Text containing "wide" character not correctly refreshed

[hejin517]

BPO	46189
Nosy	@serhiy-storchaka, @E-Paine
Files	Screenshot 2021-12-28 201447.png

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2021-12-30.08:14:48.455>
created_at = <Date 2021-12-28.15:01:14.239>
labels = ['3.8', 'type-bug', 'expert-tkinter']
title = 'Text containing "wide" character not correctly refreshed'
updated_at = <Date 2021-12-30.08:14:48.454>
user = 'https://bugs.python.org/hejin517'

bugs.python.org fields:

activity = <Date 2021-12-30.08:14:48.454>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = True
closed_date = <Date 2021-12-30.08:14:48.455>
closer = 'serhiy.storchaka'
components = ['Tkinter']
creation = <Date 2021-12-28.15:01:14.239>
creator = 'hejin517'
dependencies = []
files = ['50525']
hgrepos = []
issue_num = 46189
keywords = []
message_count = 2.0
messages = ['409258', '409271']
nosy_count = 3.0
nosy_names = ['serhiy.storchaka', 'epaine', 'hejin517']
pr_nums = []
priority = 'normal'
resolution = 'third party'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue46189'
versions = ['Python 3.8']

[hejin517]

When the app runs it first shows a black character "f" in Times New Roman.
By clicking the button, I expect that the color of the whole character will be changed to red, but actually only part is changed.

In FontForge (a font editor), I find the character "f" in Times New Roman is wider than its "width".
Please look into this problem. Thanks.

Code to reproduce:
----------------------

import tkinter

def change_color():
    canvas.itemconfig(text, fill="red")

root = tkinter.Tk()
canvas = tkinter.Canvas(root, width=500, height=500)
canvas.pack()

text = canvas.create_text((200, 200), text="f", font=("Times New Roman", 200), fill="black")

button = tkinter.Button(text="Change Color", command=change_color)
button.pack()

root.mainloop()

[E-Paine]

I have been able to reproduce this in Wish built from the current head. Interestingly, the cut-off seems to be 1px off what font measure gives (see attached). Though in this behaviour is a problem, the man page does note the following:

The return value is the total width in pixels of text, not including the extra pixels used by highly exaggerated characters such as cursive “f” [https://www.tcl.tk/man/tcl/TkCmd/font.html#M10]

Tkinter is simply a thin wrapper of Tk, so I suggest you take it up with that team so they can fix it upstream (a minimal equivalent of your code in Tcl can be found below): https://core.tcl-lang.org/tk/reportlist

pack [canvas .c -width 250 -height 500]
font create .f -family "Times New Roman" -size -500
set t [.c create text 0 250 -text f -font .f -anchor w]
update ; # A window render is required for the bug to occur
.c itemconfigure $t -fill red
set x [font measure .f f]
.c create line $x 0 $x 500