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#! /usr/bin/env python3
from tkinter import *
from Canvas import Oval, Group, CanvasText
# Fix a bug in Canvas.Group as distributed in Python 1.4. The
# distributed bind() method is broken. This is what should be used:
class Group(Group):
def bind(self, sequence=None, command=None):
return self.canvas.tag_bind(self.id, sequence, command)
class Object:
"""Base class for composite graphical objects.
Objects belong to a canvas, and can be moved around on the canvas.
They also belong to at most one ``pile'' of objects, and can be
transferred between piles (or removed from their pile).
Objects have a canonical ``x, y'' position which is moved when the
object is moved. Where the object is relative to this position
depends on the object; for simple objects, it may be their center.
Objects have mouse sensitivity. They can be clicked, dragged and
double-clicked. The behavior may actually determined by the pile
they are in.
All instance attributes are public since the derived class may
need them.
"""
def __init__(self, canvas, x=0, y=0, fill='red', text='object'):
self.canvas = canvas
self.x = x
self.y = y
self.pile = None
self.group = Group(self.canvas)
self.createitems(fill, text)
def __str__(self):
return str(self.group)
def createitems(self, fill, text):
self.__oval = Oval(self.canvas,
self.x-20, self.y-10, self.x+20, self.y+10,
fill=fill, width=3)
self.group.addtag_withtag(self.__oval)
self.__text = CanvasText(self.canvas,
self.x, self.y, text=text)
self.group.addtag_withtag(self.__text)
def moveby(self, dx, dy):
if dx == dy == 0:
return
self.group.move(dx, dy)
self.x = self.x + dx
self.y = self.y + dy
def moveto(self, x, y):
self.moveby(x - self.x, y - self.y)
def transfer(self, pile):
if self.pile:
self.pile.delete(self)
self.pile = None
self.pile = pile
if self.pile:
self.pile.add(self)
def tkraise(self):
self.group.tkraise()
class Bottom(Object):
"""An object to serve as the bottom of a pile."""
def createitems(self, *args):
self.__oval = Oval(self.canvas,
self.x-20, self.y-10, self.x+20, self.y+10,
fill='gray', outline='')
self.group.addtag_withtag(self.__oval)
class Pile:
"""A group of graphical objects."""
def __init__(self, canvas, x, y, tag=None):
self.canvas = canvas
self.x = x
self.y = y
self.objects = []
self.bottom = Bottom(self.canvas, self.x, self.y)
self.group = Group(self.canvas, tag=tag)
self.group.addtag_withtag(self.bottom.group)
self.bindhandlers()
def bindhandlers(self):
self.group.bind('<1>', self.clickhandler)
self.group.bind('<Double-1>', self.doubleclickhandler)
def add(self, object):
self.objects.append(object)
self.group.addtag_withtag(object.group)
self.position(object)
def delete(self, object):
object.group.dtag(self.group)
self.objects.remove(object)
def position(self, object):
object.tkraise()
i = self.objects.index(object)
object.moveto(self.x + i*4, self.y + i*8)
def clickhandler(self, event):
pass
def doubleclickhandler(self, event):
pass
class MovingPile(Pile):
def bindhandlers(self):
Pile.bindhandlers(self)
self.group.bind('<B1-Motion>', self.motionhandler)
self.group.bind('<ButtonRelease-1>', self.releasehandler)
movethis = None
def clickhandler(self, event):
tags = self.canvas.gettags('current')
for i in range(len(self.objects)):
o = self.objects[i]
if o.group.tag in tags:
break
else:
self.movethis = None
return
self.movethis = self.objects[i:]
for o in self.movethis:
o.tkraise()
self.lastx = event.x
self.lasty = event.y
doubleclickhandler = clickhandler
def motionhandler(self, event):
if not self.movethis:
return
dx = event.x - self.lastx
dy = event.y - self.lasty
self.lastx = event.x
self.lasty = event.y
for o in self.movethis:
o.moveby(dx, dy)
def releasehandler(self, event):
objects = self.movethis
if not objects:
return
self.movethis = None
self.finishmove(objects)
def finishmove(self, objects):
for o in objects:
self.position(o)
class Pile1(MovingPile):
x = 50
y = 50
tag = 'p1'
def __init__(self, demo):
self.demo = demo
MovingPile.__init__(self, self.demo.canvas, self.x, self.y, self.tag)
def doubleclickhandler(self, event):
try:
o = self.objects[-1]
except IndexError:
return
o.transfer(self.other())
MovingPile.doubleclickhandler(self, event)
def other(self):
return self.demo.p2
def finishmove(self, objects):
o = objects[0]
p = self.other()
x, y = o.x, o.y
if (x-p.x)**2 + (y-p.y)**2 < (x-self.x)**2 + (y-self.y)**2:
for o in objects:
o.transfer(p)
else:
MovingPile.finishmove(self, objects)
class Pile2(Pile1):
x = 150
y = 50
tag = 'p2'
def other(self):
return self.demo.p1
class Demo:
def __init__(self, master):
self.master = master
self.canvas = Canvas(master,
width=200, height=200,
background='yellow',
relief=SUNKEN, borderwidth=2)
self.canvas.pack(expand=1, fill=BOTH)
self.p1 = Pile1(self)
self.p2 = Pile2(self)
o1 = Object(self.canvas, fill='red', text='o1')
o2 = Object(self.canvas, fill='green', text='o2')
o3 = Object(self.canvas, fill='light blue', text='o3')
o1.transfer(self.p1)
o2.transfer(self.p1)
o3.transfer(self.p2)
# Main function, run when invoked as a stand-alone Python program.
def main():
root = Tk()
demo = Demo(root)
root.protocol('WM_DELETE_WINDOW', root.quit)
root.mainloop()
if __name__ == '__main__':
main()
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