All seat operations except "down" eat the button pressed event and don't send
it to clients. Thus, when ending such seat operations we shouldn't send the
button released event.
This commit moves the logic used to send pressed/released into the "down"
operation.
For example, create layout V[view view view] and resize the leftmost
view using mod+rightclick. Previously, the edge between view 2 and 3
would be adjusted as well. Now this edge will remain constant, which
matches the behaviour of i3.
To do this operation correctly, the resize tiling seatop now keeps track
of two containers, as the container that resizes horizontally will be a
different container to the one which resizes vertically (one will be an
ancestor). The tiling resize seatop now figures out these containers
during the start of the operation and keeps references to them in the
event. A new function container_find_resize_parent has been introduced
to do this. This function is also used by the resize command.
During cursor motion, the seatop logic is similar to before, but now has
to choose the correct container to resize.
In resize.c, container_resize_tiled and resize_tiled have been merged
into one. One of them originally did nothing except pass the values
through to the other.
container_resize_tiled now takes a simplified approach where it just
finds the immediate siblings on either side and resizes them without
worrying about the others. The parellel_coord and parallel_size
functions are no longer needed and have been removed.
This splits each seat operation (drag/move tiling/floating etc) into a
separate file and introduces a struct sway_seatop_impl to abstract the
operation.
The move_tiling_threshold operation has been merged into move_tiling.
The main logic for each operation is untouched aside from variable
renames.
The following previously-static functions have been made public:
* node_at_coords
* container_raise_floating
* render_rect
* premultiply_alpha
* scale_box
