gtk2/modules/input/gtkimcontextime.c

/*
 * gtkimmoduleime
 * Copyright (C) 2003 Takuro Ashie
 * Copyright (C) 2003-2004 Kazuki IWAMOTO
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * $Id$
 */

/*
 *  Please see the following site for the detail of Windows IME API.
 *  http://msdn.microsoft.com/library/default.asp?url=/library/en-us/appendix/hh/appendix/imeimes2_35ph.asp
 */

#include "gtkimcontextime.h"

#include "imm-extra.h"

#include <gdk/gdkwin32.h>
#include <gdk/gdkkeysyms.h>
#include <gtk/gtkwidget.h>

/* avoid warning */
#ifdef STRICT
# undef STRICT
# include <pango/pangowin32.h>
# ifndef STRICT
#   define STRICT 1
# endif
#else /* STRICT */
#   include <pango/pangowin32.h>
#endif /* STRICT */

/* #define BUFSIZE 4096 */

#define FREE_PREEDIT_BUFFER(ctx) \
{                                \
  g_free((ctx)->priv->comp_str); \
  g_free((ctx)->priv->read_str); \
  (ctx)->priv->comp_str = NULL;  \
  (ctx)->priv->read_str = NULL;  \
  (ctx)->priv->comp_str_len = 0; \
  (ctx)->priv->read_str_len = 0; \
}


struct _GtkIMContextIMEPrivate
{
  /* save IME context when the client window is focused out */
  DWORD conversion_mode;
  DWORD sentence_mode;

  LPVOID comp_str;
  DWORD comp_str_len;
  LPVOID read_str;
  DWORD read_str_len;
};


/* GObject class methods */
static void gtk_im_context_ime_class_init (GtkIMContextIMEClass *class);
static void gtk_im_context_ime_init       (GtkIMContextIME      *context_ime);
static void gtk_im_context_ime_dispose    (GObject              *obj);
static void gtk_im_context_ime_finalize   (GObject              *obj);

static void gtk_im_context_ime_set_property (GObject      *object,
                                             guint         prop_id,
                                             const GValue *value,
                                             GParamSpec   *pspec);
static void gtk_im_context_ime_get_property (GObject      *object,
                                             guint         prop_id,
                                             GValue       *value,
                                             GParamSpec   *pspec);

/* GtkIMContext's virtual functions */
static void gtk_im_context_ime_set_client_window   (GtkIMContext *context,
                                                    GdkWindow    *client_window);
static gboolean gtk_im_context_ime_filter_keypress (GtkIMContext   *context,
                                                    GdkEventKey    *event);
static void gtk_im_context_ime_reset               (GtkIMContext   *context);
static void gtk_im_context_ime_get_preedit_string  (GtkIMContext   *context,
                                                    gchar         **str,
                                                    PangoAttrList **attrs,
                                                    gint           *cursor_pos);
static void gtk_im_context_ime_focus_in            (GtkIMContext   *context);
static void gtk_im_context_ime_focus_out           (GtkIMContext   *context);
static void gtk_im_context_ime_set_cursor_location (GtkIMContext   *context,
                                                    GdkRectangle   *area);
static void gtk_im_context_ime_set_use_preedit     (GtkIMContext   *context,
                                                    gboolean        use_preedit);

/* GtkIMContextIME's private functions */
static void gtk_im_context_ime_set_preedit_font (GtkIMContext    *context,
                                                 PangoFont       *font);
static GdkFilterReturn
            gtk_im_context_ime_message_filter   (GdkXEvent       *xevent,
                                                 GdkEvent        *event,
                                                 gpointer         data);
static void get_window_position                 (GdkWindow       *win,
                                                 gint            *x,
                                                 gint            *y);
static void cb_client_widget_hierarchy_changed  (GtkWidget       *widget,
                                                 GtkWidget       *widget2,
                                                 GtkIMContextIME *context_ime);

GType gtk_type_im_context_ime = 0;
static GObjectClass *parent_class;


void
gtk_im_context_ime_register_type (GTypeModule *type_module)
{
  static const GTypeInfo im_context_ime_info = {
    sizeof (GtkIMContextIMEClass),
    (GBaseInitFunc) NULL,
    (GBaseFinalizeFunc) NULL,
    (GClassInitFunc) gtk_im_context_ime_class_init,
    NULL,                       /* class_finalize */
    NULL,                       /* class_data */
    sizeof (GtkIMContextIME),
    0,
    (GInstanceInitFunc) gtk_im_context_ime_init,
  };

  gtk_type_im_context_ime =
    g_type_module_register_type (type_module,
                                 GTK_TYPE_IM_CONTEXT,
                                 "GtkIMContextIME", &im_context_ime_info, 0);
}

static void
gtk_im_context_ime_class_init (GtkIMContextIMEClass *class)
{
  GtkIMContextClass *im_context_class = GTK_IM_CONTEXT_CLASS (class);
  GObjectClass *gobject_class = G_OBJECT_CLASS (class);

  parent_class = g_type_class_peek_parent (class);

  gobject_class->finalize     = gtk_im_context_ime_finalize;
  gobject_class->dispose      = gtk_im_context_ime_dispose;
  gobject_class->set_property = gtk_im_context_ime_set_property;
  gobject_class->get_property = gtk_im_context_ime_get_property;

  im_context_class->set_client_window   = gtk_im_context_ime_set_client_window;
  im_context_class->filter_keypress     = gtk_im_context_ime_filter_keypress;
  im_context_class->reset               = gtk_im_context_ime_reset;
  im_context_class->get_preedit_string  = gtk_im_context_ime_get_preedit_string;
  im_context_class->focus_in            = gtk_im_context_ime_focus_in;
  im_context_class->focus_out           = gtk_im_context_ime_focus_out;
  im_context_class->set_cursor_location = gtk_im_context_ime_set_cursor_location;
  im_context_class->set_use_preedit     = gtk_im_context_ime_set_use_preedit;
}


static void
gtk_im_context_ime_init (GtkIMContextIME *context_ime)
{
  context_ime->client_window          = NULL;
  context_ime->toplevel               = NULL;
  context_ime->use_preedit            = TRUE;
  context_ime->preediting             = FALSE;
  context_ime->opened                 = FALSE;
  context_ime->focus                  = FALSE;
  context_ime->cursor_location.x      = 0;
  context_ime->cursor_location.y      = 0;
  context_ime->cursor_location.width  = 0;
  context_ime->cursor_location.height = 0;

  context_ime->priv = g_malloc0 (sizeof (GtkIMContextIMEPrivate));
  context_ime->priv->conversion_mode  = 0;
  context_ime->priv->sentence_mode    = 0;
  context_ime->priv->comp_str         = NULL;
  context_ime->priv->comp_str_len     = 0;
  context_ime->priv->read_str         = NULL;
  context_ime->priv->read_str_len     = 0;
}


static void
gtk_im_context_ime_dispose (GObject *obj)
{
  GtkIMContext *context = GTK_IM_CONTEXT (obj);
  GtkIMContextIME *context_ime = GTK_IM_CONTEXT_IME (obj);

  if (context_ime->client_window)
    gtk_im_context_ime_set_client_window (context, NULL);

  FREE_PREEDIT_BUFFER (context_ime);

  if (G_OBJECT_CLASS (parent_class)->dispose)
    G_OBJECT_CLASS (parent_class)->dispose (obj);
}


static void
gtk_im_context_ime_finalize (GObject *obj)
{
  /* GtkIMContext *context = GTK_IM_CONTEXT (obj); */
  GtkIMContextIME *context_ime = GTK_IM_CONTEXT_IME (obj);

  g_free (context_ime->priv);
  context_ime->priv = NULL;

  if (G_OBJECT_CLASS (parent_class)->finalize)
    G_OBJECT_CLASS (parent_class)->finalize (obj);
}


static void
gtk_im_context_ime_set_property (GObject      *object,
                                 guint         prop_id,
                                 const GValue *value,
                                 GParamSpec   *pspec)
{
  GtkIMContextIME *context_ime = GTK_IM_CONTEXT_IME (object);

  g_return_if_fail (GTK_IS_IM_CONTEXT_IME (context_ime));

  switch (prop_id)
    {
    default:
      break;
    }
}


static void
gtk_im_context_ime_get_property (GObject    *object,
                                 guint       prop_id,
                                 GValue     *value,
                                 GParamSpec *pspec)
{
  GtkIMContextIME *context_ime = GTK_IM_CONTEXT_IME (object);

  g_return_if_fail (GTK_IS_IM_CONTEXT_IME (context_ime));

  switch (prop_id)
    {
    default:
      break;
    }
}


GtkIMContext *
gtk_im_context_ime_new (void)
{
  return g_object_new (GTK_TYPE_IM_CONTEXT_IME, NULL);
}


static void
gtk_im_context_ime_set_client_window (GtkIMContext *context,
                                      GdkWindow    *client_window)
{
  GtkIMContextIME *context_ime;
  HWND hwnd = NULL;

  g_return_if_fail (GTK_IS_IM_CONTEXT_IME (context));
  context_ime = GTK_IM_CONTEXT_IME (context);

  if (client_window)
    {
      HIMC himc;

      hwnd = GDK_WINDOW_HWND (client_window);

      /* get default ime context */
      himc = ImmGetContext (hwnd);
      context_ime->opened = ImmGetOpenStatus (himc);
      ImmGetConversionStatus (himc,
                              &context_ime->priv->conversion_mode,
                              &context_ime->priv->sentence_mode);
      ImmReleaseContext (hwnd, himc);

    }
  else if (context_ime->focus)
    {
      gtk_im_context_ime_focus_out (context);
    }

  context_ime->client_window = client_window;
}


static gboolean
gtk_im_context_ime_filter_keypress (GtkIMContext *context,
                                    GdkEventKey  *event)
{
  GtkIMContextIME *context_ime;
  HWND hwnd;
  HIMC himc;
  gboolean retval = FALSE;

  g_return_val_if_fail (GTK_IS_IM_CONTEXT_IME (context), FALSE);
  g_return_val_if_fail (event, FALSE);

  if (event->type == GDK_KEY_RELEASE)
    return retval;

  context_ime = GTK_IM_CONTEXT_IME (context);
  if (!context_ime->focus)
    return FALSE;
  if (!GDK_IS_WINDOW (context_ime->client_window))
    return FALSE;

  hwnd = GDK_WINDOW_HWND (context_ime->client_window);
  himc = ImmGetContext (hwnd);

  /* FIXME!! event->string is deprecated */
  if (event->string && *event->string
            && !g_unichar_iscntrl (g_utf8_get_char_validated (event->string,
                                                    strlen (event->string))))
    {
      g_signal_emit_by_name (G_OBJECT (context_ime), "commit", event->string);
      retval = TRUE;
    }

  ImmReleaseContext (hwnd, himc);

  return retval;
}


static void
gtk_im_context_ime_reset (GtkIMContext *context)
{
  GtkIMContextIME *context_ime = GTK_IM_CONTEXT_IME (context);
  HWND hwnd;
  HIMC himc;

  hwnd = GDK_WINDOW_HWND (context_ime->client_window);
  himc = ImmGetContext (hwnd);
  if (!himc)
    return;

  if (context_ime->preediting && ImmGetOpenStatus (himc))
    ImmNotifyIME (himc, NI_COMPOSITIONSTR, CPS_CANCEL, 0);

  context_ime->preediting = FALSE;
  g_signal_emit_by_name (context, "preedit_changed");

  ImmReleaseContext (hwnd, himc);
}


static gchar *
get_utf8_preedit_string (GtkIMContextIME *context_ime, gint *pos_ret)
{
  gchar *utf8str = NULL;
  HWND hwnd;
  HIMC himc;
  gint pos = 0;

  if (pos_ret)
    *pos_ret = 0;

  /*
  g_return_val_if_fail (GTK_IS_IM_CONTEXT_IME (context_ime),
  g_strdup (""));
  */

  hwnd = GDK_WINDOW_HWND (context_ime->client_window);
  himc = ImmGetContext (hwnd);

  /* shouldn't return NULL */
  g_return_val_if_fail (himc, g_strdup (""));

  if (context_ime->preediting)
    {
      gpointer buf;
      glong len;
      GError *error = NULL;

#ifdef UNICODE
      len = ImmGetCompositionString (himc, GCS_COMPSTR, NULL, 0);
      buf = g_malloc (len);
      if (len > 0 && buf)
        {
          ImmGetCompositionString (himc, GCS_COMPSTR, buf, len);
          len /= sizeof (gunichar2);
          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 = ImmGetCompositionString (himc, GCS_CURSORPOS, NULL, 0);
              if (pos < 0 || len < pos)
                {
                  g_warning ("ImmGetCompositionString: "
                             "Invalid cursor position!");
                  pos = 0;
                }
            }
          g_free (buf);
        }
#else /* not UNICODE */
      len = ImmGetCompositionString (himc, GCS_COMPSTR, NULL, 0);
      buf = g_malloc (len);
      if (len > 0 && buf)
        {
          ImmGetCompositionString (himc, GCS_COMPSTR, buf, len);
          utf8str = g_locale_to_utf8 (buf, len, NULL, NULL, &error);
          if (error)
            {
              g_warning ("%s", error->message);
              g_error_free (error);
            }

          if (pos_ret)
            {
              pos = ImmGetCompositionString (himc, GCS_CURSORPOS, NULL, 0);
              /* get cursor position by offset */
              if (pos < len && utf8str)
                {
                  gchar *tmpstr;

                  tmpstr = g_locale_to_utf8 (buf, pos, NULL, NULL, &error);
                  if (error)
                    {
                      g_warning ("%s", error->message);
                      g_error_free (error);
                    }
                  if (tmpstr)
                    {
                      pos = g_utf8_strlen (tmpstr, -1);
                    }
                  else
                    {
                      pos = 0;
                    }
                  g_free (tmpstr);
                }
              else if (pos == len && utf8str)
                {
                  pos = g_utf8_strlen (utf8str, -1);
                }
              else
                {
                  g_warning ("ImmGetCompositionString: "
                             "Invalid cursor position!");
                  pos = 0;
                }
            }
          g_free (buf);
        }
#endif /* not UNICODE */
    }

  if (!utf8str)
    {
      utf8str = g_strdup ("");
      pos = 0;
    }

  if (pos_ret)
    *pos_ret = pos;

  ImmReleaseContext (hwnd, himc);

  return utf8str;
}


static PangoAttrList *
get_pango_attr_list (GtkIMContextIME *context_ime, const gchar *utf8str)
{
  PangoAttrList *attrs = pango_attr_list_new ();
  HWND hwnd;
  HIMC himc;

  /* g_return_val_if_fail (GTK_IS_IM_CONTEXT_IME (context_ime), attr); */

  hwnd = GDK_WINDOW_HWND (context_ime->client_window);
  himc = ImmGetContext (hwnd);

  g_return_val_if_fail (himc, attrs);

  if (context_ime->preediting)
    {
      const gchar *schr = utf8str, *echr;
      guint8 *buf;
      guint16 f_red, f_green, f_blue, b_red, b_green, b_blue;
      glong len, spos = 0, epos, sidx = 0, eidx;
      PangoAttribute *attr;

      /*
       *  get attributes list of IME.
       */
      len = ImmGetCompositionString (himc, GCS_COMPATTR, NULL, 0);
      buf = g_malloc (len);
      ImmGetCompositionString (himc, GCS_COMPATTR, buf, len);

      /*
       *  schr and echr are pointer in utf8str.
       */
      for (echr = g_utf8_next_char (utf8str); *schr != '\0';
           echr = g_utf8_next_char (echr))
        {
          /*
           *  spos and epos are buf(attributes list of IME) position by
           *  bytes.
           *  If UNICODE is defined, this value is same with UTF-8 offset.
           *  If it's not defined, this value is same with bytes position
           *  of locale encoded preedit string.
           *
           */
#ifdef UNICODE
          epos = g_utf8_pointer_to_offset (utf8str, echr);
#else /* not UNICODE */
          gchar *tmpstr;
          GError *error = NULL;

          epos = spos;
          tmpstr = g_locale_from_utf8 (schr, echr - schr, NULL, NULL, &error);
          if (error)
            {
              g_warning ("%s", error->message);
              g_error_free (error);
            }
          if (tmpstr)
            {
              epos += strlen (tmpstr);
              g_free (tmpstr);
            }
#endif /* not UNICODE */
          /*
           *  sidx and eidx are positions in utf8str by bytes.
           */
          eidx = echr - utf8str;

          /*
           *  convert attributes list to PangoAttriute.
           */
          if (*echr == '\0' || buf[spos] != buf[epos])
            {
              switch (buf[spos])
                {
                case ATTR_TARGET_CONVERTED:
                  attr = pango_attr_underline_new (PANGO_UNDERLINE_DOUBLE);
                  attr->start_index = sidx;
                  attr->end_index = eidx;
                  pango_attr_list_change (attrs, attr);
                  f_red = f_green = f_blue = 0;
                  b_red = b_green = b_blue = 0xffff;
                  break;
                case ATTR_TARGET_NOTCONVERTED:
                  f_red = f_green = f_blue = 0xffff;
                  b_red = b_green = b_blue = 0;
                  break;
                case ATTR_INPUT_ERROR:
                  f_red = f_green = f_blue = 0;
                  b_red = b_green = b_blue = 0x7fff;
                  break;
                default:        /* ATTR_INPUT,ATTR_CONVERTED,ATTR_FIXEDCONVERTED */
                  attr = pango_attr_underline_new (PANGO_UNDERLINE_SINGLE);
                  attr->start_index = sidx;
                  attr->end_index = eidx;
                  pango_attr_list_change (attrs, attr);
                  f_red = f_green = f_blue = 0;
                  b_red = b_green = b_blue = 0xffff;
                }
              attr = pango_attr_foreground_new (f_red, f_green, f_blue);
              attr->start_index = sidx;
              attr->end_index = eidx;
              pango_attr_list_change (attrs, attr);
              attr = pango_attr_background_new (b_red, b_green, b_blue);
              attr->start_index = sidx;
              attr->end_index = eidx;
              pango_attr_list_change (attrs, attr);

              schr = echr;
              spos = epos;
              sidx = eidx;
            }
        }
      g_free (buf);
    }

  ImmReleaseContext (hwnd, himc);

  return attrs;
}


static void
gtk_im_context_ime_get_preedit_string (GtkIMContext   *context,
                                       gchar         **str,
                                       PangoAttrList **attrs,
                                       gint           *cursor_pos)
{
  gchar *utf8str = NULL;
  gint pos = 0;
  GtkIMContextIME *context_ime;

  context_ime = GTK_IM_CONTEXT_IME (context);

  utf8str = get_utf8_preedit_string (context_ime, &pos);

  if (attrs)
    *attrs = get_pango_attr_list (context_ime, utf8str);

  if (str)
    {
      *str = utf8str;
    }
  else
    {
      g_free (utf8str);
      utf8str = NULL;
    }

  if (cursor_pos)
    *cursor_pos = pos;
}


static void
gtk_im_context_ime_focus_in (GtkIMContext *context)
{
  GtkIMContextIME *context_ime = GTK_IM_CONTEXT_IME (context);
  GdkWindow *toplevel;
  GtkWidget *widget = NULL;
  HWND hwnd, top_hwnd;
  HIMC himc;

  if (!GDK_IS_WINDOW (context_ime->client_window))
    return;

  hwnd = GDK_WINDOW_HWND (context_ime->client_window);
  himc = ImmGetContext (hwnd);
  if (!himc)
    return;

  toplevel = gdk_window_get_toplevel (context_ime->client_window);
  if (GDK_IS_WINDOW (toplevel))
    {
      gdk_window_add_filter (toplevel,
                             gtk_im_context_ime_message_filter, context_ime);
      top_hwnd = GDK_WINDOW_HWND (toplevel);

      context_ime->toplevel = toplevel;
    }
  else
    {
      g_warning ("gtk_im_context_ime_focus_in(): "
                 "cannot find toplevel window.");
      return;
    }

  /* trace reparenting (probably no need) */
  gdk_window_get_user_data (context_ime->client_window, (gpointer) & widget);
  if (GTK_IS_WIDGET (widget))
    {
      g_signal_connect (G_OBJECT (widget), "hierarchy-changed",
                        G_CALLBACK (cb_client_widget_hierarchy_changed),
                        context_ime);
    }
  else
    {
      /* warning? */
    }

  /* swtich current context */
  context_ime->focus = TRUE;

  /* restore preedit context */
  ImmSetConversionStatus (himc,
                          context_ime->priv->conversion_mode,
                          context_ime->priv->sentence_mode);

  if (context_ime->opened)
    {
      if (!ImmGetOpenStatus (himc))
        ImmSetOpenStatus (himc, TRUE);
      if (context_ime->preediting)
        {
          ImmSetCompositionString (himc,
                                   SCS_SETSTR,
                                   context_ime->priv->comp_str,
                                   context_ime->priv->comp_str_len, NULL, 0);
          FREE_PREEDIT_BUFFER (context_ime);
        }
    }

  /* clean */
  ImmReleaseContext (hwnd, himc);
}


static void
gtk_im_context_ime_focus_out (GtkIMContext *context)
{
  GtkIMContextIME *context_ime = GTK_IM_CONTEXT_IME (context);
  GdkWindow *toplevel;
  GtkWidget *widget = NULL;
  HWND hwnd, top_hwnd;
  HIMC himc;

  if (!GDK_IS_WINDOW (context_ime->client_window))
    return;

  hwnd = GDK_WINDOW_HWND (context_ime->client_window);
  himc = ImmGetContext (hwnd);
  if (!himc)
    return;

  /* save preedit context */
  ImmGetConversionStatus (himc,
                          &context_ime->priv->conversion_mode,
                          &context_ime->priv->sentence_mode);

  if (ImmGetOpenStatus (himc))
    {
      gboolean preediting = context_ime->preediting;

      if (preediting)
        {
          FREE_PREEDIT_BUFFER (context_ime);

          context_ime->priv->comp_str_len
            = ImmGetCompositionString (himc, GCS_COMPSTR, NULL, 0);
          context_ime->priv->comp_str
            = g_malloc (context_ime->priv->comp_str_len);
          ImmGetCompositionString (himc, GCS_COMPSTR,
                                   context_ime->priv->comp_str,
                                   context_ime->priv->comp_str_len);

          context_ime->priv->read_str_len
            = ImmGetCompositionString (himc, GCS_COMPREADSTR, NULL, 0);
          context_ime->priv->read_str
            = g_malloc (context_ime->priv->read_str_len);
          ImmGetCompositionString (himc, GCS_COMPREADSTR,
                                   context_ime->priv->read_str,
                                   context_ime->priv->read_str_len);
        }

      ImmSetOpenStatus (himc, FALSE);

      context_ime->opened = TRUE;
      context_ime->preediting = preediting;
    }
  else
    {
      context_ime->opened = FALSE;
      context_ime->preediting = FALSE;
    }

  /* remove signal handler */
  gdk_window_get_user_data (context_ime->client_window, (gpointer) & widget);
  if (GTK_IS_WIDGET (widget))
    {
      g_signal_handlers_disconnect_by_func
        (G_OBJECT (widget),
         G_CALLBACK (cb_client_widget_hierarchy_changed), context_ime);
    }

  /* remove event fileter */
  toplevel = gdk_window_get_toplevel (context_ime->client_window);
  if (GDK_IS_WINDOW (toplevel))
    {
      gdk_window_remove_filter (toplevel,
                                gtk_im_context_ime_message_filter,
                                context_ime);
      top_hwnd = GDK_WINDOW_HWND (toplevel);

      context_ime->toplevel = NULL;
    }
  else
    {
      g_warning ("gtk_im_context_ime_focus_out(): "
                 "cannot find toplevel window.");
    }

  /* swtich current context */
  context_ime->focus = FALSE;

  /* clean */
  ImmReleaseContext (hwnd, himc);
}


static void
gtk_im_context_ime_set_cursor_location (GtkIMContext *context,
                                        GdkRectangle *area)
{
  gint wx = 0, wy = 0;
  GtkIMContextIME *context_ime;
  COMPOSITIONFORM cf;
  HWND hwnd;
  HIMC himc;

  g_return_if_fail (GTK_IS_IM_CONTEXT_IME (context));

  context_ime = GTK_IM_CONTEXT_IME (context);
  if (area)
    context_ime->cursor_location = *area;

  if (!context_ime->client_window)
    return;

  hwnd = GDK_WINDOW_HWND (context_ime->client_window);
  himc = ImmGetContext (hwnd);
  if (!himc)
    return;

  get_window_position (context_ime->client_window, &wx, &wy);
  cf.dwStyle = CFS_POINT;
  cf.ptCurrentPos.x = wx + context_ime->cursor_location.x;
  cf.ptCurrentPos.y = wy + context_ime->cursor_location.y;
  ImmSetCompositionWindow (himc, &cf);

  ImmReleaseContext (hwnd, himc);
}


static void
gtk_im_context_ime_set_use_preedit (GtkIMContext *context,
                                    gboolean      use_preedit)
{
  GtkIMContextIME *context_ime;

  g_return_if_fail (GTK_IS_IM_CONTEXT_IME (context));
  context_ime = GTK_IM_CONTEXT_IME (context);

  context_ime->use_preedit = use_preedit;
  if (context_ime->preediting)
    {
      /* FIXME */
      HWND hwnd;
      HIMC himc;

      hwnd = GDK_WINDOW_HWND (context_ime->client_window);
      himc = ImmGetContext (hwnd);
      if (!himc)
        return;
    }
}


static void
gtk_im_context_ime_set_preedit_font (GtkIMContext *context, PangoFont *font)
{
  GtkIMContextIME *context_ime;
  GtkWidget *widget = NULL;
  HWND hwnd;
  HIMC himc;
  PangoContext *pango_context;
  LOGFONT *logfont;

  g_return_if_fail (GTK_IS_IM_CONTEXT_IME (context));

  context_ime = GTK_IM_CONTEXT_IME (context);
  if (!context_ime->client_window)
    return;

  gdk_window_get_user_data (context_ime->client_window, (gpointer) &widget);
  if (!GTK_IS_WIDGET (widget))
    return;

  hwnd = GDK_WINDOW_HWND (context_ime->client_window);
  himc = ImmGetContext (hwnd);
  if (!himc)
    return;

  /* set font */
  pango_context = gtk_widget_get_pango_context (widget);
  if (!pango_context)
    goto ERROR_OUT;

  if (!font)
    font = pango_context_load_font (pango_context, widget->style->font_desc);
  if (!font)
    goto ERROR_OUT;

  logfont = pango_win32_font_logfont (font);
  if (logfont)
    ImmSetCompositionFont (himc, logfont);

ERROR_OUT:
  /* clean */
  ImmReleaseContext (hwnd, himc);
}


static GdkFilterReturn
gtk_im_context_ime_message_filter (GdkXEvent *xevent,
                                   GdkEvent  *event,
                                   gpointer   data)
{
  GtkIMContext *context;
  GtkIMContextIME *context_ime;
  HWND hwnd;
  HIMC himc;
  MSG *msg = (MSG *) xevent;
  GdkFilterReturn retval = GDK_FILTER_CONTINUE;

  g_return_val_if_fail (GTK_IS_IM_CONTEXT_IME (data), retval);

  context = GTK_IM_CONTEXT (data);
  context_ime = GTK_IM_CONTEXT_IME (data);
  if (!context_ime->focus)
    return retval;

  hwnd = GDK_WINDOW_HWND (context_ime->client_window);
  himc = ImmGetContext (hwnd);
  if (!himc)
    return retval;

  switch (msg->message)
    {
    case WM_IME_COMPOSITION:
      {
        gint wx = 0, wy = 0;
        CANDIDATEFORM cf;

        get_window_position (context_ime->client_window, &wx, &wy);
        /* FIXME! */
        {
          HWND hwnd_top;
          POINT pt;
          RECT rc;

          hwnd_top =
            GDK_WINDOW_HWND (gdk_window_get_toplevel
                             (context_ime->client_window));
          GetWindowRect (hwnd_top, &rc);
          pt.x = wx;
          pt.y = wy;
          ClientToScreen (hwnd_top, &pt);
          wx = pt.x - rc.left;
          wy = pt.y - rc.top;
        }
        cf.dwIndex = 0;
        cf.dwStyle = CFS_CANDIDATEPOS;
        cf.ptCurrentPos.x = wx + context_ime->cursor_location.x;
        cf.ptCurrentPos.y = wy + context_ime->cursor_location.y
          + context_ime->cursor_location.height;
        ImmSetCandidateWindow (himc, &cf);

        if ((msg->lParam & GCS_COMPSTR))
          g_signal_emit_by_name (context, "preedit_changed");

        if (msg->lParam & GCS_RESULTSTR)
          {
            gsize len;
            gpointer buf;
            gchar *utf8str = NULL;
            GError *error = NULL;

            len = ImmGetCompositionString (himc, GCS_RESULTSTR, NULL, 0);
            buf = g_alloca (len);
            if (len > 0 && buf)
              {
                ImmGetCompositionString (himc, GCS_RESULTSTR, buf, len);
#ifdef UNICODE
                len /= sizeof (gunichar2);
                utf8str = g_utf16_to_utf8 (buf, len, NULL, NULL, &error);
#else /* not UNICODE */
                utf8str = g_locale_to_utf8 (buf, len, NULL, NULL, &error);
#endif /* not UNICODE */
                if (error)
                  {
                    g_warning ("%s", error->message);
                    g_error_free (error);
                  }
              }

            if (utf8str)
              {
                g_signal_emit_by_name (G_OBJECT (context), "commit", utf8str);
                g_free (utf8str);
              }
          }

        if (context_ime->use_preedit)
          retval = TRUE;
        break;
      }

    case WM_IME_STARTCOMPOSITION:
      context_ime->preediting = TRUE;
      gtk_im_context_ime_set_cursor_location (context, NULL);
      g_signal_emit_by_name (context, "preedit_start");
      if (context_ime->use_preedit)
        retval = TRUE;
      break;

    case WM_IME_ENDCOMPOSITION:
      context_ime->preediting = FALSE;
      g_signal_emit_by_name (context, "preedit_changed");
      g_signal_emit_by_name (context, "preedit_end");
      if (context_ime->use_preedit)
        retval = TRUE;
      break;

    case WM_IME_NOTIFY:
      switch (msg->wParam)
        {
        case IMN_SETOPENSTATUS:
          context_ime->opened = ImmGetOpenStatus (himc);
          gtk_im_context_ime_set_preedit_font (context, NULL);
          break;

        default:
          break;
        }

    default:
      break;
    }

  ImmReleaseContext (hwnd, himc);
  return retval;
}


/*
 * x and y must be initialized to 0.
 */
static void
get_window_position (GdkWindow *win, gint *x, gint *y)
{
  GdkWindow *parent, *toplevel;
  gint wx, wy;

  g_return_if_fail (GDK_IS_WINDOW (win));
  g_return_if_fail (x && y);

  gdk_window_get_position (win, &wx, &wy);
  *x += wx;
  *y += wy;
  parent = gdk_window_get_parent (win);
  toplevel = gdk_window_get_toplevel (win);

  if (parent && parent != toplevel)
    get_window_position (parent, x, y);
}


/*
 *  probably, this handler isn't needed.
 */
static void
cb_client_widget_hierarchy_changed (GtkWidget       *widget,
                                    GtkWidget       *widget2,
                                    GtkIMContextIME *context_ime)
{
  GdkWindow *new_toplevel;

  g_return_if_fail (GTK_IS_WIDGET (widget));
  g_return_if_fail (GTK_IS_IM_CONTEXT_IME (context_ime));

  if (!context_ime->client_window)
    return;
  if (!context_ime->focus)
    return;

  new_toplevel = gdk_window_get_toplevel (context_ime->client_window);
  if (context_ime->toplevel == new_toplevel)
    return;

  /* remove filter from old toplevel */
  if (GDK_IS_WINDOW (context_ime->toplevel))
    {
      gdk_window_remove_filter (context_ime->toplevel,
                                gtk_im_context_ime_message_filter,
                                context_ime);
    }
  else
    {
    }

  /* add filter to new toplevel */
  if (GDK_IS_WINDOW (new_toplevel))
    {
      gdk_window_add_filter (new_toplevel,
                             gtk_im_context_ime_message_filter, context_ime);
    }
  else
    {
    }

  context_ime->toplevel = new_toplevel;
}