Improved user flag handling

[drossberg]

• User flags get the sha1 checksum of their image bitmap as UUID (if
  they don't already have one)
• This way, they will be recognized, if it isn't their first appearance,
  and duplicate entries in the user flag toolbar will be avoided
• Domain-specific flags can be provided with a custom installation in
  the flags/user directory

[drossberg]

Please, consider this as a suggestion.

[insilmaril]

This looks cool, thanks! I'd like to give it a bit more thought, will need some time.

[insilmaril]

Finally I thought a bit about your idea (which I really like): There is no "userflags" directory - these flags are saved in maps, also the default map, if necessary. A flag is only saved there, if used at least once.

So to apply a UUID based on file content, this should be created when loading that flag: Flag::load in flag.cpp Until an ID is created, it should be set to an invalid UID in the constructor.

Then in Main::setupFlag we could check for existing IDs of userflags.

A minor problem might be, that identical flags might have different uses for different users - later I wanted to add options to change the name or maybe even keysequence of flags. Then unique IDs might be an issue. Not sure yet how to handle this.

At the moment your patch does not work yet - I can load two identical images and they will create two identical userflags.

[drossberg]

No "userflags" directory:
That's right. This is a new feature. It's meant for domain/application specific installations where a special set of flags (e.g. Boolean operations) is needed. The default map isn't optimal to load them, although the .vym file can be hacked to not show them in the map.

Identical flags might have different uses:
I thought about adding the name to the bitmap where the checksum will be computed from, but rejected this idea, because I consider the image as the important part of the flag. However, the name could be still added to distinguish between different uses.

I can load two identical images...:
This version of the patch is "minimal invasive" and does not change the behaviour of Main::addUserFlag(). As the discussion moves on, I can improve the patch, e.g. move the computation of the UUID to Main::setupFlag() or Flag::load() (this also depends on if the name shall be considered).

[insilmaril]

**Userflags directory ** sounds useful, would be easier to maintain than a default map. Still would be interesting to store meta information somewhere, e.g. tooltip in various languages. Maybe later...

We then also would need a settings dialog and some doc, how this is supposed to work

** Identical flags ** Should be fine I guess

If you want to work this out, you are very welcome
(I'm more focusing on completely reworking the overall layout, when I find time these days)

[drossberg]

I'll work on it, when I find time ;)

[drossberg]

I updated the code with the current develop branch and added a small section to the user documentation.

[insilmaril]

Hi Daniel, sorry didn't really look into this PR yet, still struggling to get develop into a usable shape (currently the relinking multiple branches area is a bit of a mess, but will become quite nice soon I hope). Once I got this stabilized, I am going to have another look here.