Implement smooth panscrolling

src/WacomInterface.h

@@ -63,8 +63,10 @@ enum WacomAxisType {
 	WACOM_AXIS_WHEEL	= (1 << 9), /* Artpen rotation or airbrush wheel */
 	WACOM_AXIS_RING		= (1 << 10),
 	WACOM_AXIS_RING2	= (1 << 11),
+	WACOM_AXIS_SCROLL_X	= (1 << 12),
+	WACOM_AXIS_SCROLL_Y	= (1 << 13),
 
-	_WACOM_AXIS_LAST = WACOM_AXIS_RING2,
+	_WACOM_AXIS_LAST = WACOM_AXIS_SCROLL_Y,
 };
 
 typedef struct {
@@ -77,6 +79,7 @@ typedef struct {
 	int throttle;
 	int wheel;
 	int ring, ring2;
+	int scroll_x, scroll_y;
 } WacomAxisData;
 
 
@@ -163,6 +166,8 @@ static inline void wcmAxisSet(WacomAxisData *data,
 	case WACOM_AXIS_WHEEL: data->wheel = value; break;
 	case WACOM_AXIS_RING: data->ring = value; break;
 	case WACOM_AXIS_RING2: data->ring2 = value; break;
+	case WACOM_AXIS_SCROLL_X: data->scroll_x = value; break;
+	case WACOM_AXIS_SCROLL_Y: data->scroll_y = value; break;
 	default:
 		abort();
 	}
@@ -187,6 +192,8 @@ static inline bool wcmAxisGet(const WacomAxisData *data,
 	case WACOM_AXIS_WHEEL: *value_out = data->wheel; break;
 	case WACOM_AXIS_RING: *value_out = data->ring; break;
 	case WACOM_AXIS_RING2: *value_out = data->ring2; break;
+	case WACOM_AXIS_SCROLL_X: *value_out = data->scroll_x; break;
+	case WACOM_AXIS_SCROLL_Y: *value_out = data->scroll_y; break;
 	default:
 		abort();
 	}
@@ -224,6 +231,8 @@ static inline const char* wcmAxisName(enum WacomAxisType which)
 	case WACOM_AXIS_WHEEL: return "wheel";
 	case WACOM_AXIS_RING: return "ring";
 	case WACOM_AXIS_RING2: return "ring2";
+	case WACOM_AXIS_SCROLL_X: return "scroll-x";
+	case WACOM_AXIS_SCROLL_Y: return "scroll-y";
 	default:
 		abort();
 	}

src/gwacom/wacom-device.h

@@ -108,8 +108,10 @@ typedef enum {
 	WAXIS_WHEEL	= (1 << 9),
 	WAXIS_RING	= (1 << 10),
 	WAXIS_RING2	= (1 << 11),
+	WAXIS_SCROLL_X	= (1 << 12),
+	WAXIS_SCROLL_Y	= (1 << 13),
 
-	_WAXIS_LAST = WAXIS_RING2,
+	_WAXIS_LAST = WAXIS_SCROLL_Y,
 } WacomEventAxis;
 
 /* The pointer argument to all the event signals. If the mask is set for
@@ -124,6 +126,7 @@ typedef struct {
 	int throttle;
 	int wheel;
 	int ring, ring2;
+	int scroll_x, scroll_y;
 } WacomEventData;
 
 #define WACOM_TYPE_EVENT_DATA (wacom_event_data_get_type())

src/wcmCommon.c

@@ -95,38 +95,17 @@ Bool wcmDevSwitchModeCall(WacomDevicePtr priv, Bool absolute)
 	return TRUE;
 }
 
-
-static int wcmButtonPerNotch(WacomDevicePtr priv, int value, int threshold, int btn_positive, int btn_negative)
-{
-	int mode = is_absolute(priv);
-	int notches = value / threshold;
-	int button = (notches > 0) ? btn_positive : btn_negative;
-	int i;
-	WacomAxisData axes = {0};
-
-	for (i = 0; i < abs(notches); i++) {
-		wcmEmitButton(priv, mode, button, 1, &axes);
-		wcmEmitButton(priv, mode, button, 0, &axes);
-	}
-
-	return value % threshold;
-}
-
 static void wcmPanscroll(WacomDevicePtr priv, const WacomDeviceState *ds, int x, int y)
 {
 	WacomCommonPtr common = priv->common;
 	int threshold = common->wcmPanscrollThreshold;
-	int *accumulated_x, *accumulated_y;
 	int delta_x, delta_y;
 
 	if (!(priv->flags & SCROLLMODE_FLAG) || !(ds->buttons & 1))
 		return;
 
-	/* Tip has gone down down; store state for dragging */
+	/* Tip has gone down down; don't send pan event yet */
 	if (!(priv->oldState.buttons & 1)) {
-		priv->wcmPanscrollState = *ds;
-		priv->wcmPanscrollState.x = 0;
-		priv->wcmPanscrollState.y = 0;
 		return;
 	}
 
@@ -139,15 +118,13 @@ static void wcmPanscroll(WacomDevicePtr priv, const WacomDeviceState *ds, int x,
 		delta_y = (y - priv->oldState.y);
 	}
 
-	accumulated_x = &priv->wcmPanscrollState.x;
-	accumulated_y = &priv->wcmPanscrollState.y;
-	*accumulated_x += delta_x;
-	*accumulated_y += delta_y;
 
-	DBG(6, priv, "pan x = %d, pan y = %d\n", *accumulated_x, *accumulated_y);
+	DBG(6, priv, "pan x = %d, pan y = %d\n", delta_x, delta_y);
 
-	*accumulated_x = wcmButtonPerNotch(priv, *accumulated_x, threshold, 6, 7);
-	*accumulated_y = wcmButtonPerNotch(priv, *accumulated_y, threshold, 4, 5);
+	WacomAxisData axes = {0};
+	wcmAxisSet(&axes, WACOM_AXIS_SCROLL_X, -delta_x * PANSCROLL_INCREMENT/threshold);
+	wcmAxisSet(&axes, WACOM_AXIS_SCROLL_Y, -delta_y * PANSCROLL_INCREMENT/threshold);
+	wcmEmitMotion(priv, FALSE, &axes);
 }
 
 void wcmResetButtonAction(WacomDevicePtr priv, int button)

src/wcmConfig.c

@@ -99,7 +99,7 @@ WacomDevicePtr wcmAllocate(void *frontend, const char *name)
 	priv->touch_timer = wcmTimerNew();
 
 	/* reusable valuator mask */
-	priv->valuator_mask = valuator_mask_new(7);
+	priv->valuator_mask = valuator_mask_new(8);
 
 	return priv;
 
@@ -1220,6 +1220,14 @@ static int wcmInitAxes(WacomDevicePtr priv)
 		wcmInitAxis(priv, WACOM_AXIS_RING2, min, max, res);
 	}
 
+	if (IsPen(priv)) {
+		/* seventh valuator: scroll_x */
+		wcmInitAxis(priv, WACOM_AXIS_SCROLL_X, -1, -1, 0);
+
+		/* eighth valuator: scroll_y */
+		wcmInitAxis(priv, WACOM_AXIS_SCROLL_Y, -1, -1, 0);
+	}
+
 	return TRUE;
 }
 
@@ -1232,14 +1240,17 @@ Bool wcmDevInit(WacomDevicePtr priv)
 	if (priv->common->wcmModel->DetectConfig)
 		priv->common->wcmModel->DetectConfig (priv);
 
-	nbaxes = priv->naxes;       /* X, Y, Pressure, Tilt-X, Tilt-Y, Wheel */
+	nbaxes = priv->naxes;       /* X, Y, Pressure, Tilt-X, Tilt-Y, Wheel, Scroll-X, Scroll-Y */
 	if (!nbaxes || nbaxes > 6)
 		nbaxes = priv->naxes = 6;
 	nbbuttons = priv->nbuttons; /* Use actual number of buttons, if possible */
 
 	if (IsPad(priv) && TabletHasFeature(priv->common, WCM_DUALRING))
 		nbaxes = priv->naxes = nbaxes + 1; /* ABS wheel 2 */
 
+	if (IsPen(priv))
+		nbaxes = priv->naxes = nbaxes + 2; /* Scroll X and Y */
+
 	/* if more than 3 buttons, offset by the four scroll buttons,
 	 * otherwise, alloc 7 buttons for scroll wheel. */
 	nbbuttons = min(max(nbbuttons + 4, 7), WCM_MAX_BUTTONS);

src/x11/xf86Wacom.c

@@ -388,6 +388,8 @@ valuatorNumber(enum WacomAxisType which)
 	case WACOM_AXIS_WHEEL: pos = 5; break;
 	case WACOM_AXIS_RING: pos = 5; break;
 	case WACOM_AXIS_RING2: pos = 6; break;
+	case WACOM_AXIS_SCROLL_X: pos = 6; break;
+	case WACOM_AXIS_SCROLL_Y: pos = 7; break;
 		break;
 	default:
 		abort();
@@ -518,15 +520,28 @@ void wcmInitAxis(WacomDevicePtr priv, enum WacomAxisType type,
 			break;
 		case WACOM_AXIS_RING2:
 			break;
+		case WACOM_AXIS_SCROLL_X:
+			label = XIGetKnownProperty(AXIS_LABEL_PROP_REL_HSCROLL);
+			break;
+		case WACOM_AXIS_SCROLL_Y:
+			label = XIGetKnownProperty(AXIS_LABEL_PROP_REL_VSCROLL);
+			break;
+
 		default:
 			abort();
 	}
 
 	index = valuatorNumber(type);
 	InitValuatorAxisStruct(pInfo->dev, index,
-	                       label,
-	                       min, max, res, min_res, max_res,
-	                       Absolute);
+			       label,
+			       min, max, res, min_res, max_res,
+			       Absolute);
+
+	if (type == WACOM_AXIS_SCROLL_X)
+		SetScrollValuator(pInfo->dev, index, SCROLL_TYPE_HORIZONTAL, PANSCROLL_INCREMENT, 0);
+	else if (type == WACOM_AXIS_SCROLL_Y)
+		SetScrollValuator(pInfo->dev, index, SCROLL_TYPE_VERTICAL, PANSCROLL_INCREMENT, 0);
+
 }
 
 bool wcmInitButtons(WacomDevicePtr priv, unsigned int nbuttons)
@@ -1119,7 +1134,7 @@ valuator_mask_get(const ValuatorMask *mask, int valuator)
 TEST_CASE(test_convert_axes)
 {
 	WacomAxisData axes = {0};
-	ValuatorMask *mask = valuator_mask_new(7);
+	ValuatorMask *mask = valuator_mask_new(8);
 
 	convertAxes(&axes, mask);
 	assert(valuator_mask_num_valuators(mask) == 0);
@@ -1165,6 +1180,7 @@ TEST_CASE(test_convert_axes)
 	assert(valuator_mask_isset(mask, 5));
 	assert(valuator_mask_get(mask, 5) == 2);
 	assert(!valuator_mask_isset(mask, 6));
+	assert(!valuator_mask_isset(mask, 7));
 
 	memset(&axes, 0, sizeof(axes));
 	valuator_mask_zero(mask);
@@ -1195,6 +1211,7 @@ TEST_CASE(test_convert_axes)
 	assert(valuator_mask_get(mask, 5) == 2);
 	assert(!valuator_mask_isset(mask, 6));
 	assert(!valuator_mask_isset(mask, 7));
+	assert(!valuator_mask_isset(mask, 8));
 
 	free(mask);
 }

src/xf86WacomDefs.h

@@ -68,6 +68,11 @@
 #define BTN_STYLUS3 0x149
 #endif
 
+/* This value is arbitrary, but low enough values can cause integer division to round
+ * non-zero numbers to zero. See https://github.com/linuxwacom/xf86-input-wacom/pull/222#discussion_r927920625.
+ */
+#define PANSCROLL_INCREMENT 0xffff
+
 /******************************************************************************
  * Forward Declarations
  *****************************************************************************/

test/test_wacom.py

@@ -327,4 +327,60 @@ def test_axis_updates_wheel(mainloop, opts, stylus_type):
             assert first_wheel == current_wheel
 
 
+def test_scroll(mainloop, opts):
+    """
+    Check panscrolling works correctly
+    """
+    dev = Device.from_name("PTH660", "Pen")
+    opts["PanScrollThreshold"] = "150"
+
+    prox_in = [
+        Sev("ABS_X", 50),
+        Sev("ABS_Y", 50),
+        Sev("BTN_TOOL_PEN", 1),
+        Sev("SYN_REPORT", 0),
+    ]
+
+    prox_out = [
+        Sev("BTN_TOOL_PEN", 0),
+        Sev("SYN_REPORT", 0),
+    ]
+
+    press_button2 = [
+        Sev("BTN_STYLUS", 1),
+        Sev("SYN_REPORT", 0),
+    ]
+
+    touchdown_pen = [
+        Sev("BTN_TOUCH", 1),
+        Sev("ABS_PRESSURE", 20),
+        Sev("SYN_REPORT", 0),
+    ]
+
+    move_pen_x = [Sev("ABS_X", 75), Sev("SYN_REPORT", 0)]
+
+    up_pen = [Sev("BTN_TOUCH", 0), Sev("ABS_PRESSURE", 0), Sev("SYN_REPORT", 0)]
+
+    depress_button2 = [Sev("BTN_STYLUS", 0), Sev("SYN_REPORT", 0)]
+
+    monitor = Monitor.new_from_device(dev, opts)
+    monitor.wacom_device.set_runtime_option("PanButton", "2")
+
+    monitor.write_events(prox_in)
+    monitor.write_events(press_button2)
+    monitor.write_events(touchdown_pen)  # Pen touchdown
+    monitor.write_events(move_pen_x)  # Move pen 25% towards positive x
+    monitor.write_events(up_pen)  # Pen up
+    monitor.write_events(depress_button2)  # Depress button2
+    monitor.write_events(prox_out)
+
+    mainloop.run()
+    have_we_scrolled = False
+    for event in monitor.events:
+        if event.axes.scroll_x != 0:
+            assert event.axes.scroll_x == -1223320
+            have_we_scrolled = True
+    assert have_we_scrolled
+
+
 # vim: set expandtab tabstop=4 shiftwidth=4:

tools/wacom-record.c

@@ -233,6 +233,8 @@ static void device_added(WacomDriver *driver, WacomDevice *device)
 				case WAXIS_WHEEL: typestr = "wheel"; break;
 				case WAXIS_RING: typestr = "ring"; break;
 				case WAXIS_RING2: typestr = "ring2"; break;
+				case WAXIS_SCROLL_X: typestr = "scroll_x"; break;
+				case WAXIS_SCROLL_Y: typestr = "scroll_y"; break;
 			}
 
 			printf("          - {type: %-12s, range: [%5d, %5d], resolution: %5d}\n",