master 1bf30718dd: Improve efficency of handling DeviceChanged events

[Po Lu]

branch: master
commit 1bf30718dd1e4284af285e4a92c336f512564f01
Author: Po Lu <luangruo@yahoo.com>
Commit: Po Lu <luangruo@yahoo.com>

    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.
---
 src/xterm.c | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 82 insertions(+), 7 deletions(-)

diff --git a/src/xterm.c b/src/xterm.c
index a17b445701..198aaa69e5 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:
            {