["python","tkinter","tkinter.scrollbar"]
Adding a scrollbar to a group of widgets in Tkinter

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!
Overview You can only associate scrollbars with a few widgets, and the root widget and Frame aren't part of that group of widgets. There are at least a couple of ways to do this. If you need a simple vertical or horizontal group of widgets, you can use a text widget and the window_create method to add widgets. This method is simple, but doesn't allow for a complex layout of the widgets. A more common general-purpose 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. Why put the widgets in a frame rather than directly in the canvas? A scrollbar attached to a canvas can only scroll items created with one of the create_ methods. You cannot scroll items added to a canvas with pack, place, or grid. By using a frame, you can use those methods inside the frame, and then call create_window once for 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, parent): tk.Frame.__init__(self, parent) self.canvas = tk.Canvas(self, borderwidth=0, background="#ffffff") self.frame = tk.Frame(self.canvas, background="#ffffff") self.vsb = tk.Scrollbar(self, 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 = Example(root) example.pack(side="top", fill="both", expand=True) root.mainloop() Procedural solution Here is a solution that doesn't use a class: 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()