Python tkinter nach

Question

Ich benutze tinter.after() für die Aktualisierung der Anzeige einer analogen Uhr auf einem Raspberry Pi alle 200ms. Am Anfang ist es in Ordnung, aber allmählich dauert die Zeit zwischen jedem Auffrischen etwa 2-3 Sekunden. Gibt es eine Lösung, um das Aktualisierungsintervall auf 200ms zu halten?

#!/usr/bin/env python 
# coding: UTF-8 
# license: GPL 
# 
## @package _08c_clock 
# 
# A very simple analog clock. 
# 
# The program transforms worldcoordinates into screencoordinates 
# and vice versa according to an algorithm found in: 
# "Programming principles in computer graphics" by Leendert Ammeraal. 
# 
# Based on the code of Anton Vredegoor (anton.vredegoor@gmail.com) 
# 
# @author Paulo Roma 
# @since 01/05/2014 
# @see https://code.activestate.com/recipes/578875-analog-clock 
# @see http://orion.lcg.ufrj.br/python/figuras/fluminense.png 

import sys, types, os 
from time import localtime 
from datetime import timedelta,datetime 
from math import sin, cos, pi 
from threading import Thread 
try: 
    from tkinter import *  # python 3 
except ImportError: 
    try: 
     from mtTkinter import * # for thread safe 
    except ImportError: 
     from Tkinter import * # python 2 

hasPIL = True 
# we need PIL for resizing the background image 
# in Fedora do: yum install python-pillow-tk 
# or yum install python3-pillow-tk 
try: 
    from PIL import Image, ImageTk 
except ImportError: 
    hasPIL = False 

## Class for handling the mapping from window coordinates 
# to viewport coordinates. 
# 
class mapper: 
    ## Constructor. 
    # 
    # @param world window rectangle. 
    # @param viewport screen rectangle. 
    # 
    def __init__(self, world, viewport): 
     self.world = world 
     self.viewport = viewport 
     x_min, y_min, x_max, y_max = self.world 
     X_min, Y_min, X_max, Y_max = self.viewport 
     f_x = float(X_max-X_min)/float(x_max-x_min) 
     f_y = float(Y_max-Y_min)/float(y_max-y_min) 
     self.f = min(f_x,f_y) 
     x_c = 0.5 * (x_min + x_max) 
     y_c = 0.5 * (y_min + y_max) 
     X_c = 0.5 * (X_min + X_max) 
     Y_c = 0.5 * (Y_min + Y_max) 
     self.c_1 = X_c - self.f * x_c 
     self.c_2 = Y_c - self.f * y_c 

    ## Maps a single point from world coordinates to viewport (screen) coordinates. 
    # 
    # @param x, y given point. 
    # @return a new point in screen coordinates. 
    # 
    def __windowToViewport(self, x, y): 
     X = self.f * x + self.c_1 
     Y = self.f * -y + self.c_2  # Y axis is upside down 
     return X , Y 

    ## Maps two points from world coordinates to viewport (screen) coordinates. 
    # 
    # @param x1, y1 first point. 
    # @param x2, y2 second point. 
    # @return two new points in screen coordinates. 
    # 
    def windowToViewport(self,x1,y1,x2,y2): 
     return self.__windowToViewport(x1,y1),self.__windowToViewport(x2,y2) 

## Class for creating a new thread. 
# 
class makeThread (Thread): 
     """Creates a thread.""" 

     ## Constructor. 
     # @param func function to run on this thread. 
     # 
     def __init__ (self,func): 
      Thread.__init__(self) 
      self.__action = func 
      self.debug = False 

     ## Destructor. 
     # 
     def __del__ (self): 
      if (self.debug): print ("Thread end") 

     ## Starts this thread. 
     # 
     def run (self): 
      if (self.debug): print ("Thread begin") 
      self.__action() 

## Class for drawing a simple analog clock. 
# The backgroung image may be changed by pressing key 'i'. 
# The image path is hardcoded. It should be available in directory 'images'. 
# 
class clock: 
    ## Constructor. 
    # 
    # @param deltahours time zone. 
    # @param sImage whether to use a background image. 
    # @param w canvas width. 
    # @param h canvas height. 
    # @param useThread whether to use a separate thread for running the clock. 
    # 
    def __init__(self,root,deltahours = 0,sImage = True,w = 400,h = 400,useThread = False): 
     self.world  = [-1,-1,1,1] 
     self.imgPath  = './images/fluminense.png' # image path 
     if hasPIL and os.path.exists (self.imgPath): 
      self.showImage = sImage 
     else: 
      self.showImage = False 

     self.setColors() 
     self.circlesize = 0.09 
     self._ALL  = 'handles' 
     self.root  = root 
     width, height = w, h 
     self.pad   = width/16 

     if self.showImage: 
      self.fluImg = Image.open(self.imgPath) 

     self.root.bind("<Escape>", lambda _ : root.destroy()) 
     self.delta = timedelta(hours = deltahours) 
     self.canvas = Canvas(root, width = width, height = height, background = self.bgcolor) 
     viewport = (self.pad,self.pad,width-self.pad,height-self.pad) 
     self.T = mapper(self.world,viewport) 
     self.root.title('Clock') 
     self.canvas.bind("<Configure>",self.resize) 
     self.root.bind("<KeyPress-i>", self.toggleImage) 
     self.canvas.pack(fill=BOTH, expand=YES) 

     if useThread: 
      st=makeThread(self.poll) 
      st.debug = True 
      st.start() 
     else: 
      self.poll() 

    ## Called when the window changes, by means of a user input. 
    # 
    def resize(self,event): 
     sc = self.canvas 
     sc.delete(ALL)   # erase the whole canvas 
     width = sc.winfo_width() 
     height = sc.winfo_height() 

     imgSize = min(width, height) 
     self.pad = imgSize/16 
     viewport = (self.pad,self.pad,width-self.pad,height-self.pad) 
     self.T = mapper(self.world,viewport) 

     if self.showImage: 
      flu = self.fluImg.resize((int(0.8*0.8*imgSize), int(0.8*imgSize)), Image.ANTIALIAS) 
      self.flu = ImageTk.PhotoImage(flu) 
      sc.create_image(width/2,height/2,image=self.flu) 
     else: 
      self.canvas.create_rectangle([[0,0],[width,height]], fill = self.bgcolor) 

     self.redraw()    # redraw the clock  

    ## Sets the clock colors. 
    # 
    def setColors(self): 
     if self.showImage: 
      self.bgcolor  = 'antique white' 
      self.timecolor = 'dark orange' 
      self.circlecolor = 'dark green' 
     else: 
      self.bgcolor  = '#000000' 
      self.timecolor = '#ffffff' 
      self.circlecolor = '#808080' 

    ## Toggles the displaying of a background image. 
    # 
    def toggleImage(self,event): 
     if hasPIL and os.path.exists (self.imgPath): 
      self.showImage = not self.showImage 
      self.setColors() 
      self.resize(event) 

    ## Redraws the whole clock. 
    # 
    def redraw(self): 
     start = pi/2    # 12h is at pi/2 
     step = pi/6 
     for i in range(12):  # draw the minute ticks as circles 
      angle = start-i*step 
      x, y = cos(angle),sin(angle) 
      self.paintcircle(x,y) 
     self.painthms()   # draw the handles 
     if not self.showImage: 
      self.paintcircle(0,0) # draw a circle at the centre of the clock 

    ## Draws the handles. 
    # 
    def painthms(self): 
     self.canvas.delete(self._ALL) # delete the handles 
     T = datetime.timetuple(datetime.utcnow()-self.delta) 
     x,x,x,h,m,s,x,x,x = T 
     self.root.title('%02i:%02i:%02i' %(h,m,s)) 
     angle = pi/2 - pi/6 * (h + m/60.0) 
     x, y = cos(angle)*0.70,sin(angle)*0.70 
     scl = self.canvas.create_line 
     # draw the hour handle 
     scl(self.T.windowToViewport(0,0,x,y), fill = self.timecolor, tag=self._ALL, width = self.pad/3) 
     angle = pi/2 - pi/30 * (m + s/60.0) 
     x, y = cos(angle)*0.90,sin(angle)*0.90 
     # draw the minute handle 
     scl(self.T.windowToViewport(0,0,x,y), fill = self.timecolor, tag=self._ALL, width = self.pad/5) 
     angle = pi/2 - pi/30 * s 
     x, y = cos(angle)*0.95,sin(angle)*0.95 
     # draw the second handle 
     scl(self.T.windowToViewport(0,0,x,y), fill = self.timecolor, tag=self._ALL, arrow = 'last') 

    ## Draws a circle at a given point. 
    # 
    # @param x,y given point. 
    # 
    def paintcircle(self,x,y): 
     ss = self.circlesize/2.0 
     sco = self.canvas.create_oval 
     sco(self.T.windowToViewport(-ss+x,-ss+y,ss+x,ss+y), fill = self.circlecolor) 

    ## Animates the clock, by redrawing everything after a certain time interval. 
    # 
    def poll(self): 
     self.redraw() 
     self.root.after(200,self.poll) 

## Main program for testing. 
# 
# @param argv time zone, image background flag, 
#   clock width, clock height, create thread flag. 
# 
def main(argv=None): 
    if argv is None: 
     argv = sys.argv 
    if len(argv) > 2: 
     try: 
      deltahours = int(argv[1]) 
      sImage = (argv[2] == 'True') 
      w = int(argv[3]) 
      h = int(argv[4]) 
      t = (argv[5] == 'True') 
     except ValueError: 
      print ("A timezone is expected.") 
      return 1 
    else: 
     deltahours = 3 
     sImage = True 
     w = h = 400 
     t = False 

    root = Tk() 
    root.geometry ('+0+0') 
    # deltahours: how far are you from utc? 
    # Sometimes the clock may be run from another timezone ... 
    clock(root,deltahours,sImage,w,h,t) 

    root.mainloop() 

if __name__=='__main__': 
    sys.exit(main()) 

Answer 1

Nein, gibt es nicht. Tkinter garantiert nur, dass das Ereignis irgendwann nach die Verzögerung ausgelöst wird. Normalerweise beträgt der Unterschied nur eine oder zwei Millisekunden, aber es kann länger sein.

Das heißt, wenn Sie das neue Ereignis vor jeder Arbeit auslösen, werden Sie wahrscheinlich weniger Drift Zeuge als wenn Sie es nach der Arbeit tun.

Betrachten wir zum Beispiel diesen Code:

def callback(self): 
    <do some work> 
    self.after(200, self.callback) 

Dies wird durch driften, was auch immer viel Zeit es braucht, um „einige Arbeit zu tun“. Wenn diese Arbeit 100 ms dauert, wird der nächste Anruf erst 300 ms nach dem aktuellen Anruf ausgeführt.

Wenn Sie so wenig Drift wollen wie möglich Sie den neuen Rückruf sofort planen können, vor jedem anderen Code:

def callback(self): 
    self.after(200, self.callback) 
    <do some work> 

Wenn Sie etwas alle 200 ms tun wollen, die zweite Methode wählen. Wenn Sie nach dem ersten Rückruf 200 Sekunden warten möchten, verwenden Sie die erste Methode.