IDLE: configdialog/fonts: change font when select by key up/down

[mlouielu]

BPO	30870
Nosy	@terryjreedy, @serhiy-storchaka, @mlouielu
PRs	bpo-30870: IDLE: Change sample font when select by key-up/down #2617 [3.6] bpo-30870: IDLE: Change sample font when select by key-up/down … #2640 bpo-30870: IDLE -- fix logic error in eae2537. #2660 [3.6] bpo-30870: IDLE -- fix logic error in eae2537. (GH-2660) #2661 bpo-30870: IDLE: Add configdialog fontlist unittest #2666 [3.6] bpo-30870: IDLE: Add configdialog fontlist selection unittest (… #2701
Files	tests.py

^{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 = 'https://github.com/terryjreedy'
closed_at = <Date 2017-07-21.02:34:32.545>
created_at = <Date 2017-07-07.07:51:29.389>
labels = ['expert-IDLE', 'type-feature', '3.7']
title = 'IDLE: configdialog/fonts: change font when select by key up/down'
updated_at = <Date 2017-07-21.02:34:32.544>
user = 'https://github.com/mlouielu'

bugs.python.org fields:

activity = <Date 2017-07-21.02:34:32.544>
actor = 'terry.reedy'
assignee = 'terry.reedy'
closed = True
closed_date = <Date 2017-07-21.02:34:32.545>
closer = 'terry.reedy'
components = ['IDLE']
creation = <Date 2017-07-07.07:51:29.389>
creator = 'louielu'
dependencies = []
files = ['47006']
hgrepos = []
issue_num = 30870
keywords = []
message_count = 21.0
messages = ['297867', '298003', '298004', '298006', '298017', '298075', '298076', '298121', '298122', '298123', '298124', '298127', '298130', '298132', '298138', '298197', '298252', '298260', '298324', '298328', '298760']
nosy_count = 3.0
nosy_names = ['terry.reedy', 'serhiy.storchaka', 'louielu']
pr_nums = ['2617', '2640', '2660', '2661', '2666', '2701']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue30870'
versions = ['Python 3.6', 'Python 3.7']

[mlouielu]

Add event for KeyRelease-Up and KeyRelease-Down to change sample font.

Current code only changed font when using button-click on listbox.

[terryjreedy]

New changeset bb2bae8 by terryjreedy (Louie Lu) in branch 'master':
bpo-30870: IDLE: Change sample font when select by key-up/down (bpo-2617)
bb2bae8

[terryjreedy]

If one scrolls with the mousewheel or scrollbar, the selection does not change and the example should not change, and I presume it will not with the patch. If one presses up or down, the selection does change, just as if one clicked, and the example should change. I consider it a bug that it does not. Good catch.

[terryjreedy]

New changeset 7ab3342 by terryjreedy in branch '3.6':
[3.6] bpo-30870: IDLE: Change sample font when select by key-up/down (GH-2617) (bpo-2640)
7ab3342

[terryjreedy]

We already know that setting StringVar font_name triggers a change to changes. We also know that manually clicking or Up or Down triggers <<ListBoxSelect>>, which sets font_name and redraws the box. The challenge is to do something that will trigger the virtual event. Then we can write a test methods something like

    def test_sample(self):
        fontlist = configure.fontlist
        if fontlist.size():
            name0 = fontlist.get(0).lower()
            # fontlist.selection_set(0)  # or something
            print('\n', changes)  # temp to testing that changes changes
            self.assertEqual(changes['main']['EditorWindow']['font'], name0)
But selection_set does not trigger the event.  After fiddling around with various bindings event_generate()s and update()s and update_idletasks(), I concluded, again, that either event_generate or its documentation is badly broken.  The only thing I got to work in hours of experiments is this:

import tkinter as tk
root = tk.Tk()
seq = '<ButtonRelease-1>'
root.bind(seq, lambda event: print('generated', event))
root.update_idletasks()  # or update()
root.event_generate(seq)
# update here fails

Adding a widget and binding to the widget always failed.

Here is my attempt using Serhiy's simulate_mouse_click. (This goes in test_configdialog.FontTabTest.

    def test_sample(self):
        fontlist = configure.fontlist
        if fontlist.size():
            name0 = fontlist.get(0).lower()
            fontlist.see(0)
            x, y, dx, dy = fontlist.bbox(0)
            fontlist.bind('<ButtonRelease-1>', lambda event: print(event))
            mouse_click(fontlist, x + dx//2, y + dy//2)
            fontlist.update()
            print('\n', changes)  # temporary, see if changes has anything
            self.assertEqual(changes['main']['EditorWindow']['font'], name0)

Serhiy, do you have any idea why I cannot get event_generate to work for a listbox, even with your function? I have tried somewhere close to 20 variations.

[terryjreedy]

Serhiy, I tried tkinter.test.support.simulate_mouse_click to test this patch but it seems not to work. Code at end of previous message. Any idea on how to fix?

[serhiy-storchaka]

It isn't my. It was added by Guilherme in r69050.

I'll take a look at code tomorrow.

[serhiy-storchaka]

I don't know how to make the testing code working.

[terryjreedy]

My manual test procedure was faulty. Without a unit test, I should have asked for another person to verify.

[terryjreedy]

I believe I read somewhere (SO?) that root.withdraw sometimes affects the effectiveness of event_generate. I will try de-iconifying for just this.

[terryjreedy]

New changeset 5b62b35 by terryjreedy in branch 'master':
bpo-30870: IDLE -- fix logic error in eae2537. (bpo-2660)
5b62b35