NAME

       ALLEGRO_LOCKED_REGION - Allegro 5 API

SYNOPSIS

              #include <allegro5/allegro.h>

              typedef struct ALLEGRO_LOCKED_REGION ALLEGRO_LOCKED_REGION;

DESCRIPTION

       Users  who wish to manually edit or read from a bitmap are required to lock it first.  The
       ALLEGRO_LOCKED_REGION structure represents the locked region of  the  bitmap.   This  call
       will work with any bitmap, including memory bitmaps.

              typedef struct ALLEGRO_LOCKED_REGION {
                 void *data;
                 int format;
                 int pitch;
                 int pixel_size;
              } ALLEGRO_LOCKED_REGION;

       • data  points  to  the leftmost pixel of the first row (row 0) of the locked region.  For
         blocked formats, this points to the leftmost block of the first row of blocks.

       • format indicates the pixel format of the data.

       • pitch gives the size in bytes of a single row (also known as the stride).  The pitch may
         be greater than width * pixel_size due to padding; this is not uncommon.  It is also not
         uncommon for the pitch to be negative (the bitmap may  be  upside  down).   For  blocked
         formats, 'row' refers to the row of blocks, not of pixels.

       • pixel_size  is  the  number  of bytes used to represent a single block of pixels for the
         pixel format of this locked region.  For most formats (and historically, this used to be
         true  for  all  formats), this is just the size of a single pixel, but for blocked pixel
         formats this value is different.

SEE ALSO

       al_lock_bitmap(3alleg5),    al_lock_bitmap_region(3alleg5),     al_unlock_bitmap(3alleg5),
       ALLEGRO_PIXEL_FORMAT(3alleg5)