[PATCH synaptics 1/2] Don't unconditionally divide by scroll_dist_vert (#46617)

[Chase Douglas]

On 04/25/2012 08:00 PM, Peter Hutterer wrote:
> Regression introduced in cddab79c408db3b13905a2be72aff4f7bf1406f8.
> 
> If an event has a delta of less than scroll_dist_vert, the delta is
> unconditionally divided by the distance, leaving some remainder close to 0
> and never actually triggering the scroll amount.
> 
> Fix this by working with the increment, not the normalised values.
> 
> X.Org Bug 46617 <http://bugs.freedesktop.org/show_bug.cgi?id=46617>
> 
> Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
> ---
>  src/synaptics.c |   18 ++++++++----------
>  1 file changed, 8 insertions(+), 10 deletions(-)
> 
> diff --git a/src/synaptics.c b/src/synaptics.c
> index 2a43f95..0546ab9 100644
> --- a/src/synaptics.c
> +++ b/src/synaptics.c
> @@ -2864,31 +2864,29 @@ post_scroll_events(const InputInfoPtr pInfo)
>      SynapticsParameters *para = &priv->synpara;
>  
>      /* smooth scrolling uses the dist as increment */
> -    priv->scroll.delta_y /= para->scroll_dist_vert;
> -    priv->scroll.delta_x /= para->scroll_dist_horiz;
>  
> -    while (priv->scroll.delta_y <= -1.0)
> +    while (priv->scroll.delta_y <= -para->scroll_dist_vert)
>      {
>          post_button_click(pInfo, 4);
> -        priv->scroll.delta_y += 1.0;
> +        priv->scroll.delta_y += para->scroll_dist_vert;
>      }
>  
> -    while (priv->scroll.delta_y >= 1.0)
> +    while (priv->scroll.delta_y >= para->scroll_dist_vert)
>      {
>          post_button_click(pInfo, 5);
> -        priv->scroll.delta_y -= 1.0;
> +        priv->scroll.delta_y -= para->scroll_dist_vert;
>      }
>  
> -    while (priv->scroll.delta_x <= -1.0)
> +    while (priv->scroll.delta_x <= -para->scroll_dist_horiz)
>      {
>          post_button_click(pInfo, 6);
> -        priv->scroll.delta_x += 1.0;
> +        priv->scroll.delta_x += para->scroll_dist_horiz;
>      }
>  
> -    while (priv->scroll.delta_x >= 1.0)
> +    while (priv->scroll.delta_x >= para->scroll_dist_horiz)
>      {
>          post_button_click(pInfo, 7);
> -        priv->scroll.delta_x -= 1.0;
> +        priv->scroll.delta_x -= para->scroll_dist_horiz;
>      }
>  #endif
>  }

This is changing the units of the delta values from being normalized to
the button click thresholds to being based on device coordinates, right?
In which case, won't this affect things elsewhere? For example, in the
repeat_scrollbuttons() function it looks like calculations are based on
normalized button click thresholds.

It's late here though, maybe I'm reading things wrong.

-- Chase