[PATCH 12/18] Add pinch gesture support

[Chris Bagwell]

On Fri, Oct 8, 2010 at 12:22 PM, Takashi Iwai <tiwai at suse.de> wrote:
> + static void
> +handle_multi_touch_pinch(SynapticsPrivate *priv, struct SynapticsHwState *hw,
> +                        int *zoom_in, int *zoom_out)
> +{
> +    SynapticsParameters *para = &priv->synpara;
> +    int width = abs(priv->maxx - priv->minx);
> +    int dist, dist_diff, abs_diff;
> +
> +    *zoom_in = *zoom_out = 0;
> +
> +    if (hw->multi_touch <= 1 || hw->numFingers < 2 ||
> +       (priv->multi_touch_mode < MULTI_TOUCH_MODE_GESTURE &&
> +        priv->multi_touch_mode != MULTI_TOUCH_MODE_START))
> +       return; /* no multi-touch or in other mode */
> +    if (para->multi_touch_pinch_dist <= 0 ||
> +       para->multi_touch_pinch_start <= 0)
> +       return; /* pinch disabled */
> +

When I've implemented gesture logic in the past, I've ran into issues
with 2-finger scrolling and pinch zoom-out looking similar; especially
if user is scrolling in a V pattern and so moving apart as they go.

I bring this up because I didn't notice anything in patch to prevent
the older ST 2-finger scrolling logic from kicking in.  Isn't it
needed?

Also, should that numFingers < 2 be numFingers == 2 to prevent
confusion with 3 finger gesture in later patch?  Especially in 3
finger that is V pattern as well.

Chris