本文介紹了為什么我無法訪問 Screen.ids?的處理方法，對(duì)大家解決問題具有一定的參考價(jià)值，需要的朋友們下面隨著小編來一起學(xué)習(xí)吧！
問題描述
更新:
Ryan P 的回答提供了解決方案.但是，我采用了該解決方案并對(duì)其進(jìn)行了一些更改，丟棄了所有不存在的數(shù)據(jù)正確初始化為 RootWidget 的 on_enter 方法屏幕.這效果很好.
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 類都是 Widget 的子類，我可以毫無問題地訪問它的 id 來獲取grid"的值.然而，我只是改變了它是Screen的子類，現(xiàn)在它說由于某種原因ID是空的……Screen確實(shí)有一個(gè)ID和所有這些，但由于某種原因，它沒有注冊(cè)那個(gè)我在 kv 文件中為 id ''grid'' 分配了一個(gè) GridLayout.誰能告訴我為什么?
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 22 2014, 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, in apply
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'
kv 文件:
#:kivy 1.8.0
<RootWidget>:
GridLayout:
id: grid
size: root.size
cols: root.sides
<Blank>:
background_color: 1, 1, 1, 1
background_disabled_down: "kivy_white_bg.png"
on_press: self.parent.parent.sweep(self)
<Mine>:
background_color: 1, 1, 1, 1
background_disabled_down: "kivy_white_bg.png"
on_press: self.parent.parent.sweep(self)
<TryAgain>:
anchor_x: 'center'
anchor_y: 'center'
BoxLayout:
size: root.size
orientation: 'vertical'
padding_bottom: '20dp'
Label:
font_size: '20dp'
text: root.text
BoxLayout:
size_hint: 1, .3
spacing: 10
padding: 10
Button:
size_hint: .4, 1
font_size: '20dp'
text: "yes"
on_press: app.stop(); app.run()
Button:
size_hint: .4, 1
font_size: '20dp'
text: "no"
on_press: root.quit()
<Menu>:
GridLayout:
rows: 2
Button:
text: "8x8"
on_press: root.manager.current = 'game_screen'
Button:
text: "16x16"
on_press: root.manager.current = 'game_screen'
Button:
text: "30x16"
on_press: root.manager.current = 'game_screen'
Button:
text: "custom"
on_press: root.manager.current = 'game_screen'
<Manager>:
id: _manager
menu: menu
game: game
current: menu_screen
Menu:
id: menu
manager: _manager
name: 'menu_screen'
RootWidget:
id: game
manager: _manager
name: 'game_screen'
ma??in.py:
#!/usr/bin/env python
from 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
class Blank(Button):
index = ListProperty([0, 0])
count = NumericProperty(0)
def __init__(self, **kwargs):
super(Blank, self).__init__(**kwargs)
class Mine(Button):
index = ListProperty([0, 0])
count = NumericProperty(0) # not really necessary
def __init__(self, **kwargs):
super(Mine, self).__init__(**kwargs)
class RootWidget(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, 0
for i in xrange(self.sides**2):
if x == self.sides - 1:
x = 0
y += 1
else:
x += 1
if i not in 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 if isinstance(c, Mine)]
self.blanks = [c.index for c in self.grid.children if isinstance(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 += 1
def field(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]
def sweep(self, instance):
instance.disabled = True
if instance.index in self.mines:
print "Boom!" # It's a mine! You lose
instance.text = "Boom!"
self.game_over()
pressed = sum(1 for 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 = True
return
else:
x, y = instance.index
for index in self.field(x, y):
if index not in self.mines:
blank = self.get_child_by_index(index)
blank.disable = True
if blank.count > 0:
blank.text = str(blank.count)
self.sweep(blank)
def is_safe(self, btn):
x, y = btn.index
for index in self.field(x, y):
if index in self.mines:
return False
return True
def get_child_by_index(self, index):
for child in self.grid.children:
if child.index == index:
return child
def game_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()
class TryAgain(ModalView):
text = StringProperty('')
def quit(self):
sys.exit()
class Menu(Screen):
pass
class Manager(ScreenManager):
menu = ObjectProperty(None)
game = ObjectProperty(None)
class MineSweeperApp(App):
def build(self):
return Manager()
if __name__ == "__main__":
MineSweeperApp().run()
推薦答案
在原始 Widget 完成實(shí)例化之前，不會(huì)應(yīng)用 kv 規(guī)則.在這種情況下，您的 Manager 小部件是初始小部件 - 它反過來創(chuàng)建其他小部件，包括 RootWidget.這意味著您的 RootWidget.__init__ 中的 ids 尚未填充！它們將在 Manager 完成實(shí)例化后立即出現(xiàn) - 所以最好的方法是延遲其余的初始化，如下所示:
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:
class RootWidget(Screen):
def __init__(self, **kwargs):
super(RootWidget, self).__init__(**kwargs)
Clock.schedule_once(self._finish_init)
def _finish_init(self, dt):
self.grid = self.ids.grid
# etc
這篇關(guān)于為什么我無法訪問 Screen.ids?的文章就介紹到這了，希望我們推薦的答案對(duì)大家有所幫助，也希望大家多多支持html5模板網(wǎng)！
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