Demo/tkinter/guido/canvasevents.py

   1 #! /usr/bin/env python
   2
   3 from Tkinter import *
   4 from Canvas import Oval, Group, CanvasText
   5
   6
   7 # Fix a bug in Canvas.Group as distributed in Python 1.4.  The
   8 # distributed bind() method is broken.  This is what should be used:
   9
  10 class Group(Group):
  11     def bind(self, sequence=None, command=None):
  12         return self.canvas.tag_bind(self.id, sequence, command)
  13
  14 class Object:
  15
  16     """Base class for composite graphical objects.
  17
  18     Objects belong to a canvas, and can be moved around on the canvas.
  19     They also belong to at most one ``pile'' of objects, and can be
  20     transferred between piles (or removed from their pile).
  21
  22     Objects have a canonical ``x, y'' position which is moved when the
  23     object is moved.  Where the object is relative to this position
  24     depends on the object; for simple objects, it may be their center.
  25
  26     Objects have mouse sensitivity.  They can be clicked, dragged and
  27     double-clicked.  The behavior may actually determined by the pile
  28     they are in.
  29
  30     All instance attributes are public since the derived class may
  31     need them.
  32
  33     """
  34
  35     def __init__(self, canvas, x=0, y=0, fill='red', text='object'):
  36         self.canvas = canvas
  37         self.x = x
  38         self.y = y
  39         self.pile = None
  40         self.group = Group(self.canvas)
  41         self.createitems(fill, text)
  42
  43     def __str__(self):
  44         return str(self.group)
  45
  46     def createitems(self, fill, text):
  47         self.__oval = Oval(self.canvas,
  48                            self.x-20, self.y-10, self.x+20, self.y+10,
  49                            fill=fill, width=3)
  50         self.group.addtag_withtag(self.__oval)
  51         self.__text = CanvasText(self.canvas,
  52                            self.x, self.y, text=text)
  53         self.group.addtag_withtag(self.__text)
  54
  55     def moveby(self, dx, dy):
  56         if dx == dy == 0:
  57             return
  58         self.group.move(dx, dy)
  59         self.x = self.x + dx
  60         self.y = self.y + dy
  61
  62     def moveto(self, x, y):
  63         self.moveby(x - self.x, y - self.y)
  64
  65     def transfer(self, pile):
  66         if self.pile:
  67             self.pile.delete(self)
  68             self.pile = None
  69         self.pile = pile
  70         if self.pile:
  71             self.pile.add(self)
  72
  73     def tkraise(self):
  74         self.group.tkraise()
  75
  76
  77 class Bottom(Object):
  78
  79     """An object to serve as the bottom of a pile."""
  80
  81     def createitems(self, *args):
  82         self.__oval = Oval(self.canvas,
  83                            self.x-20, self.y-10, self.x+20, self.y+10,
  84                            fill='gray', outline='')
  85         self.group.addtag_withtag(self.__oval)
  86
  87
  88 class Pile:
  89
  90     """A group of graphical objects."""
  91
  92     def __init__(self, canvas, x, y, tag=None):
  93         self.canvas = canvas
  94         self.x = x
  95         self.y = y
  96         self.objects = []
  97         self.bottom = Bottom(self.canvas, self.x, self.y)
  98         self.group = Group(self.canvas, tag=tag)
  99         self.group.addtag_withtag(self.bottom.group)
 100         self.bindhandlers()
 101
 102     def bindhandlers(self):
 103         self.group.bind('<1>', self.clickhandler)
 104         self.group.bind('<Double-1>', self.doubleclickhandler)
 105
 106     def add(self, object):
 107         self.objects.append(object)
 108         self.group.addtag_withtag(object.group)
 109         self.position(object)
 110
 111     def delete(self, object):
 112         object.group.dtag(self.group)
 113         self.objects.remove(object)
 114
 115     def position(self, object):
 116         object.tkraise()
 117         i = self.objects.index(object)
 118         object.moveto(self.x + i*4, self.y + i*8)
 119
 120     def clickhandler(self, event):
 121         pass
 122
 123     def doubleclickhandler(self, event):
 124         pass
 125
 126
 127 class MovingPile(Pile):
 128
 129     def bindhandlers(self):
 130         Pile.bindhandlers(self)
 131         self.group.bind('<B1-Motion>', self.motionhandler)
 132         self.group.bind('<ButtonRelease-1>', self.releasehandler)
 133
 134     movethis = None
 135
 136     def clickhandler(self, event):
 137         tags = self.canvas.gettags('current')
 138         for i in range(len(self.objects)):
 139             o = self.objects[i]
 140             if o.group.tag in tags:
 141                 break
 142         else:
 143             self.movethis = None
 144             return
 145         self.movethis = self.objects[i:]
 146         for o in self.movethis:
 147             o.tkraise()
 148         self.lastx = event.x
 149         self.lasty = event.y
 150
 151     doubleclickhandler = clickhandler
 152
 153     def motionhandler(self, event):
 154         if not self.movethis:
 155             return
 156         dx = event.x - self.lastx
 157         dy = event.y - self.lasty
 158         self.lastx = event.x
 159         self.lasty = event.y
 160         for o in self.movethis:
 161             o.moveby(dx, dy)
 162
 163     def releasehandler(self, event):
 164         objects = self.movethis
 165         if not objects:
 166             return
 167         self.movethis = None
 168         self.finishmove(objects)
 169
 170     def finishmove(self, objects):
 171         for o in objects:
 172             self.position(o)
 173
 174
 175 class Pile1(MovingPile):
 176
 177     x = 50
 178     y = 50
 179     tag = 'p1'
 180
 181     def __init__(self, demo):
 182         self.demo = demo
 183         MovingPile.__init__(self, self.demo.canvas, self.x, self.y, self.tag)
 184
 185     def doubleclickhandler(self, event):
 186         try:
 187             o = self.objects[-1]
 188         except IndexError:
 189             return
 190         o.transfer(self.other())
 191         MovingPile.doubleclickhandler(self, event)
 192
 193     def other(self):
 194         return self.demo.p2
 195
 196     def finishmove(self, objects):
 197         o = objects[0]
 198         p = self.other()
 199         x, y = o.x, o.y
 200         if (x-p.x)**2 + (y-p.y)**2 < (x-self.x)**2 + (y-self.y)**2:
 201             for o in objects:
 202                 o.transfer(p)
 203         else:
 204             MovingPile.finishmove(self, objects)
 205
 206 class Pile2(Pile1):
 207
 208     x = 150
 209     y = 50
 210     tag = 'p2'
 211
 212     def other(self):
 213         return self.demo.p1
 214
 215
 216 class Demo:
 217
 218     def __init__(self, master):
 219         self.master = master
 220         self.canvas = Canvas(master,
 221                              width=200, height=200,
 222                              background='yellow',
 223                              relief=SUNKEN, borderwidth=2)
 224         self.canvas.pack(expand=1, fill=BOTH)
 225         self.p1 = Pile1(self)
 226         self.p2 = Pile2(self)
 227         o1 = Object(self.canvas, fill='red', text='o1')
 228         o2 = Object(self.canvas, fill='green', text='o2')
 229         o3 = Object(self.canvas, fill='light blue', text='o3')
 230         o1.transfer(self.p1)
 231         o2.transfer(self.p1)
 232         o3.transfer(self.p2)
 233
 234
 235 # Main function, run when invoked as a stand-alone Python program.
 236
 237 def main():
 238     root = Tk()
 239     demo = Demo(root)
 240     root.protocol('WM_DELETE_WINDOW', root.quit)
 241     root.mainloop()
 242
 243 if __name__ == '__main__':
 244     main()