从另一个线程更改 kivy 属性
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【中文标题】从另一个线程更改 kivy 属性【英文标题】：Altering a kivy property from another thread 【发布时间】：2014-03-28 16:24:04 【问题描述】：我正在尝试一些 kivy 代码。我尝试从使用线程库创建的胎面修改 kivy 属性（text_colour）。程序运行正常，但线程没有改变属性。
我还尝试在类中创建一个将值作为参数的方法，但也失败了。
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.properties import ListProperty
import threading
import random
import time
def zaaa():
import time
time.sleep(3)
ScatterTextWidget.text_colour = [0, 0, 1, 1]
print "function ran"
t = threading.Thread(target= zaaa)
t.start()
class ScatterTextWidget(BoxLayout):
text_colour = ListProperty([1, 0, 0, 1])
def change_label_colour(self, *args):
colour = [random.random() for i in xrange(3)] + [1]
self.text_colour = colour
def press(self, *args):
self.text_colour = [1, 1, 1, 1]
class TataApp(App):
def build(self):
return ScatterTextWidget()
if __name__ == "__main__":
TataApp().run()
输出：
[INFO ] Kivy v1.8.0
[INFO ] [Logger ] Record log in /home/mbp/.kivy/logs/kivy_14-02-26_44.txt
[INFO ] [Factory ] 157 symbols loaded
[DEBUG ] [Cache ] register <kv.lang> with limit=None, timeout=Nones
[DEBUG ] [Cache ] register <kv.image> with limit=None, timeout=60s
[DEBUG ] [Cache ] register <kv.atlas> with limit=None, timeout=Nones
[INFO ] [Image ] Providers: img_tex, img_dds, img_pygame, img_pil, img_gif
[DEBUG ] [Cache ] register <kv.texture> with limit=1000, timeout=60s
[DEBUG ] [Cache ] register <kv.shader> with limit=1000, timeout=3600s
[DEBUG ] [App ] Loading kv </home/mbp/workspace/KiviPlay/tata.kv>
[DEBUG ] [Window ] Ignored <egl_rpi> (import error)
[INFO ] [Window ] Provider: pygame(['window_egl_rpi'] ignored)
libpng warning: iCCP: known incorrect sRGB profile
[DEBUG ] [Window ] Display driver x11
[DEBUG ] [Window ] Actual window size: 800x600
[DEBUG ] [Window ] Actual color bits r8 g8 b8 a8
[DEBUG ] [Window ] Actual depth bits: 24
[DEBUG ] [Window ] Actual stencil bits: 8
[DEBUG ] [Window ] Actual multisampling samples: 2
[INFO ] [GL ] OpenGL version <4.3.12618 Compatibility Profile Context 13.251>
[INFO ] [GL ] OpenGL vendor <ATI Technologies Inc.>
[INFO ] [GL ] OpenGL renderer <AMD Radeon HD 7700 Series>
[INFO ] [GL ] OpenGL parsed version: 4, 3
[INFO ] [GL ] Shading version <4.30>
[INFO ] [GL ] Texture max size <16384>
[INFO ] [GL ] Texture max units <32>
[DEBUG ] [Shader ] Fragment compiled successfully
[DEBUG ] [Shader ] Vertex compiled successfully
[DEBUG ] [ImagePygame ] Load </usr/lib/python2.7/site-packages/Kivy-1.8.0-py2.7-linux-x86_64.egg/kivy/data/glsl/default.png>
[INFO ] [Window ] virtual keyboard not allowed, single mode, not docked
[INFO ] [Text ] Provider: pygame
[DEBUG ] [Cache ] register <kv.loader> with limit=500, timeout=60s
[INFO ] [Loader ] using a thread pool of 2 workers
[DEBUG ] [Cache ] register <textinput.label> with limit=None, timeout=60.0s
[DEBUG ] [Cache ] register <textinput.width> with limit=None, timeout=60.0s
[DEBUG ] [Atlas ] Load </usr/lib/python2.7/site-packages/Kivy-1.8.0-py2.7-linux-x86_64.egg/kivy/data/../data/images/defaulttheme.atlas>
[DEBUG ] [Atlas ] Need to load 1 images
[DEBUG ] [Atlas ] Load </usr/lib/python2.7/site-packages/Kivy-1.8.0-py2.7-linux-x86_64.egg/kivy/data/../data/images/defaulttheme-0.png>
[DEBUG ] [ImagePygame ] Load </usr/lib/python2.7/site-packages/Kivy-1.8.0-py2.7-linux-x86_64.egg/kivy/data/../data/images/defaulttheme-0.png>
[INFO ] [GL ] NPOT texture support is available
[INFO ] [OSC ] using <multiprocessing> for socket
[DEBUG ] [Base ] Create provider from mouse
[DEBUG ] [Base ] Create provider from probesysfs
[DEBUG ] [ProbeSysfs ] using probsysfs!
[INFO ] [Base ] Start application main loop
<kivy.properties.ListProperty object at 0x124f870>
function ran
[INFO ] [Base ] Leaving application in progress...
【问题讨论】：
【参考方案1】：您不能从外部线程修改 kivy 属性或执行任何与 OpenGL 相关的工作。
解决方案是安排callbacks 与kivy 的Clock 一起从kivy 的主线程调用一个函数并为您完成工作。
就个人而言，当我使用第二个线程时，我使用队列进行线程间通信，如下所示：
from Queue import Queue
class KivyQueue(Queue):
'''
A Multithread safe class that calls a callback whenever an item is added
to the queue. Instead of having to poll or wait, you could wait to get
notified of additions.
>>> def callabck():
... print('Added')
>>> q = KivyQueue(notify_func=callabck)
>>> q.put('test', 55)
Added
>>> q.get()
('test', 55)
:param notify_func: The function to call when adding to the queue
'''
notify_func = None
def __init__(self, notify_func, **kwargs):
Queue.__init__(self, **kwargs)
self.notify_func = notify_func
def put(self, key, val):
'''
Adds a (key, value) tuple to the queue and calls the callback function.
'''
Queue.put(self, (key, val), False)
self.notify_func()
def get(self):
'''
Returns the next items in the queue, if non-empty, otherwise a
:py:attr:`Queue.Empty` exception is raised.
'''
return Queue.get(self, False)
第二个线程使用 put 将东西放入队列。回调在调用时会使用trigger 安排一个kivy 回调。然后kivy的主线程调用的函数调用队列的get函数并设置相应的属性。
如果您需要设置许多属性，这将很有帮助。如果您只需要设置一个属性，我所做的是从第二个线程中安排一个 callabck，它使用 partial 来使 value 成为函数的一部分。例如：
# this may only be called from the main kivy thread
def set_property(value, *largs):
self.kivy_property = value
# the second thread does this when it wants to set self.kivy_property to 10
Clock.schedule_once(partial(set_property, 10))
【讨论】：
【参考方案2】：它对我有用：
from kivy.app import App
from kivy.uix.label import Label
import threading
import time
class ScatterTextWidget(Label):
def __init__(self,**kwargs):
self.text = 'nima'
self.color = [0, 1, 1, 1]
super(ScatterTextWidget, self).__init__(**kwargs)
a = ScatterTextWidget()
def zaaa():
import time
time.sleep(3)
a.color = [0, 0, 1, 1]
print "function ran"
t = threading.Thread(target= zaaa)
t.start()
class TataApp(App):
def build(self):
return a
if __name__ == "__main__":
TataApp().run()
【讨论】：
这在 kivy 中是不安全的，即使它有时会起作用。 为什么不安全？ 另外，2021 年还是不安全吗？以上是关于从另一个线程更改 kivy 属性的主要内容，如果未能解决你的问题，请参考以下文章
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