Tkinter scrollbar for frame
My objective is to add a vertical scroll bar to a frame which has several labels in it. The scroll bar should automatically enabled as soon as the labels inside the frame exceed the height of the frame. After searching through, I found this useful post. Based on that post I understand that in order to achieve what i want, (correct me if I am wrong, I am a beginner) I have to create a Frame first, then create a Canvas inside that frame and stick the scroll bar to that frame as well. After that, create another frame and put it inside the canvas as a window object. So, I finally come up with this:
from Tkinter import *
def data():
for i in range(50):
Label(frame,text=i).grid(row=i,column=0)
Label(frame,text="my text"+str(i)).grid(row=i,column=1)
Label(frame,text="..........").grid(row=i,column=2)
def myfunction(event):
canvas.configure(scrollregion=canvas.bbox("all"),width=200,height=200)
root=Tk()
sizex = 800
sizey = 600
posx = 100
posy = 100
root.wm_geometry("%dx%d+%d+%d" % (sizex, sizey, posx, posy))
myframe=Frame(root,relief=GROOVE,width=50,height=100,bd=1)
myframe.place(x=10,y=10)
canvas=Canvas(myframe)
frame=Frame(canvas)
myscrollbar=Scrollbar(myframe,orient="vertical",command=canvas.yview)
canvas.configure(yscrollcommand=myscrollbar.set)
myscrollbar.pack(side="right",fill="y")
canvas.pack(side="left")
canvas.create_window((0,0),window=frame,anchor='nw')
frame.bind("<Configure>",myfunction)
data()
root.mainloop()
- Am I doing it right? Is there better/smarter way to achieve the output this code gave me?
- Why must I use grid method? (I tried place method, but none of the labels appear on the canvas.)
- What so special about using
anchor='nw'when creating window on canvas?
Please keep your answer simple, as I am a beginner.
Please note that the proposed code is only valid with Python 2
Here is an example:
from Tkinter import * # from x import * is bad practice
from ttk import *
# http://tkinter.unpythonic.net/wiki/VerticalScrolledFrame
class VerticalScrolledFrame(Frame):
"""A pure Tkinter scrollable frame that actually works!
* Use the 'interior' attribute to place widgets inside the scrollable frame
* Construct and pack/place/grid normally
* This frame only allows vertical scrolling
"""
def __init__(self, parent, *args, **kw):
Frame.__init__(self, parent, *args, **kw)
# create a canvas object and a vertical scrollbar for scrolling it
vscrollbar = Scrollbar(self, orient=VERTICAL)
vscrollbar.pack(fill=Y, side=RIGHT, expand=FALSE)
canvas = Canvas(self, bd=0, highlightthickness=0,
yscrollcommand=vscrollbar.set)
canvas.pack(side=LEFT, fill=BOTH, expand=TRUE)
vscrollbar.config(command=canvas.yview)
# reset the view
canvas.xview_moveto(0)
canvas.yview_moveto(0)
# create a frame inside the canvas which will be scrolled with it
self.interior = interior = Frame(canvas)
interior_id = canvas.create_window(0, 0, window=interior,
anchor=NW)
# track changes to the canvas and frame width and sync them,
# also updating the scrollbar
def _configure_interior(event):
# update the scrollbars to match the size of the inner frame
size = (interior.winfo_reqwidth(), interior.winfo_reqheight())
canvas.config(scrollregion="0 0 %s %s" % size)
if interior.winfo_reqwidth() != canvas.winfo_width():
# update the canvas's width to fit the inner frame
canvas.config(width=interior.winfo_reqwidth())
interior.bind('<Configure>', _configure_interior)
def _configure_canvas(event):
if interior.winfo_reqwidth() != canvas.winfo_width():
# update the inner frame's width to fill the canvas
canvas.itemconfigure(interior_id, width=canvas.winfo_width())
canvas.bind('<Configure>', _configure_canvas)
if __name__ == "__main__":
class SampleApp(Tk):
def __init__(self, *args, **kwargs):
root = Tk.__init__(self, *args, **kwargs)
self.frame = VerticalScrolledFrame(root)
self.frame.pack()
self.label = Label(text="Shrink the window to activate the scrollbar.")
self.label.pack()
buttons = []
for i in range(10):
buttons.append(Button(self.frame.interior, text="Button " + str(i)))
buttons[-1].pack()
app = SampleApp()
app.mainloop()
It does not yet have the mouse wheel bound to the scrollbar but it is possible. Scrolling with the wheel can get a bit bumpy, though.
edit:
to 1)
IMHO scrolling frames is somewhat tricky in Tkinter and does not seem to be done a lot. It seems there is no elegant way to do it.
One problem with your code is that you have to set the canvas size manually - that's what the example code I posted solves.
to 2)
You are talking about the data function? Place works for me, too. (In general I prefer grid).
to 3)
Well, it positions the window on the canvas.
One thing I noticed is that your example handles mouse wheel scrolling by default while the one I posted does not. Will have to look at that some time.
"Am i doing it right?Is there better/smarter way to achieve the output this code gave me?"
Generally speaking, yes, you're doing it right. Tkinter has no native scrollable container other than the canvas. As you can see, it's really not that difficult to set up. As your example shows, it only takes 5 or 6 lines of code to make it work -- depending on how you count lines.
"Why must i use grid method?(i tried place method, but none of the labels appear on the canvas?)"
You ask about why you must use grid. There is no requirement to use grid. Place, grid and pack can all be used. It's simply that some are more naturally suited to particular types of problems. In this case it looks like you're creating an actual grid -- rows and columns of labels -- so grid is the natural choice.
"What so special about using anchor='nw' when creating window on canvas?"
The anchor tells you what part of the window is positioned at the coordinates you give. By default, the center of the window will be placed at the coordinate. In the case of your code above, you want the upper left ("northwest") corner to be at the coordinate.
Please see my class that is a scrollable frame. It's vertical scrollbar is binded to <Mousewheel> event as well. So, all you have to do is to create a frame, fill it with widgets the way you like, and then make this frame a child of my ScrolledWindow.scrollwindow. Feel free to ask if something is unclear.
Used a lot from @ Brayan Oakley answers to close to this questions
class ScrolledWindow(tk.Frame):
"""
1. Master widget gets scrollbars and a canvas. Scrollbars are connected
to canvas scrollregion.
2. self.scrollwindow is created and inserted into canvas
Usage Guideline:
Assign any widgets as children of <ScrolledWindow instance>.scrollwindow
to get them inserted into canvas
__init__(self, parent, canv_w = 400, canv_h = 400, *args, **kwargs)
docstring:
Parent = master of scrolled window
canv_w - width of canvas
canv_h - height of canvas
"""
def __init__(self, parent, canv_w = 400, canv_h = 400, *args, **kwargs):
"""Parent = master of scrolled window
canv_w - width of canvas
canv_h - height of canvas
"""
super().__init__(parent, *args, **kwargs)
self.parent = parent
# creating a scrollbars
self.xscrlbr = ttk.Scrollbar(self.parent, orient = 'horizontal')
self.xscrlbr.grid(column = 0, row = 1, sticky = 'ew', columnspan = 2)
self.yscrlbr = ttk.Scrollbar(self.parent)
self.yscrlbr.grid(column = 1, row = 0, sticky = 'ns')
# creating a canvas
self.canv = tk.Canvas(self.parent)
self.canv.config(relief = 'flat',
width = 10,
heigh = 10, bd = 2)
# placing a canvas into frame
self.canv.grid(column = 0, row = 0, sticky = 'nsew')
# accociating scrollbar comands to canvas scroling
self.xscrlbr.config(command = self.canv.xview)
self.yscrlbr.config(command = self.canv.yview)
# creating a frame to inserto to canvas
self.scrollwindow = ttk.Frame(self.parent)
self.canv.create_window(0, 0, window = self.scrollwindow, anchor = 'nw')
self.canv.config(xscrollcommand = self.xscrlbr.set,
yscrollcommand = self.yscrlbr.set,
scrollregion = (0, 0, 100, 100))
self.yscrlbr.lift(self.scrollwindow)
self.xscrlbr.lift(self.scrollwindow)
self.scrollwindow.bind('<Configure>', self._configure_window)
self.scrollwindow.bind('<Enter>', self._bound_to_mousewheel)
self.scrollwindow.bind('<Leave>', self._unbound_to_mousewheel)
return
def _bound_to_mousewheel(self, event):
self.canv.bind_all("<MouseWheel>", self._on_mousewheel)
def _unbound_to_mousewheel(self, event):
self.canv.unbind_all("<MouseWheel>")
def _on_mousewheel(self, event):
self.canv.yview_scroll(int(-1*(event.delta/120)), "units")
def _configure_window(self, event):
# update the scrollbars to match the size of the inner frame
size = (self.scrollwindow.winfo_reqwidth(), self.scrollwindow.winfo_reqheight())
self.canv.config(scrollregion='0 0 %s %s' % size)
if self.scrollwindow.winfo_reqwidth() != self.canv.winfo_width():
# update the canvas's width to fit the inner frame
self.canv.config(width = self.scrollwindow.winfo_reqwidth())
if self.scrollwindow.winfo_reqheight() != self.canv.winfo_height():
# update the canvas's width to fit the inner frame
self.canv.config(height = self.scrollwindow.winfo_reqheight())
We can add scroll bar even without using Canvas. I have read it in many other post we can't add vertical scroll bar in frame directly etc etc. But after doing many experiment found out way to add vertical as well as horizontal scroll bar :). Please find below code which is used to create scroll bar in treeView and frame.
f = Tkinter.Frame(self.master,width=3)
f.grid(row=2, column=0, columnspan=8, rowspan=10, pady=30, padx=30)
f.config(width=5)
self.tree = ttk.Treeview(f, selectmode="extended")
scbHDirSel =tk.Scrollbar(f, orient=Tkinter.HORIZONTAL, command=self.tree.xview)
scbVDirSel =tk.Scrollbar(f, orient=Tkinter.VERTICAL, command=self.tree.yview)
self.tree.configure(yscrollcommand=scbVDirSel.set, xscrollcommand=scbHDirSel.set)
self.tree["columns"] = (self.columnListOutput)
self.tree.column("#0", width=40)
self.tree.heading("#0", text='SrNo', anchor='w')
self.tree.grid(row=2, column=0, sticky=Tkinter.NSEW,in_=f, columnspan=10, rowspan=10)
scbVDirSel.grid(row=2, column=10, rowspan=10, sticky=Tkinter.NS, in_=f)
scbHDirSel.grid(row=14, column=0, rowspan=2, sticky=Tkinter.EW,in_=f)
f.rowconfigure(0, weight=1)
f.columnconfigure(0, weight=1)