From 6070f1092258e053ecdbe2dbf6148d2dd9d8b326 Mon Sep 17 00:00:00 2001
From: Carlos Garnacho <carlosg@gnome.org>
Date: Tue, 13 Jun 2023 22:11:15 +0200
Subject: [PATCH] gdk/wayland: Create pad devices on enter

We were creating the pad device on wp_tablet_pad.done, but
at that time we do not know what tablet it is associated with,
thus we cannot get appropriate vid/pid/name properties for it.

To get that, we need to wait for the pad to enter a surface,
at that time we do know what tablet it is associated with, so
we can get better information about the device.

There are pads that may plausibly "change" tablet between
one .enter event and the next (e.g. Wacom Express Key Remote),
but this situation is highly unlikely. The pad devices created
are thus persistent until that situation happens.
---
 gdk/wayland/gdkdevice-wayland.c | 86 ++++++++++++++++++++++-----------
 1 file changed, 57 insertions(+), 29 deletions(-)

diff --git a/gdk/wayland/gdkdevice-wayland.c b/gdk/wayland/gdkdevice-wayland.c
index 9dc86a3257..7e7beac9d1 100644
--- a/gdk/wayland/gdkdevice-wayland.c
+++ b/gdk/wayland/gdkdevice-wayland.c
@@ -2921,13 +2921,17 @@ _gdk_wayland_seat_remove_tablet_pad (GdkWaylandSeat          *seat,
 
   seat->tablet_pads = g_list_remove (seat->tablet_pads, pad);
 
-  device_manager->devices =
-    g_list_remove (device_manager->devices, pad->device);
-  g_signal_emit_by_name (device_manager, "device-removed", pad->device);
+  if (pad->device)
+    {
+      device_manager->devices =
+        g_list_remove (device_manager->devices, pad->device);
+      g_signal_emit_by_name (device_manager, "device-removed", pad->device);
 
-  _gdk_device_set_associated_device (pad->device, NULL);
+      _gdk_device_set_associated_device (pad->device, NULL);
+
+      g_object_unref (pad->device);
+    }
 
-  g_object_unref (pad->device);
   g_free (pad);
 }
 
@@ -4439,27 +4443,8 @@ static void
 tablet_pad_handle_done (void                     *data,
                         struct zwp_tablet_pad_v2 *wp_tablet_pad)
 {
-  GdkWaylandTabletPadData *pad = data;
-  GdkWaylandSeat *seat = GDK_WAYLAND_SEAT (pad->seat);
-  GdkWaylandDeviceManager *device_manager =
-    GDK_WAYLAND_DEVICE_MANAGER (seat->device_manager);
-
   GDK_NOTE (EVENTS,
             g_message ("tablet pad handle done, pad = %p", wp_tablet_pad));
-
-  pad->device =
-    g_object_new (GDK_TYPE_WAYLAND_DEVICE_PAD,
-                  "name", "Pad device",
-                  "type", GDK_DEVICE_TYPE_SLAVE,
-                  "input-source", GDK_SOURCE_TABLET_PAD,
-                  "input-mode", GDK_MODE_SCREEN,
-                  "display", gdk_seat_get_display (pad->seat),
-                  "device-manager", device_manager,
-                  "seat", seat,
-                  NULL);
-
-  _gdk_device_set_associated_device (pad->device, seat->master_keyboard);
-  g_signal_emit_by_name (device_manager, "device-added", pad->device);
 }
 
 static void
@@ -4506,14 +4491,60 @@ tablet_pad_handle_enter (void                     *data,
 {
   GdkWaylandTabletPadData *pad = data;
   GdkWaylandTabletData *tablet = zwp_tablet_v2_get_user_data (wp_tablet);
+  GdkWaylandSeat *seat = GDK_WAYLAND_SEAT (pad->seat);
+  GdkWaylandDeviceManager *device_manager =
+    GDK_WAYLAND_DEVICE_MANAGER (seat->device_manager);
 
   GDK_NOTE (EVENTS,
             g_message ("tablet pad handle enter, pad = %p, tablet = %p surface = %p",
                        wp_tablet_pad, wp_tablet, surface));
 
+  if (pad->device && pad->current_tablet != tablet)
+    {
+      device_manager->devices =
+        g_list_remove (device_manager->devices, pad->device);
+      g_signal_emit_by_name (device_manager, "device-removed", pad->device);
+      _gdk_device_set_associated_device (pad->device, NULL);
+      g_clear_object (&pad->device);
+    }
+
   /* Relate pad and tablet */
-  tablet->pads = g_list_prepend (tablet->pads, pad);
+  tablet->pads = g_list_append (tablet->pads, pad);
   pad->current_tablet = tablet;
+
+  if (!pad->device)
+    {
+      GdkWaylandTabletPadData *pad = data;
+      gchar *name, *vid, *pid;
+
+      name = g_strdup_printf ("%s Pad %d",
+                              tablet->name,
+                              g_list_index (tablet->pads, pad) + 1);
+      vid = g_strdup_printf ("%.4x", tablet->vid);
+      pid = g_strdup_printf ("%.4x", tablet->pid);
+
+      pad->device =
+        g_object_new (GDK_TYPE_WAYLAND_DEVICE_PAD,
+                      "name", name,
+                      "vendor-id", vid,
+                      "product-id", pid,
+                      "type", GDK_DEVICE_TYPE_SLAVE,
+                      "input-source", GDK_SOURCE_TABLET_PAD,
+                      "input-mode", GDK_MODE_SCREEN,
+                      "display", gdk_seat_get_display (pad->seat),
+                      "device-manager", device_manager,
+                      "seat", seat,
+                      NULL);
+
+      _gdk_device_set_associated_device (pad->device, seat->master_keyboard);
+      device_manager->devices =
+        g_list_prepend (device_manager->devices, pad->device);
+      g_signal_emit_by_name (device_manager, "device-added", pad->device);
+
+      g_free (name);
+      g_free (vid);
+      g_free (pid);
+    }
 }
 
 static void
@@ -4529,10 +4560,7 @@ tablet_pad_handle_leave (void                     *data,
                        wp_tablet_pad, surface));
 
   if (pad->current_tablet)
-    {
-      pad->current_tablet->pads = g_list_remove (pad->current_tablet->pads, pad);
-      pad->current_tablet = NULL;
-    }
+    pad->current_tablet->pads = g_list_remove (pad->current_tablet->pads, pad);
 }
 
 static void