Fix bug 522430. Switching between frames should always complete.
Switching between frames sometimes fails in Krita. This happens because Krita doesn't complete frame switching if the frame it's switching to is busy. And it's often busy if the file is large. It leaves Krita in an inconsistent state: the animation timeline shows the new frame, while everything else still works with the old one.
I've added a blocking call that waits for the frame to complete its work and then switches to it.
Test Plan
Load a large animation file and try switching between frames. It always succeeds, but sometimes you have to wait a bit.
Formalities Checklist
- I confirmed this builds.
- I confirmed Krita ran and the relevant functions work.
- I tested the relevant unit tests and can confirm they are not broken. (If not possible, don't hesitate to ask for help!)
- I made sure my commits build individually and have good descriptions as per KDE guidelines.
- I made sure my code conforms to the standards set in the HACKING file.
- I can confirm the code is licensed and attributed appropriately, and that unattributed code is mine, as per KDE Licensing Policy.
- Does the patch add a user-visible feature? If yes, is there a documentation MR ready for it at Krita Documentation Repository?
Reminder: the reviewer is responsible for merging the patch, this is to ensure at the least two people can build the patch. In case a patch breaks the build, both the author and the reviewer should be contacted to fix the build. If this is not possible, the commits shall be reverted, and a notification with the reasoning and any relevant logs shall be sent to the mailing list, kimageshop@kde.org.