https://bugs.kde.org/show_bug.cgi?id=409867
Bug ID: 409867
Summary: KTimeComboBox may not allow valid time entry,
depending on format (timeFormatToInputMask() too
fragile)
Product: frameworks-kwidgetsaddons
Version: 5.60.0
Platform: Other
OS: All
Status: REPORTED
Severity: normal
Priority: NOR
Component: general
Assignee: cf...@kde.org
Reporter: chea...@gmail.com
CC: kdelibs-b...@kde.org
Target Milestone: ---
KTimeComboBox extends QLineEdit for time entry, using the inputMask property to
set an input mask so users only need to type digits:
https://doc.qt.io/qt-5/qlineedit.html#inputMask-prop
Typically, it is used to enter a short time (hours and minutes only). Very
often, the format is "23:59". For that, the simple input mask "09:99" works.
Very often though, the format is more complicated. For example, "11:59 PM".
Unfortunately, as can be seen in the Formats panel of systemsettings (in
Regional parameters), there are numerous short time formats possible. As a
result, rather than having a mapping of each possible format to each
corresponding input mask, KTimeComboBox uses a rather complicated algorithm
implemented in KTimeComboBoxPrivate::timeFormatToInputMask(). Unfortunately,
that algorithm is fragile (in my book, it's a hack), as the "TODO" at the top
acknowledges.
Following the change of the fr_CA sublocale's short time format from the
standard "23:59" to the much more particular "23 h 59", the generated input
mask is "09 h 99", which is incorrect, since:
1. "h" is a special character for a position with a "Hexadecimal character
permitted but not required". This position is therefore initialized to the
blank character, which is " ". The field therefore has 7 characters, but on the
third, "h" cannot be entered (only 0-9 and A-F).
2. If I understand correctly, the "blank character" being the space, all spaces
are removed after input. This means the 3 consecutive spaces in the middle are
removed, so if the field contains "12 34", the text value must be "1234",
which is absolutely invalid. I am not entirely sure about this though, as the
"11:59 PM" should also have a problem with the space, yet it works, and the
documentation of QLineEdit's inputMask property is poor (I filed
https://bugreports.qt.io/browse/QTBUG-77063 which requests improvement).
One avenue to fix would be to change QLocale again and switch fr_CA back to
"23:59", and this is under discussion:
https://unicode-org.atlassian.net/browse/CLDR-8503
But this would only help fr_CA, and timeFormatToInputMask() should not be so
sensitive in any case. On the KTimeComboBox side, as a minimum, a broken mask
should never be returned.
One way this could probably be achieved is by escaping all characters from the
initial mask. For this to work, it would need to be verified that if a
backslash precedes a non-special character in QLineEdit's inputMask, the
backslash is just ignored. So for example, if we start from "12:34 PM", this
would be escaped to "\1\2\:\3\4\ \P\M".
But this would complicate the substitutions, which would need to replace
escaped sequences (hours, minutes, seconds and AM/PM) by corresponding special
characters. So for example, mask could evolve as follows:
12:34 PM
\1\2\:\3\4\ \P\M
09\:\3\4\ \P\M
09\:99\ \P\M
09\:99\ aa
This may cause issues with non-latin digits, but I must say that if the
function is supposed to already support non-latin digits, I am not sure it does
well.
I am filing this at normal severity, but I will file a more severe report
against incidenceeditor, as the combination of issues creates a severe symptom
for KOrganizer.
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