[gtk] gtkimcontextime.c: Fix Korean input

[Chun-wei Fan <fanchunwei src gnome org>]

commit 1ca5b415711111cc037dff9a52d10d632137a3cb
Author: Chun-wei Fan <fanc999 yahoo com tw>
Date:   Tue Oct 9 17:06:39 2018 +0800

    gtkimcontextime.c: Fix Korean input
    
    Commit 64a489ad inadvertently introduced a regression that broke Korean
    text input because the changes there resulted that only the last input
    string that we have from ImmGetCompositionStringW() for each time the
    commit signal is emitted is kept, and also as a result the final Korean
    character that is input by hitting space is also lost as a result, as we
    didn't check for whether we are done with preediting.
    
    Fix these issues by doing the following when we receive the
    WM_IME_COMPOSITION message with GCS_RESULTSTR from Windows:
    -Do not emit the commit signal during WM_IME_ENDCOMPOSITION, and...
    -Emit the commit signal anyways, as we did before c255ba68, however...
    -We still save up the string to commit, because we need to re-compute
     the cursor position when we do ->get_preedit_string(), which needs to
     take the GCS_RESULTSTR string we get from WM_IME_COMPOSITION into
     account as well, so that we avoid getting the Pango criticals that
     occur during Chinese (and most likely Japanese) input as the cursor
     position is out-of-range.
    
    Fixes issue #1350.

 gtk/gtkimcontextime.c | 89 +++++++++++++++++++++++++++++++--------------------
 1 file changed, 55 insertions(+), 34 deletions(-)
---
diff --git a/gtk/gtkimcontextime.c b/gtk/gtkimcontextime.c
index 706c1e54f2..2d776b4560 100644
--- a/gtk/gtkimcontextime.c
+++ b/gtk/gtkimcontextime.c
@@ -466,30 +466,53 @@ get_utf8_preedit_string (GtkIMContextIME *context_ime, gint *pos_ret)
 
       len = ImmGetCompositionStringW (himc, GCS_COMPSTR, NULL, 0);
       if (len > 0)
-       {
-         GError *error = NULL;
-         gpointer buf = g_alloca (len);
-
-         ImmGetCompositionStringW (himc, GCS_COMPSTR, buf, len);
-         len /= 2;
-         utf8str = g_utf16_to_utf8 (buf, len, NULL, NULL, &error);
-         if (error)
-           {
-             g_warning ("%s", error->message);
-             g_error_free (error);
-           }
-
-         if (pos_ret)
-           {
-             pos = ImmGetCompositionStringW (himc, GCS_CURSORPOS, NULL, 0);
-             if (pos < 0 || len < pos)
-               {
-                 g_warning ("ImmGetCompositionString: "
-                            "Invalid cursor position!");
-                 pos = 0;
-               }
-           }
-       }
+        {
+          GError *error = NULL;
+          gpointer buf = g_alloca (len);
+
+          ImmGetCompositionStringW (himc, GCS_COMPSTR, buf, len);
+          len /= 2;
+          utf8str = g_utf16_to_utf8 (buf, len, NULL, NULL, &error);
+          if (error)
+            {
+               g_warning ("%s", error->message);
+               g_error_free (error);
+            }
+
+          if (pos_ret)
+            {
+              pos = ImmGetCompositionStringW (himc, GCS_CURSORPOS, NULL, 0);
+              if (pos < 0 || len < pos)
+                {
+                  g_warning ("ImmGetCompositionString: "
+                             "Invalid cursor position!");
+                  pos = 0;
+                }
+            }
+        }
+    }
+
+  if (context_ime->commit_string)
+    {
+      if (utf8str)
+        {
+          gchar *utf8str_new = g_strdup (utf8str);
+
+          /* Note: We *don't* want to update context_ime->commit_string here!
+           * Otherwise it will be updated repeatedly, not what we want!
+           */
+          g_free (utf8str);
+          utf8str = g_strconcat (context_ime->commit_string,
+                                 utf8str_new,
+                                 NULL);
+          g_free (utf8str_new);
+          pos += g_utf8_strlen (context_ime->commit_string, -1);
+        }
+      else
+        {
+          utf8str = g_strdup (context_ime->commit_string);
+          pos = g_utf8_strlen (context_ime->commit_string, -1);
+        }
     }
 
   if (!utf8str)
@@ -1065,10 +1088,15 @@ gtk_im_context_ime_message_filter (GdkWin32Display *display,
                     g_warning ("%s", error->message);
                     g_error_free (error);
                   }
-              }
 
-            if (context_ime->commit_string)
-              retval = GDK_WIN32_MESSAGE_FILTER_REMOVE;
+                if (context_ime->commit_string)
+                  {
+                    g_signal_emit_by_name (context, "commit", context_ime->commit_string);
+                    g_free (context_ime->commit_string);
+                    context_ime->commit_string = NULL;
+                    retval = GDK_WIN32_MESSAGE_FILTER_REMOVE;
+                  }
+              }
           }
 
         if (context_ime->use_preedit)
@@ -1089,13 +1117,6 @@ gtk_im_context_ime_message_filter (GdkWin32Display *display,
       g_signal_emit_by_name (context, "preedit-changed");
       g_signal_emit_by_name (context, "preedit-end");
 
-      if (context_ime->commit_string)
-        {
-          g_signal_emit_by_name (context, "commit", context_ime->commit_string);
-          g_free (context_ime->commit_string);
-          context_ime->commit_string = NULL;
-        }
-
       if (context_ime->use_preedit)
         retval = GDK_WIN32_MESSAGE_FILTER_REMOVE;
       break;