[gtk+] win32: use the input locale to decide the default input method

[Matthias Clasen <matthiasc src gnome org>]

commit 90de3c4fc016379284061aebfb3c970728deb46c
Author: Aleksander Morgado <aleksander lanedo com>
Date:   Sat Aug 31 13:58:12 2013 -0400

    win32: use the input locale to decide the default input method
    
    GTK+ tries to automatically assign the best input module based on the
    'system locale'. In the specific case of the IME input method, it will
    be the default for the whole GTK+ application if the system locale is
    either Japanese (ja), Korean (ko) or Chinese (zh). Other defaults are
    equally applicable, e.g. if system locale is Catalan (ca), the special
    'Cedilla' input module is chosen.
    
    System locale can be changed (e.g. Win7) through the following sequence
    (reboot required):
      Control Panel
        Region and Language
          Administrative
            Language for non-Unicode Programs
              Change system locale...
    
    The problem with this behaviour is that changing the 'default input
    language' (e.g. from English to Japanese+IME) doesn't affect the GTK+
    application. Therefore, I can have an English system locale (where GTK+
    will choose Simple IM by default) but then have Japanese+IME as input
    language.
    
    Default input language can be changed (e.g. Win7) through the following
    sequence (no reboot required):
      System locale can be changed (e.g. Win7) through:
        Control Panel
          Region and Language
            Keyboards and Languages
              Keyboards and other input languages
                Change keyboards...
    
    Default input language can also be changed using the language bar directly.
    
    So, instead of using the system-wide default locale to decide which input
    method to use as default, better use the input language specified by the
    user, which may be the same as the system-wide default locale, or different.
    Following the previous example, with an English system locale and a
    Japanese+IME input language, the default input method will now be IME
    instead of Simple, which is closer to what's expected by the user.
    
    This change only affects the application during startup; i.e. if the user
    changes the input language while the application is running, we wouldn't be
    changing the default input method to use. We could do this processing the
    WM_INPUTLANGCHANGE messages, though.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=700428

 gtk/gtkimmodule.c |   76 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 75 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkimmodule.c b/gtk/gtkimmodule.c
index f17672b..1660ba3 100644
--- a/gtk/gtkimmodule.c
+++ b/gtk/gtkimmodule.c
@@ -49,6 +49,10 @@
 #include "win32/gdkwin32.h"
 #endif
 
+#ifdef G_OS_WIN32
+#include <windows.h>
+#endif
+
 #undef GDK_DEPRECATED
 #undef GDK_DEPRECATED_FOR
 #define GDK_DEPRECATED
@@ -693,6 +697,67 @@ lookup_immodule (gchar **immodules_list)
   return NULL;
 }
 
+#ifdef G_OS_WIN32
+
+/* max size for LOCALE_SISO639LANGNAME and LOCALE_SISO3166CTRYNAME is 9 */
+#define MAX_NAME_SIZE 9
+
+static gchar *
+get_current_input_language (void)
+{
+  LCID lcid;
+  LANGID langid;
+  HKL kblayout;
+  int name_size;
+  wchar_t name[MAX_NAME_SIZE];
+  gchar *language;
+  gchar *country;
+  gchar *full;
+
+  /* Current thread's keyboard layout */
+  kblayout = GetKeyboardLayout(0);
+  /* lowest word in the HKL is the LANGID */
+  langid = ((guint32)kblayout) & 0xFFFF;
+  /* LCID is the LANGID without order */
+  lcid = langid;
+
+  /* Get Language ID */
+  name_size = GetLocaleInfoW (lcid, LOCALE_SISO639LANGNAME, NULL, 0);
+  if (name_size <= 1)
+    return NULL;
+
+  g_assert (name_size <= MAX_NAME_SIZE);
+  GetLocaleInfoW (lcid, LOCALE_SISO639LANGNAME, name, name_size);
+
+  language = g_utf16_to_utf8 (name, name_size, NULL, NULL, NULL);
+  if (!language)
+    return NULL;
+
+  if (SUBLANGID (langid) == SUBLANG_NEUTRAL)
+    return language;
+
+  /* Get Country ID */
+  name_size = GetLocaleInfoW (lcid, LOCALE_SISO3166CTRYNAME, NULL, 0);
+  if (name_size <= 1)
+    return language;
+
+  g_assert (name_size <= MAX_NAME_SIZE);
+  GetLocaleInfoW (lcid, LOCALE_SISO3166CTRYNAME, name, name_size);
+
+  country = g_utf16_to_utf8 (name, name_size, NULL, NULL, NULL);
+  if (!country)
+    return language;
+
+  full = g_strdup_printf ("%s_%s", language, country);
+
+  g_free (language);
+  g_free (country);
+
+  return full;
+}
+
+#endif
+
 /**
  * _gtk_im_module_get_default_context_id:
  * @client_window: a window
@@ -744,9 +809,18 @@ _gtk_im_module_get_default_context_id (GdkWindow *client_window)
         return context_id;
     }
 
+#ifdef G_OS_WIN32
+  /* Read current input locale from the current keyboard info */
+  tmp_locale = get_current_input_language ();
+  if (!tmp_locale)
+    /* Default to system locale when input language is unknown */
+    tmp_locale = _gtk_get_lc_ctype ();
+#else
+  tmp_locale = _gtk_get_lc_ctype ();
+#endif
+
   /* Strip the locale code down to the essentials
    */
-  tmp_locale = _gtk_get_lc_ctype ();
   tmp = strchr (tmp_locale, '.');
   if (tmp)
     *tmp = '\0';