backends/native: Fix relative motion calculation if monitor isn't found

The method `relative_motion_across_outputs` is used to adjust the
distance/delta of a mouse movement across multiple monitors to take the
different scale factors of those monitors into account. This works by
getting the adjacent monitors that the movement-line/vector intersects
with and adjusting the final position (or end point of the
movement-line) by multiplying the parts of the line spanning across
different monitors with the scale factors of those monitors.

In the end of this calculation, we always want to set the new end
coordinates of the relative motion to the new end coordinates of the
adjusted movement-line. We currently only do that if all adjacent
monitors the line is crossing actually exist, because only then we end
up inside the "We reached the dest logical monitor" else-block and set
`x` and `y` to the correct values. Fix that and make sure the returned
values are also correct in case an adjacent monitor doesn't exist by
adding separate `target_x` and `target_y` variables which we update during
each pass of the while loop so we're always prepared for the while loop
exiting before the destination monitor was found.

Thanks to Axel Kittenberger for reporting the initial bug and tracking
the issue down to `relative_motion_across_outputs`.

Fixes https://gitlab.gnome.org/GNOME/mutter/issues/774
This commit is contained in:
Jonas Dreßler 2019-12-08 12:02:51 +01:00 committed by Georges Basile Stavracas Neto
parent 84ea4ad990
commit c4fa30ac7d

View File

@ -227,6 +227,7 @@ relative_motion_across_outputs (MetaMonitorManager *monitor_manager,
{
MetaLogicalMonitor *cur = current;
float x = cur_x, y = cur_y;
float target_x = cur_x, target_y = cur_y;
float dx = *dx_inout, dy = *dy_inout;
MetaDisplayDirection direction = -1;
@ -256,6 +257,9 @@ relative_motion_across_outputs (MetaMonitorManager *monitor_manager,
{ cur->rect.x + cur->rect.width, cur->rect.y + cur->rect.height }
};
target_x = motion.b.x;
target_y = motion.b.y;
if (direction != META_DISPLAY_RIGHT &&
meta_line2_intersects_with (&motion, &left, &intersection))
direction = META_DISPLAY_LEFT;
@ -269,12 +273,8 @@ relative_motion_across_outputs (MetaMonitorManager *monitor_manager,
meta_line2_intersects_with (&motion, &bottom, &intersection))
direction = META_DISPLAY_DOWN;
else
{
/* We reached the dest logical monitor */
x = motion.b.x;
y = motion.b.y;
break;
}
/* We reached the dest logical monitor */
break;
x = intersection.x;
y = intersection.y;
@ -285,8 +285,8 @@ relative_motion_across_outputs (MetaMonitorManager *monitor_manager,
cur, direction);
}
*dx_inout = x - cur_x;
*dy_inout = y - cur_y;
*dx_inout = target_x - cur_x;
*dy_inout = target_y - cur_y;
}
static void