Add DeJitter functionality to Wacom driver and update documentation

include/wacom-properties.h

@@ -122,4 +122,13 @@
 #define WACOM_PROP_XI_TYPE_PAD    "PAD"
 #define WACOM_PROP_XI_TYPE_TOUCH  "TOUCH"
 
+/* BOOL, 1 value */
+#define WACOM_PROP_DEJITTER_ENABLED "Wacom DeJitter Enabled"
+
+/* 32 bit, 1 value */
+#define WACOM_PROP_DEJITTER_THRESHOLD "Wacom DeJitter Threshold"
+
+/* 32 bit, 1 value */
+#define WACOM_PROP_DEJITTER_TIME_THRESHOLD "Wacom DeJitter Time Threshold"
+
 #endif

man/xsetwacom.man

@@ -97,6 +97,21 @@ device's native orientation, regardless of the actual rotation currently
 applied. Input outside of these coordinates will be clipped to the edges
 of the area defined.  Default:  0 0 x2 y2; with x2 and y2 tablet specific.
 .TP
+\fBDeJitterEnable\fR on|off
+Enable or disable the de-jittering feature. When enabled, the device will
+attempt to suppress small, erratic movements based on the thresholds defined
+below. Default: off.
+.TP
+\fBDeJitterThreshold\fR distance
+Set the spatial threshold for de-jittering in device units. Movements below
+this distance will be suppressed if de-jittering is enabled. Default: 150,
+range: 0 to 1000.
+.TP
+\fBDeJitterTimeThreshold\fR milliseconds
+Set the time threshold for de-jittering in milliseconds. Movements that occur
+within this time and below the spatial threshold will be suppressed. Default:
+100 ms, range: 0 to 10000 ms.
+.TP
 \fBResetArea
 Set the tablet input area to the default set.
 The set is defined device's native orientation, regardless of the actual rotation currently

src/wcmCommon.c

@@ -880,6 +880,58 @@ void wcmSendEvents(WacomDevicePtr priv, const WacomDeviceState* ds)
 		wcmAxisSet(&axes, WACOM_AXIS_PRESSURE, ds->pressure);
 	}
 
+	bool supressing = false;
+	if (priv->wcmDejitterEnabled)
+	{
+		CARD32 now = GetTimeInMillis();
+		const int Thresh = priv->wcmDejitterThreshold == 0 ? 150 : priv->wcmDejitterThreshold;
+		const int TimeThresh = priv->wcmDejitterTimeThreshold == 0 ? 100 : priv->wcmDejitterTimeThreshold;
+		if (ds->buttons > 0)
+		{
+			if (priv->dejitterState.is_suppresed)
+			{
+				int dx = priv->dejitterState.x - x;
+				int dy = priv->dejitterState.y - y;
+				if (now < priv->dejitterState.suppress_start + TimeThresh &&
+					dx * dx + dy * dy < Thresh * Thresh)
+				{
+					DBG(10, priv, "suppressing\n");
+					x = priv->dejitterState.x;
+					y = priv->dejitterState.y;
+					wcmAxisSet(&axes, WACOM_AXIS_X, x);
+					wcmAxisSet(&axes, WACOM_AXIS_Y, y);
+					supressing = true;
+				}
+			}
+			else
+			{
+				DBG(10, priv, "start suppressing\n");
+				priv->dejitterState.is_suppresed = true;
+				priv->dejitterState.x = x;
+				priv->dejitterState.y = y;
+				priv->dejitterState.suppress_start = now;
+			}
+		}
+		else
+		{
+			if (priv->dejitterState.is_suppresed)
+			{
+				DBG(10, priv, "stop suppressing\n");
+				priv->dejitterState.is_suppresed = false;
+				int dx = priv->dejitterState.x - x;
+				int dy = priv->dejitterState.y - y;
+				if (now < priv->dejitterState.suppress_start + TimeThresh &&
+					dx * dx + dy * dy < Thresh * Thresh)
+				{
+					x = priv->dejitterState.x;
+					y = priv->dejitterState.y;
+					wcmAxisSet(&axes, WACOM_AXIS_X, x);
+					wcmAxisSet(&axes, WACOM_AXIS_Y, y);
+				}
+			}
+		}
+	}
+
 	if (type == PAD_ID)
 	{
 		wcmAxisSet(&axes, WACOM_AXIS_STRIP_X, ds->stripx);
@@ -925,28 +977,31 @@ void wcmSendEvents(WacomDevicePtr priv, const WacomDeviceState* ds)
 		ds->proximity, dump, id, serial, is_button ? "true" : "false",
 		ds->buttons);
 
-	/* when entering prox, replace the zeroed-out oldState with a copy of
-	 * the current state to prevent jumps. reset the prox and button state
-	 * to zero to properly detect changes.
-	 */
-	if(!priv->oldState.proximity)
+	if (!supressing)
 	{
-		int old_key_state = priv->oldState.keys;
-
-		wcmUpdateOldState(priv, ds, x, y);
-		priv->oldState.proximity = 0;
-		priv->oldState.buttons = 0;
-
-		/* keys can happen without proximity */
-		priv->oldState.keys = old_key_state;
-	}
-
-	if (type == PAD_ID)
-		wcmSendPadEvents(priv, ds, &axes);
-	else {
-		/* don't move the cursor if in gesture mode (except drag mode) */
-		if ((type != TOUCH_ID) || wcmTouchNeedSendEvents(priv->common))
+	  /* when entering prox, replace the zeroed-out oldState with a copy of
+		* the current state to prevent jumps. reset the prox and button state
+		* to zero to properly detect changes.
+		*/
+	  if (!priv->oldState.proximity)
+	  {
+		 int old_key_state = priv->oldState.keys;
+
+		 wcmUpdateOldState(priv, ds, x, y);
+		 priv->oldState.proximity = 0;
+		 priv->oldState.buttons = 0;
+
+		 /* keys can happen without proximity */
+		 priv->oldState.keys = old_key_state;
+	  }
+
+	  if (type == PAD_ID)
+		 wcmSendPadEvents(priv, ds, &axes);
+	  else {
+		 /* don't move the cursor if in gesture mode (except drag mode) */
+		 if ((type != TOUCH_ID) || wcmTouchNeedSendEvents(priv->common))
 			wcmSendNonPadEvents(priv, ds, &axes);
+	  }
 	}
 
 	if (ds->proximity)

src/x11/xf86WacomProperties.c

@@ -61,6 +61,9 @@ static Atom prop_panscroll_threshold;
 #ifdef DEBUG
 static Atom prop_debuglevels;
 #endif
+static Atom prop_dejitter_enabled;
+static Atom prop_dejitter_threshold;
+static Atom prop_dejitter_time_threshold;
 
 /**
  * Calculate a user-visible pressure level from a driver-internal pressure
@@ -295,6 +298,15 @@ void InitWcmDeviceProperties(WacomDevicePtr priv)
 	prop_debuglevels = InitWcmAtom(pInfo->dev, WACOM_PROP_DEBUGLEVELS, XA_INTEGER, 8, 2, values);
 #endif
 
+	values[0] = priv->wcmDejitterEnabled;
+	prop_dejitter_enabled = InitWcmAtom(pInfo->dev, WACOM_PROP_DEJITTER_ENABLED, XA_INTEGER, 8, 1, values);
+
+	values[0] = priv->wcmDejitterThreshold;
+	prop_dejitter_threshold = InitWcmAtom(pInfo->dev, WACOM_PROP_DEJITTER_THRESHOLD, XA_INTEGER, 32, 1, values);
+
+	values[0] = priv->wcmDejitterTimeThreshold;
+	prop_dejitter_time_threshold = InitWcmAtom(pInfo->dev, WACOM_PROP_DEJITTER_TIME_THRESHOLD, XA_INTEGER, 32, 1, values);
+
 	XIRegisterPropertyHandler(pInfo->dev, wcmSetProperty, wcmGetProperty, wcmDeleteProperty);
 }
 
@@ -945,6 +957,42 @@ static int wcmSetProperty(DeviceIntPtr dev, Atom property, XIPropertyValuePtr pr
 
 		if (!checkonly)
 			common->wcmPanscrollThreshold = values[0];
+	} else if (property == prop_dejitter_enabled)
+	{
+		CARD8 *values = (CARD8*)prop->data;
+
+		if (prop->size != 1 || prop->format != 8)
+			return BadValue;
+
+		if ((values[0] != 0) && (values[0] != 1))
+			return BadValue;
+
+		if (!checkonly && priv->wcmDejitterEnabled != values[0])
+			priv->wcmDejitterEnabled = values[0];
+	} else if (property == prop_dejitter_threshold)
+	{
+		INT32 *values = (INT32*)prop->data;
+
+		if (prop->size != 1 || prop->format != 32)
+			return BadValue;
+
+		if (values[0] > 1000)
+			return BadValue;
+
+		if (!checkonly && priv->wcmDejitterThreshold != values[0])
+			priv->wcmDejitterThreshold = values[0];
+	} else if (property == prop_dejitter_time_threshold)
+	{
+		INT32 *values = (INT32*)prop->data;
+
+		if (prop->size != 1 || prop->format != 32)
+			return BadValue;
+
+		if (values[0] > 10000)
+			return BadValue;
+
+		if (!checkonly && priv->wcmDejitterTimeThreshold != values[0])
+			priv->wcmDejitterTimeThreshold = values[0];
 	} else
 	{
 		Atom *handler = NULL;

src/xf86WacomDefs.h

@@ -218,6 +218,14 @@ struct _WacomDeviceState
 	unsigned int keys; /* bitmask for IDX_KEY_CONTROLPANEL, etc. */
 };
 
+struct _WacomDejitterState
+{
+	int x;
+	int y;
+	bool is_suppresed;
+	CARD32 suppress_start;
+};
+
 static const struct _WacomDeviceState OUTPROX_STATE = {
   .abswheel = INT_MAX,
   .abswheel2 = INT_MAX
@@ -310,6 +318,10 @@ struct _WacomDeviceRec
 	WacomTimerPtr serial_timer; /* timer used for serial number property update */
 	WacomTimerPtr tap_timer;   /* timer used for tap timing */
 	WacomTimerPtr touch_timer; /* timer used for touch switch property update */
+	struct _WacomDejitterState dejitterState;
+	int wcmDejitterEnabled;
+	int wcmDejitterThreshold;
+	int wcmDejitterTimeThreshold;
 
 	ValuatorMask *valuator_mask; /* reusable valuator mask for sending events without reallocation */
 };

tools/xsetwacom.c

@@ -550,6 +550,31 @@ static param_t parameters[] =
 		.arg_count = 1,
 		.prop_flags = PROP_FLAG_WRITEONLY | PROP_FLAG_OUTPUT,
 	},
+	{
+		.name = "DeJitterEnable",
+		.desc = "Enable or disable de-jittering (default is off).",
+		.prop_name = WACOM_PROP_DEJITTER_ENABLED,
+		.prop_format = 8,
+		.prop_offset = 0,
+		.arg_count = 1,
+		.prop_flags = PROP_FLAG_BOOLEAN,
+	},
+	{
+		.name = "DeJitterThreshold",
+		.desc = "Set the spatial threshold for de-jittering (default is 150).",
+		.prop_name = WACOM_PROP_DEJITTER_THRESHOLD,
+		.prop_format = 32,
+		.prop_offset = 0,
+		.arg_count = 1,
+	},
+	{
+		.name = "DeJitterTimeThreshold",
+		.desc = "Set the time threshold (in ms) for de-jittering (default is 100).",
+		.prop_name = WACOM_PROP_DEJITTER_TIME_THRESHOLD,
+		.prop_format = 32,
+		.prop_offset = 0,
+		.arg_count = 1,
+	},
 	{
 		.name = "all",
 		.desc = "Get value for all parameters. ",