Implement "pan" scrolling functionality

When enabled through `xsetwacom set <id> button <n> pan`, this causes the driver
to appear to "drag" scrollable window contents by emitting appropriate scroll
events as the pen is dragged around.

Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>

9 files changed, 161 insertions, 7 deletions

diff --git a/include/Xwacom.h b/include/Xwacom.h
index 49489ff..c2af381 100644
--- a/include/Xwacom.h
+++ b/include/Xwacom.h
@@ -60,6 +60,7 @@
 #define AC_MODETOGGLE       0x00020000	/* Toggle absolute/relative mode */
 #define AC_DBLCLICK         0x00030000	/* DEPRECATED: use two button events instead */
 #define AC_DISPLAYTOGGLE    0x00040000  /* DEPRECATED: has no effect (used to toggle among screens) */
+#define AC_PANSCROLL        0x00050000  /* Enter/exit panscroll mode */
 #define AC_BUTTON           0x00080000	/* Emit button events */
 #define AC_TYPE             0x000f0000	/* The mask to isolate event type bits */
 #define AC_KEYBTNPRESS      0x00100000  /* bit set for key/button presses */
diff --git a/include/wacom-properties.h b/include/wacom-properties.h
index b845083..0796ab0 100644
--- a/include/wacom-properties.h
+++ b/include/wacom-properties.h
@@ -111,6 +111,9 @@
 */
 #define WACOM_PROP_PRESSURE_RECAL "Wacom Pressure Recalibration"
 
+/* 32 bit, 1 values */
+#define WACOM_PROP_PANSCROLL_THRESHOLD "Wacom Panscroll Threshold"
+
 /* The following are tool types used by the driver in WACOM_PROP_TOOL_TYPE
  * or in the 'type' field for XI1 clients. Clients may check for one of
  * these types to identify tool types.
diff --git a/man/wacom.man b/man/wacom.man
index 3693c94..3e9c7bd 100644
--- a/man/wacom.man
+++ b/man/wacom.man
@@ -277,6 +277,13 @@ initial pressure reading may be unequal to zero even for a perfectly
 good pen. If the consecutive pressure readings are not higher than
 the initial pressure by a threshold no button event will be generated.
 This option allows to disable the recalibration.
+.TP 4
+.B Option \fI"PanScrollThreshold"\fP \fI"number"\fP
+Specifies the distance the pen must move (in tablet units) before a
+scroll event is generated when using the "pan" action. Smaller values
+will require less distance and be more sensitive. Larger values will
+require more distance and be less sensitive.  Default: 1300 or 2600
+depending on tablet resolution (corresponds to 13 mm of distance).
 .RE
 .SH "TOUCH GESTURES"
 .SS Single finger (1FG)
diff --git a/man/xsetwacom.man b/man/xsetwacom.man
index 234e9ba..6e82301 100644
--- a/man/xsetwacom.man
+++ b/man/xsetwacom.man
@@ -134,6 +134,13 @@ numbers.
 The "modetoggle" keyword is also recognized; it takes no arguments,
 and toggles the device mode between relative and absolute pointer tracking.
 
+The "pan" keyword causes the driver to send scroll events while the pen
+is dragged. This makes it easy to scroll through lists and documents,
+pan around 2D canvases, and zoom in/out of 3D scenes (exact behavior
+depends on application interpretation of scrollwheel events). Dragging
+the pen up/down will send scrollwheel down/up events; dragging it left/right
+will send scrollwheel right/left events.
+
 The events in the action mapping are sent when the physical button is pressed.
 If the action mapping leaves any buttons or keys pressed (such as a modifier
 key), they will be released when the physical button is released.
@@ -273,6 +280,13 @@ initial pressure reading may be unequal to zero even for a perfectly
 good pen. If the consecutive pressure readings are not higher than
 the initial pressure by a threshold no button event will be generated.
 This option allows to disable the recalibration.  Default:  on
+.TP
+\fBPanScrollThreshold\fR distance
+This specifies the distance the pen must move (in tablet units) before
+a scroll event is generated when using the "pan" action. Smaller values
+will require less distance and be more sensitive. Larger values will
+require more distance and be less sensitive.  Default: 1300 or 2600
+depending on tablet resolution (corresponds to 13 mm of distance).
 
 
 .SH "AUTHORS"
diff --git a/src/wcmCommon.c b/src/wcmCommon.c
index 595c933..e56045a 100644
--- a/src/wcmCommon.c
+++ b/src/wcmCommon.c
@@ -88,6 +88,50 @@ void set_absolute(InputInfoPtr pInfo, Bool absolute)
 		priv->flags &= ~ABSOLUTE_FLAG;
 }
 
+static int wcmButtonPerNotch(WacomDevicePtr priv, int value, int threshold, int btn_positive, int btn_negative)
+{
+	int mode = is_absolute(priv->pInfo);
+	int notches = value / threshold;
+	int button = (notches > 0) ? btn_positive : btn_negative;
+	int i;
+
+	for (i = 0; i < abs(notches); i++) {
+		xf86PostButtonEventP(priv->pInfo->dev, mode, button, 1, 0, 0, 0);
+		xf86PostButtonEventP(priv->pInfo->dev, mode, button, 0, 0, 0, 0);
+	}
+
+	return value % threshold;
+}
+
+static void wcmPanscroll(WacomDevicePtr priv, const WacomDeviceState *ds)
+{
+	WacomCommonPtr common = priv->common;
+	int threshold = common->wcmPanscrollThreshold;
+	int *accumulated_x, *accumulated_y;
+
+	if (!(priv->flags & SCROLLMODE_FLAG) || !(ds->buttons & 1))
+		return;
+
+	/* Tip has gone down down; store state for dragging */
+	if (!(priv->oldState.buttons & 1)) {
+		priv->wcmPanscrollState = *ds;
+		priv->wcmPanscrollState.x = 0;
+		priv->wcmPanscrollState.y = 0;
+		return;
+	}
+
+	accumulated_x = &priv->wcmPanscrollState.x;
+	accumulated_y = &priv->wcmPanscrollState.y;
+
+	*accumulated_x += (ds->x - priv->oldState.x);
+	*accumulated_y += (ds->y - priv->oldState.y);
+
+	DBG(6, priv, "pan x = %d, pan y = %d\n", *accumulated_x, *accumulated_y);
+
+	*accumulated_x = wcmButtonPerNotch(priv, *accumulated_x, threshold, 6, 7);
+	*accumulated_y = wcmButtonPerNotch(priv, *accumulated_y, threshold, 4, 5);
+}
+
 /*****************************************************************************
  * wcmSendButtons --
  *   Send button events by comparing the current button mask with the
@@ -169,6 +213,7 @@ static void sendAction(InputInfoPtr pInfo,  const WacomDeviceState* ds,
 		       int press, unsigned int *keys, int nkeys,
 		       int first_val, int num_val, int *valuators)
 {
+	WacomDevicePtr priv = (WacomDevicePtr) pInfo->private;
 	int i;
 
 	/* Actions only trigger on press, not release */
@@ -185,10 +230,15 @@ static void sendAction(InputInfoPtr pInfo,  const WacomDeviceState* ds,
 				{
 					int btn_no = (action & AC_CODE);
 					int is_press = (action & AC_KEYBTNPRESS);
-					xf86PostButtonEventP(pInfo->dev,
-							    is_absolute(pInfo), btn_no,
-							    is_press, first_val, num_val,
-							    VCOPY(valuators, num_val));
+					if (btn_no == 1 && (priv->flags & SCROLLMODE_FLAG)) {
+						/* Don't send clicks in scroll mode */
+					}
+					else {
+						xf86PostButtonEventP(pInfo->dev,
+								    is_absolute(pInfo), btn_no,
+								    is_press, first_val, num_val,
+								    VCOPY(valuators, num_val));
+					}
 				}
 				break;
 			case AC_KEY:
@@ -203,6 +253,12 @@ static void sendAction(InputInfoPtr pInfo,  const WacomDeviceState* ds,
 					wcmDevSwitchModeCall(pInfo,
 							(is_absolute(pInfo)) ? Relative : Absolute); /* not a typo! */
 				break;
+			case AC_PANSCROLL:
+				priv->flags |= SCROLLMODE_FLAG;
+				priv->wcmPanscrollState = *ds;
+				priv->wcmPanscrollState.x = 0;
+				priv->wcmPanscrollState.y = 0;
+				break;
 		}
 	}
 
@@ -239,8 +295,11 @@ static void sendAction(InputInfoPtr pInfo,  const WacomDeviceState* ds,
 					if (countPresses(key_code, &keys[i], nkeys - i))
 						wcmEmitKeycode(pInfo->dev, key_code, 0);
 				}
+				break;
+			case AC_PANSCROLL:
+				priv->flags &= ~SCROLLMODE_FLAG;
+				break;
 		}
-
 	}
 }
 
@@ -427,6 +486,9 @@ static void sendCommonEvents(InputInfoPtr pInfo, const WacomDeviceState* ds,
 	WacomDevicePtr priv = (WacomDevicePtr) pInfo->private;
 	int buttons = ds->buttons;
 
+	/* send scrolling events if necessary */
+	wcmPanscroll(priv, ds);
+
 	/* send button events when state changed or first time in prox and button unpresses */
 	if (priv->oldState.buttons != buttons || (!priv->oldState.proximity && !buttons))
 		wcmSendButtons(pInfo, ds, buttons, first_val, num_vals, valuators);
@@ -567,7 +629,8 @@ wcmSendNonPadEvents(InputInfoPtr pInfo, const WacomDeviceState *ds,
 						VCOPY(valuators, num_vals));
 
 		/* Move the cursor to where it should be before sending button events */
-		if(!(priv->flags & BUTTONS_ONLY_FLAG))
+		if(!(priv->flags & BUTTONS_ONLY_FLAG) &&
+		   !(priv->flags & SCROLLMODE_FLAG && priv->oldState.buttons & 1))
 		{
 			xf86PostMotionEventP(pInfo->dev, is_absolute(pInfo),
 					     first_val, num_vals,
@@ -649,6 +712,10 @@ void wcmSendEvents(InputInfoPtr pInfo, const WacomDeviceState* ds)
 		ty = ds->stripy;
 	}
 
+	/* cancel panscroll */
+	if (!ds->proximity)
+		priv->flags &= ~SCROLLMODE_FLAG;
+
 	DBG(7, priv, "[%s] o_prox=%s x=%d y=%d z=%d "
 		"b=%s b=%d tx=%d ty=%d wl=%d wl2=%d rot=%d th=%d\n",
 		pInfo->type_name,
@@ -1361,6 +1428,16 @@ int wcmInitTablet(InputInfoPtr pInfo, const char* id, float version)
 			pInfo->name, common->wcmThreshold);
 	}
 
+	/* Calculate default panscroll threshold if not set */
+	xf86Msg(X_CONFIG, "%s: panscroll is %d\n", pInfo->name, common->wcmPanscrollThreshold);
+	if (common->wcmPanscrollThreshold < 1) {
+		common->wcmPanscrollThreshold = common->wcmResolY * 13 / 1000; /* 13mm */
+	}
+	if (common->wcmPanscrollThreshold < 1) {
+		common->wcmPanscrollThreshold = 1000;
+	}
+	xf86Msg(X_CONFIG, "%s: panscroll modified to %d\n", pInfo->name, common->wcmPanscrollThreshold);
+
 	/* output tablet state as probed */
 	if (IsPen(priv))
 		xf86Msg(X_PROBED, "%s: maxX=%d maxY=%d maxZ=%d "
@@ -1473,6 +1550,7 @@ WacomCommonPtr wcmNewCommon(void)
 			/* transmit position if increment is superior */
 	common->wcmRawSample = DEFAULT_SAMPLES;
 			/* number of raw data to be used to for filtering */
+	common->wcmPanscrollThreshold = 0;
 	common->wcmPressureRecalibration = 1;
 	return common;
 }
diff --git a/src/wcmValidateDevice.c b/src/wcmValidateDevice.c
index 21ccd5f..486235b 100644
--- a/src/wcmValidateDevice.c
+++ b/src/wcmValidateDevice.c
@@ -912,6 +912,9 @@ Bool wcmPreInitParseOptions(InputInfoPtr pInfo, Bool is_primary,
 	tool = priv->tool;
 	tool->serial = priv->serial;
 
+	common->wcmPanscrollThreshold = xf86SetIntOption(pInfo->options, "PanScrollThreshold",
+			common->wcmPanscrollThreshold);
+
 	/* The first device doesn't need to add any tools/areas as it
 	 * will be the first anyway. So if different, add tool
 	 * and/or area to the existing lists
diff --git a/src/wcmXCommand.c b/src/wcmXCommand.c
index e18fb8f..63d1b3d 100644
--- a/src/wcmXCommand.c
+++ b/src/wcmXCommand.c
@@ -99,6 +99,7 @@ static Atom prop_tooltype;
 static Atom prop_btnactions;
 static Atom prop_product_id;
 static Atom prop_pressure_recal;
+static Atom prop_panscroll_threshold;
 #ifdef DEBUG
 static Atom prop_debuglevels;
 #endif
@@ -336,6 +337,9 @@ void InitWcmDeviceProperties(InputInfoPtr pInfo)
 						  XA_INTEGER, 8, 1, values);
 	}
 
+	values[0] = common->wcmPanscrollThreshold;
+	prop_panscroll_threshold = InitWcmAtom(pInfo->dev, WACOM_PROP_PANSCROLL_THRESHOLD, XA_INTEGER, 32, 1, values);
+
 	values[0] = common->vendor_id;
 	values[1] = common->tablet_id;
 	prop_product_id = InitWcmAtom(pInfo->dev, XI_PROP_PRODUCT_ID, XA_INTEGER, 32, 2, values);
@@ -455,6 +459,8 @@ static int wcmCheckActionProperty(WacomDevicePtr priv, Atom property, XIProperty
 				break;
 			case AC_MODETOGGLE:
 				break;
+			case AC_PANSCROLL:
+				break;
 			default:
 				DBG(3, priv, "ERROR: Unknown command\n");
 				return BadValue;
@@ -972,6 +978,21 @@ int wcmSetProperty(DeviceIntPtr dev, Atom property, XIPropertyValuePtr prop,
 
 		if (!checkonly)
 			common->wcmPressureRecalibration = values[0];
+	} else if (property == prop_panscroll_threshold)
+	{
+		CARD32 *values = (CARD32*)prop->data;
+
+		if (prop->size != 1 || prop->format != 32)
+			return BadValue;
+
+		if (values[0] <= 0)
+			return BadValue;
+
+		if (IsTouch(priv))
+			return BadMatch;
+
+		if (!checkonly)
+			common->wcmPanscrollThreshold = values[0];
 	} else
 	{
 		Atom *handler = NULL;
diff --git a/src/xf86WacomDefs.h b/src/xf86WacomDefs.h
index a772597..a2053a8 100644
--- a/src/xf86WacomDefs.h
+++ b/src/xf86WacomDefs.h
@@ -175,6 +175,7 @@ struct _WacomModel
 #define ABSOLUTE_FLAG		0x00000100
 #define BAUD_19200_FLAG		0x00000400
 #define BUTTONS_ONLY_FLAG	0x00000800
+#define SCROLLMODE_FLAG		0x00001000
 
 #define IsCursor(priv) (DEVICE_ID((priv)->flags) == CURSOR_ID)
 #define IsStylus(priv) (DEVICE_ID((priv)->flags) == STYLUS_ID)
@@ -288,6 +289,7 @@ struct _WacomDeviceRec
 	WacomCommonPtr common;  /* common info pointer */
 
 	/* state fields in device coordinates */
+	struct _WacomDeviceState wcmPanscrollState; /* panscroll state tracking */
 	struct _WacomDeviceState oldState; /* previous state information */
 	int oldCursorHwProx;	/* previous cursor hardware proximity */
 
@@ -467,6 +469,7 @@ struct _WacomCommonRec
 	int wcmRawSample;	     /* Number of raw data used to filter an event */
 	int wcmPressureRecalibration; /* Determine if pressure recalibration of
 					 worn pens should be performed */
+	int wcmPanscrollThreshold;	/* distance pen must move to send a panscroll event */
 
 	int bufpos;                        /* position with buffer */
 	unsigned char buffer[BUFFER_SIZE]; /* data read from device */
diff --git a/tools/xsetwacom.c b/tools/xsetwacom.c
index c098b5f..e2810a0 100644
--- a/tools/xsetwacom.c
+++ b/tools/xsetwacom.c
@@ -472,6 +472,15 @@ static param_t parameters[] =
 		.prop_flags = PROP_FLAG_BOOLEAN
 	},
 	{
+		.name = "PanScrollThreshold",
+		.x11name = "PanScrollThreshold",
+		.desc = "Adjusts distance required for pan actions to generate a scroll event",
+		.prop_name = WACOM_PROP_PANSCROLL_THRESHOLD,
+		.prop_format = 32,
+		.prop_offset = 0,
+		.arg_count = 1,
+	},
+	{
 		.name = "MapToOutput",
 		.desc = "Map the device to the given output. ",
 		.set_func = set_output,
@@ -1011,6 +1020,7 @@ static int special_map_button(Display *dpy, int argc, char **argv, unsigned long
 static int special_map_core(Display *dpy, int argc, char **argv, unsigned long *ndata, unsigned long *data, const size_t size);
 static int special_map_modetoggle(Display *dpy, int argc, char **argv, unsigned long *ndata, unsigned long *data, const size_t size);
 static int special_map_displaytoggle(Display *dpy, int argc, char **argv, unsigned long *ndata, unsigned long *data, const size_t size);
+static int special_map_panscroll(Display *dpy, int argc, char **argv, unsigned long *ndata, unsigned long *data, const size_t size);
 
 /* Valid keywords for the --set ButtonX options */
 static struct keywords {
@@ -1022,6 +1032,7 @@ static struct keywords {
 	{"core", special_map_core},
 	{"modetoggle", special_map_modetoggle},
 	{"displaytoggle", special_map_displaytoggle},
+	{"pan", special_map_panscroll},
 	{ NULL, NULL }
 };
 
@@ -1066,6 +1077,19 @@ static int special_map_displaytoggle(Display *dpy, int argc, char **argv, unsign
 	return 0;
 }
 
+static int special_map_panscroll(Display *dpy, int argc, char **argv, unsigned long *ndata, unsigned long *data, const size_t size)
+{
+	if (*ndata + 1 > size) {
+		fprintf(stderr, "Insufficient space to store all commands.\n");
+		return 0;
+	}
+	data[*ndata] = AC_PANSCROLL;
+
+	*ndata += 1;
+
+	return 0;
+}
+
 static inline int is_valid_keyword(const char *keyword)
 {
 	struct keywords *kw = keywords;
@@ -2978,7 +3002,7 @@ static void test_parameter_number(void)
 	 * deprecated them.
 	 * Numbers include trailing NULL entry.
 	 */
-	assert(ARRAY_SIZE(parameters) == 39);
+	assert(ARRAY_SIZE(parameters) == 40);
 	assert(ARRAY_SIZE(deprecated_parameters) == 17);
 }