[Tutor] Continuously slower program

[Michael P. Reilly]

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On Wed, Jun 12, 2002 at 01:32:09PM -0500, SA wrote:
> On 6/12/02 11:49 AM, "Michael P. Reilly" <arcege@speakeasy.net> wrote:
> 
> > On Tue, Jun 11, 2002 at 04:57:28PM -0700, Seiji Funai wrote:
> >> This is a test for the beginning of a meter that I'm
> >> writing for a GUI.  The application slows
> >> continuously.  Does my computer just suck, or is there
> >> something I can do?  Please let me know.
> > 
> > Your problem is that you continually create new canvas objects inside the
> > while loop.  You should be creating the objects once, and changing them
> > as needed.  That was increasing the processing of the Canvas object,
> > increasing the memory of it, and sucking up CPU time.
> > 
> I get the following error when I run the revamped script:
>  File "./TestMeter2.py", line 35
>     self.testMeterCanvas.coords(self.c, 33, 33, self.x, self.y)
>     ^
> SyntaxError: invalid syntax
> 
> What did I do wrong?

I'm not sure... the line looks correct.  Is the indentation correct?
The error suggests that it is not indented with the rest of the block.
(Don't align the line with the commented line, but with the other lines.)

I'm enclosing the changes that I had made; maybe it can help you.

  -Arcege


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from Tkinter import *
import math

class TestMeter:
  def __init__(self, master):
    testMeterFrame = Frame(master)
    testMeterFrame.pack()
    self.count = 0
    self.box = 8, 8, 57, 57
    self.testMeterCanvas = Canvas(testMeterFrame, bg = "gray", width = 65, height = 65)
    self.testMeterCanvas.grid(row = 1, column = 1)
    self.testMeterCanvas.create_oval(2, 2, 63, 63, fill = "black")
    self.testMeterCanvas.create_oval(5, 5, 60, 60, fill = "gray")
    self.testMeterCanvas.create_arc(self.box, start = 0, extent = 180, fill = "white")
    self.testMeterCanvas.create_line(33, 33, 33, 8, fill = "red")
    self.testMeterCanvas.create_text(33, 47, text = "M1")
    self.testMeterCanvas.create_text(10, 38, text = "0")
    self.testMeterCanvas.create_text(55, 38, text = "1")
    self.startButton = Button(testMeterFrame, text = "Start", command = self.start)
    self.startButton.grid(row = 2, column = 1, sticky = W+E+N+S)

  def start(self):
    self.testMeterCanvas.create_arc(self.box, start = 0, extent = 180, fill = "white")

    self.x = 25 * math.sin(self.count) + 33
    self.y = -25 * math.fabs(math.cos(self.count)) + 33
    self.c = self.testMeterCanvas.create_line(33, 33, self.x, self.y, fill="red")
    while 1:
      self.count = self.count + .1
      if self.count == 1000:
        self.count = 0
#     self.testMeterCanvas.create_arc(self.box, start = 0, extent = 180, fill = "white")
      self.x = 25 * math.sin(self.count) + 33
      self.y = -25 * math.fabs(math.cos(self.count)) + 33
#     self.testMeterCanvas.create_line(33, 33, self.x, self.y, fill = "red")      
      self.testMeterCanvas.coords(self.c, 33, 33, self.x, self.y)
      root.update()
    
  def stop(self):
    self.testMeterCanvas.coords(self.c, 33, 33, 33, 8)

root = Tk()
testMeter = TestMeter(root)
root.mainloop()

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