lern-tracking-system/raspberry-pi/gui/graph.py

import tkinter as tk
import time, math
from PIL import Image, ImageDraw, ImageTk

class Graph(tk.Canvas):
  def __init__(self, root, scale=(-100, 500), **kwargs):
    self.root = root
    tk.Canvas.__init__(self, root, **kwargs)
    self.height = self.winfo_reqheight()
    self.width = self.winfo_reqwidth()
    self.lastPoints = [(0, 0)] * 3
    self.scale = scale
    self.colors = [(100, 255, 100, 255), (255, 100, 100, 255) ,(100, 100, 255, 255)]
    
    self.drawBackground()
    self.canvas = self.bg.copy()
    self.image = self.create_image(0, 0, image=None, anchor='nw')

    self.bind("<Configure>", self.on_resize)

  def drawBackground(self):
    self.bg = Image.new('RGB', (self.width, self.height), (0,20,0))
    draw = ImageDraw.Draw(self.bg)
    draw.line([(0, self.height/2), (self.width, self.height/2)], (0,127,127), 1)
    draw.line([(self.width/2, 0), (self.width/2, self.height)], (0,127,127), 1)


  def on_resize(self,event):
    self.width = max(100, event.width-4)
    self.height = max(100, event.height-4)
    # resize the canvas 
    self.canvas = self.canvas.resize((self.width, self.height))
    self.drawBackground()
    self.canvas = Image.blend(self.canvas, self.bg, 0.1)

  def pointToCoord(self, point):
    return ((point[0] - self.scale[0]) / (self.scale[1]-self.scale[0]) * self.width, 
      self.height - (point[1] - self.scale[0]) / (self.scale[1]-self.scale[0]) * self.height - 1)

  def update(self, data):
    coord = [[self.pointToCoord(p)] for p in self.lastPoints]

    for i in range(len(data)):
      for point in data[i]:
        coord[i].append(self.pointToCoord(point))

    self.lastPoints = [line[-1] for line in data]

    self.canvas = Image.blend(self.canvas, self.bg, 1/200)
    draw = ImageDraw.Draw(self.canvas)
    for i in range(len(coord)):
      draw.line(coord[i], fill=self.colors[i], width=int(self.height/100), joint='curve')

    self.photo = ImageTk.PhotoImage(self.canvas)
    self.itemconfig(self.image, image=self.photo)