1 from Tkinter import *

     2 

     3 # allows moving dots with multiple selection.

     4 

     5 SELECTED_COLOR = "red"

     6 UNSELECTED_COLOR = "blue"

     7 

     8 class Test(Frame):

     9     ###################################################################

    10     ###### Event callbacks for THE CANVAS (not the stuff drawn on it)

    11     ###################################################################

    12     def mouseDown(self, event):

    13         # see if we're inside a dot. If we are, it

    14         # gets tagged as CURRENT for free by tk.

    15 

    16         if not event.widget.find_withtag(CURRENT):

    17             # we clicked outside of all dots on the canvas. unselect all.

    18 

    19             # re-color everything back to an unselected color

    20             self.draw.itemconfig("selected", fill=UNSELECTED_COLOR)

    21             # unselect everything

    22             self.draw.dtag("selected")

    23         else:

    24             # mark as "selected" the thing the cursor is under

    25             self.draw.addtag("selected", "withtag", CURRENT)

    26             # color it as selected

    27             self.draw.itemconfig("selected", fill=SELECTED_COLOR)

    28 

    29         self.lastx = event.x

    30         self.lasty = event.y

    31 

    32 

    33     def mouseMove(self, event):

    34         self.draw.move("selected", event.x - self.lastx, event.y - self.lasty)

    35         self.lastx = event.x

    36         self.lasty = event.y

    37 

    38     def makeNewDot(self):

    39         # create a dot, and mark it as current

    40         fred = self.draw.create_oval(0, 0, 20, 20,

    41                                      fill=SELECTED_COLOR, tags=CURRENT)

    42         # and make it selected

    43         self.draw.addtag("selected", "withtag", CURRENT)

    44 

    45     def createWidgets(self):

    46         self.QUIT = Button(self, text='QUIT', foreground='red',

    47                            command=self.quit)

    48 

    49         ################

    50         # make the canvas and bind some behavior to it

    51         ################

    52         self.draw = Canvas(self, width="5i", height="5i")

    53         Widget.bind(self.draw, "<1>", self.mouseDown)

    54         Widget.bind(self.draw, "<B1-Motion>", self.mouseMove)

    55 

    56         # and other things.....

    57         self.button = Button(self, text="make a new dot", foreground="blue",

    58                              command=self.makeNewDot)

    59 

    60         message = ("%s dots are selected and can be dragged.\n"

    61                    "%s are not selected.\n"

    62                    "Click in a dot to select it.\n"

    63                    "Click on empty space to deselect all dots."

    64                    ) % (SELECTED_COLOR, UNSELECTED_COLOR)

    65         self.label = Message(self, width="5i", text=message)

    66 

    67         self.QUIT.pack(side=BOTTOM, fill=BOTH)

    68         self.label.pack(side=BOTTOM, fill=X, expand=1)

    69         self.button.pack(side=BOTTOM, fill=X)

    70         self.draw.pack(side=LEFT)

    71 

    72     def __init__(self, master=None):

    73         Frame.__init__(self, master)

    74         Pack.config(self)

    75         self.createWidgets()

    76 

    77 test = Test()

    78 test.mainloop()