On Tue, Nov 01, 2016 at 11:45:25AM -0700, Jason Gerecke wrote:
> Cursor (puck) devices are typically left on the sensor and can emit
> spurious events that can potentially cause the driver to steal "active"
> status from another tool. In the past we'd only considered the case where
> the active tool was a touch but it is reasonable to extend this logic to
> other tool types. If a cursor emits a spurious event in the middle of a
> pen dragging, for example, the drag will momentarily stop as the pen is
> temporarily sent out of prox -- with potentially disasterous results.
> Additionally, when the pen "returns" in prox on the next event, any
> currently-applied pressure will be taken as the preload and result in
> incorrect pressure scaling until the pen is removed from contact.
>
> This commit removes the "IsTouch" conditions from the handling of
> spurious cursor events in check_arbitrated_control. The result is that a
> cursor will not be granted "active" status in preference to any other
> tool (and will drop "active" status if gained after 100ms and while
> no buttons are pressed).
>
> Signed-off-by: Jason Gerecke <jason.gere...@wacom.com>
Reviewed-by: Peter Hutterer <peter.hutte...@who-t.net>
Cheers,
Peter
> ---
> src/wcmCommon.c | 27 ++++++++++++++++++---------
> 1 file changed, 18 insertions(+), 9 deletions(-)
>
> diff --git a/src/wcmCommon.c b/src/wcmCommon.c
> index 4fbe775..1471fa5 100644
> --- a/src/wcmCommon.c
> +++ b/src/wcmCommon.c
> @@ -854,29 +854,38 @@ static Bool check_arbitrated_control(InputInfoPtr
> pInfo, WacomDeviceStatePtr ds)
>
> if (IsPad(priv)) {
> /* Pad may never be the "active" pointer controller */
> + DBG(6, priv, "Event from pad; not yielding pointer control\n.");
> return FALSE;
> }
>
> if (active == NULL || active->oldState.device_id == ds->device_id) {
> - DBG(11, priv, "Same device ID as active; allowing access.\n");
> + DBG(11, priv, "Event from active device; maintaining pointer
> control.\n");
> return TRUE;
> }
> - else if (IsCursor(active) && IsTouch(priv)) {
> - /* Cursor devices are often left idle in range, so allow touch
> to
> - * grab control if the tool has not been used for some time.
> + else if (IsCursor(active)) {
> + /* Cursor devices are often left idle in range, so allow other
> devices
> + * to grab control if the tool has not been used for some time.
> */
> - return (ds->time - active->oldState.time > 100) &&
> !active->oldState.buttons;
> + Bool yield = (ds->time - active->oldState.time > 100) &&
> !active->oldState.buttons;
> + DBG(6, priv, "Currently-active cursor %s idle; %s pointer
> control.\n",
> + yield ? "is" : "is not", yield ? "yielding" : "not
> yielding");
> + return yield;
> }
> - else if (IsTouch(active) && IsCursor(priv)) {
> + else if (IsCursor(priv)) {
> /* An otherwise idle cursor may still occasionally jitter and
> send
> - * events while the user is making active touches. Do not allow
> - * the cursor to grab control in this particular case.
> + * events while the user is actively using other tools or
> touching
> + * the device. Do not allow the cursor to grab control in this
> + * particular case.
> */
> + DBG(6, priv, "Event from non-active cursor; not yielding
> pointer control.\n");
> return FALSE;
> }
> else {
> /* Non-touch input has priority over touch in general */
> - return !IsTouch(priv);
> + Bool yield = !IsTouch(priv);
> + DBG(6, priv, "Event from non-active %s device; %s pointer
> control.\n",
> + yield ? "non-touch" : "touch", yield ? "yielding" : "not
> yielding");
> + return yield;
> }
> }
>
> --
> 2.10.1
>
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