dix: fix scale_to_desktop for edge ABS events

Scale_to_desktop() converts ABS events from device coordinates
to screen coordinates:
[dev_X_min, dev_X_max]  -> [screen_X_min, screen_X_max]
[dev_Y_min, dev_Y_max]  -> [screen_Y_min, screen_Y_max]

An edge ABS event with X = dev_X_max (e.g., generated from the
edge of a touchscreen) will be converted to have screen X value
= screen_X_max, which, however, will be filterd out when xserver
tries to find proper Window to receive the event, because the
range check for a Window to receive events is
       window_X_min <= event_screen_X < window_X_max
Events with event_screen_X = screen_X_max will fail the test get
and rejected by the Window.

To fix this, we change the device to screen coordinates mapping to
[dev_X_min, dev_X_max]  -> [screen_X_min, screen_X_max-1]
[dev_Y_min, dev_Y_max]  -> [screen_Y_min, screen_Y_max-1]

Reviewed-by: Chase Douglas <chase.douglas@canonical.com>
Reviewed-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com>
Signed-off-by: Yufeng Shen <miletus@chromium.org>
Signed-off-by: Keith Packard <keithp@keithp.com>

0 files changed, 0 insertions, 0 deletions