GSoC 2018: Score Comparison Tool — Week 12

Hello!

In my last blog post I wrote about things that need to be finished to consider the score comparison tool in its basic version be complete. In general, those points I mentioned in that post were accomplished during this week. So the key changes are:
1. Read-only mode for scores
This was implemented for the purpose of being used for the versions comparison feature. The implemented read-only mode is far from being perfect and certainly lacks any user-visible signal of being applied but it is able to prevent user from editing a read-only score. Technically, user can edit the read-only score but it reverts every operation that is done on it. Undoing/redoing operations and saving the score to the file from which it was loaded are also disabled when read-only mode is active.
2. Comparison of most recent versions of the score
Currently MuseScore creates some backup copies of the scores being processed during the working session. They can be used to offer users a possibility to compare them with the current version of the score to view results of some recent work. The score comparison tool now offers up to three versions of each score to be compared: the currently displayed, the last saved version and the version of the score at the working session start. All versions except the most recent one are opened in read-only mode.
3. Handle voice changes and position shifts in score diff
Now voices changes are handled more correctly so more precise information on voice changes can be offered to user.
4. Add command-line options for viewing score diff
This can be useful for various automation purposes as well as for performing a brief scores comparison without launching a full MuseScore application.

Next week will be devoted to preparing a pull request on the changes that were made and fixing various errors if any will be found. Some work could also be needed on updating my first large pull request concerning MSCX format changes.

Thank you,
Dmitri Ovodok