Ryan P 的回答提供了解决方案.但是，我采用了该解决方案并对其进行了一些更改，丢弃了所有不存在的数据正确初始化为 RootWidget 的 on_enter 方法屏幕.这效果很好.
Ryan P's answer provided the solution. However, I took that solution
and changed it up a bit, throwing all of the data that wasn't being
properly initialised into the on_enter method of the RootWidget
Screen. This has worked nicely.
直到今天，我的 RootWidget 类都是 Widget 的子类，我可以毫无问题地访问它的 id 来获取grid"的值.然而，我只是改变了它是Screen的子类，现在它说由于某种原因ID是空的……Screen确实有一个ID和所有这些，但由于某种原因，它没有注册那个我在 kv 文件中为 id ''grid'' 分配了一个 GridLayout.谁能告诉我为什么?
My RootWidget class was subclassing Widget until today, and I had no problem accessing it's ids to get the value of "grid". However, I just changed
it to subclass Screen, and now it says the ids is empty for some reason... Screen does have an ids and all that, but for some reason, it isn't registering that
I assigned a GridLayout to the id ''grid'' in the kv file. Can anyone tell me why?
回溯:
[INFO ][Logger ] Record log in/home/yerman/.kivy/logs/kivy_14-11-13_201.txt
[INFO ] Kivy v1.9.0-dev
[INFO ][Python ] v2.7.6(default, Mar 222014,22:59:56)[GCC 4.8.2][INFO ][Factory ]172 symbols loaded
[INFO ][Image ] Providers: img_tex, img_dds, img_pygame, img_pil, img_gif (img_sdl2, img_ffpyplayer ignored)[INFO ][Window ] Provider: pygame(['window_egl_rpi'] ignored)[WARNING][WinPygame ] Video: failed (multisamples=2)[WARNING][WinPygame ] trying without antialiasing
[INFO ][GL ] OpenGL version <2.1 Mesa 10.1.3>[INFO ][GL ] OpenGL vendor <Intel Open Source Technology Center>[INFO ][GL ] OpenGL renderer <Mesa DRI Intel(R) Ironlake Mobile >[INFO ][GL ] OpenGL parsed version:2,1[INFO ][GL ] Shading version <1.20>[INFO ][GL ] Texture max size <8192>[INFO ][GL ] Texture max units <16>[INFO ][Window ] virtual keyboard not allowed, single mode,not docked
[INFO ][Text ] Provider: pygame(['text_sdl2'] ignored){}#<<< note the emtpy ids I printed out
Traceback (most recent call last):
File "main.py", line 169,in<module>
MineSweeperApp().run()
File "/usr/lib/python2.7/dist-packages/kivy/app.py", line 799,in run
root = self.build()
File "main.py", line 163,in build
return Manager()
File "/usr/lib/python2.7/dist-packages/kivy/uix/screenmanager.py", line 844,in __init__
super(ScreenManager, self).__init__(**kwargs)
File "/usr/lib/python2.7/dist-packages/kivy/uix/floatlayout.py", line 66,in __init__
super(FloatLayout, self).__init__(**kwargs)
File "/usr/lib/python2.7/dist-packages/kivy/uix/layout.py", line 66,in __init__
super(Layout, self).__init__(**kwargs)
File "/usr/lib/python2.7/dist-packages/kivy/uix/widget.py", line 269,in __init__
Builder.apply(self)
File "/usr/lib/python2.7/dist-packages/kivy/lang.py", line 1837,inapply
self._apply_rule(widget, rule, rule)
File "/usr/lib/python2.7/dist-packages/kivy/lang.py", line 1942,in _apply_rule
child = cls(__no_builder=True)
File "main.py", line 43,in __init__
self.grid = self.ids["grid"]
KeyError:'grid'
#!/usr/bin/env pythonfrom random import sample
import sys
import kivy
kivy.require('1.8.0')from kivy.app import App
from kivy.core.window import Window
from kivy.uix.widget import Widget
from kivy.uix.button import Button
from kivy.properties import NumericProperty, ListProperty, StringProperty, ObjectProperty
from kivy.uix.gridlayout import GridLayout
from kivy.uix.modalview import ModalView
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.clock import Clock
classBlank(Button):
index = ListProperty([0,0])
count = NumericProperty(0)def__init__(self,**kwargs):super(Blank, self).__init__(**kwargs)classMine(Button):
index = ListProperty([0,0])
count = NumericProperty(0)# not really necessarydef__init__(self,**kwargs):super(Mine, self).__init__(**kwargs)classRootWidget(Screen):
sides = NumericProperty(10)
mine_count = NumericProperty(20)def__init__(self,**kwargs):super(RootWidget, self).__init__(**kwargs)
self.grid = self.ids["grid"]# generate random mine indices
mines = sample(xrange(self.sides**2), self.mine_count)
x, y =-1,0for i inxrange(self.sides**2):if x == self.sides -1:
x =0
y +=1else:
x +=1if i notin mines:
b = Blank(index=[x, y])else:
b = Mine(index=[x, y])
self.grid.add_widget(b)# record mine, blank and safe blank indices
self.all_btns =[c.index for c in self.grid.children]
self.mines =[c.index for c in self.grid.children ifisinstance(c, Mine)]
self.blanks =[c.index for c in self.grid.children ifisinstance(c, Blank)]# a safe blank has no adjacent mines
self.safe_blanks =[c.index for c in self.grid.children if self.is_safe(c)]# give each btn an 'adjacent mines count'for x, y in self.all_btns:
btn = self.get_child_by_index([x, y])for index in self.field(x, y):if index in self.mines:
btn.count +=1deffield(self, x, y):""" the minefield surrounding a btn """
field =[[x-1, y],[x+1, y],[x, y+1],[x, y-1],[x+1, y+1],[x-1, y-1],[x+1, y-1],[x-1, y+1]]
get = self.get_child_by_index
return[i for i in field if i in self.all_btns and get(i).disabled ==False]defsweep(self, instance):
instance.disabled =Trueif instance.index in self.mines:print"Boom!"# It's a mine! You lose
instance.text ="Boom!"
self.game_over()
pressed =sum(1for c in self.grid.children if c.disabled ==True)print pressed
if self.sides**2- pressed == self.mine_count:
self.game_over(win=True)if instance.count >0:
instance.text =str(instance.count)
instance.disabled =Truereturnelse:
x, y = instance.index
for index in self.field(x, y):if index notin self.mines:
blank = self.get_child_by_index(index)
blank.disable =Trueif blank.count >0:
blank.text =str(blank.count)
self.sweep(blank)defis_safe(self, btn):
x, y = btn.index
for index in self.field(x, y):if index in self.mines:returnFalsereturnTruedefget_child_by_index(self, index):for child in self.grid.children:if child.index == index:return child
defgame_over(self, q=False, win=False):if q ==True:
sys.exit()if win ==True:
result ="Win"elif win ==False:
result ="lost"
view = TryAgain(
size_hint =(None,None),
width = self.width/2,
height = self.height/2,
center = self.center,
text ="You {}! Try Again?".format(result))
view.open()classTryAgain(ModalView):
text = StringProperty('')defquit(self):
sys.exit()classMenu(Screen):passclassManager(ScreenManager):
menu = ObjectProperty(None)
game = ObjectProperty(None)classMineSweeperApp(App):defbuild(self):return Manager()if __name__ =="__main__":
MineSweeperApp().run()
kv rules are not applied until the original Widget has finished instantiating. In this case, your Manager widget is the initial widget - it, in turn, creates the other widgets including RootWidget. This means that in your RootWidget.__init__ the ids are not yet populated! They will be as soon as Manager finishes instantiating - so the best approach is to just delay the rest of your initialization, like so:
