Simplify scroll valuator reset handling

* src/xterm.c (xi_populate_device_from_info)
(xi_reset_scroll_valuators_for_device_id, xi_handle_device_changed)
(handle_one_xevent):
* src/xterm.h (struct xi_scroll_valuator_t): Get rid of
`pending_enter_reset', which was extremely convoluted and kept
hitting server bugs.  Now, valuators are reset upon all crossing
events.

2 files changed, 36 insertions, 34 deletions

diff --git a/src/xterm.c b/src/xterm.c
index f2d6be5d46b..f1bccddb6c3 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -5369,7 +5369,6 @@ xi_populate_device_from_info (struct xi_device_t *xi_device,
             valuator->emacs_value = DBL_MIN;
             valuator->increment = info->increment;
             valuator->number = info->number;
-            valuator->pending_enter_reset = false;
 
             break;
           }
@@ -5415,7 +5414,6 @@ xi_populate_device_from_info (struct xi_device_t *xi_device,
             {
               xi_device->valuators[c].invalid_p = false;
               xi_device->valuators[c].current_value = tem->current_value;
-              xi_device->valuators[c].pending_enter_reset = true;
             }
         }
     }
@@ -5609,8 +5607,8 @@ xi_find_touch_point (struct xi_device_t *device, int detail)
 #ifdef HAVE_XINPUT2_1
 
 static void
-xi_reset_scroll_valuators_for_device_id (struct x_display_info *dpyinfo, int id,
-                                         bool pending_only)
+xi_reset_scroll_valuators_for_device_id (struct x_display_info *dpyinfo,
+                                         int id)
 {
   struct xi_device_t *device = xi_device_from_id (dpyinfo, id);
   struct xi_scroll_valuator_t *valuator;
@@ -5624,11 +5622,6 @@ xi_reset_scroll_valuators_for_device_id (struct x_display_info *dpyinfo, int id,
   for (int i = 0; i < device->scroll_valuator_count; ++i)
     {
       valuator = &device->valuators[i];
-
-      if (pending_only && !valuator->pending_enter_reset)
-        continue;
-
-      valuator->pending_enter_reset = false;
       valuator->invalid_p = true;
       valuator->emacs_value = 0.0;
     }
@@ -13113,14 +13106,6 @@ xi_handle_device_changed (struct x_display_info *dpyinfo,
                 {
                   valuator->invalid_p = false;
                   valuator->current_value = valuator_info->value;
-
-                  /* Make sure that this is reset if the pointer moves
-                     into a window of ours.
-
-                     Otherwise the valuator state could be left
-                     invalid if the DeviceChange event happened with
-                     the pointer outside any Emacs frame. */
-                  valuator->pending_enter_reset = true;
                 }
 
               break;
@@ -21412,8 +21397,8 @@ handle_one_xevent (struct x_display_info *dpyinfo,
                   && enter->mode != XINotifyGrab
                   && enter->mode != XINotifyPassiveGrab
                   && enter->mode != XINotifyPassiveUngrab)
-                xi_reset_scroll_valuators_for_device_id (dpyinfo, enter->deviceid,
-                                                         true);
+                xi_reset_scroll_valuators_for_device_id (dpyinfo,
+                                                         enter->deviceid);
 #endif
 
               {
@@ -21526,13 +21511,18 @@ handle_one_xevent (struct x_display_info *dpyinfo,
                  retrieve the value of a valuator outside of each motion
                  event.
 
-                 As such, to prevent wildly inaccurate results when the
-                 valuators have changed outside Emacs, we reset our
-                 records of each valuator's value whenever the pointer
-                 moves out of a frame (and not into one of its
-                 children, which we know about).  */
+                 As such, to prevent wildly inaccurate results when
+                 the valuators have changed outside Emacs, we reset
+                 our records of each valuator's value whenever the
+                 pointer moves out of a frame.  Ideally, this would
+                 ignore events with a detail of XINotifyInferior, as
+                 the window the pointer moved to would be one known to
+                 Emacs, but the code to keep track of which valuators
+                 had to be reset upon the corresponding XI_Enter event
+                 was very complicated and kept running into server
+                 bugs.  */
 #ifdef HAVE_XINPUT2_1
-              if (leave->detail != XINotifyInferior && any
+              if (any
                   /* xfwm4 selects for button events on the frame
                      window, resulting in passive grabs being
                      generated along with the delivery of emulated
@@ -21547,7 +21537,7 @@ handle_one_xevent (struct x_display_info *dpyinfo,
                   && leave->mode != XINotifyPassiveUngrab
                   && leave->mode != XINotifyPassiveGrab)
                 xi_reset_scroll_valuators_for_device_id (dpyinfo,
-                                                         leave->deviceid, false);
+                                                         leave->deviceid);
 #endif
 
               x_display_set_last_user_time (dpyinfo, leave->time,
@@ -21584,13 +21574,12 @@ handle_one_xevent (struct x_display_info *dpyinfo,
                  just looks up a top window on Xt builds.  */
 
 #ifdef HAVE_XINPUT2_1
-              if (leave->detail != XINotifyInferior && f
-                  && leave->mode != XINotifyUngrab
+              if (f && leave->mode != XINotifyUngrab
                   && leave->mode != XINotifyGrab
                   && leave->mode != XINotifyPassiveUngrab
                   && leave->mode != XINotifyPassiveGrab)
                 xi_reset_scroll_valuators_for_device_id (dpyinfo,
-                                                         leave->deviceid, false);
+                                                         leave->deviceid);
 #endif
 
               if (!f)
diff --git a/src/xterm.h b/src/xterm.h
index 537cabc9577..1124dcceb4a 100644
--- a/src/xterm.h
+++ b/src/xterm.h
@@ -213,20 +213,32 @@ struct color_name_cache_entry
 #ifdef HAVE_XINPUT2
 
 #ifdef HAVE_XINPUT2_1
+
 struct xi_scroll_valuator_t
 {
-  bool invalid_p;
-  bool pending_enter_reset;
+  /* The ID of the valuator.  */
+  int number;
+
+  /* Whether or not it represents X axis movement.  */
+  bool_bf horizontal : 1;
+
+  /* Whether or not the value is currently invalid.  */
+  bool_bf invalid_p : 1;
+
+  /* The current value.  */
   double current_value;
+
+  /* Value used to tally up deltas until a threshold is met.  */
   double emacs_value;
-  double increment;
 
-  int number;
-  int horizontal;
+  /* The scroll increment.  */
+  double increment;
 };
+
 #endif
 
 #ifdef HAVE_XINPUT2_2
+
 struct xi_touch_point_t
 {
   struct xi_touch_point_t *next;
@@ -234,6 +246,7 @@ struct xi_touch_point_t
   int number;
   double x, y;
 };
+
 #endif
 
 struct xi_device_t