Increase Undo History Length

Faergen · April 8, 2020, 7:55am

When I try to undo a lot of strokes the undo-history seems to have gone.

I would like to increase the persistency of the history and/or the amount of input saved in the history. How do I do that?

Basic System Details

MyPaint version: 64bit 2.0.0+git.af5225a2

Operating System + Version: Windoes 10

toniw · April 8, 2020, 3:44pm

I’d also appreciate an option for this. I think, currently it’s still hard-coded to 30 and that is really not much.

There is an open issue about this to be handled dynamically here:

github.com/mypaint/mypaint

Command stack length: allow to be longer if memory allows

opened 11:23AM - 11 Apr 15 UTC

achadwick

type.Enhancement cat.UX cat.Data

User Shinmera on Twitter complains about the undo stack being too short: - https…://twitter.com/Shinmera/status/586829319470772225 - https://twitter.com/Shinmera/status/586829423674007552 - https://twitter.com/Shinmera/status/586829534026211328 I haven't quoted because there's cussing and some developer-directed rudeness in there, but the core criticism is still valid. 30 steps _is_ probably too short. Affects master at 94505b0b53fed7d429fb01d02f6e5a850c02ac5b. All systems. We have a comment in the code about using [psutil](https://github.com/giampaolo/psutil) for this: [lib/command.py:32](https://github.com/mypaint/mypaint/blob/afda9820d22dcd0d8b2072af65897eb1206375c5/lib/command.py#L32). I think this could be workable: the undo stack has a lot of churn, so that's a lot of events to hook a function that trims it to the size of available RAM minus a generous overhead as needed. There should probably be a hard upper limit of 100 or 200 steps, and a hard lower limit of one step. Best candidate appears to be `psutil.virtual_memory().available`: > ``` > - available: > the actual amount of available memory that can be given > instantly to processes that request more memory in bytes; this > is calculated by summing different memory values depending on > the platform (e.g. free + buffers + cached on Linux) and it is > supposed to be used to monitor actual memory usage in a cross > platform fashion. > ``` Might be worth profiling this first to see approximately by how much this figure might go down in a single undo step, because that's going to determine how much slack will be needed. Initially though, 256MiB seems reasonable [**EDIT**: add link to psutil, https://github.com/giampaolo/psutil ]

I personally dont see the memory problem as a valid argument for 99% of users but maybe there is a better solution that someone has in mind. I’m also not sure whether the undo stack is even one of the most memory intense components in mypaint.

I also made some (testing) modifications back in 2018 that set the limit higher and uses a deque instead of rewriting a stack manually whenever it was full. That resulted in a noticable performance boost when using high undo limits.

See the changes HERE

jpll · April 8, 2020, 6:51pm

Yeah, memory might have been more of an issue in 2009/2011, but I see no reason to leave this as a constant. At the very least it should be possible to set in the user config.

@toniw
If you don’t mind, I’ll cherry pick your first commit and then factor out the size to a parameter (and maybe increase the default to 50).

odysseywestra · April 9, 2020, 5:55am

Moved to Feature Requests and Adjusted title accordingly.

jpll · April 9, 2020, 8:41pm

Configurable undo stack size is now in the master branch, and since it involves no gui string changes it will be backported to the upcoming 2.0.1 (mostly) bugfix release. For now the size is only configurable by editing the settings.json file, but proper inputs will most likely be added for the next minor release.