Restore wheel emulation for absolute devices

Wheel emulation relies on oldVals, which stopped updating in 3dcf6f123c.

Since wheel emulation may filter the abs event, store the event before we do
anything with it. If we really want the abs_event, abs_queued will be set to
1, otherwise the value will be ignored.

And now that we know abs_value is always valied, we can copy its value into
old_vals, so that wheel emulation can calculate the delta correctly.

https://bugs.freedesktop.org/show_bug.cgi?id=93617

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

src/evdev.c

@@ -430,6 +430,14 @@ static void
 EvdevProcessValuators(InputInfoPtr pInfo)
 {
     EvdevPtr pEvdev = pInfo->private;
+    int val;
+
+    if (pEvdev->abs_vals) {
+            if (valuator_mask_fetch(pEvdev->abs_vals, 0, &val))
+                    valuator_mask_set(pEvdev->old_vals, 0, val);
+            if (valuator_mask_fetch(pEvdev->abs_vals, 1, &val))
+                    valuator_mask_set(pEvdev->old_vals, 1, val);
+    }
 
     /* Apply transformations on relative coordinates */
     if (pEvdev->rel_queued) {
@@ -765,6 +773,12 @@ EvdevProcessAbsoluteMotionEvent(InputInfoPtr pInfo, struct input_event *ev)
     if (ev->code > ABS_MAX)
         return;
 
+    /* Always store the current abs valuator, we need it to update old_vals
+     * which is required by wheel emulation */
+    map = pEvdev->abs_axis_map[ev->code];
+    if (map < 2)
+            valuator_mask_set(pEvdev->abs_vals, map, value);
+
     if (EvdevWheelEmuFilterMotion(pInfo, ev))
         return;
 
@@ -781,10 +795,7 @@ EvdevProcessAbsoluteMotionEvent(InputInfoPtr pInfo, struct input_event *ev)
                 valuator_mask_set(pEvdev->rel_vals, map, value - oldval);
                 pEvdev->rel_queued = 1;
             }
-            valuator_mask_set(pEvdev->old_vals, map, value);
         } else {
-            /* the normal case: just store the number. */
-            valuator_mask_set(pEvdev->abs_vals, map, value);
             pEvdev->abs_queued = 1;
         }
     }