ibus/ibus-435880-surrounding-text.patch

From 27788fb3bf62411c2b13d24bac45eb060483162f Mon Sep 17 00:00:00 2001
From: Daiki Ueno <ueno@unixuser.org>
Date: Tue, 8 Feb 2011 18:27:00 +0900
Subject: [PATCH] Support surrounding-text retrieval.

This change adds a new API function ibus_engine_get_surrounding_text().
In the implementation, engines do not proactively requests surrounding-text to
target applications via the GTK+ client (IBusIMContext) every time the
function is called.  Instead, IBusIMContext retrieves surrounding-text when
certain events occur in the input context (IBusInputContext) and maintains
it within the input context.

This logic is similar to Qt's QInputContext.  The following events trigger
surrounding-text retrieval:

- focus_in
- commit_text
- show_preedit_text
- (just before) process_key_event

Also,
- destroy
resets the current surrounding-text.
---
 bus/engineproxy.c               |   43 ++++++++++++
 bus/engineproxy.h               |   11 +++
 bus/inputcontext.c              |   36 ++++++++++
 client/gtk2/ibusimcontext.c     |  138 ++++++++++++++++++++++++++++++++++-----
 configure.ac                    |   14 ++++
 ibus/engine.py                  |    6 ++
 ibus/interface/iengine.py       |    3 +
 ibus/interface/iinputcontext.py |    5 ++
 src/ibusengine.c                |  138 +++++++++++++++++++++++++++++++++++++++
 src/ibusengine.h                |   21 ++++++-
 src/ibusenginedesc.c            |  132 +++++++++++++++++++++++++++++++++++++
 src/ibusenginedesc.h            |   11 +++
 src/ibusinputcontext.c          |   91 +++++++++++++++++++++++++
 src/ibusinputcontext.h          |   11 +++
 src/ibusmarshalers.list         |    1 +
 15 files changed, 644 insertions(+), 17 deletions(-)

diff --git a/bus/engineproxy.c b/bus/engineproxy.c
index f808727..b35933f 100644
--- a/bus/engineproxy.c
+++ b/bus/engineproxy.c
@@ -47,6 +47,10 @@ struct _BusEngineProxy {
     /* a key mapping for the engine that converts keycode into keysym. the mapping is used only when use_sys_layout is FALSE. */
     IBusKeymap     *keymap;
     /* private member */
+
+    /* surrounding text */
+    IBusText *surrounding_text;
+    guint     surrounding_cursor_pos;
 };
 
 struct _BusEngineProxyClass {
@@ -83,6 +87,8 @@ enum {
 
 static guint    engine_signals[LAST_SIGNAL] = { 0 };
 
+static IBusText *text_empty = NULL;
+
 /* functions prototype */
 static void     bus_engine_proxy_set_property   (BusEngineProxy      *engine,
                                                  guint                prop_id,
@@ -330,11 +336,16 @@ bus_engine_proxy_class_init (BusEngineProxyClass *class)
             G_TYPE_NONE,
             1,
             IBUS_TYPE_PROPERTY);
+
+    text_empty = ibus_text_new_from_static_string ("");
+    g_object_ref_sink (text_empty);
 }
 
 static void
 bus_engine_proxy_init (BusEngineProxy *engine)
 {
+    engine->surrounding_text = g_object_ref_sink (text_empty);
+    engine->surrounding_cursor_pos = 0;
 }
 
 static void
@@ -393,6 +404,11 @@ bus_engine_proxy_real_destroy (IBusProxy *proxy)
         engine->keymap = NULL;
     }
 
+    if (engine->surrounding_text) {
+        g_object_unref (engine->surrounding_text);
+        engine->surrounding_text = NULL;
+    }
+
     IBUS_PROXY_CLASS (bus_engine_proxy_parent_class)->destroy ((IBusProxy *)engine);
 }
 
@@ -950,6 +966,33 @@ void bus_engine_proxy_property_hide (BusEngineProxy *engine,
                        NULL);
 }
 
+void bus_engine_proxy_set_surrounding_text (BusEngineProxy *engine,
+                                            IBusText       *text,
+                                            guint           cursor_pos)
+{
+    g_assert (BUS_IS_ENGINE_PROXY (engine));
+    g_assert (text != NULL);
+
+    if (!engine->surrounding_text ||
+        g_strcmp0 (text->text, engine->surrounding_text->text) != 0 ||
+        cursor_pos != engine->surrounding_cursor_pos) {
+        GVariant *variant = ibus_serializable_serialize ((IBusSerializable *)text);
+        if (engine->surrounding_text)
+            g_object_unref (engine->surrounding_text);
+        engine->surrounding_text = (IBusText *) g_object_ref_sink (text);
+        engine->surrounding_cursor_pos = cursor_pos;
+
+        g_dbus_proxy_call ((GDBusProxy *)engine,
+                           "SetSurroundingText",
+                           g_variant_new ("(vu)", variant, cursor_pos),
+                           G_DBUS_CALL_FLAGS_NONE,
+                           -1,
+                           NULL,
+                           NULL,
+                           NULL);
+    }
+}
+
 /* a macro to generate a function to call a nullary D-Bus method. */
 #define DEFINE_FUNCTION(Name, name)                         \
     void                                                    \
diff --git a/bus/engineproxy.h b/bus/engineproxy.h
index 2a82fc6..0680917 100644
--- a/bus/engineproxy.h
+++ b/bus/engineproxy.h
@@ -212,5 +212,16 @@ void             bus_engine_proxy_property_hide     (BusEngineProxy *engine,
  */
 gboolean         bus_engine_proxy_is_enabled        (BusEngineProxy *engine);
 
+/**
+ * bus_engine_proxy_set_surrounding_text:
+ *
+ * Call "SetSurroundingText" method of an engine asynchronously.
+ */
+void             bus_engine_proxy_set_surrounding_text
+                                                    (BusEngineProxy *engine,
+                                                     IBusText       *text,
+                                                     guint           cursor_pos);
+
+
 G_END_DECLS
 #endif
diff --git a/bus/inputcontext.c b/bus/inputcontext.c
index 32d51e8..20f561c 100644
--- a/bus/inputcontext.c
+++ b/bus/inputcontext.c
@@ -247,6 +247,11 @@ static const gchar introspection_xml[] =
     "    <method name='GetEngine'>"
     "      <arg direction='out' type='v' name='desc' />"
     "    </method>"
+    "    <method name='SetSurroundingText'>"
+    "      <arg direction='in' type='v' name='text' />"
+    "      <arg direction='in' type='u' name='cursor_pos' />"
+    "    </method>"
+
     /* signals */
     "    <signal name='CommitText'>"
     "      <arg type='v' name='text' />"
@@ -961,6 +966,32 @@ _ic_get_engine (BusInputContext       *context,
  * Handle a D-Bus method call whose destination and interface name are both "org.freedesktop.IBus.InputContext"
  */
 static void
+_ic_set_surrounding_text (BusInputContext       *context,
+                          GVariant              *parameters,
+                          GDBusMethodInvocation *invocation)
+{
+    GVariant *variant = NULL;
+    IBusText *text;
+    guint cursor_pos = 0;
+
+    g_variant_get (parameters, "(vu)", &variant, &cursor_pos);
+    text = IBUS_TEXT (ibus_serializable_deserialize (variant));
+    g_variant_unref (variant);
+
+    if ((context->capabilities & IBUS_CAP_SURROUNDING_TEXT) &&
+         context->has_focus && context->enabled && context->engine) {
+        bus_engine_proxy_set_surrounding_text (context->engine,
+                                               text,
+                                               cursor_pos);
+    }
+
+    if (g_object_is_floating (text))
+        g_object_unref (text);
+
+    g_dbus_method_invocation_return_value (invocation, NULL);
+}
+
+static void
 bus_input_context_service_method_call (IBusService            *service,
                                        GDBusConnection        *connection,
                                        const gchar            *sender,
@@ -999,6 +1030,7 @@ bus_input_context_service_method_call (IBusService            *service,
         { "IsEnabled",         _ic_is_enabled },
         { "SetEngine",         _ic_set_engine },
         { "GetEngine",         _ic_get_engine },
+        { "SetSurroundingText", _ic_set_surrounding_text},
     };
 
     gint i;
@@ -2059,6 +2091,10 @@ bus_input_context_set_engine (BusInputContext *context,
             bus_engine_proxy_set_cursor_location (context->engine, context->x, context->y, context->w, context->h);
         }
     }
+    bus_input_context_emit_signal (context,
+                                   "EngineChanged",
+                                   NULL,
+                                   NULL);
     g_signal_emit (context,
                    context_signals[ENGINE_CHANGED],
                    0);
diff --git a/client/gtk2/ibusimcontext.c b/client/gtk2/ibusimcontext.c
index a4e46cb..d029b5c 100644
--- a/client/gtk2/ibusimcontext.c
+++ b/client/gtk2/ibusimcontext.c
@@ -27,6 +27,7 @@
 #include <gtk/gtk.h>
 #include <gdk/gdkkeysyms.h>
 #include <ibus.h>
+#include <string.h>
 #include "ibusimcontext.h"
 
 #if !GTK_CHECK_VERSION (2, 91, 0)
@@ -60,7 +61,8 @@ struct _IBusIMContext {
     gboolean         has_focus;
 
     guint32          time;
-    gint             caps;
+    guint            supported_caps;
+    guint            caps;
 };
 
 struct _IBusIMContextClass {
@@ -111,11 +113,18 @@ static void     ibus_im_context_set_cursor_location
 static void     ibus_im_context_set_use_preedit
                                             (GtkIMContext           *context,
                                              gboolean               use_preedit);
+static void     ibus_im_context_set_surrounding
+                                            (GtkIMContext  *slave,
+                                             const gchar   *text,
+                                             gint           len,
+                                             gint           cursor_index);
+
 
 /* static methods*/
 static void     _create_input_context       (IBusIMContext      *context);
 static void     _set_cursor_location_internal
                                             (GtkIMContext       *context);
+static void     _negotiate_capabilities     (IBusIMContext      *context);
 
 static void     _bus_connected_cb           (IBusBus            *bus,
                                              IBusIMContext      *context);
@@ -129,14 +138,15 @@ static void     _slave_preedit_start_cb     (GtkIMContext       *slave,
                                              IBusIMContext       *context);
 static void     _slave_preedit_end_cb       (GtkIMContext       *slave,
                                              IBusIMContext       *context);
-static void     _slave_retrieve_surrounding_cb
+static gboolean _slave_retrieve_surrounding_cb
                                             (GtkIMContext       *slave,
-                                             IBusIMContext       *context);
-static void     _slave_delete_surrounding_cb
+                                             IBusIMContext      *context);
+static gboolean _slave_delete_surrounding_cb
                                             (GtkIMContext       *slave,
-                                             gint               offset_from_cursor,
-                                             guint              nchars,
-                                             IBusIMContext       *context);
+                                             gint                offset_from_cursor,
+                                             guint               nchars,
+                                             IBusIMContext      *context);
+static void     _request_surrounding_text   (IBusIMContext      *context);
 static void     _create_fake_input_context  (void);
 
 
@@ -248,6 +258,17 @@ _process_key_event_done (GObject      *object,
 }
 
 
+static void
+_request_surrounding_text (IBusIMContext *context)
+{
+    if (context->enable &&
+        (context->caps & IBUS_CAP_SURROUNDING_TEXT)) {
+        gboolean return_value;
+        g_signal_emit (context, _signal_retrieve_surrounding_id, 0,
+                       &return_value);
+    }
+}
+
 static gint
 _key_snooper_cb (GtkWidget   *widget,
                  GdkEventKey *event,
@@ -334,6 +355,8 @@ _key_snooper_cb (GtkWidget   *widget,
 
     } while (0);
 
+    _request_surrounding_text (ibusimcontext);
+
     if (ibusimcontext != NULL) {
         ibusimcontext->time = event->time;
     }
@@ -430,6 +453,7 @@ ibus_im_context_class_init (IBusIMContextClass *class)
     im_context_class->set_client_window = ibus_im_context_set_client_window;
     im_context_class->set_cursor_location = ibus_im_context_set_cursor_location;
     im_context_class->set_use_preedit = ibus_im_context_set_use_preedit;
+    im_context_class->set_surrounding = ibus_im_context_set_surrounding;
     gobject_class->finalize = ibus_im_context_finalize;
 
     _signal_commit_id =
@@ -577,7 +601,12 @@ ibus_im_context_init (GObject *obj)
     ibusimcontext->ibuscontext = NULL;
     ibusimcontext->has_focus = FALSE;
     ibusimcontext->time = GDK_CURRENT_TIME;
-    ibusimcontext->caps = IBUS_CAP_PREEDIT_TEXT | IBUS_CAP_FOCUS | IBUS_CAP_SURROUNDING_TEXT;
+#ifdef ENABLE_SURROUNDING
+    ibusimcontext->supported_caps = IBUS_CAP_PREEDIT_TEXT | IBUS_CAP_FOCUS | IBUS_CAP_SURROUNDING_TEXT;
+#else
+    ibusimcontext->supported_caps = IBUS_CAP_PREEDIT_TEXT | IBUS_CAP_FOCUS;
+#endif
+    ibusimcontext->caps = ibusimcontext->supported_caps;
 
 
     // Create slave im context
@@ -674,6 +703,8 @@ ibus_im_context_filter_keypress (GtkIMContext *context,
         if (ibusimcontext->client_window == NULL && event->window != NULL)
             gtk_im_context_set_client_window ((GtkIMContext *)ibusimcontext, event->window);
 
+        _request_surrounding_text (ibusimcontext);
+
         if (ibusimcontext != NULL) {
             ibusimcontext->time = event->time;
         }
@@ -768,6 +799,8 @@ ibus_im_context_focus_in (GtkIMContext *context)
                                    (gpointer *) &_focus_im_context);
         _focus_im_context = context;
     }
+
+    _request_surrounding_text (ibusimcontext);
 }
 
 static void
@@ -925,6 +958,25 @@ ibus_im_context_set_cursor_location (GtkIMContext *context, GdkRectangle *area)
 }
 
 static void
+_negotiate_capabilities (IBusIMContext *context)
+{
+    IBusEngineDesc *engine;
+
+    engine = ibus_input_context_get_engine (context->ibuscontext);
+    if (engine) {
+        context->caps = context->supported_caps &
+            ibus_engine_desc_get_requires (engine);
+        ibus_input_context_set_capabilities (context->ibuscontext,
+                                             context->caps);
+        IDEBUG ("engine %s: supported caps = %u, engine wants = %u, caps = %u",
+                ibus_engine_desc_get_name (engine)
+                context->supported_caps,
+                ibus_engine_desc_get_requires (engine),
+                context->caps);
+    }
+}
+
+static void
 ibus_im_context_set_use_preedit (GtkIMContext *context, gboolean use_preedit)
 {
     IDEBUG ("%s", __FUNCTION__);
@@ -933,17 +985,50 @@ ibus_im_context_set_use_preedit (GtkIMContext *context, gboolean use_preedit)
 
     if(ibusimcontext->ibuscontext) {
         if (use_preedit) {
-            ibusimcontext->caps |= IBUS_CAP_PREEDIT_TEXT;
+            ibusimcontext->supported_caps |= IBUS_CAP_PREEDIT_TEXT;
         }
         else {
-            ibusimcontext->caps &= ~IBUS_CAP_PREEDIT_TEXT;
+            ibusimcontext->supported_caps &= ~IBUS_CAP_PREEDIT_TEXT;
         }
-        ibus_input_context_set_capabilities (ibusimcontext->ibuscontext, ibusimcontext->caps);
+        _negotiate_capabilities (ibusimcontext);
     }
     gtk_im_context_set_use_preedit (ibusimcontext->slave, use_preedit);
 }
 
 static void
+ibus_im_context_set_surrounding (GtkIMContext  *context,
+                                 const gchar   *text,
+                                 gint           len,
+                                 gint           cursor_index)
+{
+    g_return_if_fail (context != NULL);
+    g_return_if_fail (IBUS_IS_IM_CONTEXT (context));
+    g_return_if_fail (text != NULL);
+    g_return_if_fail (strlen (text) >= len);
+    g_return_if_fail (0 <= cursor_index && cursor_index <= len);
+
+    IBusIMContext *ibusimcontext = IBUS_IM_CONTEXT (context);
+
+    if (ibusimcontext->enable && ibusimcontext->ibuscontext) {
+        IBusText *ibustext;
+        guint cursor_pos;
+        gchar *p;
+
+        p = g_strndup (text, len);
+        cursor_pos = g_utf8_strlen (p, cursor_index);
+        ibustext = ibus_text_new_from_string (p);
+        g_free (p);
+        ibus_input_context_set_surrounding_text (ibusimcontext->ibuscontext,
+                                                 ibustext,
+                                                 cursor_pos);
+    }
+    gtk_im_context_set_surrounding (ibusimcontext->slave,
+                                    text,
+                                    len,
+                                    cursor_index);
+}
+
+static void
 _bus_connected_cb (IBusBus          *bus,
                    IBusIMContext    *ibusimcontext)
 {
@@ -962,6 +1047,8 @@ _ibus_context_commit_text_cb (IBusInputContext *ibuscontext,
     IDEBUG ("%s", __FUNCTION__);
 
     g_signal_emit (ibusimcontext, _signal_commit_id, 0, text->text);
+
+    _request_surrounding_text (ibusimcontext);
 }
 
 static gboolean
@@ -1256,6 +1343,8 @@ _ibus_context_show_preedit_text_cb (IBusInputContext   *ibuscontext,
     ibusimcontext->preedit_visible = TRUE;
     g_signal_emit (ibusimcontext, _signal_preedit_start_id, 0);
     g_signal_emit (ibusimcontext, _signal_preedit_changed_id, 0);
+
+    _request_surrounding_text (ibusimcontext);
 }
 
 static void
@@ -1321,6 +1410,14 @@ _ibus_context_destroy_cb (IBusInputContext *ibuscontext,
 }
 
 static void
+_ibus_context_engine_changed_cb (IBusInputContext *ibuscontext,
+                                 IBusIMContext    *ibusimcontext)
+{
+    IDEBUG ("%s", __FUNCTION__);
+    _negotiate_capabilities (ibusimcontext);
+}
+
+static void
 _create_input_context (IBusIMContext *ibusimcontext)
 {
     IDEBUG ("%s", __FUNCTION__);
@@ -1363,6 +1460,10 @@ _create_input_context (IBusIMContext *ibusimcontext)
                       "disabled",
                       G_CALLBACK (_ibus_context_disabled_cb),
                       ibusimcontext);
+    g_signal_connect (ibusimcontext->ibuscontext,
+                      "engine-changed",
+                      G_CALLBACK (_ibus_context_engine_changed_cb),
+                      ibusimcontext);
     g_signal_connect (ibusimcontext->ibuscontext, "destroy",
                       G_CALLBACK (_ibus_context_destroy_cb),
                       ibusimcontext);
@@ -1419,17 +1520,21 @@ _slave_preedit_end_cb (GtkIMContext  *slave,
     g_signal_emit (ibusimcontext, _signal_preedit_end_id, 0);
 }
 
-static void
+static gboolean
 _slave_retrieve_surrounding_cb (GtkIMContext  *slave,
                                 IBusIMContext *ibusimcontext)
 {
+    gboolean return_value;
+
     if (ibusimcontext->enable && ibusimcontext->ibuscontext) {
-        return;
+        return FALSE;
     }
-    g_signal_emit (ibusimcontext, _signal_retrieve_surrounding_id, 0);
+    g_signal_emit (ibusimcontext, _signal_retrieve_surrounding_id, 0,
+                   &return_value);
+    return return_value;
 }
 
-static void
+static gboolean
 _slave_delete_surrounding_cb (GtkIMContext  *slave,
                               gint           offset_from_cursor,
                               guint          nchars,
@@ -1438,9 +1543,10 @@ _slave_delete_surrounding_cb (GtkIMContext  *slave,
     gboolean return_value;
 
     if (ibusimcontext->enable && ibusimcontext->ibuscontext) {
-        return;
+        return FALSE;
     }
     g_signal_emit (ibusimcontext, _signal_delete_surrounding_id, 0, offset_from_cursor, nchars, &return_value);
+    return return_value;
 }
 
 #ifdef OS_CHROMEOS
diff --git a/configure.ac b/configure.ac
index 81efe81..e5fe925 100644
--- a/configure.ac
+++ b/configure.ac
@@ -364,6 +364,19 @@ AC_ARG_WITH(sync-mode-apps,
 AC_DEFINE_UNQUOTED(SYNC_MODE_APPS, "$SYNC_MODE_APPS",
     [Enbale sync mode in those applications])
 
+# option for enable surrounding-text
+AC_ARG_ENABLE(surrounding-text,
+    AS_HELP_STRING([--enable-surrounding-text],
+        [Enable surrounding-text support]),
+    [enable_surrounding_text=$enableval],
+    [enable_surrounding_text=no]
+)
+if test x"$enable_surrounding_text" = x"yes"; then
+    AC_DEFINE(ENABLE_SURROUNDING, TRUE, [Enable surrounding-text support])
+else
+    enable_surrounding_text="no (disabled, use --enable-surrounding-text to enable)"
+fi
+
 # check iso-codes
 PKG_CHECK_MODULES(ISOCODES, [
     iso-codes
@@ -435,5 +448,6 @@ Build options:
   Enable key snooper        $enable_key_snooper
   Sync mode regexes         "$SYNC_MODE_APPS"
   No snooper regexes        "$NO_SNOOPER_APPS"
+  Enable surrounding-text   $enable_surrounding_text
 ])
 
diff --git a/ibus/engine.py b/ibus/engine.py
index b1df2fe..ec42fa4 100644
--- a/ibus/engine.py
+++ b/ibus/engine.py
@@ -46,6 +46,9 @@ class EngineBase(object.Object):
     def set_cursor_location(self, x, y, w, h):
         pass
 
+    def set_surrounding_text(self, text, cursor_index):
+        pass
+
     def set_capabilities(self, cap):
         pass
 
@@ -163,6 +166,9 @@ class EngineProxy(interface.IEngine):
     def SetCursorLocation(self, x, y, w, h):
         return self.__engine.set_cursor_location(x, y, w, h)
 
+    def SetSurroundingText(self, text, cursor_index):
+        return self.__engine.set_surrounding_text(text, cursor_index)
+
     def SetCapabilities(self, caps):
         return self.__engine.set_capabilities(caps)
 
diff --git a/ibus/interface/iengine.py b/ibus/interface/iengine.py
index 2386c0f..5db2012 100644
--- a/ibus/interface/iengine.py
+++ b/ibus/interface/iengine.py
@@ -50,6 +50,9 @@ class IEngine(dbus.service.Object):
     @method(in_signature="iiii")
     def SetCursorLocation(self, x, y, w, h): pass
 
+    @method(in_signature="vu")
+    def SetSurroundingText(self, text, cursor_index): pass
+
     @method(in_signature="u")
     def SetCapabilities(self, cap): pass
 
diff --git a/ibus/interface/iinputcontext.py b/ibus/interface/iinputcontext.py
index 89f6dbd..bb25c5a 100644
--- a/ibus/interface/iinputcontext.py
+++ b/ibus/interface/iinputcontext.py
@@ -49,6 +49,9 @@ class IInputContext(dbus.service.Object):
     @method(in_signature="iiii")
     def SetCursorLocation(self, x, y, w, h): pass
 
+    @method(in_signature="vu")
+    def SetSurroundingText(self, text, cursor_index): pass
+
     @method()
     def FocusIn(self): pass
 
@@ -137,4 +140,6 @@ class IInputContext(dbus.service.Object):
     @signal(signature="v")
     def UpdateProperty(self, prop): pass
 
+    @signal()
+    def EngineChanged(self): pass
 
diff --git a/src/ibusengine.c b/src/ibusengine.c
index 519d7ca..fc129a2 100644
--- a/src/ibusengine.c
+++ b/src/ibusengine.c
@@ -45,6 +45,7 @@ enum {
     PROPERTY_SHOW,
     PROPERTY_HIDE,
     CANDIDATE_CLICKED,
+    SET_SURROUNDING_TEXT,
     LAST_SIGNAL,
 };
 
@@ -58,10 +59,15 @@ enum {
 struct _IBusEnginePrivate {
     gchar *engine_name;
     GDBusConnection *connection;
+
+    IBusText *surrounding_text;
+    guint surrounding_cursor_pos;
 };
 
 static guint            engine_signals[LAST_SIGNAL] = { 0 };
 
+static IBusText *text_empty = NULL;
+
 /* functions prototype */
 static void      ibus_engine_destroy         (IBusEngine         *engine);
 static void      ibus_engine_set_property    (IBusEngine         *engine,
@@ -135,6 +141,10 @@ static void      ibus_engine_property_show   (IBusEngine         *engine,
                                               const gchar        *prop_name);
 static void      ibus_engine_property_hide   (IBusEngine         *engine,
                                               const gchar        *prop_name);
+static void      ibus_engine_set_surrounding_text
+                                            (IBusEngine         *engine,
+                                             IBusText           *text,
+                                             guint               cursor_pos);
 static void      ibus_engine_emit_signal     (IBusEngine         *engine,
                                               const gchar        *signal_name,
                                               GVariant           *parameters);
@@ -185,6 +195,10 @@ static const gchar introspection_xml[] =
     "    <method name='PageDown' />"
     "    <method name='CursorUp' />"
     "    <method name='CursorDown' />"
+    "    <method name='SetSurroundingText'>"
+    "      <arg direction='in'  type='v' name='text' />"
+    "      <arg direction='in'  type='u' name='cursor_pos' />"
+    "    </method>"
     /* FIXME signals */
     "    <signal name='CommitText'>"
     "      <arg type='v' name='text' />"
@@ -250,6 +264,7 @@ ibus_engine_class_init (IBusEngineClass *class)
     class->property_hide        = ibus_engine_property_hide;
     class->set_cursor_location  = ibus_engine_set_cursor_location;
     class->set_capabilities     = ibus_engine_set_capabilities;
+    class->set_surrounding_text = ibus_engine_set_surrounding_text;
 
     /* install properties */
     /**
@@ -616,12 +631,39 @@ ibus_engine_class_init (IBusEngineClass *class)
             G_TYPE_STRING);
 
     g_type_class_add_private (class, sizeof (IBusEnginePrivate));
+
+    /**
+     * IBusEngine::set-surrounding-text:
+     * @engine: An IBusEngine.
+     *
+     * Emitted when a surrounding text is set.
+     * Implement the member function set_surrounding_text() in extended class to receive this signal.
+     *
+     * <note><para>Argument @user_data is ignored in this function.</para></note>
+     */
+    engine_signals[SET_SURROUNDING_TEXT] =
+        g_signal_new (I_("set-surrounding-text"),
+            G_TYPE_FROM_CLASS (gobject_class),
+            G_SIGNAL_RUN_LAST,
+            G_STRUCT_OFFSET (IBusEngineClass, set_surrounding_text),
+            NULL, NULL,
+            _ibus_marshal_VOID__OBJECT_UINT,
+            G_TYPE_NONE,
+            2,
+            G_TYPE_OBJECT,
+            G_TYPE_UINT);
+
+    text_empty = ibus_text_new_from_static_string ("");
+    g_object_ref_sink (text_empty);
 }
 
 static void
 ibus_engine_init (IBusEngine *engine)
 {
     engine->priv = IBUS_ENGINE_GET_PRIVATE (engine);
+
+    engine->priv->surrounding_text = g_object_ref_sink (text_empty);
+    engine->priv->surrounding_cursor_pos = 0;
 }
 
 static void
@@ -630,6 +672,11 @@ ibus_engine_destroy (IBusEngine *engine)
     g_free (engine->priv->engine_name);
     engine->priv->engine_name = NULL;
 
+    if (engine->priv->surrounding_text) {
+        g_object_unref (engine->priv->surrounding_text);
+        engine->priv->surrounding_text = NULL;
+    }
+
     IBUS_OBJECT_CLASS(ibus_engine_parent_class)->destroy (IBUS_OBJECT (engine));
 }
 
@@ -801,6 +848,25 @@ ibus_engine_service_method_call (IBusService           *service,
         return;
     }
 
+    if (g_strcmp0 (method_name, "SetSurroundingText") == 0) {
+        GVariant *variant = NULL;
+        IBusText *text;
+        guint cursor_pos;
+
+        g_variant_get (parameters, "(vu)", &variant, &cursor_pos);
+        text = IBUS_TEXT (ibus_serializable_deserialize (variant));
+        g_variant_unref (variant);
+
+        g_signal_emit (engine, engine_signals[SET_SURROUNDING_TEXT], 0,
+                       text,
+                       cursor_pos);
+        if (g_object_is_floating (text)) {
+            g_object_unref (text);
+        }
+        g_dbus_method_invocation_return_value (invocation, NULL);
+        return;
+    }
+
     /* should not be reached */
     g_return_if_reached ();
 }
@@ -955,6 +1021,26 @@ ibus_engine_property_hide (IBusEngine *engine, const gchar *prop_name)
 }
 
 static void
+ibus_engine_set_surrounding_text (IBusEngine *engine,
+                                  IBusText   *text,
+                                  guint       cursor_pos)
+{
+    g_assert (IBUS_IS_ENGINE (engine));
+
+    IBusEnginePrivate *priv;
+
+    priv = IBUS_ENGINE_GET_PRIVATE (engine);
+
+    if (priv->surrounding_text) {
+        g_object_unref (priv->surrounding_text);
+    }
+
+    priv->surrounding_text = (IBusText *) g_object_ref_sink (text ? text : text_empty);
+    priv->surrounding_cursor_pos = cursor_pos;
+    // g_debug ("set-surrounding-text ('%s', %d)", text->text, cursor_pos);
+}
+
+static void
 ibus_engine_emit_signal (IBusEngine  *engine,
                          const gchar *signal_name,
                          GVariant    *parameters)
@@ -1138,14 +1224,66 @@ void ibus_engine_delete_surrounding_text (IBusEngine      *engine,
                                           gint             offset_from_cursor,
                                           guint            nchars)
 {
+    IBusEnginePrivate *priv;
+
     g_return_if_fail (IBUS_IS_ENGINE (engine));
 
+    priv = IBUS_ENGINE_GET_PRIVATE (engine);
+
+    /* Update surrounding-text cache.  This is necessary since some
+       engines call ibus_engine_get_surrounding_text() immediately
+       after ibus_engine_delete_surrounding_text(). */
+    if (priv->surrounding_text) {
+        IBusText *text;
+        glong cursor_pos, len;
+
+        cursor_pos = priv->surrounding_cursor_pos + offset_from_cursor;
+        len = ibus_text_get_length (priv->surrounding_text);
+        if (cursor_pos >= 0 && len - cursor_pos >= nchars) {
+            gunichar *ucs;
+
+            ucs = g_utf8_to_ucs4_fast (priv->surrounding_text->text,
+                                       -1,
+                                       NULL);
+            memmove (&ucs[cursor_pos],
+                     &ucs[cursor_pos + nchars],
+                     sizeof(gunichar) * (len - cursor_pos - nchars));
+            ucs[len - nchars] = 0;
+            text = ibus_text_new_from_ucs4 (ucs);
+            g_free (ucs);
+            priv->surrounding_cursor_pos = cursor_pos;
+        } else {
+            text = text_empty;
+            priv->surrounding_cursor_pos = 0;
+        }
+
+        g_object_unref (priv->surrounding_text);
+        priv->surrounding_text = g_object_ref_sink (text);
+    }
+
     ibus_engine_emit_signal (engine,
                              "DeleteSurroundingText",
                              g_variant_new ("(iu)", offset_from_cursor, nchars));
 }
 
 void
+ibus_engine_get_surrounding_text (IBusEngine   *engine,
+                                  IBusText    **text,
+                                  guint        *cursor_pos)
+{
+    IBusEnginePrivate *priv;
+
+    g_return_if_fail (IBUS_IS_ENGINE (engine));
+    g_return_if_fail (text != NULL);
+    g_return_if_fail (cursor_pos != NULL);
+
+    priv = IBUS_ENGINE_GET_PRIVATE (engine);
+
+    *text = g_object_ref (priv->surrounding_text);
+    *cursor_pos = priv->surrounding_cursor_pos;
+}
+
+void
 ibus_engine_register_properties (IBusEngine   *engine,
                                  IBusPropList *prop_list)
 {
diff --git a/src/ibusengine.h b/src/ibusengine.h
index 46d0a04..a5f5aea 100644
--- a/src/ibusengine.h
+++ b/src/ibusengine.h
@@ -136,10 +136,14 @@ struct _IBusEngineClass {
                                      guint           index,
                                      guint           button,
                                      guint           state);
+    void        (* set_surrounding_text)
+                                    (IBusEngine     *engine,
+                                     IBusText       *text,
+                                     guint           cursor_index);
 
     /*< private >*/
     /* padding */
-    gpointer pdummy[8];
+    gpointer pdummy[7];
 };
 
 GType        ibus_engine_get_type       (void);
@@ -394,6 +398,21 @@ void ibus_engine_delete_surrounding_text(IBusEngine         *engine,
                                          guint               nchars);
 
 /**
+ * ibus_engine_get_surrounding_text:
+ * @engine: An IBusEngine.
+ * @text: Location to store surrounding text.
+ * @cursor_pos: Cursor position in characters in @text.
+ *
+ * Get surrounding text.
+ *
+ * @see_also #IBusEngine::set-surrounding-text
+ */
+void ibus_engine_get_surrounding_text(IBusEngine         *engine,
+                                      IBusText          **text,
+                                      guint              *cursor_pos);
+
+
+/**
  * ibus_engine_get_name:
  * @engine: An IBusEngine.
  * @returns: Name of IBusEngine.
diff --git a/src/ibusenginedesc.c b/src/ibusenginedesc.c
index ca5ef60..956ce73 100644
--- a/src/ibusenginedesc.c
+++ b/src/ibusenginedesc.c
@@ -22,6 +22,7 @@
 #include <stdlib.h>
 #include "ibusenginedesc.h"
 #include "ibusxml.h"
+#include "ibusenumtypes.h"
 
 enum {
     LAST_SIGNAL,
@@ -39,6 +40,7 @@ enum {
     PROP_LAYOUT,
     PROP_RANK,
     PROP_HOTKEYS,
+    PROP_REQUIRES,
 };
 
 
@@ -54,6 +56,7 @@ struct _IBusEngineDescPrivate {
     gchar      *layout;
     guint       rank;
     gchar      *hotkeys;
+    guint       requires;
 };
 
 #define IBUS_ENGINE_DESC_GET_PRIVATE(o)  \
@@ -79,9 +82,20 @@ static gboolean     ibus_engine_desc_copy           (IBusEngineDesc         *des
                                                      const IBusEngineDesc   *src);
 static gboolean     ibus_engine_desc_parse_xml_node (IBusEngineDesc         *desc,
                                                      XMLNode                *node);
+static void         ibus_engine_desc_output_capabilities
+                                                    (guint                   caps,
+                                                     GString                *output,
+                                                     gint                    indent);
+static guint        ibus_engine_desc_parse_capabilities
+                                                    (XMLNode                *node);
 
 G_DEFINE_TYPE (IBusEngineDesc, ibus_engine_desc, IBUS_TYPE_SERIALIZABLE)
 
+#define DEFAULT_REQUIRES (IBUS_CAP_PREEDIT_TEXT |   \
+                          IBUS_CAP_AUXILIARY_TEXT | \
+                          IBUS_CAP_LOOKUP_TABLE |   \
+                          IBUS_CAP_FOCUS |          \
+                          IBUS_CAP_PROPERTY)
 
 static void
 ibus_engine_desc_class_init (IBusEngineDescClass *class)
@@ -232,6 +246,21 @@ ibus_engine_desc_class_init (IBusEngineDescClass *class)
                         "The hotkeys of engine description",
                         "",
                         G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY));
+
+    /**
+     * IBusEngineDesc:requires:
+     *
+     * The required capabilities of engine description
+     */
+    g_object_class_install_property (gobject_class,
+                    PROP_REQUIRES,
+                    g_param_spec_uint ("requires",
+                        "description requires",
+                        "The required capabilities of engine description",
+                        0,
+                        G_MAXUINT,
+                        DEFAULT_REQUIRES,
+                        G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY));
 }
 
 static void
@@ -249,6 +278,7 @@ ibus_engine_desc_init (IBusEngineDesc *desc)
     desc->priv->layout = NULL;
     desc->priv->rank = 0;
     desc->priv->hotkeys = NULL;
+    desc->priv->requires = DEFAULT_REQUIRES;
 }
 
 static void
@@ -313,6 +343,9 @@ ibus_engine_desc_set_property (IBusEngineDesc *desc,
         g_assert (desc->priv->hotkeys == NULL);
         desc->priv->hotkeys = g_value_dup_string (value);
         break;
+    case PROP_REQUIRES:
+        desc->priv->requires = g_value_get_uint (value);
+        break;
     default:
         G_OBJECT_WARN_INVALID_PROPERTY_ID (desc, prop_id, pspec);
     }
@@ -355,6 +388,9 @@ ibus_engine_desc_get_property (IBusEngineDesc *desc,
     case PROP_HOTKEYS:
         g_value_set_string (value, ibus_engine_desc_get_hotkeys (desc));
         break;
+    case PROP_REQUIRES:
+        g_value_set_uint (value, ibus_engine_desc_get_requires (desc));
+        break;
     default:
         G_OBJECT_WARN_INVALID_PROPERTY_ID (desc, prop_id, pspec);
     }
@@ -382,9 +418,28 @@ ibus_engine_desc_serialize (IBusEngineDesc  *desc,
     g_variant_builder_add (builder, "u", desc->priv->rank);
     g_variant_builder_add (builder, "s", NOTNULL (desc->priv->hotkeys));
 #undef NOTNULL
+
+    /* append extra properties */
+    GVariantBuilder array;
+    g_variant_builder_init (&array, G_VARIANT_TYPE ("a{sv}"));
+    g_variant_builder_add (&array, "{sv}", "requires", g_variant_new_uint32 (desc->priv->requires));
+    g_variant_builder_add (builder, "v", g_variant_builder_end (&array));
+
     return TRUE;
 }
 
+static gboolean
+ibus_engine_desc_deserialize_property (IBusEngineDesc *desc,
+                                       const gchar    *name,
+                                       GVariant       *variant)
+{
+    if (g_strcmp0 (name, "requires") == 0) {
+        g_variant_get (variant, "u", &desc->priv->requires);
+        return TRUE;
+    }
+    return FALSE;
+}
+
 static gint
 ibus_engine_desc_deserialize (IBusEngineDesc *desc,
                               GVariant       *variant)
@@ -405,6 +460,23 @@ ibus_engine_desc_deserialize (IBusEngineDesc *desc,
     g_variant_get_child (variant, retval++, "u", &desc->priv->rank);
     g_variant_get_child (variant, retval++, "s", &desc->priv->hotkeys);
 
+    /* extract extra properties */
+    GVariantIter iter;
+    GVariant *child, *array;
+
+    g_variant_get_child (variant, retval++, "v", &array);
+    g_variant_iter_init (&iter, array);
+    while ((child = g_variant_iter_next_value (&iter))) {
+        gchar *name;
+        GVariant *value;
+        g_variant_get (child, "{sv}", &name, &value);
+        if (ibus_engine_desc_deserialize_property (desc, name, value))
+            retval++;
+        g_free (name);
+        g_variant_unref (value);
+        g_variant_unref (child);
+    }
+
     return retval;
 }
 
@@ -428,6 +500,7 @@ ibus_engine_desc_copy (IBusEngineDesc       *dest,
     dest->priv->layout           = g_strdup (src->priv->layout);
     dest->priv->rank             = src->priv->rank;
     dest->priv->hotkeys          = g_strdup (src->priv->hotkeys);
+    dest->priv->requires         = src->priv->requires;
     return TRUE;
 }
 
@@ -439,6 +512,52 @@ ibus_engine_desc_copy (IBusEngineDesc       *dest,
         }                                       \
     }
 
+static void
+ibus_engine_desc_output_capabilities (guint    caps,
+                                      GString *output,
+                                      gint     indent)
+{
+    GFlagsClass *flags_class;
+    gint i;
+
+    flags_class = g_type_class_ref (IBUS_TYPE_CAPABILITE);
+    g_return_if_fail (G_TYPE_IS_FLAGS (IBUS_TYPE_CAPABILITE));
+    for (i = 0; i < flags_class->n_values; i++) {
+        GFlagsValue *flags_value = &flags_class->values[i];
+        if (caps & flags_value->value) {
+            g_string_append_indent (output, indent + 1);
+            g_string_append_printf (output, "<capability>%s</capability>\n",
+                                    flags_value->value_nick);
+        }
+    }
+    g_type_class_unref (flags_class);
+}
+
+static guint
+ibus_engine_desc_parse_capabilities (XMLNode *node)
+{
+    GFlagsClass *flags_class;
+    guint caps = 0;
+    GList *p;
+
+    flags_class = g_type_class_ref (IBUS_TYPE_CAPABILITE);
+    for (p = node->sub_nodes; p != NULL; p = p->next) {
+        XMLNode *sub_node = (XMLNode *) p->data;
+
+        if (g_strcmp0 (sub_node->name, "capability") == 0) {
+            gint i;
+            for (i = 0; i < flags_class->n_values; i++) {
+                GFlagsValue *flags_value = &flags_class->values[i];
+                if (g_strcmp0 (flags_value->value_nick, sub_node->text) == 0)
+                    caps |= flags_value->value;
+            }
+        }
+    }
+    g_type_class_unref (flags_class);
+
+    return caps;
+}
+
 void
 ibus_engine_desc_output (IBusEngineDesc *desc,
                          GString        *output,
@@ -467,6 +586,13 @@ ibus_engine_desc_output (IBusEngineDesc *desc,
     OUTPUT_ENTRY_1(hotkeys);
     g_string_append_indent (output, indent + 1);
     g_string_append_printf (output, "<rank>%u</rank>\n", desc->priv->rank);
+
+    g_string_append_indent (output, indent + 1);
+    g_string_append (output, "<requires>\n");
+    ibus_engine_desc_output_capabilities (desc->priv->requires, output,
+                                          indent + 2);
+    g_string_append_indent (output, indent + 1);
+    g_string_append (output, "</requires>\n");
 #undef OUTPUT_ENTRY
 #undef OUTPUT_ENTRY_1
     g_string_append_indent (output, indent);
@@ -504,6 +630,11 @@ ibus_engine_desc_parse_xml_node (IBusEngineDesc *desc,
             desc->priv->rank = atoi (sub_node->text);
             continue;
         }
+        if (g_strcmp0 (sub_node->name , "requires") == 0) {
+            desc->priv->requires =
+                ibus_engine_desc_parse_capabilities (sub_node);
+            continue;
+        }
         g_warning ("<engines> element contains invalidate element <%s>", sub_node->name);
     }
     return TRUE;
@@ -526,6 +657,7 @@ IBUS_ENGINE_DESC_GET_PROPERTY (icon, const gchar *)
 IBUS_ENGINE_DESC_GET_PROPERTY (layout, const gchar *)
 IBUS_ENGINE_DESC_GET_PROPERTY (rank, guint)
 IBUS_ENGINE_DESC_GET_PROPERTY (hotkeys, const gchar *)
+IBUS_ENGINE_DESC_GET_PROPERTY (requires, guint)
 #undef IBUS_ENGINE_DESC_GET_PROPERTY
 
 IBusEngineDesc *
diff --git a/src/ibusenginedesc.h b/src/ibusenginedesc.h
index 9718b15..209d460 100644
--- a/src/ibusenginedesc.h
+++ b/src/ibusenginedesc.h
@@ -90,6 +90,8 @@ typedef struct _IBusEngineDescClass IBusEngineDescClass;
  * the front.
  * hotkeys: One or more hotkeys for switching to this engine, separated by
  *  semi-colon.
+ * requires: Capabilities this engine will utilize.  The value is the
+ * union of the IBusCapability flags.
  */
 struct _IBusEngineDesc {
     IBusSerializable parent;
@@ -249,6 +251,15 @@ guint            ibus_engine_desc_get_rank      (IBusEngineDesc *info);
 const gchar     *ibus_engine_desc_get_hotkeys   (IBusEngineDesc *info);
 
 /**
+ * ibus_engine_desc_get_requires:
+ * @info: An IBusEngineDesc
+ * @returns: request capabilites property in IBusEngineDesc
+ *
+ * Return the capabilites property in IBusEngineDesc.
+ */
+guint            ibus_engine_desc_get_requires  (IBusEngineDesc *info);
+
+/**
  * ibus_engine_desc_output:
  * @info: An IBusEngineDesc
  * @output: XML-formatted Input method engine description.
diff --git a/src/ibusinputcontext.c b/src/ibusinputcontext.c
index f8f5848..9556df3 100644
--- a/src/ibusinputcontext.c
+++ b/src/ibusinputcontext.c
@@ -28,6 +28,9 @@
 #include "ibuslookuptable.h"
 #include "ibusproplist.h"
 
+#define IBUS_INPUT_CONTEXT_GET_PRIVATE(o)  \
+   (G_TYPE_INSTANCE_GET_PRIVATE ((o), IBUS_TYPE_INPUT_CONTEXT, IBusInputContextPrivate))
+
 enum {
     ENABLED,
     DISABLED,
@@ -49,12 +52,25 @@ enum {
     CURSOR_DOWN_LOOKUP_TABLE,
     REGISTER_PROPERTIES,
     UPDATE_PROPERTY,
+    ENGINE_CHANGED,
     LAST_SIGNAL,
 };
 
+/* BusInputContextPrivate */
+struct _IBusInputContextPrivate {
+    /* surrounding text */
+    IBusText *surrounding_text;
+    guint     surrounding_cursor_pos;
+};
+
+typedef struct _IBusInputContextPrivate IBusInputContextPrivate;
+
 static guint            context_signals[LAST_SIGNAL] = { 0 };
 
+static IBusText *text_empty = NULL;
+
 /* functions prototype */
+static void     ibus_input_context_real_destroy (IBusProxy              *context);
 static void     ibus_input_context_g_signal     (GDBusProxy             *proxy,
                                                  const gchar            *sender_name,
                                                  const gchar            *signal_name,
@@ -65,8 +81,13 @@ G_DEFINE_TYPE (IBusInputContext, ibus_input_context, IBUS_TYPE_PROXY)
 static void
 ibus_input_context_class_init (IBusInputContextClass *class)
 {
+    IBusProxyClass *ibus_proxy_class = IBUS_PROXY_CLASS (class);
     GDBusProxyClass *g_dbus_proxy_class = G_DBUS_PROXY_CLASS (class);
 
+    g_type_class_add_private (class, sizeof (IBusInputContextPrivate));
+
+    ibus_proxy_class->destroy = ibus_input_context_real_destroy;
+
     g_dbus_proxy_class->g_signal = ibus_input_context_g_signal;
 
     /* install signals */
@@ -101,6 +122,21 @@ ibus_input_context_class_init (IBusInputContextClass *class)
             G_TYPE_NONE, 0);
 
     /**
+     * IBusInputContext::engine-changed:
+     * @context: An IBusInputContext.
+     *
+     * Emitted when an IME is changed.
+     */
+    context_signals[ENGINE_CHANGED] =
+        g_signal_new (I_("engine-changed"),
+            G_TYPE_FROM_CLASS (class),
+            G_SIGNAL_RUN_LAST,
+            0,
+            NULL, NULL,
+            _ibus_marshal_VOID__VOID,
+            G_TYPE_NONE, 0);
+
+    /**
      * IBusInputContext::commit-text:
      * @context: An IBusInputContext.
      * @text: Text to be committed.
@@ -429,11 +465,33 @@ ibus_input_context_class_init (IBusInputContextClass *class)
             G_TYPE_NONE,
             1,
             IBUS_TYPE_PROPERTY);
+
+    text_empty = ibus_text_new_from_static_string ("");
+    g_object_ref_sink (text_empty);
 }
 
 static void
 ibus_input_context_init (IBusInputContext *context)
 {
+    IBusInputContextPrivate *priv;
+
+    priv = IBUS_INPUT_CONTEXT_GET_PRIVATE (context);
+    priv->surrounding_text = g_object_ref_sink (text_empty);
+    priv->surrounding_cursor_pos = 0;
+}
+
+static void
+ibus_input_context_real_destroy (IBusProxy *context)
+{
+    IBusInputContextPrivate *priv;
+    priv = IBUS_INPUT_CONTEXT_GET_PRIVATE (IBUS_INPUT_CONTEXT (context));
+
+    if (priv->surrounding_text) {
+        g_object_unref (priv->surrounding_text);
+        priv->surrounding_text = NULL;
+    }
+
+    IBUS_PROXY_CLASS(ibus_input_context_parent_class)->destroy (context);
 }
 
 static void
@@ -463,6 +521,7 @@ ibus_input_context_g_signal (GDBusProxy  *proxy,
         { "PageDownLookupTable",    PAGE_DOWN_LOOKUP_TABLE   },
         { "CursorUpLookupTable",    CURSOR_UP_LOOKUP_TABLE   },
         { "CursorDownLookupTable",  CURSOR_DOWN_LOOKUP_TABLE },
+        { "EngineChanged",          ENGINE_CHANGED           },
     };
 
     if (g_strcmp0 (signal_name, "CommitText") == 0) {
@@ -848,6 +907,38 @@ ibus_input_context_property_hide (IBusInputContext *context,
                        );
 }
 
+void
+ibus_input_context_set_surrounding_text (IBusInputContext   *context,
+                                         IBusText           *text,
+                                         guint32             cursor_pos)
+{
+    g_assert (IBUS_IS_INPUT_CONTEXT (context));
+    g_assert (IBUS_IS_TEXT (text));
+
+    IBusInputContextPrivate *priv;
+    priv = IBUS_INPUT_CONTEXT_GET_PRIVATE (context);
+
+    if (priv->surrounding_text == NULL ||
+        g_strcmp0 (text->text, priv->surrounding_text->text) != 0 ||
+        cursor_pos != priv->surrounding_cursor_pos) {
+        GVariant *variant = ibus_serializable_serialize ((IBusSerializable *)text);
+        if (priv->surrounding_text)
+            g_object_unref (priv->surrounding_text);
+        priv->surrounding_text = (IBusText *) g_object_ref_sink (text);
+        priv->surrounding_cursor_pos = cursor_pos;
+
+        g_dbus_proxy_call ((GDBusProxy *) context,
+                         "SetSurroundingText",              /* method_name */
+                         g_variant_new ("(vu)", variant, cursor_pos), /* parameters */
+                         G_DBUS_CALL_FLAGS_NONE,            /* flags */
+                         -1,                                /* timeout */
+                         NULL,                              /* cancellable */
+                         NULL,                              /* callback */
+                         NULL                               /* user_data */
+                         );
+    }
+}
+
 gboolean
 ibus_input_context_is_enabled (IBusInputContext *context)
 {
diff --git a/src/ibusinputcontext.h b/src/ibusinputcontext.h
index 96fd00e..1f8ae86 100644
--- a/src/ibusinputcontext.h
+++ b/src/ibusinputcontext.h
@@ -41,6 +41,7 @@
 
 #include "ibusproxy.h"
 #include "ibusenginedesc.h"
+#include "ibustext.h"
 
 /*
  * Type macros.
@@ -324,6 +325,16 @@ IBusEngineDesc
 void         ibus_input_context_set_engine  (IBusInputContext   *context,
                                              const gchar        *name);
 
+/**
+ * ibus_input_context_set_surrounding_text:
+ * @context: An IBusInputContext.
+ * @text: An IBusText surrounding the current cursor on the application.
+ * @cursor_po: Current cursor position in characters in @text.
+*/
+void         ibus_input_context_set_surrounding_text
+                                            (IBusInputContext   *context,
+                                             IBusText           *text,
+                                             guint32             cursor_pos);
 
 G_END_DECLS
 #endif
diff --git a/src/ibusmarshalers.list b/src/ibusmarshalers.list
index 5184278..5dc7fc2 100644
--- a/src/ibusmarshalers.list
+++ b/src/ibusmarshalers.list
@@ -13,6 +13,7 @@ VOID:INT,INT,INT,INT
 VOID:UINT,UINT
 VOID:INT,UINT
 VOID:UINT,UINT,UINT
+VOID:OBJECT,UINT
 VOID:OBJECT,UINT,BOOL
 VOID:OBJECT,UINT,BOOL,UINT
 VOID:OBJECT,BOOL
-- 
1.7.3.2