gpar                  package:grid                  R Documentation

_F_u_n_c_t_i_o_n _t_o _p_r_o_d_u_c_e _a _G_r_a_p_h_i_c_a_l _P_a_r_a_m_e_t_e_r _O_b_j_e_c_t

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

     This function returns an object of class `"gpar"'.  This is
     basically a list of name-value pairs.

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

     gpar(...)

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

     ...: Any number of named arguments. 

_D_e_t_a_i_l_s:

     All grid viewports and (predefined) graphical objects have a slot
     called `gp', which contains a `"gpar"' object.  When a viewport is
     pushed onto the viewport stack and when a graphical object is
     drawn, the settings in the `"gpar"' object are enforced. In this
     way, the graphical output is modified by the `gp' settings until
     the graphical object has finished drawing, or until the viewport
     is popped off the viewport stack, or until some other viewport or
     graphical object is pushed or begins drawing.

     Valid parameter names are:

       col         Colour for lines and borders.
       fill        Colour for filling rectangles, polygons, ...
       lty         Line type
       lwd         Line width
       fontsize    The size of text (in points)
       lineheight  The height of a line as a multiple of fontsize
       font        Font face

     Specifying the value `NULL' for a parameter is the same as not
     specifying any value for that parameter, except for `col' and
     `fill', where `NULL' indicates not to draw a border or not to fill
     an area (respectively).

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

     An object of class `"gpar"'.

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

     Paul Murrell

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

     gpar(col="red")
     gpar(col="blue", lty="solid", lwd=3, fontsize=16)
     grid.newpage()
     vp <- viewport(w=.8, h=.8, gp=gpar(col="blue"))
     grid.collection(grid.rect(gp=gpar(col="red"), draw=FALSE),
                     grid.text("The rect is its own colour (red)\nbut this text is the colour\nset by the collection (green)", draw=FALSE),
                     gp=gpar(col="green"), vp=vp)
     grid.text("This text is the colour set by the viewport (blue)",
               y=1, just=c("center", "bottom"), gp=gpar(fontsize=20), vp=vp)

