# Tk_sling.py

# Tk_sling.py

from Tkinter import *
import random
from math import *


WIDTH = 400
HEIGHT = 400

farben = ["#ff0000","#00ff00","#0000ff","#ffff00","#ff00ff","#00ffff"]
ball_count = 0

gravity = 0.05
friction = 0.001

class GUI():
    def __init__(self):
        self.root = Tk()
        self.root.title("Sling")
        self.root.bind_all('<Escape>',self.quit)
        self.canvas = Canvas(self.root,width=WIDTH,height=HEIGHT,bg="#000000")

        self.arrow = self.canvas.create_line(-100,-100,-100,-100,
                                             fill="#a0a0a0",width=3,
                                             arrow="first",arrowshape=(12,16,6))

        self.canvas.pack()

    def quit(self,event):
        self.root.quit()
        self.root.destroy()


class Ball():
    def __init__(self,field,gui,x=None,y=None,vx=0,vy=0):
        self.field = field
        self.RADIUS = random.randint(10,40)

        if x:
            if x<self.RADIUS: x = self.RADIUS
            if x>WIDTH-self.RADIUS: x=WIDTH-self.RADIUS
            self.x = x
        else:
            self.x = random.randint(WIDTH/4,WIDTH*3/4)

        if y:
            if y<self.RADIUS: y = self.RADIUS
            if y>HEIGHT-self.RADIUS: y=HEIGHT-self.RADIUS
            self.y = y
        else:
            self.y = random.randint(HEIGHT/4,HEIGHT*3/4)

        farbe = random.choice(farben)
        self.ball = field.create_oval(self.x-self.RADIUS,self.y-self.RADIUS,
                                          self.x+self.RADIUS,self.y+self.RADIUS,
                                          fill=farbe,outline="")
        field.tag_lower(self.ball,gui.arrow)
        self.vx, self.vy = vx,vy

    def move(self):
        if self.NOMOVE: return
        self.x += self.vx
        self.y += self.vy
        if self.x<self.RADIUS or self.x>WIDTH-self.RADIUS:
            self.vx = -self.vx
            self.x += self.vx
        if self.y<self.RADIUS or self.y>HEIGHT-self.RADIUS:
            self.vy = -self.vy
            self.y += self.vy

        self.vy += gravity

        self.vx *= (1-friction)
        self.vy *= (1-friction)

        self.field.coords(self.ball,self.x-self.RADIUS,self.y-self.RADIUS,
                              self.x+self.RADIUS,self.y+self.RADIUS)


class Play():
    def __init__(self):
        self.gui = GUI()
        self.gui.canvas.bind("<Button-1>",self.clicked)
        self.gui.canvas.bind("<ButtonRelease-1>",self.dragged)
        self.gui.canvas.bind("<B1-Motion>",self.moved)

        self.gui.canvas.bind("<Button-3>",self.unclicked)

        self.balls = []
        for i in range(ball_count):
            self.balls.append(Ball(self.gui.canvas,self.gui))
        self.action()


    def clicked(self,event):
        self.gui.root["cursor"] = "target"
        self.balls.append(Ball(self.gui.canvas,self.gui,event.x,event.y))
        self.balls[-1].NOMOVE = True
        self.mouse_x0, self.mouse_y0 = event.x, event.y

    def moved(self,event):
        if len(self.balls)==0: return
        ball = self.balls[-1]
        self.gui.canvas.coords(self.gui.arrow,self.mouse_x0,self.mouse_y0,
                               event.x,event.y)

    def dragged(self,event):
        self.gui.canvas.coords(self.gui.arrow,-100,-100,-100,-100)
        if len(self.balls)==0: return
        self.gui.root["cursor"] = "arrow"
        distance_x, distance_y  = event.x-self.mouse_x0, event.y-self.mouse_y0
        ball = self.balls[-1]
        ball.vx = -distance_x/20.0
        ball.vy = -distance_y/20.0
        self.balls[-1].NOMOVE = False

    def unclicked(self,event):
        if len(self.balls)>0:
            removeball = self.balls[-1]
            self.gui.canvas.delete(removeball.ball)
            self.balls = self.balls[:-1]


    def action(self):
        while True:
            for ball in self.balls:
                ball.move()
            self.gui.canvas.after(10)
            self.gui.canvas.update()

Play()