[mutter/wip/carlosg/fix-preedit-offsets] wayland: Represent preedit string cursor offset in bytes

[Carlos Garnacho <carlosg src gnome org>]

commit 5d3e1af14eb309911e2a6591cf08e2ad9314c9f4
Author: Carlos Garnacho <carlosg gnome org>
Date:   Tue Mar 17 16:11:57 2020 +0100

    wayland: Represent preedit string cursor offset in bytes
    
    Both IBus and ClutterInputFocus work in character offsets for the cursor
    position in the preedit string. However the zwp_text_input protocol does
    define the preedit string cursor offset to be in bytes.
    
    Fixes client bugs in representing the caret within the preedit string,
    as we were clearly giving the wrong offset.
    
    Fixes: https://gitlab.gnome.org/GNOME/gtk/issues/2517
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1132

 src/wayland/meta-wayland-text-input.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
---
diff --git a/src/wayland/meta-wayland-text-input.c b/src/wayland/meta-wayland-text-input.c
index ee9b895cb..deff44c1b 100644
--- a/src/wayland/meta-wayland-text-input.c
+++ b/src/wayland/meta-wayland-text-input.c
@@ -207,12 +207,14 @@ meta_wayland_text_input_focus_set_preedit_text (ClutterInputFocus *focus,
 {
   MetaWaylandTextInput *text_input;
   struct wl_resource *resource;
+  gsize pos;
 
   text_input = META_WAYLAND_TEXT_INPUT_FOCUS (focus)->text_input;
+  pos = g_utf8_offset_to_pointer (text, cursor) - text;
 
   wl_resource_for_each (resource, &text_input->focus_resource_list)
     {
-      zwp_text_input_v3_send_preedit_string (resource, text, cursor, cursor);
+      zwp_text_input_v3_send_preedit_string (resource, text, pos, pos);
     }
 
   meta_wayland_text_input_focus_defer_done (focus);