From 2233566f4854c07d89deeeb8505e82bad544787c Mon Sep 17 00:00:00 2001
From: =?utf8?q?=D0=A0=D1=83=D1=81=D0=BB=D0=B0=D0=BD=20=D0=98=D0=B6=D0=B1?=
 =?utf8?q?=D1=83=D0=BB=D0=B0=D1=82=D0=BE=D0=B2?= <lrn1986@gmail.com>
Date: Sun, 24 Jul 2016 14:26:06 +0000
Subject: [PATCH] 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 4f01da9300..7f050a4e73 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 ab5f0fe258..508087beb9 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;
-- 
2.30.2