{
 "cells": [
  {
   "cell_type": "markdown",
   "id": "77eaeea0",
   "metadata": {},
   "source": [
    "# basic GUI for billiard ball"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "70dd065c",
   "metadata": {},
   "source": [
    "This basic GUI to model a billiard ball consists\n",
    "of a canvas, a start and stop button."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "id": "30ac11fe",
   "metadata": {},
   "outputs": [],
   "source": [
    "from tkinter import Tk, Canvas, Button, W, E\n",
    "from math import cos, sin, pi\n",
    "from random import randint, uniform"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "e46e4309",
   "metadata": {},
   "outputs": [],
   "source": [
    "class BilliardBall(object):\n",
    "    \"\"\"\n",
    "    GUI to simulate billiard ball movement.\n",
    "    \"\"\"\n",
    "    def __init__(self, wdw, dimension, increment, delay):\n",
    "        \"\"\"\n",
    "        determines the layout of the GUI\n",
    "        \"\"\"\n",
    "        wdw.title('a pool table')\n",
    "        self.dim = dimension # dimension of the canvas\n",
    "        self.inc = increment\n",
    "        self.dly = delay\n",
    "        self.togo = False # state of animation\n",
    "        # initial coordinates of the ball\n",
    "        self.xpos = randint(10, self.dim-10)\n",
    "        self.ypos = randint(10, self.dim-10)\n",
    "        self.cnv = Canvas(wdw, width=self.dim, \\\n",
    "            height=self.dim, bg ='green')\n",
    "        self.cnv.grid(row=0, column=0, columnspan=2)\n",
    "        self.startbut = Button(wdw, text='start', \\\n",
    "            command = self.start)\n",
    "        self.startbut.grid(row=1, column=0, sticky=W+E)\n",
    "        self.stopbut = Button(wdw, text='stop', \\\n",
    "            command = self.stop)\n",
    "        self.stopbut.grid(row=1, column=1, sticky=W+E)\n",
    "\n",
    "    def map_to_table(self, pos):\n",
    "        \"\"\"\n",
    "        keeps the ball on the pool table\n",
    "        \"\"\"\n",
    "        if pos < 0:\n",
    "            (quot, remd) = divmod(-pos, self.dim)\n",
    "        else:\n",
    "            (quot, remd) = divmod(pos, self.dim)\n",
    "        if quot % 2 == 1:\n",
    "            remd = self.dim - remd\n",
    "        return remd\n",
    "\n",
    "    def draw_ball(self):\n",
    "        \"\"\"\n",
    "        draws the ball on the pool table\n",
    "        \"\"\"\n",
    "        xvl = self.map_to_table(self.xpos)\n",
    "        yvl = self.map_to_table(self.ypos)\n",
    "        self.cnv.delete('dot')\n",
    "        self.cnv.create_oval(xvl-6, yvl-6, xvl+6, yvl+6, \\\n",
    "            width=1, outline='black', fill='red', \\\n",
    "            tags='dot')\n",
    "\n",
    "    def animate(self):\n",
    "        \"\"\"\n",
    "        performs the animation\n",
    "        \"\"\"\n",
    "        self.draw_ball()\n",
    "        angle = uniform(0, 2*pi)\n",
    "        xdir = cos(angle)\n",
    "        ydir = sin(angle)\n",
    "        while self.togo:\n",
    "            xvl = self.xpos\n",
    "            yvl = self.ypos\n",
    "            self.xpos = xvl + xdir*self.inc\n",
    "            self.ypos = yvl + ydir*self.inc\n",
    "            self.cnv.after(self.dly)\n",
    "            self.draw_ball()\n",
    "            self.cnv.update()\n",
    "\n",
    "    def start(self):\n",
    "        \"\"\"\n",
    "        starts the animation\n",
    "        \"\"\"\n",
    "        self.togo = True\n",
    "        self.animate()\n",
    "\n",
    "    def stop(self):\n",
    "        \"\"\"\n",
    "        stops the animation\n",
    "        \"\"\"\n",
    "        self.togo = False"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "aca79655",
   "metadata": {},
   "source": [
    "The next cell launches the GUI."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "id": "42ace809",
   "metadata": {},
   "outputs": [],
   "source": [
    "top = Tk()\n",
    "dimension = 400 # dimension of pool table\n",
    "dims = \"%dx%d\" % (dimension, dimension)\n",
    "top.geometry(dims)\n",
    "increment = 10  # increment for coordinates\n",
    "delay = 60      # how much sleep before update\n",
    "BilliardBall(top, dimension, increment, delay)\n",
    "top.mainloop()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "a75ecfbd-448b-4cd7-acc0-48395ee56e94",
   "metadata": {},
   "outputs": [],
   "source": []
  }
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