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       ggi_mode, ggi_coord, ggi_graphtype - LibGGI mode description


       #include <ggi/ggi.h>

       typedef struct { int16_t x, y; } ggi_coord;

       typedef uint32_t ggi_graphtype;

       typedef struct {
             int32_t          frames;
             ggi_coord       visible;
             ggi_coord       virt;
             ggi_coord       size;
             ggi_graphtype   graphtype;
             ggi_coord       dpp;
       } ggi_mode;


       The  mode  structure describes a visual configuration given by its size
       and other graphic properties.


       frames The  number  of  frames.   Some   displays   have   multi-buffer
              capabilities   (double-buffering,   triple-buffering,...).   See
              libggi                  frame-related                  functions
              (ggi{s,g}et{Read,Write,Display}Frame) for information on working
              with multiple frames.

              The size of the visible area in pixels. This is  what  the  user
              will see.

       virt   The  virtual size of the visual in pixels. It can be larger (but
              not smaller) than the visible area, in which case only a part of
              it  is  displayed.   It  is  useful  for scrolling or backing up
              portions  of   screen   efficiently.    See   ggi[Set|Get]Origin
              functions for more.

       size   The size of the visible area in mm.

              It  holds  information  on  the type of display.  libggi defines
              macros to  construct  graphtypes  values  or  access  individual

              depth ( access via GT_DEPTH(gt), GT_SETDEPTH(gt,x) )
                     The number of significant bits holding color information.

              size ( access via  GT_SIZE(gt), GT_SETSIZE(gt,x) )
                     The actual size (in bits) of a pixel.  For instance, on a
                     32  bits  X  server the pixel size is 32 but the depth is
                     only 24 (8bits RGB channels, 8 unused).

              scheme ( access via  GT_SCHEME(gt), GT_SETSCHEME(gt,x) )
                     The following schemes are available :

                     ·   GT_TEXT : text mode only

                     ·   GT_TRUECOLOR : true color mode

                     ·   GT_GREYSCALE : pixels represent level of gray

                     ·   GT_PALETTE : pixels are  entries  in  a  CLUT  (Color
                         Look-Up Table)

                     ·   GT_STATIC_PALETTE

                     ·   GT_SUBSAMPLE_YUV

                     ·   GT_SUBSAMPLE_U_YCRBR

                     ·   GT_SUBSAMPLE_S_YCRBR

                     ·   GT_NIL

              subscheme ( access via GT_SUBSCHEME(gt), GT_SETSUBSCHEME(gt,x) )
                     One of:

                     ·   GT_SUB_REVERSE_ENDIAN

                     ·   GT_SUB_HIGHBIT_RIGHT

                     ·   GT_SUB_PACKED_GETPUT

              Graphtypes    can   be   constructed   directly   or   via   the
              GT_CONSTRUCT(depth,scheme,size)  macro.   The  following  common
              graphtypes are defined :

              ·   GT_TEXT16

              ·   GT_TEXT32

              ·   GT_1BIT

              ·   GT_2BIT

              ·   GT_4BIT

              ·   GT_8BIT

              ·   GT_15BIT

              ·   GT_16BIT

              ·   GT_24BIT

              ·   GT_32BIT

              ·   GT_AUTO

              ·   GT_INVALID

       dpp    It stands for dot-per-pixel.

       When  filling  a  mode structure for setting a visual, any field can be
       assigned GGI_AUTO (GT_AUTO for graphtype) if  a  specific  value  isn’t


       ggiCheckMode(3), ggiSetMode(3)