[PATCH 08/18] Avoid unexpected jumps

[Chris Bagwell]

On Fri, Oct 8, 2010 at 12:22 PM, Takashi Iwai <tiwai at suse.de> wrote:
> Limit the movement size for avoiding the unexpected pointer jumps.
>

Hi Takashi,

This is type of patch I was concerned with.  Using only 1/5 distance
of touchpad to discard invalid packets seems pretty low threshold.

If we can prevent change of ABS_X/ABS_Y only at touch transitions then
we can make use of following commit to prevent unwanted jumps.

Basically, its "if (prevFinger != currentFinger) count_packet_finger = 0;".

http://cgit.freedesktop.org/xorg/driver/xf86-input-synaptics/commit/?id=a6ca4d2523904b7ce49edc29ba408979bdf0d45e

Chris

> Signed-off-by: Takashi Iwai <tiwai at suse.de>
> ---
>  src/synaptics.c    |   10 ++++++++++
>  src/synapticsstr.h |    1 +
>  2 files changed, 11 insertions(+), 0 deletions(-)
>
> diff --git a/src/synaptics.c b/src/synaptics.c
> index 3ba918a..bd52730 100644
> --- a/src/synaptics.c
> +++ b/src/synaptics.c
> @@ -467,6 +467,8 @@ static void set_default_parameters(InputInfoPtr pInfo)
>     edgeMotionMaxSpeed = diag * .080;
>     accelFactor = 200.0 / diag; /* trial-and-error */
>
> +    priv->move_ptr_threshold = width / 5;
> +
>     range = priv->maxp - priv->minp;
>
>     /* scaling based on defaults and a pressure of 256 */
> @@ -1949,6 +1951,14 @@ ComputeDeltas(SynapticsPrivate *priv, const struct SynapticsHwState *hw,
>            break;
>        }
>     }
> +
> +    if (moving_state && priv->count_packet_finger > 0 &&
> +       priv->move_ptr_threshold > 0 ) {
> +       int d = move_distance(HIST(0).x - hw->x, HIST(0).y - hw->y);
> +       if (d > priv->move_ptr_threshold)
> +           priv->count_packet_finger = 0; /* to avoid unexpected jumps */
> +    }
> +
>     if (inside_area && moving_state && !priv->palm &&
>        !priv->vert_scroll_edge_on && !priv->horiz_scroll_edge_on &&
>        !priv->vert_scroll_twofinger_on && !priv->horiz_scroll_twofinger_on &&
> diff --git a/src/synapticsstr.h b/src/synapticsstr.h
> index 44140f2..44925e5 100644
> --- a/src/synapticsstr.h
> +++ b/src/synapticsstr.h
> @@ -245,6 +245,7 @@ typedef struct _SynapticsPrivateRec
>     unsigned int clickpad_threshold;
>     int clickpad_dx, clickpad_dy;
>     struct SynapticsHwState prev_hw;   /* previous h/w state (for clickpad) */
> +    int move_ptr_threshold;
>     int prop_change_pending;
>     Bool led_touch_state;
>     Bool led_tapped;
> --
> 1.7.3.1
>
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