[gtk+] input/IME: Defer the emit of the "commit" signal

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

commit 64a489adbf67af2154df92896024ae8403b42af4
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Thu Aug 31 18:43:07 2017 +0800

    input/IME: Defer the emit of the "commit" signal
    
    On Windows, when IME is used, each keystroke results in the
    WM_IME_COMPOSITION event being sent first.  This means that in our case
    when one decides on to accept the input that is in the preedit buffer,
    we first get from Windows the WM_IME_COMPOSITION event
    (where we emit the commit signal), followed by the WM_IME_ENDCOMPOSITION
    event (where we emit the pair of preedit-changed and preedit-end
    signals).
    
    Since commit f11f989 (GtkEntry: Remove recompute idle), we do the input
    recomputation directly, this will cause a pair of "Pango-WARNING:
    Assertion failed: (index >= 0 && index <= layout->length)" being shown,
    as gtkentry.c's priv->preedit_length and priv->preedit_cursor was unable
    to be reset to 0 in time as a result of the recomputation triggered by
    the commit being done before the reset of priv->preedit_length and
    priv->preedit_cursor (which are no longer valid as we essentially say
    that we are done with the preedit buffer).
    
    As we could only acquire the final string that was entered in this
    preedit session when we handle the WM_IME_COMPOSITION event, fix this by
    saving up the final string we acquire from Windows IME in UTF-8 when we
    handle the WM_IME_COMPOSITION event from Windows, and emit the commit
    signal with that string after we emit the preedit-changed and
    preedit-end signals when we handle the WM_IME_ENDCOMPOSITION event from
    Windows, which comes afterwards.
    
    Also fix the formatting of the code around the parts of the files that
    was changed.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=787142

 modules/input/gtkimcontextime.c |   27 ++++++++++++++++-----------
 modules/input/gtkimcontextime.h |    1 +
 2 files changed, 17 insertions(+), 11 deletions(-)
---
diff --git a/modules/input/gtkimcontextime.c b/modules/input/gtkimcontextime.c
index cc46535..704dc58 100644
--- a/modules/input/gtkimcontextime.c
+++ b/modules/input/gtkimcontextime.c
@@ -187,6 +187,7 @@ gtk_im_context_ime_init (GtkIMContextIME *context_ime)
   context_ime->cursor_location.y      = 0;
   context_ime->cursor_location.width  = 0;
   context_ime->cursor_location.height = 0;
+  context_ime->commit_string          = NULL;
 
   context_ime->priv = g_malloc0 (sizeof (GtkIMContextIMEPrivate));
   context_ime->priv->conversion_mode  = 0;
@@ -1071,14 +1072,14 @@ gtk_im_context_ime_message_filter (GdkXEvent *xevent,
             gchar *utf8str = NULL;
             GError *error = NULL;
 
-           len = ImmGetCompositionStringW (himc, GCS_RESULTSTR, NULL, 0);
+            len = ImmGetCompositionStringW (himc, GCS_RESULTSTR, NULL, 0);
 
             if (len > 0)
               {
-               gpointer buf = g_alloca (len);
-               ImmGetCompositionStringW (himc, GCS_RESULTSTR, buf, len);
-               len /= 2;
-               utf8str = g_utf16_to_utf8 (buf, len, NULL, NULL, &error);
+                gpointer buf = g_alloca (len);
+                ImmGetCompositionStringW (himc, GCS_RESULTSTR, buf, len);
+                len /= 2;
+                context_ime->commit_string = g_utf16_to_utf8 (buf, len, NULL, NULL, &error);
                 if (error)
                   {
                     g_warning ("%s", error->message);
@@ -1086,12 +1087,8 @@ gtk_im_context_ime_message_filter (GdkXEvent *xevent,
                   }
               }
 
-            if (utf8str)
-              {
-                g_signal_emit_by_name (context, "commit", utf8str);
-                g_free (utf8str);
-               retval = TRUE;
-              }
+            if (context_ime->commit_string)
+              retval = TRUE;
           }
 
         if (context_ime->use_preedit)
@@ -1111,6 +1108,14 @@ gtk_im_context_ime_message_filter (GdkXEvent *xevent,
       context_ime->preediting = FALSE;
       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 = TRUE;
       break;
diff --git a/modules/input/gtkimcontextime.h b/modules/input/gtkimcontextime.h
index 8beee09..c8858cb 100644
--- a/modules/input/gtkimcontextime.h
+++ b/modules/input/gtkimcontextime.h
@@ -45,6 +45,7 @@ struct _GtkIMContextIME
   guint opened : 1;
   guint focus : 1;
   GdkRectangle cursor_location;
+  gchar *commit_string;
 
   GtkIMContextIMEPrivate *priv;
 };