Add active area outside of which movements, scrolling, tapping are ignored.

On some touchpads physical buttons are located under the touchpad surface. As a
result, when users try to perform a click, by pressing that part of the surface
of the touchpad, they get a click, a movement, a tap and (in some cases) a scroll,
which can make clicks quite inaccurate.

The "Synaptics Area" property can be used to define the edges of the active area of
the touchpad so that all movement, scrolling and tapping which take place outside
of this area will be ignored. This property is disabled by default.

Fixes xorg bug #21613.

Signed-off-by: Alberto Milone <alberto.milone@canonical.com>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

3 files changed, 85 insertions, 17 deletions

diff --git a/src/properties.c b/src/properties.c
index 43bcabb..d03ea6e 100644
--- a/src/properties.c
+++ b/src/properties.c
@@ -83,6 +83,7 @@ Atom prop_grab                  = 0;
 Atom prop_gestures              = 0;
 Atom prop_capabilities          = 0;
 Atom prop_resolution            = 0;
+Atom prop_area                  = 0;
 
 static Atom
 InitAtom(DeviceIntPtr dev, char *name, int format, int nvalues, int *values)
@@ -268,6 +269,11 @@ InitDeviceProperties(LocalDevicePtr local)
     values[1] = para->resolution_horiz;
     prop_resolution = InitAtom(local->dev, SYNAPTICS_PROP_RESOLUTION, 32, 2, values);
 
+    values[0] = para->area_left_edge;
+    values[1] = para->area_right_edge;
+    values[2] = para->area_top_edge;
+    values[3] = para->area_bottom_edge;
+    prop_area = InitAtom(local->dev, SYNAPTICS_PROP_AREA, 32, 4, values);
 }
 
 int
@@ -622,6 +628,20 @@ SetProperty(DeviceIntPtr dev, Atom property, XIPropertyValuePtr prop,
     {
         /* read-only */
         return BadValue;
+    } else if (property == prop_area)
+    {
+        INT32 *area;
+        if (prop->size != 4 || prop->format != 32 || prop->type != XA_INTEGER)
+            return BadMatch;
+
+        area = (INT32*)prop->data;
+        if ((((area[0] != 0) && (area[1] != 0)) && (area[0] > area[1]) ) || (((area[2] != 0) && (area[3] != 0)) && (area[2] > area[3])))
+            return BadValue;
+
+        para->area_left_edge   = area[0];
+        para->area_right_edge  = area[1];
+        para->area_top_edge    = area[2];
+        para->area_bottom_edge = area[3];
     }
 
     return Success;
diff --git a/src/synaptics.c b/src/synaptics.c
index d95aa30..dc833c5 100644
--- a/src/synaptics.c
+++ b/src/synaptics.c
@@ -465,6 +465,11 @@ static void set_default_parameters(LocalDevicePtr local)
     pars->top_edge = xf86SetIntOption(opts, "TopEdge", t);
     pars->bottom_edge = xf86SetIntOption(opts, "BottomEdge", b);
 
+    pars->area_top_edge = xf86SetIntOption(opts, "AreaTopEdge", 0);
+    pars->area_bottom_edge = xf86SetIntOption(opts, "AreaBottomEdge", 0);
+    pars->area_left_edge = xf86SetIntOption(opts, "AreaLeftEdge", 0);
+    pars->area_right_edge = xf86SetIntOption(opts, "AreaRightEdge", 0);
+
     pars->finger_low = xf86SetIntOption(opts, "FingerLow", fingerLow);
     pars->finger_high = xf86SetIntOption(opts, "FingerHigh", fingerHigh);
     pars->finger_press = xf86SetIntOption(opts, "FingerPress", fingerPress);
@@ -1079,6 +1084,29 @@ propertyTimerFunc(OsTimerPtr timer, CARD32 now, pointer arg)
 }
 #endif
 
+/* Checks whether coordinates are in the Synaptics Area
+ * or not. If no Synaptics Area is defined (i.e. if
+ * priv->synpara.area_{left|right|top|bottom}_edge are
+ * all set to zero), the function returns TRUE.
+ */
+static Bool
+is_inside_active_area(SynapticsPrivate *priv, int x, int y)
+{
+    Bool inside_area = TRUE;
+
+    if ((priv->synpara.area_left_edge != 0) && (x < priv->synpara.area_left_edge))
+	inside_area = FALSE;
+    else if ((priv->synpara.area_right_edge != 0) && (x > priv->synpara.area_right_edge))
+	inside_area = FALSE;
+
+    if ((priv->synpara.area_top_edge != 0) && (y < priv->synpara.area_top_edge))
+	inside_area = FALSE;
+    else if ((priv->synpara.area_bottom_edge != 0) && (y > priv->synpara.area_bottom_edge))
+	inside_area = FALSE;
+
+    return inside_area;
+}
+
 static CARD32
 timerFunc(OsTimerPtr timer, CARD32 now, pointer arg)
 {
@@ -1427,7 +1455,7 @@ GetTimeOut(SynapticsPrivate *priv)
 
 static int
 HandleTapProcessing(SynapticsPrivate *priv, struct SynapticsHwState *hw,
-		    edge_type edge, enum FingerState finger)
+		    edge_type edge, enum FingerState finger, Bool inside_active_area)
 {
     SynapticsParameters *para = &priv->synpara;
     Bool touch, release, is_timeout, move;
@@ -1478,6 +1506,10 @@ HandleTapProcessing(SynapticsPrivate *priv, struct SynapticsHwState *hw,
 	    goto restart;
 	} else if (release) {
 	    SelectTapButton(priv, edge);
+	    /* Disable taps outside of the active area */
+	    if (!inside_active_area) {
+		priv->tap_button = 0;
+	    }
 	    SetTapState(priv, TS_2A, hw->millis);
 	}
 	break;
@@ -2092,6 +2124,7 @@ HandleState(LocalDevicePtr local, struct SynapticsHwState *hw)
     int delay = 1000000000;
     int timeleft;
     int i;
+    Bool inside_active_area;
 
     /* update hardware state in shared memory */
     if (shm)
@@ -2231,11 +2264,12 @@ HandleState(LocalDevicePtr local, struct SynapticsHwState *hw)
     }
 
     edge = edge_detection(priv, hw->x, hw->y);
+    inside_active_area = is_inside_active_area(priv, hw->x, hw->y);
 
     finger = SynapticsDetectFinger(priv, hw);
 
     /* tap and drag detection */
-    timeleft = HandleTapProcessing(priv, hw, edge, finger);
+    timeleft = HandleTapProcessing(priv, hw, edge, finger, inside_active_area);
     if (timeleft > 0)
 	delay = MIN(delay, timeleft);
 
@@ -2278,6 +2312,13 @@ HandleState(LocalDevicePtr local, struct SynapticsHwState *hw)
     }
 
     /* Post events */
+
+    /* Process movements only if coordinates are
+     * in the Synaptics Area
+     */
+    if (!inside_active_area)
+	dx = dy = 0;
+
     if (dx || dy)
 	xf86PostMotionEvent(local->dev, 0, 0, 2, dx, dy);
 
@@ -2300,22 +2341,28 @@ HandleState(LocalDevicePtr local, struct SynapticsHwState *hw)
 	xf86PostButtonEvent(local->dev, FALSE, id, (buttons & (1 << (id - 1))), 0, 0);
     }
 
-    while (scroll.up-- > 0) {
-	xf86PostButtonEvent(local->dev, FALSE, 4, !hw->up, 0, 0);
-	xf86PostButtonEvent(local->dev, FALSE, 4, hw->up, 0, 0);
-    }
-    while (scroll.down-- > 0) {
-	xf86PostButtonEvent(local->dev, FALSE, 5, !hw->down, 0, 0);
-	xf86PostButtonEvent(local->dev, FALSE, 5, hw->down, 0, 0);
-    }
-    while (scroll.left-- > 0) {
-	xf86PostButtonEvent(local->dev, FALSE, 6, TRUE, 0, 0);
-	xf86PostButtonEvent(local->dev, FALSE, 6, FALSE, 0, 0);
-    }
-    while (scroll.right-- > 0) {
-	xf86PostButtonEvent(local->dev, FALSE, 7, TRUE, 0, 0);
-	xf86PostButtonEvent(local->dev, FALSE, 7, FALSE, 0, 0);
+    /* Process scroll events only if coordinates are
+     * in the Synaptics Area
+     */
+    if (inside_active_area) {
+        while (scroll.up-- > 0) {
+		xf86PostButtonEvent(local->dev, FALSE, 4, !hw->up, 0, 0);
+		xf86PostButtonEvent(local->dev, FALSE, 4, hw->up, 0, 0);
+        }
+        while (scroll.down-- > 0) {
+		xf86PostButtonEvent(local->dev, FALSE, 5, !hw->down, 0, 0);
+		xf86PostButtonEvent(local->dev, FALSE, 5, hw->down, 0, 0);
+        }
+        while (scroll.left-- > 0) {
+		xf86PostButtonEvent(local->dev, FALSE, 6, TRUE, 0, 0);
+		xf86PostButtonEvent(local->dev, FALSE, 6, FALSE, 0, 0);
+        }
+        while (scroll.right-- > 0) {
+		xf86PostButtonEvent(local->dev, FALSE, 7, TRUE, 0, 0);
+		xf86PostButtonEvent(local->dev, FALSE, 7, FALSE, 0, 0);
+        }
     }
+
     if (double_click) {
 	int i;
 	for (i = 0; i < 2; i++) {
diff --git a/src/synapticsstr.h b/src/synapticsstr.h
index 8348e72..f2bf7d4 100644
--- a/src/synapticsstr.h
+++ b/src/synapticsstr.h
@@ -166,6 +166,7 @@ typedef struct _SynapticsParameters
     Bool tap_and_drag_gesture;		    /* Switches the tap-and-drag gesture on/off */
     unsigned int resolution_horiz;          /* horizontal resolution of touchpad in units/mm */
     unsigned int resolution_vert;           /* vertical resolution of touchpad in units/mm */
+    int area_left_edge, area_right_edge, area_top_edge, area_bottom_edge; /* area coordinates absolute */
 } SynapticsParameters;