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

import time, math

import tkinter as tk
from PIL import Image, ImageDraw, ImageTk, ImageFont


class Graph(tk.Canvas):
  def __init__(self, root, scale=(-50, 450), **kwargs):
    self.root = root
    tk.Canvas.__init__(self, root, **kwargs)
    self.image = self.create_image(0, 0, image=None, anchor='nw')
    self.height = self.winfo_reqheight()
    self.width = self.winfo_reqwidth()
    # store last point of plot to connect the lines
    self.lastPoints = [(0, 0)] * 3
    # scale contains the (min, max) values of both axes
    self.scale = scale
    # appearance of the plots
    self.colors = [(100, 255, 100, 255), (255, 100, 100, 255) ,(100, 100, 255, 255)]
    self.font = ImageFont.truetype("gui/SourceSansPro-Semibold.otf", 12)
    self.lineWidth = 1
    
    # the background contains all static elements
    self.drawBackground()
    # the plots will be drawn on a separate canvas
    self.canvas = self.bg.copy()

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

  def drawBackground(self):
    self.bg = Image.new('RGB', (self.width, self.height), (0,10,0))
    draw = ImageDraw.Draw(self.bg)
    # draw x and y axis
    axes = self.pointToCoord((0, 0))
    draw.line([(0, axes[1]), (self.width, axes[1])], (60,127,127), self.lineWidth)
    draw.line([(axes[0], 0), (axes[0], self.height)], (60,127,127), self.lineWidth)

    step  = 10**int(math.log10(self.scale[1]-self.scale[0]))
    begin = math.floor(self.scale[0] / step) * step
    end   = math.ceil(self.scale[1] / step) * step
    halfStep = int(step / 2)
    for p in range(begin, end, halfStep):
      tickPosX = self.pointToCoord((p, 0))
      tickPosY = self.pointToCoord((0, p))
      #draw grid
      draw.line([(tickPosX[0], self.height), (tickPosX[0], 0)], (60,127,60), 1)
      draw.line([(self.width, tickPosY[1]), (0, tickPosY[1])], (60,127,60), 1)
    for p in range(begin, end, step):
      tickPosX = self.pointToCoord((p, 0))
      tickPosY = self.pointToCoord((0, p))
      # draw ticks
      draw.line([(tickPosX[0], tickPosX[1]+self.lineWidth*3), (tickPosX[0], tickPosX[1]-self.lineWidth*3)], (60,127,100), int(self.lineWidth/2))
      draw.line([(tickPosY[0]+self.lineWidth*3, tickPosY[1]), (tickPosY[0]-self.lineWidth*3, tickPosY[1])], (60,127,100), int(self.lineWidth/2))
      # draw tick labels
      draw.text((tickPosX[0]+3, tickPosX[1]+self.lineWidth*4), str(p) + " mm", font=self.font)
      if p != 0:
        draw.text((tickPosY[0]-self.lineWidth*4-35, tickPosY[1]), str(p) + " mm", font=self.font)

  def on_resize(self,event):
    self.width = max(100, event.width-4)
    self.height = max(100, event.height-4)
    self.lineWidth = int(max(min(self.width,self.height) / 100, 1))
    # resize the canvas 
    self.canvas = self.canvas.resize((self.width, self.height))
    self.drawBackground()
    self.canvas = Image.blend(self.canvas, self.bg, 1)

  # convert physical space to screen space
  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):
    # load first point of line
    coord = [[self.pointToCoord(p)] for p in self.lastPoints]
    # append new points
    for i in range(len(data)):
      for point in data[i]:
        coord[i].append(self.pointToCoord(point))

    self.canvas = Image.blend(self.canvas, self.bg, 1/100)
    if len(data[0]) > 0:
      self.lastPoints = [line[-1] for line in data]
      #fade out old lines by mixing with background
      draw = ImageDraw.Draw(self.canvas)
      for i in range(len(coord)):
        draw.line(coord[i], fill=self.colors[i], width=self.lineWidth+2, joint='curve')

    # draw to tk.Canvas
    self.photo = ImageTk.PhotoImage(self.canvas)
    self.itemconfig(self.image, image=self.photo)

  def clear(self):
    self.canvas = self.bg.copy()