## GtkIMContext

GtkIMContext — Base class for input method contexts

## Synopsis

    #include <gtk/gtk.h>

                GtkIMContext;
    void        gtk_im_context_set_client_window
                                                (GtkIMContext *context,
                                                 GdkWindow *window);
    void        gtk_im_context_get_preedit_string
                                                (GtkIMContext *context,
                                                 gchar **str,
                                                 PangoAttrList **attrs,
                                                 gint *cursor_pos);
    gboolean    gtk_im_context_filter_keypress  (GtkIMContext *context,
                                                 GdkEventKey *event);
    void        gtk_im_context_focus_in         (GtkIMContext *context);
    void        gtk_im_context_focus_out        (GtkIMContext *context);
    void        gtk_im_context_reset            (GtkIMContext *context);
    void        gtk_im_context_set_cursor_location
                                                (GtkIMContext *context,
                                                 GdkRectangle *area);
    void        gtk_im_context_set_use_preedit  (GtkIMContext *context,
                                                 gboolean use_preedit);
    void        gtk_im_context_set_surrounding  (GtkIMContext *context,
                                                 const gchar *text,
                                                 gint len,
                                                 gint cursor_index);
    gboolean    gtk_im_context_get_surrounding  (GtkIMContext *context,
                                                 gchar **text,
                                                 gint *cursor_index);
    gboolean    gtk_im_context_delete_surrounding
                                                (GtkIMContext *context,
                                                 gint offset,
                                                 gint n_chars);

## Object Hierarchy

      GObject
       +----GtkIMContext
             +----GtkIMContextSimple
             +----GtkIMMulticontext

## Signal Prototypes

    "commit"    void        user_function      (GtkIMContext *imcontext,
                                                gchar *arg1,
                                                gpointer user_data);
    "delete-surrounding"
                gboolean    user_function      (GtkIMContext *imcontext,
                                                gint arg1,
                                                gint arg2,
                                                gpointer user_data);
    "preedit-changed"
                void        user_function      (GtkIMContext *imcontext,
                                                gpointer user_data);
    "preedit-end"
                void        user_function      (GtkIMContext *imcontext,
                                                gpointer user_data);
    "preedit-start"
                void        user_function      (GtkIMContext *imcontext,
                                                gpointer user_data);
    "retrieve-surrounding"
                gboolean    user_function      (GtkIMContext *imcontext,
                                                gpointer user_data);

## Description

## Details

### GtkIMContext

    typedef struct _GtkIMContext GtkIMContext;

### gtk_im_context_set_client_window ()

    void        gtk_im_context_set_client_window
                                                (GtkIMContext *context,
                                                 GdkWindow *window);

Set the client window for the input context; this is the GdkWindow in which the input appears. This window is used in order to correctly position status windows, and may also be used for purposes internal to the input method.

`context` : | a GtkIMContext
`window` : | the client window. This may be `NULL` to indicate that the previous client window no longer exists.

### gtk_im_context_get_preedit_string ()

    void        gtk_im_context_get_preedit_string
                                                (GtkIMContext *context,
                                                 gchar **str,
                                                 PangoAttrList **attrs,
                                                 gint *cursor_pos);

Retrieve the current preedit string for the input context, and a list of attributes to apply to the string. This string should be displayed inserted at the insertion point.

`context` : | a GtkIMContext
`str` : | location to store the retrieved string. The string retrieved must be freed with `g_free()`.
`attrs` : | location to store the retrieved attribute list. When you are done with this list, you must unreference it with `pango_attr_list_unref()`.
`cursor_pos` : | location to store position of cursor (in characters) within the preedit string.

### gtk_im_context_filter_keypress ()

    gboolean    gtk_im_context_filter_keypress  (GtkIMContext *context,
                                                 GdkEventKey *event);

Allow an input method to internally handle a key press event. If this function returns `TRUE`, then no further processing should be done for this keystroke.

`context` : | a GtkIMContext
`event` : | the key event
Returns : | `TRUE` if the input method handled the keystroke.

### gtk_im_context_focus_in ()

    void        gtk_im_context_focus_in         (GtkIMContext *context);

Notify the input method that the widget to which this input context corresponds has gained focus. The input method may, for example, change the displayed feedback to reflect this change.

`context` : | a GtkIMContext

### gtk_im_context_focus_out ()

    void        gtk_im_context_focus_out        (GtkIMContext *context);

Notify the input method that the widget to which this input context corresponds has lost focus. The input method may, for example, change the displayed feedback or reset the contexts state to reflect this change.

`context` : | a GtkIMContext

### gtk_im_context_reset ()

    void        gtk_im_context_reset            (GtkIMContext *context);

Notify the input method that a change such as a change in cursor position has been made. This will typically cause the input method to clear the preedit state.

`context` : | a GtkIMContext

### gtk_im_context_set_cursor_location ()

    void        gtk_im_context_set_cursor_location
                                                (GtkIMContext *context,
                                                 GdkRectangle *area);

Notify the input method that a change in cursor position has been made. The location is relative to the client window.

`context` : | a GtkIMContext
`area` : | new location

### gtk_im_context_set_use_preedit ()

    void        gtk_im_context_set_use_preedit  (GtkIMContext *context,
                                                 gboolean use_preedit);

Sets whether the IM context should use the preedit string to display feedback. If `use_preedit` is FALSE (default is TRUE), then the IM context may use some other method to display feedback, such as displaying it in a child of the root window.

`context` : | a GtkIMContext
`use_preedit` : | whether the IM context should use the preedit string.

### gtk_im_context_set_surrounding ()

    void        gtk_im_context_set_surrounding  (GtkIMContext *context,
                                                 const gchar *text,
                                                 gint len,
                                                 gint cursor_index);

Sets surrounding context around the insertion point and preedit string. This function is expected to be called in response to the GtkIMContext::retrieve_surrounding signal, and will likely have no effect if called at other times.

`context` : | a GtkIMContext
`text` : | text surrounding the insertion point, as UTF-8. the preedit string should not be included within `text`.
`len` : | the length of `text`, or -1 if `text` is nul-terminated
`cursor_index` : | the byte index of the insertion cursor within `text`.

### gtk_im_context_get_surrounding ()

    gboolean    gtk_im_context_get_surrounding  (GtkIMContext *context,
                                                 gchar **text,
                                                 gint *cursor_index);

Retrieves context around the insertion point. Input methods typically want context in order to constrain input text based on existing text; this is important for languages such as Thai where only some sequences of characters are allowed.

This function is implemented by emitting the GtkIMContext::retrieve_surrounding signal on the input method; in response to this signal, a widget should provide as much context as is available, up to an entire paragraph, by calling `gtk_im_context_set_surrounding()`. Note that there is no obligation for a widget to respond to the ::retrieve_surrounding signal, so input methods must be prepared to function without context.

`context` : | a GtkIMContext
`text` : | location to store a UTF-8 encoded string of text holding context around the insertion point. If the function returns `TRUE`, then you must free the result stored in this location with `g_free()`.
`cursor_index` : | location to store byte index of the insertion cursor within `text`.
Returns : | `TRUE` if surrounding text was provided; in this case you must free the result stored in *text.

### gtk_im_context_delete_surrounding ()

    gboolean    gtk_im_context_delete_surrounding
                                                (GtkIMContext *context,
                                                 gint offset,
                                                 gint n_chars);

Asks the widget that the input context is attached to to delete characters around the cursor position by emitting the GtkIMContext::delete_surrounding signal. Note that `offset` and `n_chars` are in characters not in bytes which differs from the usage other places in GtkIMContext.

In order to use this function, you should first call `gtk_im_context_get_surrounding()` to get the current context, and call this function immediately afterwards to make sure that you know what you are deleting. You should also account for the fact that even if the signal was handled, the input context might not have deleted all the characters that were requested to be deleted.

This function is used by an input method that wants to make subsitutions in the existing text in response to new input. It is not useful for applications.

`context` : | a GtkIMContext
`offset` : | offset from cursor position in chars; a negative value means start before the cursor.
`n_chars` : | number of characters to delete.
Returns : | `TRUE` if the signal was handled.

## Signals

### The "commit" signal

    void        user_function                  (GtkIMContext *imcontext,
                                                gchar *arg1,
                                                gpointer user_data);

`imcontext` : | the object which received the signal.
`arg1` : |
`user_data` : | user data set when the signal handler was connected.

### The "delete-surrounding" signal

    gboolean    user_function                  (GtkIMContext *imcontext,
                                                gint arg1,
                                                gint arg2,
                                                gpointer user_data);

`imcontext` : | the object which received the signal.
`arg1` : |
`arg2` : |
`user_data` : | user data set when the signal handler was connected.
Returns : |

### The "preedit-changed" signal

    void        user_function                  (GtkIMContext *imcontext,
                                                gpointer user_data);

`imcontext` : | the object which received the signal.
`user_data` : | user data set when the signal handler was connected.

### The "preedit-end" signal

    void        user_function                  (GtkIMContext *imcontext,
                                                gpointer user_data);

`imcontext` : | the object which received the signal.
`user_data` : | user data set when the signal handler was connected.

### The "preedit-start" signal

    void        user_function                  (GtkIMContext *imcontext,
                                                gpointer user_data);

`imcontext` : | the object which received the signal.
`user_data` : | user data set when the signal handler was connected.

### The "retrieve-surrounding" signal

    gboolean    user_function                  (GtkIMContext *imcontext,
                                                gpointer user_data);

`imcontext` : | the object which received the signal.
`user_data` : | user data set when the signal handler was connected.
Returns : |