Demo/tkinter/matt/canvas-moving-or-creating.py

   1 from Tkinter import *
   2
   3 # this file demonstrates a more sophisticated movement --
   4 # move dots or create new ones if you click outside the dots
   5
   6 class Test(Frame):
   7     ###################################################################
   8     ###### Event callbacks for THE CANVAS (not the stuff drawn on it)
   9     ###################################################################
  10     def mouseDown(self, event):
  11         # see if we're inside a dot. If we are, it
  12         # gets tagged as CURRENT for free by tk.
  13         if not event.widget.find_withtag(CURRENT):
  14             # there is no dot here, so we can make one,
  15             # and bind some interesting behavior to it.
  16             # ------
  17             # create a dot, and mark it as CURRENT
  18             fred = self.draw.create_oval(
  19                 event.x - 10, event.y -10, event.x +10, event.y + 10,
  20                 fill="green", tags=CURRENT)
  21
  22             self.draw.tag_bind(fred, "<Any-Enter>", self.mouseEnter)
  23             self.draw.tag_bind(fred, "<Any-Leave>", self.mouseLeave)
  24
  25         self.lastx = event.x
  26         self.lasty = event.y
  27
  28     def mouseMove(self, event):
  29         self.draw.move(CURRENT, event.x - self.lastx, event.y - self.lasty)
  30         self.lastx = event.x
  31         self.lasty = event.y
  32
  33     ###################################################################
  34     ###### Event callbacks for canvas ITEMS (stuff drawn on the canvas)
  35     ###################################################################
  36     def mouseEnter(self, event):
  37         # the CURRENT tag is applied to the object the cursor is over.
  38         # this happens automatically.
  39         self.draw.itemconfig(CURRENT, fill="red")
  40
  41     def mouseLeave(self, event):
  42         # the CURRENT tag is applied to the object the cursor is over.
  43         # this happens automatically.
  44         self.draw.itemconfig(CURRENT, fill="blue")
  45
  46     def createWidgets(self):
  47         self.QUIT = Button(self, text='QUIT', foreground='red',
  48                            command=self.quit)
  49         self.QUIT.pack(side=LEFT, fill=BOTH)
  50         self.draw = Canvas(self, width="5i", height="5i")
  51         self.draw.pack(side=LEFT)
  52
  53         Widget.bind(self.draw, "<1>", self.mouseDown)
  54         Widget.bind(self.draw, "<B1-Motion>", self.mouseMove)
  55
  56     def __init__(self, master=None):
  57         Frame.__init__(self, master)
  58         Pack.config(self)
  59         self.createWidgets()
  60
  61 test = Test()
  62 test.mainloop()