Swap the relwheel actions triggered and defaults for vertical scrolling

Relative wheel actions are backwards from how the user thinks about them.
If you want to get/set the action that occurs when scrolling up, you
currently need to work with the REL_WHEEL_DOWN action. This is difficult
to explain to users and is also makes the code more difficult to follow.

This commit changes the behavior so that programming the REL_WHEEL_UP
action actually affects what happens when you physically scroll the
wheel up. The behavior is now: physical scroll wheel up -> positive
delta from kernel -> REL_WHEEL_UP action -> X11 mouse button 4 ->
window scrolls up.

Note that this commit will break any xsetwacom scripts that users may
have which change the relative wheel actions from their defaults. It
would also affect control panels that rely on xsetwacom or configuring
the driver directly. We don't expect this to cause significant
problems in reality since Wacom has not produced tools with relative
wheels in many years and so there are few scripts/control panels to
break.

Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>

Author: jigpu

src/wcmCommon.c

@@ -513,17 +513,17 @@ static int getScrollDelta(int current, int old, int wrap, int flags)
  * the scrolling axis and the possible events that can be
  * sent.
  *
- * @param delta        Amount of change in the scrolling axis
- * @param action_up    Array index of action to send on scroll up
- * @param action_dn    Array index of action to send on scroll down
- * @return             Array index of action that should be performed, or -1 if none.
+ * @param delta            Amount of change in the scrolling axis
+ * @param action_positive  Array index of action to send on a positive delta
+ * @param action_negative  Array index of action to send on negative delta
+ * @return                 Array index of action that should be performed, or -1 if none.
  */
-static int getWheelButton(int delta, int action_up, int action_dn)
+static int getWheelButton(int delta, int action_positive, int action_negative)
 {
 	if (delta > 0)
-		return action_up;
+		return action_positive;
 	else if (delta < 0)
-		return action_dn;
+		return action_negative;
 	else
 		return -1;
 }
@@ -571,7 +571,8 @@ static void sendWheelStripEvents(WacomDevicePtr priv, const WacomDeviceState* ds
 		sendWheelStripEvent(priv, &priv->strip_actions[idx], ds, axes);
 	}
 
-	/* emulate events for relative wheel */
+	/* emulate events for relative wheel:
+	 * positive delta = scroll up */
 	delta = getScrollDelta(ds->relwheel, 0, 0, 0);
 	idx = getWheelButton(delta, WHEEL_REL_UP, WHEEL_REL_DN);
 	if (idx >= 0 && (IsCursor(priv) || IsPad(priv)) && priv->oldState.proximity == ds->proximity)

src/wcmConfig.c

@@ -70,8 +70,8 @@ WacomDevicePtr wcmAllocate(void *frontend, const char *name)
 		priv->button_default[i] = (i < 3) ? i + 1 : i + 5;
 
 	priv->nbuttons = WCM_MAX_BUTTONS;       /* Default number of buttons */
-	priv->wheel_default[WHEEL_REL_UP] = 5;
-	priv->wheel_default[WHEEL_REL_DN] = 4;
+	priv->wheel_default[WHEEL_REL_UP] = 4;  /* scroll up */
+	priv->wheel_default[WHEEL_REL_DN] = 5;  /* scroll down */
 	/* wheel events are set to 0, but the pad overwrites this default
 	 * later in wcmParseOptions, when we have IsPad() available */
 	priv->wheel_default[WHEEL_ABS_UP] = 0;

src/wcmUSB.c

@@ -1935,7 +1935,7 @@ static void usbDispatchEvents(WacomDevicePtr priv)
 		{
 			switch (event->code) {
 			case REL_WHEEL:
-				ds->relwheel = -event->value;
+				ds->relwheel = event->value;
 				ds->time = wcmTimeInMillis();
 				common->wcmChannel[channel].dirty |= TRUE;
 				break;