Overhaul navigation tools UI

[iirelu]

Splitting off from #81, relevant comment below:

Does there even need to be a discrete pan tool?

Edit: To expand upon that, I believe that from a UX perspective, there shouldn't be any navigation tools at all. All navigation related buttons should be for directly affecting the navigation, for example, zooming in and zooming out, rotating left/right by fixed amounts, resetting rotation, resetting zoom, etc. As you can tell, implementing panning as up/down/left/right buttons is massively clunky, so it's best not to do it at all.

Taking inspiration from Paint Tool SAI's design is a good idea. It's not like its patented or copyrighted, and Paint Tool SAI is one of the most popular art programs with artists for a very good reason; It's core UI principals work well. Of course, a lot if it is incredibly clunky, but the basics work, especially the bar at the top (ignore the buttons related to selections):

Undo/redo, zoom level as a drop-down, zoom in, zoom out, reset zoom, rotation as a drop-down (clunkier than zoom as a drop-down), rotate left, rotate right, reset rotation, the current view flip status, flip view, and stabiliser.

The important ones to take away from that are the zoom and rotation related ones. It's exceptionally rare to want to reset both at once (Mypaint's reset button even does position in addition), as most of the time I just want to reset the angle.

Another edit: Sorry, I'm kind of hijacking this issue as a complete overhaul of the navigation buttons but eh, whatever.

This is what Mypaint's current navigation options look like:

• Pan canvas: Discrete tool, already has TWO buttons dedicated to it (space, middle-mouse)
• Zoom canvas: Discrete tool, again already has two buttons (with a modifier this time)
• Rotate canvas: Yet another discrete tool, etc.
• Flip canvas: First actually useful one!
• Reset zoom, rotation, and mirroring: Does too much in a single button. Should be split off into reset zoom and reset rotation (no "reset mirroring", the mirroring button itself already does this as its a binary switch)
• Move view to document: This should stay in some shape or form, but not in the navigation section. It's perfectly possible to get entirely lost on an infinite grid, so this would be useful in an emergency. Otherwise, fitting the view to the document is easily done by hand.

[achadwick]

Thanks for that - there's also the four single-action "View (Alternative/Secondary)" ones on teh right button menu. Those are:

• rotate left / right one step
• zoom in/out one step

They were considered to be fairly useless to anyone other than a tablet PC (no physical keyboard) user back when they were first made, so they're off by default. But that could be changed.

Per #87 we should change up how the movement tools operate as well.

[odysseywestra]

@iirelu Could you move this thread over to https://community.mypaint.org/c/feature-requests? I'm working on cleaning up the issue tracker by move all feature requests there so we can get community feedback. If you can also set your post as a wiki that way we can edit the scope of the feature request that would be awesome as well. Don't forget to link back to here as well so I can keep track of it incase we need to reopen the issue. Thanks.