On Wed, Feb 12, 2014 at 11:02 AM, Egbert Eich <e...@freedesktop.org> wrote:
> From: Egbert Eich <e...@suse.com>
>
> Worn out pens have an initial pressure != 0. If this condition happens
> 3 consecutive times warn about it. If the condition doesn't persist,
> also notify.
> This condition may also occur intermittently on abusive operation.
>
> Signed-off-by: Egbert Eich <e...@suse.com>
> ---
> src/wcmCommon.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 55 insertions(+)
>
> diff --git a/src/wcmCommon.c b/src/wcmCommon.c
> index 9b83e72..ec7ea7e 100644
> --- a/src/wcmCommon.c
> +++ b/src/wcmCommon.c
> @@ -1124,6 +1124,60 @@ setPressureButton(const WacomDevicePtr priv, const
> WacomDeviceState *ds)
> return buttons;
> }
>
> +/*
> + * Broken pen with a broken tip might give high pressure values
> + * all the time. The following counter count the number of time a high
> prox-in
> + * pressure is detected. As soon as a low pressure event is received, the
> + * value is reset to 0.
> + */
> +static int highProxInPressureCounter = 0;
> +#define LIMIT_HIGH_PRESSURE_COUNTER 3
> +#define LIMIT_LOW_PRESSURE 40 /* percentage of max value */
You could probably increase the first and decrease the latter and
still maintain accuracy. A LIMIT_LOW_PRESSURE of 20 would catch more
pens that are beginning to go bad, and as long of
LIMIT_HIGH_PRESSURE_COUNTER were increased you shouldn't really see an
increase in false-positives (10 consecutive high-pressure events, for
instance, would filter all but the most pathological cases of repeated
"jabs") or decrease in false-negatives (from what I understand, the
reported "zero pressure" value simply drifts up as the pen wears).
> +
> +
> +static void detectPressureIssue(WacomDevicePtr priv,
> + WacomCommonPtr common,
> + WacomDeviceStatePtr ds)
> +{
> + int serial = ds->serial_num;
> + int pressureThreshold = common->wcmMaxZ * LIMIT_LOW_PRESSURE / 100;
> +
> + /* detect broken pens which always have high tip pressure */
> + if (!priv->oldProximity)
> + {
> + if (ds->pressure > pressureThreshold)
> + {
> + highProxInPressureCounter++;
> +
> + /* seen enough high prox-in pressure events? */
> + if (highProxInPressureCounter ==
> LIMIT_HIGH_PRESSURE_COUNTER)
> + {
> + LogMessageVerbSigSafe(
> + X_WARNING, 0,
> + "%s(%u) has seen an initial pressure
> (%d) %d times "
> + "which is too close to the maximum
> value (%d). "
> + "Time to change your tool. \n",
> + priv->pInfo->name, serial,
> ds->pressure,
> + highProxInPressureCounter,
> + common->wcmMaxZ);
I second Peter's suggestion for a wiki link here. Its an elegant way
to effectively communicate the condition.
> + }
> + }
> + }
> + /* got a low pressure event? Then the pen is maybe not broken, in
> fact. */
> + if (ds->pressure < pressureThreshold && ds->pressure != 0) {
> + /* printed a "broken pen" warning before? */
> + if (highProxInPressureCounter >= LIMIT_HIGH_PRESSURE_COUNTER)
> + LogMessageVerbSigSafe(
> + X_WARNING, 0,
> + "Tool %s(%u) maybe not broken, "
> + "even after %d times high prox-in pressure.\n",
> + priv->pInfo->name, serial,
> highProxInPressureCounter);
> +
I would remove this if-statement and the associated log message
entirely. On the odd chance the user is looking at the logs in the
first place, an "oops, I might be wrong" message isn't exactly
enlightening :D
> + /* restart counter game */
> + highProxInPressureCounter = 0;
> + }
> +}
> +
> static void commonDispatchDevice(WacomCommonPtr common, unsigned int channel,
> const WacomChannelPtr pChannel,
> enum WacomSuppressMode suppress)
> @@ -1206,6 +1260,7 @@ static void commonDispatchDevice(WacomCommonPtr common,
> unsigned int channel,
>
> if ((IsPen(priv) || IsTouch(priv)) && common->wcmMaxZ)
> {
> + detectPressureIssue(priv, common, &filtered);
> priv->minPressure = rebasePressure(priv, &filtered);
> filtered.pressure = normalizePressure(priv, &filtered);
> if (IsPen(priv))
> --
> 1.8.1.4
>
>
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