Implement dead key combination on Android

* src/android.c (android_init_key_character_map)
(android_get_dead_char): New functions.
(android_wc_lookup_string): New argument COMPOSE_STATE.  Ignore
key events with the COMBINING_ACCENT flag set while recording
their character values there, and combine such characters with
the key event when processing a subsequent key event.

* src/androidgui.h (struct android_compose_status): New
structure.

* src/androidterm.c (handle_one_android_event): Port dead key
combination code from X.  (bug#69321)

1 files changed, 18 insertions, 1 deletions

diff --git a/src/androidterm.c b/src/androidterm.c
index 2bd2b45743d..baf26abe322 100644
--- a/src/androidterm.c
+++ b/src/androidterm.c
@@ -811,6 +811,7 @@ handle_one_android_event (struct android_display_info *dpyinfo,
   int keysym;
   ptrdiff_t nchars, i;
   struct window *w;
+  static struct android_compose_status compose_status;
 
   /* It is okay for this to not resemble handle_one_xevent so much.
      Differences in event handling code are much less nasty than
@@ -947,6 +948,14 @@ handle_one_android_event (struct android_display_info *dpyinfo,
                                                extra_keyboard_modifiers);
       modifiers = event->xkey.state;
 
+      /* In case Meta is ComposeCharacter, clear its status.  According
+         to Markus Ehrnsperger
+         Markus.Ehrnsperger@lehrstuhl-bross.physik.uni-muenchen.de this
+         enables ComposeCharacter to work whether or not it is combined
+         with Meta.  */
+      if (modifiers & ANDROID_ALT_MASK)
+        memset (&compose_status, 0, sizeof (compose_status));
+
       /* Common for all keysym input events.  */
       XSETFRAME (inev.ie.frame_or_window, any);
       inev.ie.modifiers
@@ -960,7 +969,8 @@ handle_one_android_event (struct android_display_info *dpyinfo,
 
         nchars = android_wc_lookup_string (&event->xkey, copy_bufptr,
                                            copy_bufsiz, &keysym,
-                                           &status_return);
+                                           &status_return,
+                                           &compose_status);
 
         /* android_lookup_string can't be called twice, so there's no
            way to recover from buffer overflow.  */
@@ -1000,6 +1010,13 @@ handle_one_android_event (struct android_display_info *dpyinfo,
           }
       }
 
+      /* If a compose sequence is in progress, we break here.
+         Otherwise, chars_matched is always 0.  */
+      if (compose_status.chars_matched > 0 && nchars == 0)
+        break;
+
+      memset (&compose_status, 0, sizeof (compose_status));
+
       if (nchars == 1 && copy_bufptr[0] >= 32)
         {
           /* Deal with characters.  */