IDLE: Tiny font on HiDPI display

[serhiy-storchaka]

BPO	31500
Nosy	@terryjreedy, @taleinat, @ned-deily, @serhiy-storchaka, @mlouielu, @csabella
PRs	bpo-31500: IDLE: Scale default fonts on HiDPI displays. #3639 bpo-31500: Removed fixed size of IDLE config dialog. #3664 [3.6] bpo-31500: Removed fixed size of IDLE config dialog. (GH-3664) #3665 [3.6] bpo-31500: IDLE: Scale default fonts on HiDPI displays. (GH-3639) #3686 [2.7] bpo-31500: IDLE: Scale default fonts on HiDPI displays. (GH-3639) #6585 [2.7] bpo-31500: Add idlelib news items about HiDPI scaling #10015
Files	Screenshot_20170917_213616.png configdialogkeys_old.png configdialogkeys_new.png configkey_2.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 = 'https://github.com/terryjreedy'
closed_at = <Date 2018-10-20.23:35:31.284>
created_at = <Date 2017-09-17.18:54:06.429>
labels = ['expert-IDLE', 'type-bug']
title = 'IDLE: Tiny font on HiDPI display'
updated_at = <Date 2018-10-21.09:05:30.847>
user = 'https://github.com/serhiy-storchaka'

bugs.python.org fields:

activity = <Date 2018-10-21.09:05:30.847>
actor = 'taleinat'
assignee = 'terry.reedy'
closed = True
closed_date = <Date 2018-10-20.23:35:31.284>
closer = 'terry.reedy'
components = ['IDLE']
creation = <Date 2017-09-17.18:54:06.429>
creator = 'serhiy.storchaka'
dependencies = []
files = ['47141', '47148', '47149', '47155']
hgrepos = []
issue_num = 31500
keywords = ['patch']
message_count = 32.0
messages = ['302381', '302417', '302463', '302464', '302471', '302477', '302509', '302563', '302566', '302572', '302573', '302574', '302579', '302580', '302595', '302605', '302607', '302640', '302672', '302695', '313199', '313204', '313206', '315664', '315666', '316455', '316485', '316506', '316574', '328177', '328182', '328200']
nosy_count = 6.0
nosy_names = ['terry.reedy', 'taleinat', 'ned.deily', 'serhiy.storchaka', 'louielu', 'cheryl.sabella']
pr_nums = ['3639', '3664', '3665', '3686', '6585', '10015']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue31500'
versions = ['Python 2.7']

[serhiy-storchaka]

My new laptop has a HiDPI display (3840x2160). IDLE (as well as other Tk applications) looks ugly on it. The font of menu and dialogs is tiny. The font used in editor and shell looks normal size. I use Linux with X Window.

It seems to me this issue doesn't have solution. Related links:

https://wiki.tcl.tk/41949
https://core.tcl.tk/tk/tktview/0917069c05e9c354a27c8105a7a22264090b9274
https://stackoverflow.com/questions/34132203/scaling-of-tkinter-gui-in-4k-38402160-resolution

[serhiy-storchaka]

PR 3639 adapts the receipt from [1]. I'm not sure that it doesn't add regressions on low-DPI displays.

[1] https://wiki.tcl.tk/8488

[terryjreedy]

The TkFixedFont initially used in Shell and editor has its size set to 10 if initially negative. Users can only replace this with a real font, not another of tk's abstract fonts.

On windows, the sizes of the nearly 20 fonts touched by the patch range from 8 to 12. So no possible regression there. If the sizes on Linux were in the range -8 to -12, then the effect is to replace the size with numbers around 10 instead of exactly 10 (as IDLE currently does). But from what you said on the patch, the negative numbers are not exactly the negative of their real size, but are tuned for positioning.

Cheryy, Louie, and Ned: the patch needs to be test on multiple *nix machines, especially on OSX, to make sure it does not mess up on standard monitors. A quick 'git pr 3639' and 'python -m test.test_idle' would be helpful.

[csabella]

Tests run on Ubuntu. The menubar is bigger now though, so it's default is
different than before. Maybe that was the only way to fix it, but it's now
about twice as big as the shell font.

[csabella]

Attached screen prints of configdialog. It's messed up.

[terryjreedy]

Thank you Cheryl. That is enough to reject the patch is it is now.

The negative sizes are pixels. I think it might be better to multiply them by a systems specific factor, but only when needed.

One might wish that the scaling should be handled automatically, in tkinter if not in tk itself. But it was mentioned in one of the links that displays do not always report their dpi correctly.

One possibility is a tkinter calibration app that displays a 500 or 1000 pixel line (user selects) and asks the user to input the physical length (centimeters or inches). (Some games do something similar with brightness.)

To check whether a tkinter scaling app could be used, I sized Serhiy's image so that the sample font in the Settings Font tab matched the sample font in a real box. The system font around it is tiny but readable, especially with a magnifier.

This is a tkinter issue, not only an IDLE issue, but IDLE is a good test app, with realistically complex dialogs. Lacking a Python-wide fix, something could be added to the Font tab -- for instance a dpi multiplier that defaults to one. It would only be used if not 1.0.

I reread config.IdleConf.GetFont. Rather than manipulate one of tk's default fonts ('TkFixedFont'), it creates a normal font sized in points. It uses 'TkFixedFont' as a handy key for finding a system-specific sure-to-exist fixed pitch font: "actualFont = Font.actual(f)", where f is a TkFixedFont instance. Thus it does not affect the dialogs.

It would be helpful to know if HiDPI screens on Windows have a problem.

bpo-31496 is about test_configdialog failing on the same HiDPI screen.

[serhiy-storchaka]

The Keys and General tabs are messed up even more on my computer. Some sections are just not visible. This is because The dialog window uses hardcoded size in pixels, it is too small for all content. After removing the hardcoded size all looks good.

[terryjreedy]

Cheryl, what do you get with

import tkinter as tk
root = tk.Tk()
print(float(root.tk.call('tk', 'scaling')))

If it is less than 1.2, then Serhiy's revised patch should leave config dialog as it should be.

[terryjreedy]

New changeset d6e2f26 by Terry Jan Reedy in branch 'master':
bpo-31500: Removed fixed size of IDLE config dialog. (bpo-3664)
d6e2f26

[terryjreedy]

New changeset 97be149 by Terry Jan Reedy (Miss Islington (bot)) in branch '3.6':
[3.6] bpo-31500: Removed fixed size of IDLE config dialog. (GH-3664) (bpo-3665)
97be149

[csabella]

>>> import tkinter as tk
>>> root = tk.Tk()
>>> print(float(root.tk.call('tk', 'scaling')))
1.3333333333333333