屏幕尺寸更改后的奇异图像更新

Question

So my problem is this. I have a background image that works great, when i rescale the window everything works out and the image moves like designed but in my login class my 'check-icon.png' does not show up at all. The log says it was loaded but it is not on the window anywhere. Also by changing the login class statement to say:

with self.canvas.before:
    self.image = Image(stuff)

instead of

with root.canvas.before:
    self.image = Image(stuff)

(root changed to self) I can get the check-icon.png to appear but it still does not realign when the window size changes like the background image does at the bottom.

import kivy
kivy.require('1.8.0') # current kivy version
import ConfigParser
from kivy.app import App
from kivy.uix.widget import Widget
from kivy.uix.label import Label
from kivy.uix.textinput import TextInput
from kivy.uix.image import Image
from kivy.graphics import Rectangle


class login(Widget):
    #checking to see if the user logging in has privilage to access program
    def validate(self, *args):

        username = self.ids['user']
        user = username.text
        config = ConfigParser.ConfigParser()
        config.read('Privilage.cfg')

        if not config.has_section('users'):
            print 'the Privilage.cfg file has been tampered with'

        if not config.has_option('users',user):
            print 'user is not listed'
        else:
            userPriv = config.get('users',user)
            print 'user',user,'has privilage',userPriv
            valid = '/Users/Kevin/Desktop/Python-extras/SSS Assistant/Manager_images/check-icon.png'

        #Put a check or x next to username based on if its in the system
        self.root = root = login()
        root.bind(size=self._update_image,pos=self._update_image)
        with root.canvas.before:
            self.image = Image(source=valid, pos=((self.width / 2)+130,(self.top / 2)), size=(25,25))


    def _update_image(self,instance,value):
        self.image.pos = instance.pos
        self.image.size = instance.size

class DataApp(App):
    def build(self):
        #login is the root Widget here
        self.root = root = login()
        root.bind(size=self._update_rect,pos=self._update_rect)
        with root.canvas.before:
            self.rect = Rectangle(source="/Users/Kevin/Desktop/Python-extras/SSS Assistant/Manager_images/background.jpg",size=root.size,pos=root.pos)
        return root

    def _update_rect(self,instance,value):
        self.rect.pos = instance.pos
        self.rect.size = instance.size



if __name__ == '__main__':
    DataApp().run()

Also, sorry I posted this super long thing. I know I should only post the really relevant code but since I'm new at this I wanted to be sure the mistake isn't somewhere else in the code.

the new code is this:

    self.bind(size=self._update_image,pos=self._update_image)
    #Put a check or x next to username based on if its in the system
    self.image = self.add_widget(Image(source=valid, pos=((self.width / 2)+115,(self.top / 2)+50), size=(20,20)))



def _update_image(self,instance,value):
    self.image.pos = instance.pos
    self.image.size = instance.size

Answer 1

You've bound your size update function to self.root, but this is an instance of login that isn't ever added to the widget tree and never does anything - in particular, it never changes size and so the update never happens.

You should bind simply to self instead, self.bind(pos=...) .

Also, you should make your widgets names starting with capital letters, both because it's a good python convention worth following and because kv language relies on this to distinguish widgets from properties...and you'll probably want to use kv language as much as possible!