[gtk+] GDK W32: Support UTF-16 surrogate pairs passed via VK_PACKET

[Руслан Ижбулатов <ruslanizhb src gnome org>]

commit 2233566f4854c07d89deeeb8505e82bad544787c
Author: Руслан Ижбулатов <lrn1986 gmail com>
Date:   Sun Jul 24 14:26:06 2016 +0000

    GDK W32: Support UTF-16 surrogate pairs passed via VK_PACKET
    
    This is, essentially, a piece of g_utf16_to_ucs4() built into GDK
    W32 keyboard message processing.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=769126

 gdk/win32/gdkevents-win32.c |   75 ++++++++++++++++++++++++++++++++++++------
 gdk/win32/gdkwindow-win32.h |    8 ++++
 2 files changed, 72 insertions(+), 11 deletions(-)
---
diff --git a/gdk/win32/gdkevents-win32.c b/gdk/win32/gdkevents-win32.c
index 4f01da9..7f050a4 100644
--- a/gdk/win32/gdkevents-win32.c
+++ b/gdk/win32/gdkevents-win32.c
@@ -2288,6 +2288,8 @@ gdk_event_translate (MSG  *msg,
       if (GDK_WINDOW_DESTROYED (window))
        break;
 
+      impl = GDK_WINDOW_IMPL_WIN32 (window->impl);
+
       if (msg->message == WM_KEYUP &&
           !GDK_WINDOW_DESTROYED (gdk_window_get_toplevel (window)) &&
           _gdk_win32_window_lacks_wm_decorations (gdk_window_get_toplevel (window)) && /* For CSD only */
@@ -2330,6 +2332,33 @@ gdk_event_translate (MSG  *msg,
            }
        }
 
+      API_CALL (GetKeyboardState, (key_state));
+
+      ccount = 0;
+
+      if (msg->wParam == VK_PACKET)
+       {
+         ccount = ToUnicode (VK_PACKET, HIWORD (msg->lParam), key_state, wbuf, 1, 0);
+         if (ccount == 1)
+           {
+             if (wbuf[0] >= 0xD800 && wbuf[0] < 0xDC00)
+               {
+                 if (msg->message == WM_KEYDOWN)
+                   impl->leading_surrogate_keydown = wbuf[0];
+                 else
+                   impl->leading_surrogate_keyup = wbuf[0];
+
+                 /* don't emit an event */
+                 return_val = TRUE;
+                 break;
+               }
+             else
+               {
+                 /* wait until an event is created */;
+               }
+           }
+       }
+
       event = gdk_event_new ((msg->message == WM_KEYDOWN ||
                              msg->message == WM_SYSKEYDOWN) ?
                             GDK_KEY_PRESS : GDK_KEY_RELEASE);
@@ -2365,22 +2394,46 @@ gdk_event_translate (MSG  *msg,
               LOBYTE (HIWORD (msg->lParam)) == _scancode_rshift)
        event->key.hardware_keycode = VK_RSHIFT;
 
-      API_CALL (GetKeyboardState, (key_state));
-
       /* g_print ("ctrl:%02x lctrl:%02x rctrl:%02x alt:%02x lalt:%02x ralt:%02x\n", key_state[VK_CONTROL], 
key_state[VK_LCONTROL], key_state[VK_RCONTROL], key_state[VK_MENU], key_state[VK_LMENU], 
key_state[VK_RMENU]); */
 
       build_key_event_state (event, key_state);
 
-      if (msg->wParam == VK_PACKET &&
-         ToUnicode (VK_PACKET, HIWORD (msg->lParam), key_state, wbuf, 1, 0) == 1)
-       event->key.keyval = gdk_unicode_to_keyval (wbuf[0]);
+      if (msg->wParam == VK_PACKET && ccount == 1)
+       {
+         if (wbuf[0] >= 0xD800 && wbuf[0] < 0xDC00)
+           {
+             g_assert_not_reached ();
+           }
+         else if (wbuf[0] >= 0xDC00 && wbuf[0] < 0xE000)
+           {
+             wchar_t leading;
+
+              if (msg->message == WM_KEYDOWN)
+               leading = impl->leading_surrogate_keydown;
+             else
+               leading = impl->leading_surrogate_keyup;
+
+             event->key.keyval = gdk_unicode_to_keyval ((leading - 0xD800) * 0x400 + wbuf[0] - 0xDC00 + 
0x10000);
+           }
+         else
+           {
+             event->key.keyval = gdk_unicode_to_keyval (wbuf[0]);
+           }
+       }
+      else
+       {
+         gdk_keymap_translate_keyboard_state (_gdk_win32_display_get_keymap (display),
+                                              event->key.hardware_keycode,
+                                              event->key.state,
+                                              event->key.group,
+                                              &event->key.keyval,
+                                              NULL, NULL, NULL);
+       }
+
+      if (msg->message == WM_KEYDOWN)
+       impl->leading_surrogate_keydown = 0;
       else
-       gdk_keymap_translate_keyboard_state (_gdk_win32_display_get_keymap (display),
-                                            event->key.hardware_keycode,
-                                            event->key.state,
-                                            event->key.group,
-                                            &event->key.keyval,
-                                            NULL, NULL, NULL);
+       impl->leading_surrogate_keyup = 0;
 
       fill_key_event_string (event);
 
diff --git a/gdk/win32/gdkwindow-win32.h b/gdk/win32/gdkwindow-win32.h
index ab5f0fe..508087b 100644
--- a/gdk/win32/gdkwindow-win32.h
+++ b/gdk/win32/gdkwindow-win32.h
@@ -228,6 +228,14 @@ struct _GdkWindowImplWin32
   HICON   hicon_big;
   HICON   hicon_small;
 
+  /* When VK_PACKET sends us a leading surrogate, it's stashed here.
+   * Later, when another VK_PACKET sends a tailing surrogate, we make up
+   * a full unicode character from them, or discard the leading surrogate,
+   * if the next key is not a tailing surrogate.
+   */
+  wchar_t leading_surrogate_keydown;
+  wchar_t leading_surrogate_keyup;
+
   /* Window size hints */
   gint hint_flags;
   GdkGeometry hints;