问题
I am using Python to parse entries from a log file, and display the entry contents using Tkinter and so far it\'s been excellent. The output is a grid of label widgets, but sometimes there are more rows than can be displayed on the screen. I\'d like to add a scrollbar, which looks like it should be very easy, but I can\'t figure it out.
The documentation implies that only the List, Textbox, Canvas and Entry widgets support the scrollbar interface. None of these appear to be suitable for displaying a grid of widgets. It\'s possible to put arbitrary widgets in a Canvas widget, but you appear to have to use absolute co-ordinates, so I wouldn\'t be able to use the grid layout manager?
I\'ve tried putting the widget grid into a Frame, but that doesn\'t seem to support the scrollbar interface, so this doesn\'t work:
mainframe = Frame(root, yscrollcommand=scrollbar.set)
Can anyone suggest a way round this limitation? I\'d hate to have to rewrite in PyQt and increase my executable image size by so much, just to add a scrollbar!
回答1:
Overview
You can only associate scrollbars with a few widgets, and the root widget and Frame
aren't part of that group of widgets.
The most common solution is to create a canvas widget and associate the scrollbars with that widget. Then, into that canvas embed the frame that contains your label widgets. Determine the width/height of the frame and feed that into the canvas scrollregion
option so that the scrollregion exactly matches the size of the frame.
Drawing the text items directly on the canvas isn't very hard, so you might want to reconsider that approach if the frame-embedded-in-a-canvas solution seems too complex. Since you're creating a grid, the coordinates of each text item is going to be very easy to compute, especially if each row is the same height (which it probably is if you're using a single font).
For drawing directly on the canvas, just figure out the line height of the font you're using (and there are commands for that). Then, each y coordinate is row*(lineheight+spacing)
. The x coordinate will be a fixed number based on the widest item in each column. If you give everything a tag for the column it is in, you can adjust the x coordinate and width of all items in a column with a single command.
Object-oriented solution
Here's an example of the frame-embedded-in-canvas solution, using an object-oriented approach:
import tkinter as tk
class Example(tk.Frame):
def __init__(self, root):
tk.Frame.__init__(self, root)
self.canvas = tk.Canvas(root, borderwidth=0, background="#ffffff")
self.frame = tk.Frame(self.canvas, background="#ffffff")
self.vsb = tk.Scrollbar(root, orient="vertical", command=self.canvas.yview)
self.canvas.configure(yscrollcommand=self.vsb.set)
self.vsb.pack(side="right", fill="y")
self.canvas.pack(side="left", fill="both", expand=True)
self.canvas.create_window((4,4), window=self.frame, anchor="nw",
tags="self.frame")
self.frame.bind("<Configure>", self.onFrameConfigure)
self.populate()
def populate(self):
'''Put in some fake data'''
for row in range(100):
tk.Label(self.frame, text="%s" % row, width=3, borderwidth="1",
relief="solid").grid(row=row, column=0)
t="this is the second column for row %s" %row
tk.Label(self.frame, text=t).grid(row=row, column=1)
def onFrameConfigure(self, event):
'''Reset the scroll region to encompass the inner frame'''
self.canvas.configure(scrollregion=self.canvas.bbox("all"))
if __name__ == "__main__":
root=tk.Tk()
Example(root).pack(side="top", fill="both", expand=True)
root.mainloop()
Procedural solution
Here is a solution that doesn't use objects:
import tkinter as tk
def populate(frame):
'''Put in some fake data'''
for row in range(100):
tk.Label(frame, text="%s" % row, width=3, borderwidth="1",
relief="solid").grid(row=row, column=0)
t="this is the second column for row %s" %row
tk.Label(frame, text=t).grid(row=row, column=1)
def onFrameConfigure(canvas):
'''Reset the scroll region to encompass the inner frame'''
canvas.configure(scrollregion=canvas.bbox("all"))
root = tk.Tk()
canvas = tk.Canvas(root, borderwidth=0, background="#ffffff")
frame = tk.Frame(canvas, background="#ffffff")
vsb = tk.Scrollbar(root, orient="vertical", command=canvas.yview)
canvas.configure(yscrollcommand=vsb.set)
vsb.pack(side="right", fill="y")
canvas.pack(side="left", fill="both", expand=True)
canvas.create_window((4,4), window=frame, anchor="nw")
frame.bind("<Configure>", lambda event, canvas=canvas: onFrameConfigure(canvas))
populate(frame)
root.mainloop()
Note: to make this work in python 2.x, use Tkinter
rather than tkinter
in the import statement
回答2:
Make it scrollable
Use this handy class to make scrollable the frame containing your widgets . Follow these steps:
- create the frame
- display it (pack, grid, etc)
- make it scrollable
- add widgets inside it
- call the update() method
import tkinter as tk
from tkinter import ttk
class Scrollable(tk.Frame):
"""
Make a frame scrollable with scrollbar on the right.
After adding or removing widgets to the scrollable frame,
call the update() method to refresh the scrollable area.
"""
def __init__(self, frame, width=16):
scrollbar = tk.Scrollbar(frame, width=width)
scrollbar.pack(side=tk.RIGHT, fill=tk.Y, expand=False)
self.canvas = tk.Canvas(frame, yscrollcommand=scrollbar.set)
self.canvas.pack(side=tk.LEFT, fill=tk.BOTH, expand=True)
scrollbar.config(command=self.canvas.yview)
self.canvas.bind('<Configure>', self.__fill_canvas)
# base class initialization
tk.Frame.__init__(self, frame)
# assign this obj (the inner frame) to the windows item of the canvas
self.windows_item = self.canvas.create_window(0,0, window=self, anchor=tk.NW)
def __fill_canvas(self, event):
"Enlarge the windows item to the canvas width"
canvas_width = event.width
self.canvas.itemconfig(self.windows_item, width = canvas_width)
def update(self):
"Update the canvas and the scrollregion"
self.update_idletasks()
self.canvas.config(scrollregion=self.canvas.bbox(self.windows_item))
Usage example
root = tk.Tk()
header = ttk.Frame(root)
body = ttk.Frame(root)
footer = ttk.Frame(root)
header.pack()
body.pack()
footer.pack()
ttk.Label(header, text="The header").pack()
ttk.Label(footer, text="The Footer").pack()
scrollable_body = Scrollable(body, width=32)
for i in range(30):
ttk.Button(scrollable_body, text="I'm a button in the scrollable frame").grid()
scrollable_body.update()
root.mainloop()
来源:https://stackoverflow.com/questions/3085696/adding-a-scrollbar-to-a-group-of-widgets-in-tkinter