Sean McIlroy wrote:
> What I want to do is simply to move a shape around on
> the screen using the mouse. I've looked at Tkdnd.py but
> I can't seem to extract what I need from the more involved
> stuff in there.
Here's a simple sample that displays random rectangles that can be dragged
around a Canvas:
=-=-=-=-=-=-=-=-=-=
#!/usr/bin/python
# dsimp.py -- test object dragging
import sys
import math
import Tkinter
import random
class DragCanvas(Tkinter.Frame):
"""A canvas containing 'nrect' random draggable rectangles."""
tilecolors = (
"cyan", "gold", "lightgreen", "green",
"darkgreen", "lightblue", "blue",
"darkblue", "pink", "red",
)
def __init__(self,master,nrect=1):
"""Create the Canvas and a bunch of rectangles."""
Tkinter.Frame.__init__(self,master)
self.bbox = (0,0,600,400)
self.master = master
self.nrect = nrect
self.rand = random.Random()
self.dragging = 0
self.item = -1
self.xbase = 0
self.ybase = 0
self.xscroll = Tkinter.Scrollbar(self,
orient=Tkinter.HORIZONTAL)
self.yscroll = Tkinter.Scrollbar(self,
orient=Tkinter.VERTICAL)
self.xscroll.pack(side=Tkinter.BOTTOM,fill=Tkinter.X)
self.yscroll.pack(side=Tkinter.RIGHT,fill=Tkinter.Y)
self.world = Tkinter.Canvas(self,
width=self.bbox[2],
height=self.bbox[3],
xscrollcommand=self.xscroll.set,
yscrollcommand=self.yscroll.set,
borderwidth=1,
relief=Tkinter.GROOVE)
self.xscroll.config(command=self.world.xview)
self.yscroll.config(command=self.world.yview)
self.world.pack(fill=Tkinter.BOTH)
# Mouse commands for this view.
self.world.bind("<Button-1>",self.__doimageClick)
self.world.bind("<ButtonRelease-1>",self.__doimageUnclick)
self.world.bind("<B1-Motion>",self.__doimageDrag)
for i in range(0,self.nrect):
# Compute graphics coordinates of tile.
# (Note first row/col offset by 1 pixel from top/left.)
xsize = self.rand.randrange(30,80)
ysize = self.rand.randrange(20,50)
x1 = self.rand.randrange(0,360)
y1 = self.rand.randrange(0,260)
# Create a random rectangle.
rectnum = self.world.create_rectangle(
x1,y1,x1+xsize,y1+ysize,
fill=self.rand.choice(DragCanvas.tilecolors))
# Limit scrolling in the view.
#self.world.config(scrollregion=self.world.bbox(Tkinter.ALL))
self.world.config(scrollregion=self.bbox)
def __doimageClick(self,event):
"""User clicked mouse; start dragging if item found."""
x = self.world.canvasx(event.x)
y = self.world.canvasy(event.y)
items = self.world.find_overlapping(x-2,y-2,x+2,y+2)
if len(items) > 0:
self.dragging = 1
self.item = items[-1] # Topmost item is returned last.
self.xbase = x
self.ybase = y
def __doimageUnclick(self,event):
"""User released mouse; stop dragging."""
self.dragging = 0
self.item = -1
def __doimageDrag(self,event):
"""Drag an item around the map."""
if not self.dragging:
return
x = self.world.canvasx(event.x)
y = self.world.canvasy(event.y)
self.world.move(self.item,x-self.xbase,y-self.ybase)
self.xbase = x
self.ybase = y
def doexit():
"""Exit the program, discarding changes."""
sys.exit(0)
root = Tkinter.Tk()
root.geometry("400x300")
root.title("Draggable?")
mbar = Tkinter.Menu(root)
root.config(menu=mbar)
filemenu = Tkinter.Menu(mbar)
mbar.add_cascade(label="File",menu=filemenu)
filemenu.add_separator()
filemenu.add_command(label="Exit",command=doexit)
worldview = DragCanvas(root,12)
worldview.pack()
root.mainloop()
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