[Libreoffice-bugs] [Bug 138250] New: Need to apply multiple repeated keystrokes at once when lagging

[bugzilla-daemon at bugs.documentfoundation.org]

https://bugs.documentfoundation.org/show_bug.cgi?id=138250

            Bug ID: 138250
           Summary: Need to apply multiple repeated keystrokes at once
                    when lagging
           Product: LibreOffice
           Version: unspecified
          Hardware: All
                OS: All
            Status: UNCONFIRMED
          Severity: normal
          Priority: medium
         Component: LibreOffice
          Assignee: libreoffice-bugs at lists.freedesktop.org
          Reporter: eyalroz at technion.ac.il

Description:
Suppose you have some document which is "heavy" to render (because of lots of
complicated content, or because of inefficiencies/other bugs). Specifically,
suppose that the time to render (and otherwise update the app state) takes more
than the time difference between consecutive/repeated keystrokes.

This means that if you press down some key - typically, an arrow key - one of
two things can happen:

1. The app insists on rendering the result of each and every movement; the app
will update/repaint/re-render based on keystrokes farther and farther away in
the past.

2. The app notices it has a sequence of incoming keystrokes (or at least - a
sequence of incoming identical keystrokes) beyond some length. At that point it
collects the result of all of them (or all but the last few) and applies them
altogether, rendering/updating state just once for all of them. This allows
rendering/app state update to catch up with the physical typing.

Currently, and mostly, it seems LO is choosing option (1.) rather than option
(2.) If it were super-fast, then that would be an annoyance only in esoteric
cases; but I get this occasionally - at least with Impress, with Draw and with
Calc.

Steps to Reproduce:
1. Open a slow-rendering document.
2. Move through a "difficult" area in that document using keyboard scrolling

Actual Results:
Rendering as though individual intermittent keystrokes were made; typing in
"runs away" from rendering/updating

Expected Results:
App doesn't let typing "run away" like this.


Reproducible: Always


User Profile Reset: No


OpenGL enabled: Yes

Additional Info:
As explained above - "catch up" to the typing by rendering the effect of
multiple keystrokes together.

A build within which I see this:

Version: 7.0.3.1
Build ID: d7547858d014d4cf69878db179d326fc3483e082
CPU threads: 4; OS: Linux 5.2; UI render: default; VCL: gtk3
Locale: he-IL (en_IL); UI: en-US
Calc: threaded

GLX seems to be enabled. But I'll emphasize that this isn't about a particular
recent version, I've noticed this repeatedly over the years.

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