Tkinter live graph canvas stops updating until mouse movement

Question

Here's a Python 2.7 question form a n00b:

I am running an App that reads data from a serial port and makes a live graph using a Tkinter-Canvas. I am not using matplotlib, since this lib is not available on the A20 plattform I want to run the program on. (some dependencies of mpl are not at the necessary version yet on the A20)

I know this is not the most elegant way to draw a live graph, but to me it seemed to be the most compatible, since its just relying on Tkinter as lib, which is available on really every plattform. I am basically deleting the canvas and redrawing it with one postion offset every time new data comes in. It flickers a bit, but as I said... i am a n00b. :)

here's my code for drawing the graph:

class TeleGraph(Canvas):
    def __init__(self, master, FrameTitle, Col, Row, Height):
        Canvas.__init__(self, master)
        self.FrameTitle = FrameTitle
        self.Value1 = range(60)
        self.Value2 = range(60)
        self.Value3 = range(60)
        self.configure(height = Height, width = 750, bg = 'grey', bd = 3,relief = GROOVE)
        self.grid()
        self.grid_propagate(0)
        self.Col = Col
        self.Row = Row
        self.place(y = Col, x = Row)

    def NewEntry(self, NewValue1, NewValue2, NewValue3 = 0, Centerline = False, ThirdLine = False):
        self.delete("all")
        self.create_text( 380,20,text = self.FrameTitle, fill = 'black')
        if Centerline == True:
            self.create_line(0,90,760,90, fill = 'dark grey')
        for x in range(1,59):
            self.Value1[x] = self.Value1[x+1]
            self.Value2[x] = self.Value2[x+1]
            self.Value3[x] = self.Value3[x+1]
        self.Value1[59] = NewValue1
        self.Value2[59] = NewValue2
        self.Value3[59] = NewValue3
        for x in range(0,59):
            self.create_line(-13+(x*13),self.Value1[x],0+(x*13),self.Value1[x+1], fill='blue' )
            self.create_line(-13+(x*13),self.Value2[x],0+(x*13),self.Value2[x+1], fill='red' )
            if ThirdLine == True:
                self.create_line(-13+(x*13),self.Value3[x],0+(x*13),self.Value3[x+1], fill='yellow' )

It is working fine so far, but I noticed an odd error:

After half a minute or so the Canvas stops updating, even thou the programm itself is still running perfectly. When i move the mouse over the app, the Canvas updates again. I call the NewEntry Function every 0.5 seconds. I thought of generating a mouse event every now and then, but that would be a nasty work around... Any help is highly appreciated!

Thanks,

deck

Answer 1

First I thought a new Code solved the issue, but it turns out, it just happens less often. Also it seems it doesn't happen on Debian on A20ARM.

Here is the code:

class TeleGraph(Canvas):
    def __init__(self, master, FrameTitle, Col, Row, Height):
        Canvas.__init__(self, master)
        self.FrameTitle = FrameTitle
        self.Value1 = range(60)
        self.Value2 = range(60)
        self.Value3 = range(60)
        self.Line1 = range(60)
        self.Line2 = range(60)
        self.Line3 = range(60)
        self.configure(height = Height, width = 750, bg = 'grey', bd = 3,relief = GROOVE)
        self.grid()
        self.grid_propagate(0)
        self.Col = Col
        self.Row = Row
        self.place(y = Col, x = Row)
        self.create_text( 380,20,text = self.FrameTitle, fill = 'black')
        for x in range(0,59):
            self.Line1[x] = self.create_line(-13+(x*13),90,0+(x*13),90, fill='blue', width = 0 )
            self.Line2[x] = self.create_line(-13+(x*13),90,0+(x*13),90, fill='red' , width = 0 )
            self.Line3[x] = self.create_line(-13+(x*13),90,0+(x*13),90, fill='yellow' , width = 0 )

    def NewEntry(self, NewValue1, NewValue2 = 0, NewValue3 = 0, Centerline = False, Dritter = False):
        for x in range(1,59):
            self.Value1[x] = self.Value1[x+1]
            self.Value2[x] = self.Value2[x+1]
            self.Value3[x] = self.Value3[x+1]
        self.Value1[59] = NewValue1
        self.Value2[59] = NewValue2
        self.Value3[59] = NewValue3
        for x in range(0,59):
            self.coords(self.Line1[x], -13+(x*13), self.Value1[x],(x*13), self.Value1[x+1])
            self.coords(self.Line2[x], -13+(x*13), self.Value2[x],(x*13), self.Value2[x+1])
            self.coords(self.Line3[x], -13+(x*13), self.Value3[x],(x*13), self.Value3[x+1])