Improve efficency of handling DeviceChanged events

* src/xterm.c (handle_one_xevent): Just update the device that
was changed on DeviceChanged and only do hierarchy recalculation
upon HierarchyChanged events.

1 files changed, 82 insertions, 7 deletions

diff --git a/src/xterm.c b/src/xterm.c
index a17b445701b..198aaa69e5f 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -10783,6 +10783,7 @@ handle_one_xevent (struct x_display_info *dpyinfo,
         XIEnterEvent *enter = (XIEnterEvent *) xi_event;
         XIFocusInEvent *focusin = (XIFocusInEvent *) xi_event;
         XIFocusOutEvent *focusout = (XIFocusOutEvent *) xi_event;
+        XIDeviceChangedEvent *device_changed = (XIDeviceChangedEvent *) xi_event;
         XIValuatorState *states;
         double *values;
         bool found_valuator = false;
@@ -11861,17 +11862,91 @@ handle_one_xevent (struct x_display_info *dpyinfo,
             goto XI_OTHER;
 
           case XI_PropertyEvent:
+            goto XI_OTHER;
+
           case XI_HierarchyChanged:
-          case XI_DeviceChanged:
-#ifdef XISlaveSwitch
-            if (xi_event->evtype == XI_DeviceChanged
-                && (((XIDeviceChangedEvent *) xi_event)->reason
-                    == XISlaveSwitch))
-              goto XI_OTHER;
-#endif
             x_init_master_valuators (dpyinfo);
             goto XI_OTHER;
 
+          case XI_DeviceChanged:
+            {
+              struct xi_device_t *device;
+              struct xi_touch_point_t *tem, *last;
+              int c;
+
+              device = xi_device_from_id (dpyinfo, device_changed->sourceid);
+
+              if (!device)
+                emacs_abort ();
+
+              /* Free data that we will regenerate from new
+                 information.  */
+              device->valuators = xrealloc (device->valuators,
+                                            (device_changed->num_classes
+                                             * sizeof *device->valuators));
+              device->scroll_valuator_count = 0;
+              device->direct_p = false;
+
+              for (c = 0; c < device_changed->num_classes; ++c)
+                {
+                  switch (device_changed->classes[c]->type)
+                    {
+#ifdef XIScrollClass
+                    case XIScrollClass:
+                      {
+                        XIScrollClassInfo *info =
+                          (XIScrollClassInfo *) device_changed->classes[c];
+                        struct xi_scroll_valuator_t *valuator;
+
+                        if (device->master_p)
+                          {
+                            valuator = &device->valuators[device->scroll_valuator_count++];
+                            valuator->horizontal
+                              = (info->scroll_type == XIScrollTypeHorizontal);
+                            valuator->invalid_p = true;
+                            valuator->emacs_value = DBL_MIN;
+                            valuator->increment = info->increment;
+                            valuator->number = info->number;
+                          }
+
+                        break;
+                      }
+#endif
+
+#ifdef XITouchClass
+                    case XITouchClass:
+                      {
+                        XITouchClassInfo *info;
+
+                        info = (XITouchClassInfo *) device_changed->classes[c];
+                        device->direct_p = info->mode == XIDirectTouch;
+                      }
+#endif
+                    default:
+                      break;
+                    }
+                }
+
+              /* The device is no longer a DirectTouch device, so
+                 remove any touchpoints that we might have
+                 recorded.  */
+              if (!device->direct_p)
+                {
+                  tem = device->touchpoints;
+
+                  while (tem)
+                    {
+                      last = tem;
+                      tem = tem->next;
+                      xfree (last);
+                    }
+
+                  device->touchpoints = NULL;
+                }
+
+              goto XI_OTHER;
+            }
+
 #ifdef XI_TouchBegin
           case XI_TouchBegin:
             {