Add reverse scrolling mode to the Pimoroni Trackball module

Signed-off-by: Salvatore La Bua <slabua@gmail.com>

docs/pimoroni_trackball.md

@@ -32,7 +32,8 @@ trackball = Trackball(i2c, mode=TrackballMode.MOUSE_MODE, handlers=[
     KeyHandler(KC.UP, KC.RIGHT, KC.DOWN, KC.LEFT, KC.ENTER), 
     # on layer 1 and above use the default pointing behavior
     PointingHandler(),
-    ScrollHandler()
+    # use scrolling='natural' (default) or 'reverse' to change the scrolling direction
+    ScrollHandler(scrolling='natural')
 ])
 
 # now you can use these KeyCodes:

kmk/modules/pimoroni_trackball.py

@@ -96,7 +96,13 @@ class PointingHandler(TrackballHandler):
 
 
 class ScrollHandler(TrackballHandler):
+    def __init__(self, scrolling='natural'):
+        self.scrolling = scrolling
+        
     def handle(self, keyboard, trackball, x, y, switch, state):
+        if self.scrolling == 'reverse':
+            y = -y
+
         pointing_device = trackball.pointing_device
         pointing_device.report_w[0] = 0xFF & y
         pointing_device.hid_pending = y != 0