The KeySym into which the KeyCode from the event was mapped is returned in the keysym_return argument if it is non-NULL and the status_return argument indicates that a KeySym was returned. If both a string and a KeySym are returned, the KeySym value does not necessarily correspond to the string returned.
_X_m_b_L_o_o_k_u_p_S_t_r_i_n_g and _X_u_t_f_8_L_o_o_k_u_p_S_t_r_i_n_g return the length of the string in bytes, and _X_w_c_L_o_o_k_u_p_S_t_r_i_n_g returns the length of the string in characters. Both _X_m_b_L_o_o_k_u_p_S_t_r_i_n_g and _X_w_c_L_o_o_k_u_p_S_t_r_i_n_g return text in the encoding of the locale bound to the input method of the specified input context, and _X_u_t_f_8_L_o_o_k_u_p_S_t_r_i_n_g returns text in UTF-8 encoding.
Each string returned by
_X_m_b_L_o_o_k_u_p_S_t_r_i_n_g
and
_X_w_c_L_o_o_k_u_p_S_t_r_i_n_g
begins in the initial state of the encoding of the locale
(if the encoding of the locale is state-dependent).
Note
To ensure proper input processing,
it is essential that the client pass only
_K_e_y_P_r_e_s_s
events to
_X_m_b_L_o_o_k_u_p_S_t_r_i_n_g,
_X_w_c_L_o_o_k_u_p_S_t_r_i_n_g
and
_X_u_t_f_8_L_o_o_k_u_p_S_t_r_i_n_g.
Their behavior when a client passes a
_K_e_y_R_e_l_e_a_s_e
event is undefined.
Clients should check the status_return argument before using the other returned values. These three functions each return a value to status_return that indicates what has been returned in the other arguments. The possible values returned are:
lw(1.5i) lw(4.3i). T{ _X_B_u_f_f_e_r_O_v_e_r_f_l_o_w T} T{ The input string to be returned is too large for the supplied buffer_return. The required size (for _X_m_b_L_o_o_k_u_p_S_t_r_i_n_g, _X_u_t_f_8_L_o_o_k_u_p_S_t_r_i_n_g in bytes; for _X_w_c_L_o_o_k_u_p_S_t_r_i_n_g in characters) is returned as the value of the function, and the contents of buffer_return and keysym_return are not modified. The client should recall the function with the same event and a buffer of adequate size to obtain the string. T} T{ _X_L_o_o_k_u_p_N_o_n_e T} T{ No consistent input has been composed so far. The contents of buffer_return and keysym_return are not modified, and the function returns zero. T} T{ _X_L_o_o_k_u_p_C_h_a_r_s T} T{ Some input characters have been composed. They are placed in the buffer_return argument, using the encoding described above, and the string length is returned as the value of the function. The content of the keysym_return argument is not modified. T} T{ _X_L_o_o_k_u_p_K_e_y_S_y_m T} T{ A KeySym has been returned instead of a string and is returned in keysym_return. The content of the buffer_return argument is not modified, and the function returns zero. T} T{ _X_L_o_o_k_u_p_B_o_t_h T} T{ Both a KeySym and a string are returned; _X_L_o_o_k_u_p_C_h_a_r_s and _X_L_o_o_k_u_p_K_e_y_S_y_m occur simultaneously. T}
It does not make any difference if the input context passed as an argument to _X_m_b_L_o_o_k_u_p_S_t_r_i_n_g, _X_w_c_L_o_o_k_u_p_S_t_r_i_n_g and _X_u_t_f_8_L_o_o_k_u_p_S_t_r_i_n_g is the one currently in possession of the focus or not. Input may have been composed within an input context before it lost the focus, and that input may be returned on subsequent calls to _X_m_b_L_o_o_k_u_p_S_t_r_i_n_g, _X_w_c_L_o_o_k_u_p_S_t_r_i_n_g or _X_u_t_f_8_L_o_o_k_u_p_S_t_r_i_n_g even though it does not have any more keyboard focus.
The function _X_u_t_f_8_L_o_o_k_u_p_S_t_r_i_n_g is an XFree86 extension introduced in XFree86 4.0.2. Its presence is indicated by the macro _X___H_A_V_E___U_T_F_8___S_T_R_I_N_G.