Use TransitionBuilder for maximizing

[leolost2605]

Use TransitionBuilder for maximizing. While here do a bit of cleanup and drop some hacks. I checked how GNOME Shell handles the general flow and followed that a bit more:

• If we already know we won't animate, don't capture a snapshot and complete size change immediately
• Introduce a pending size change map. Now instead of having only one size change info we can have multiple pending. This is required because it sometimes happens that we have multiple size_change before size_changed and we would drop snapshots then and animate a window with a wrong snapshot
• The last one also fixes the last error in size accouting errors.
• In the actual maximize animation we can remove the hack with the FLASH_PREVENT_TIMEOUT
• By dropping the unnecessary workarounds the animation code is now the same when maximizing and unmaximizing (just like in gnome shell) so we can merge it

Fixes elementary/wingpanel#661
Fixes #2674

[lenemter]

With this branch I get this when unmaximizing:

The reason we calculate offset there is because maximized windows don't have shadows, but non-maximized do have them.

And about FLASH_PREVENT_TIMEOUT. It was needed on X11 because some gtk3 windows are so slow to redraw that it flashed in places the window texture was missing, but this doesn't happen on Wayland for some reason. Since we don't plan to support X11 anymore, 👍 from me

[leolost2605]

@lenemter thanks for the info that's really useful!

The reason we calculate offset there is because maximized windows don't have shadows, but non-maximized do have them.

I added back the offset calculation but since we have access to the window after its rects have been updated we can get the unmaximized geometry immediately from there and don't need window listener unmaximized geometry tracking. However I still kept the tracking since it will be needed anyways in #2789

I double checked with a 10 seconds animation time that both when maximizing and unmaximizing the actor and the snapshot match exactly.

Regarding the screenshot just to be sure: It was meant to illustrate the offset or did the snapshot stay after the animation finished?

[lenemter]

@leolost2605 I wanted to illustrate the incorrect offset. Sorry for the confusion

[leolost2605]

@leolost2605 I wanted to illustrate the incorrect offset. Sorry for the confusion

Ah great then this should be ready again :)

[lenemter]

Code looks good and works as expected. Great cleanup!