isTransparent        package:RGraphicsDevice        R Documentation

_T_e_s_t _w_h_e_t_h_e_r _a _i_n_t_e_g_e_r _c_o_r_r_e_s_p_o_n_d_s _t_o _t_h_e _c_o_l_o_r '_t_r_a_n_s_p_a_r_e_n_t'

_D_e_s_c_r_i_p_t_i_o_n:

     This function takes an R graphics engine color specified as an
     integer and determines whether this is actually the special color
     'transparent'.

_U_s_a_g_e:

     isTransparent(col)

_A_r_g_u_m_e_n_t_s:

     col: an integer typically from either the 'col' or 'fill' field in
          an instance of the 'R_GE_gcontextPtr' type. 

_V_a_l_u_e:

     A logical value. This is 'TRUE' if the color is the special
     transparent color.

_A_u_t_h_o_r(_s):

     Duncan Temple Lang

_R_e_f_e_r_e_n_c_e_s:

     The R Internals Manual, R Development Core Team.

_S_e_e _A_l_s_o:

     'R_GE_gcontextPtr'

_E_x_a_m_p_l_e_s:

       isTransparent(-16776961)

       isTransparent(as("transparent", "RGBInt"))
       isTransparent(as("transparent", "RGBInt"))

