint=(.3,.3))


            #self.add_widget(Image(MyPicture.picture))

    def update(self):
        MyPicture.picture.reload()

    Clock.schedule_interval(update,1)



#Create the Application that will change screens. Add App(App) to end of wanted classname
class ScreenChangeApp(App):

#Create a function that builds the app. Keyword self make sures to reference
#current instantiation

    def build(self):
        screen_manager = ScreenManager()

        screen_manager.add_widget(ScreenOne(name = "screen_one")) 
        screen_manager.add_widget(ScreenTwo(name = "screen_two"))

        return screen_manager #after building the screens, return them
#MyScreenManager.login()

sample_app = ScreenChangeApp()
sample_app.run()

我的 KV 文件如下所示

#: import os os
<CustomButton@Button>:
    font_size: 12
    size_hint: .2,.1

<Picture@Image>:
    id: image

<ScreenOne>: #define The First Screen
    BoxLayout: #Use box layout
        Button: #create button
            text: "Connect to the Raspberry Pi"
            on_press:
                root.login()
                root.gpioSet()
                root.manager.transition.direction= "left"
                root.manager.transition.duration = 1
                root.manager.current = "screen_two"

<ScreenTwo>:
    BoxLayout:
        spacing: 10
        padding: 10
        orientation: "vertical"
        CustomButton:
            text: "Send an ls command"
            on_press:
                root.command("ls")

        CustomButton:
            text: "Take picture"
            on_press:
                root.command("python cameradaemon.py &") #'&' runs script in background
                root.command("sleep .1")
                root.command("echo '1' > /sys/class/gpio/gpio18/value") #set pin high to take pic
                root.command("echo '0' > /sys/class/gpio/gpio18/value") #take it off to prevent another photo 

                root.command("scp TEST.jpg Jason@192.168.1.10:C:/Users/Jason/Desktop/RaspberryPiTransferred")          
                root.command("kill %1")



        CustomButton:
            text: "Create Histogram"
            on_press:
                os.system("cd C:/Users/Jason/Desktop/KivyFiles/Histogram & python histogram.py")


    MyPicture

我得到的是以下 GUI 屏幕GUI Screen。

图像显示在屏幕的左下方。

当我按下“拍照按钮”时，它会更新，如截图所示Image after pic is taken

但是我无法像我想要的那样控制展示位置。

最初我用不同的代码将图像显示在屏幕的右上角，但我无法动态更新图像Older GUI placement 我之前的代码将该图像设置为锚布局，但它是静态的。现在我正在使用画布，它会使用我当前的代码进行更新，但我不能像以前那样放置它。

我设置“size_hint”的部分没有做任何事情，我只是在猜测和检查这一点。

有没有更简单的方法可以在 KV 类中调用该 Picture 类，以便在特定布局中设置图像？例如

AnchorLayout:
    anchor_x: 'right'
    anchor_y: 'left'
    BoxLayout:
        spacing: 10
        padding: 10
        Image:
            <Dynamic image goes here>

我在哪里而不是“动态图像到这里”

source: <location of image>

Answer 1

您可以使用另一个具有水平（默认）方向的 BoxLayout：

<ScreenTwo>:
    BoxLayout:
        BoxLayout:
            size_hint_x: .5
            spacing: 10
            padding: 10
            orientation: "vertical"

            ...

        AnchorLayout:
            anchor_x: 'right'
            anchor_y:'top'
            MyPicture:
                size_hint_y: .5

有了代码我得到了输出：

但老实说，我更喜欢使用浮动布局并自己修复位置和大小

类似这样的浮动布局：

<ScreenTwo>:
    BoxLayout:
        BoxLayout:
            size_hint_x: .5
            spacing: 10
            padding: 10
            orientation: "vertical"

            ...

        FloatLayout:
            size_hint_x: .5
            MyPicture:
                pos_hint: {'center_x': .5, 'y': .5} #edit this like you want