When testing Xwayland multi-HiDPI support with Wine + SimCity4
I encountered a 100% CPU lockup from sway. This turned out to be
triggering a bug in the wlroots pointer contraint code.
region_confine() contains multiple recursive calls where arguments
are modified and resubmitted to the function. One of the calls
is however made using the original arguments, if/when this triggers
it results in the same codepath being followed each loop so the
condition always applies.
It makes much more sense if this was intended to apply the clamped
values x,y instead of the original x1,y1, and indeed this fixes the
infinite loop and results in correct behaviour.
The Wayland protocol specifies output transform rotations to be
counterclockwise and applied to the surface. Previously, wlroots
copied Weston and incorrectly made rotations act clockwise on
surfaces. This commit fixes that.
This change will break compositors which expect transform rotations
to be clockwise, and the rare applications that make use of surface
transforms.
I do not think the conversion is specifically defined, but on my system and SirCmpwn's
the floats are rounded instead of floored, which is incorrect in this case, since
for a range from 0 to 256, any value greater or equal to 0 and less than 256 is valid.
I.e. [0;256[, or 0 <= x < 256, but if x is e.g. -0.1, then it will be rounded to 0, which
is invalid. The correct behavior would be to floor to -1.
It was broken because the damage extents were rotated about its
own center, not about the center of the surface.
This adds a new wlr_region_rotated_bounds that rotates regions.
This allows us to have only one code path (for both non-rotated
views and rotated views) and optimizes rendering for rotated
views.
