clutter: Move evdev evcode data to Clutter button/key events

We have this as platform-dependent data in the native backend, and
a bunch of fallback code done in place in the evcode users. Stop
making this platform-dependent data, and move it to the relevant
ClutterEvents.

The fallback code for the X11 backend case is about the same, but
now it is done directly by the X11 backend.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1623>

src/backends/native/meta-event-native.c

@@ -28,8 +28,6 @@ typedef struct _MetaEventNative MetaEventNative;
 
 struct _MetaEventNative
 {
-  uint32_t evcode;
-
   uint64_t time_usec;
 
   gboolean has_relative_motion;
@@ -75,16 +73,6 @@ meta_event_native_ensure_platform_data (ClutterEvent *event)
   return event_evdev;
 }
 
-void
-meta_event_native_set_event_code (ClutterEvent *event,
-                                  uint32_t      evcode)
-{
-  MetaEventNative *event_evdev;
-
-  event_evdev = meta_event_native_ensure_platform_data (event);
-  event_evdev->evcode = evcode;
-}
-
 void
 meta_event_native_set_time_usec (ClutterEvent *event,
                                  uint64_t      time_usec)
@@ -112,26 +100,6 @@ meta_event_native_set_relative_motion (ClutterEvent *event,
   event_evdev->has_relative_motion = TRUE;
 }
 
-/**
- * meta_event_native_get_event_code:
- * @event: a #ClutterEvent
- *
- * Returns the event code of the original event. See linux/input.h for more
- * information.
- *
- * Returns: The event code.
- **/
-uint32_t
-meta_event_native_get_event_code (const ClutterEvent *event)
-{
-  MetaEventNative *event_evdev = _clutter_event_get_platform_data (event);
-
-  if (event_evdev)
-    return event_evdev->evcode;
-
-  return 0;
-}
-
 /**
  * meta_event_native_get_time_usec:
  * @event: a #ClutterEvent

src/backends/native/meta-event-native.h

@@ -28,9 +28,6 @@ typedef struct _MetaEventNative MetaEventNative;
 MetaEventNative * meta_event_native_copy (MetaEventNative *event_evdev);
 void              meta_event_native_free (MetaEventNative *event_evdev);
 
-uint32_t          meta_event_native_get_event_code (const ClutterEvent *event);
-void              meta_event_native_set_event_code (ClutterEvent *event,
-                                                    uint32_t      evcode);
 uint64_t          meta_event_native_get_time_usec  (const ClutterEvent *event);
 void              meta_event_native_set_time_usec  (ClutterEvent *event,
                                                     uint64_t      time_usec);

src/backends/native/meta-seat-impl.c

@@ -397,7 +397,7 @@ meta_seat_impl_notify_key_in_impl (MetaSeatImpl       *seat_impl,
                                          seat_impl->xkb,
                                          seat_impl->button_state,
                                          us2ms (time_us), key, state);
-  meta_event_native_set_event_code (event, key);
+  event->key.evdev_code = key;
 
   keycode = meta_xkb_evdev_to_keycode (key);
 
@@ -712,7 +712,7 @@ meta_seat_impl_notify_button_in_impl (MetaSeatImpl       *seat_impl,
         button = mapped_button;
     }
 
-  meta_event_native_set_event_code (event, button);
+  event->button.evdev_code = button;
 
   if (clutter_input_device_get_device_type (input_device) == CLUTTER_TABLET_DEVICE)
     {

src/backends/x11/meta-seat-x11.c

@@ -18,6 +18,7 @@
  */
 #include "config.h"
 
+#include <linux/input-event-codes.h>
 #include <X11/extensions/XInput2.h>
 #include <X11/extensions/XKB.h>
 
@@ -1709,6 +1710,35 @@ get_source_device_checked (MetaSeatX11   *seat,
   return source_device;
 }
 
+static uint32_t
+evdev_button_code (uint32_t x_button)
+{
+  uint32_t button;
+
+  switch (x_button)
+    {
+    case 1:
+      button = BTN_LEFT;
+      break;
+
+      /* The evdev input right and middle button numbers are swapped
+         relative to how Clutter numbers them */
+    case 2:
+      button = BTN_MIDDLE;
+      break;
+
+    case 3:
+      button = BTN_RIGHT;
+      break;
+
+    default:
+      button = x_button + (BTN_LEFT - 1) + 4;
+      break;
+    }
+
+  return button;
+}
+
 gboolean
 meta_seat_x11_translate_event (MetaSeatX11  *seat,
                                XEvent       *xevent,
@@ -1812,6 +1842,10 @@ meta_seat_x11_translate_event (MetaSeatX11  *seat,
         meta_input_device_x11_translate_state (event, &xev->mods, &xev->buttons, &xev->group);
         event->key.hardware_keycode = xev->detail;
 
+        /* clutter-xkb-utils.c adds a fixed offset of 8 to go into XKB's
+         * range, so we do the reverse here. */
+        event->key.evdev_code = event->key.hardware_keycode - 8;
+
           /* keyval is the key ignoring all modifiers ('1' vs. '!') */
         event->key.keyval =
           meta_keymap_x11_translate_key_state (keymap_x11,
@@ -1992,6 +2026,7 @@ meta_seat_x11_translate_event (MetaSeatX11  *seat,
             event->button.time = xev->time;
             translate_coords (stage_x11, xev->event_x, xev->event_y, &event->button.x, &event->button.y);
             event->button.button = xev->detail;
+            event->button.evdev_code = evdev_button_code (xev->detail);
             meta_input_device_x11_translate_state (event,
                                                    &xev->mods,
                                                    &xev->buttons,