Crash going from page to continuous view and then clicking on score element....

[worldwideweary]

Issue type

Crash or freeze

Bug description

Oh gosh, this one took me a while to figure out (realize that there was a problem, let alone solve it). Since I'm still on 3.7 for now this was rare but important enough under certain circumstances

The crash actually doesn't happen often (but it did happen often on one particular score I was working on when switching into continuous view. Not sure what it's contingent upon. I think it has to do with the spacing of staves and the footer/header. Anyways...

Steps to reproduce

1.) Make a score
2.) Make sure to have header/footers on
3.) Make sure to have score be filled up to an entire page to some sort, spilling into page 2
4.) Click on score elements while in continuous view after switching from page view

Now open that score in page-view, then switch to continuous view
Then attempt to select an element on the score. Odds are a crash occurs, but not always couldn't figure out what it was... The reason has something to do with a text pointer being given a parent of type "page" instead of null... when from backporting musescore#9193

I figured I'd bring this up as one of those "Obscure" 3.7 bugs.

Author: Nick Mazuk Nick-Mazuk@users.noreply.github.com 2021-09-21 00:03:03
Committer: Joachim Schmitz jojo@schmitz-digital.de 2022-05-11 23:34:48

and i'm 99% sure the culprit is that "pseudo" valid text pointer which will trigger a "valid" parent but it isn't set up so that when handling the mouse press event handler to find the elements surrounding it... it picks up sometimes this "text" that doesn't have a full setup to it, but it passes the null pointer check and then hell breaks loose later

Text* Page::layoutHeaderFooter(int area, const QString& ss) const

has this:

text->setParent((Page*) this); <-------
      Align flags = Align::LEFT;
      switch (area) {
            case 0: flags = Align::LEFT    | Align::TOP;    break;

and the text->setParent((Page*)this) needs to become

text->setParent(nullptr);

since the text has no business being attached to the score like that, from what I can tell. After setting parent to nullptr, I can't replicate the crash. Apparently in the 4.0 code they had something like text->moveToDummy();

... just in case I'm not the only one who cares about this shit..

Screenshots/Screen recordings

Here's a peculiar score demonstrating the crash

demonstration.mp4

MuseScore Version

3.7

Regression

Yes, this used to work in MuseScore 3.x and now is broken

Operating system

XFCE

Additional context

No response

[Jojo-Schmitz]

So far I've not been able to reproduce the crash, but anyway, do you mean something like #146 ?

[Jojo-Schmitz]

resolved via #146

[Jojo-Schmitz]

Apparently the fix for this caused #150

[Jojo-Schmitz]

@worldwideweary please check #151, whether that fixes the issue for you.

[Jojo-Schmitz]

Fixed via #151