tkinter-canvas – Tarik Billa

tkinter: using scrollbars on a canvas

December 16, 2023 by Tarik

Your scrollbars need to have the Frame as a parent, not the Canvas: from tkinter import * root=Tk() frame=Frame(root,width=300,height=300) frame.pack(expand=True, fill=BOTH) #.grid(row=0,column=0) canvas=Canvas(frame,bg=’#FFFFFF’,width=300,height=300,scrollregion=(0,0,500,500)) hbar=Scrollbar(frame,orient=HORIZONTAL) hbar.pack(side=BOTTOM,fill=X) hbar.config(command=canvas.xview) vbar=Scrollbar(frame,orient=VERTICAL) vbar.pack(side=RIGHT,fill=Y) vbar.config(command=canvas.yview) canvas.config(width=300,height=300) canvas.config(xscrollcommand=hbar.set, yscrollcommand=vbar.set) canvas.pack(side=LEFT,expand=True,fill=BOTH) root.mainloop() The reason why this works is due to how pack works. By default it will attempt to shrink (or grow) a … Read more

How to bind events to Canvas items?

November 30, 2023 by Tarik

To interact with objects contained in a Canvas object you need to use tag_bind() which has this format: tag_bind(item, event=None, callback=None, add=None) The item parameter can be either a tag or an id. Here is an example to illustrate the concept: from tkinter import * def onObjectClick(event): print(‘Got object click’, event.x, event.y) print(event.widget.find_closest(event.x, event.y)) root … Read more

Tkinter canvas zoom + move/pan

September 28, 2023 by Tarik

Advanced zoom example. Like in Google Maps. Example video (longer video here): It zooms only a tile, but not the whole image. So the zoomed tile occupies constant memory and not crams it with a huge resized image for the large zooms. For the simplified zoom example look here. Tested on Windows 7 64-bit and … Read more

How to draw polygons with Python?

August 11, 2023 by Tarik

Using matplotlib.pyplot import matplotlib.pyplot as plt coord = [[1,1], [2,1], [2,2], [1,2], [0.5,1.5]] coord.append(coord[0]) #repeat the first point to create a ‘closed loop’ xs, ys = zip(*coord) #create lists of x and y values plt.figure() plt.plot(xs,ys) plt.show() # if you need…

How do I remove the light grey border around my Canvas widget?

May 1, 2023 by Tarik

Section 6.8 Why doesn’t the canvas seem to start at 0,0? of the Tk Usage FAQ describes the phenomenon. I was able to eliminate the border artefact with slight changes to the posted source… Change this: w = Canvas(master, width=150, height=40, bd=0, relief=”ridge”) w.pack() to: w = Canvas(master, width=150, height=40, bd=0, highlightthickness=0, relief=”ridge”) w.pack() and … Read more

How to clear Tkinter Canvas?

April 4, 2023 by Tarik

Every canvas item is an object that Tkinter keeps track of. If you are clearing the screen by just drawing a black rectangle, then you effectively have created a memory leak — eventually your program will crash due to the millions of items that have been drawn. To clear a canvas, use the delete method. … Read more

Why does Tkinter image not show up if created in a function?

February 3, 2023 by Tarik

The variable photo is a local variable which gets garbage collected after the class is instantiated. Save a reference to the photo, for example: self.photo = tkinter.PhotoImage(…) If you do a Google search on “tkinter image doesn’t display”, the first result is this: Why do my Tkinter images not appear? (The FAQ answer is currently … Read more