Meter with needle

meter_with_needle.py

import tkinter as tk
from PIL import Image, ImageTk, ImageDraw
from tkinter import StringVar, IntVar
from tkinter import ttk
from tkinter.ttk import Frame


class NeedleMeter(Frame):

    def __init__(self,
                 master=None,
                 amounttotal=100,
                 amountused=0,
                 metersize=200,
                 meterthickness=10,
                 **kw):

        super().__init__(master=master, **kw)
        self.box = ttk.Frame(self, width=metersize, height=metersize)
        self.arcoffset = -180
        self.arcrange = 180
        self.amountusedvariable = IntVar(value=amountused)
        self.amounttotalvariable = IntVar(value=amounttotal)
        self.amountusedvariable.trace_add('write', self.draw_needle)

        self.towardsmaximum = True
        self.metersize = metersize
        self.meterthickness = meterthickness
        self.metercolorsuccess = '#22b24c'
        self.metercolorwarning = '#f5e625'
        self.metercolordanger = '#f57a00'
        self.needlecolor = '#272525'

        # meter image
        self.meter = ttk.Label(self.box)
        self.draw_base_image()
        self.draw_needle()

        self.meter.place(x=0, y=0)
        self.box.pack()

    @property
    def amountused(self):
        return self.amountusedvariable.get()

    @amountused.setter
    def amountused(self, value):
        self.amountusedvariable.set(value)

    @property
    def amounttotal(self):
        return self.amounttotalvariable.get()

    @amounttotal.setter
    def amounttotal(self, value):
        self.amounttotalvariable.set(value)

    def draw_base_image(self):
        """Draw the base image to be used for subsequent updates"""
        self.base_image = Image.new('RGBA', (self.metersize * 5, self.metersize * 5))
        draw = ImageDraw.Draw(self.base_image)

        # success
        draw.arc((0, 0, self.metersize * 5 - 20, self.metersize * 5 - 20),
                 -180, -90, self.metercolorsuccess, self.meterthickness * 5)
        # warning
        draw.arc((0, 0, self.metersize * 5 - 20, self.metersize * 5 - 20),
                 -90, -45, self.metercolorwarning, self.meterthickness * 5)
        # warning
        draw.arc((0, 0, self.metersize * 5 - 20, self.metersize * 5 - 20),
                 -45, 0, self.metercolordanger, self.meterthickness * 5)

    def draw_needle(self, *args):
        """Draw a meter

        Args:
            *args: if triggered by a trace, will be `variable`, `index`, `mode`.
        """
        im = self.base_image.copy()
        draw = ImageDraw.Draw(im)
        scaled_xy = self.metersize * 5
        scaled_half = scaled_xy // 2
        draw.arc((40, 40, scaled_xy - 40, scaled_xy - 40),
                 self.meter_value() - 1, self.meter_value() + 1, self.needlecolor, scaled_xy)
        needle_base_xy = (scaled_half - 20, scaled_half - 20, scaled_half + 20, scaled_half + 20)
        draw.ellipse(needle_base_xy, fill=self.needlecolor)
        self.meterimage = ImageTk.PhotoImage(im.resize((self.metersize, self.metersize), Image.CUBIC))
        self.meter.configure(image=self.meterimage)

    def meter_value(self):
        """Calculate the meter value

        Returns:
            int: the value to be used to draw the arc length of the progress meter
        """
        return int((self.amountused / self.amounttotal) * self.arcrange + self.arcoffset)

    def step(self, delta=1):
        """Increase the indicator value by ``delta``.

        The default increment is 1. The indicator will reverse direction and count down once it reaches the maximum
        value.

        Keyword Args:
            delta (int): the amount to change the indicator.
        """
        if self.amountused >= self.amounttotal:
            self.towardsmaximum = True
            self.amountused = self.amountused - delta
        elif self.amountused <= 0:
            self.towardsmaximum = False
            self.amountused = self.amountused + delta
        elif self.towardsmaximum:
            self.amountused = self.amountused - delta
        else:
            self.amountused = self.amountused + delta


if __name__ == '__main__':
    def test(meter):
        meter.step(1)
        meter.after(1, test, meter)


    m = NeedleMeter(meterthickness=25, padding=20)
    m.pack()
    test(m)
    m.mainloop()