**CIGAL Reference Manual, Chapter 6 (RealTime): r_bwrite**
===== r_bwrite -- Write a rectangular image to a larger image =====
**usage: r_bwrite  opflg eflag ltime   DatBuf BlkBuf Box BlkWid Flag**

R_BWRITE is a REALTIME operator. It transfers a rectangular block of data
from DATBUF to the larger block BLKBUF.  The portion of BLKBUF to be written
is specified by the rectangle in BOX. BOX is a short integer array. It usually 
has 4 values that define the size of the rectangle (left, top, right, bottom).
If FLAG has the CenterPoint (8) option selected, BOX has 2 values that
specify just the center location in BLKBUF where all of DATBUF should be
copied.  In that case DATBUF must have at least 2 dimensions and the size
of DATBUF must be smaller than BLKBUF.

The width of BLKBUF is specified in BLKWID. 

FLAG specifies options. Values 0-7 control data transfer options:
          0 - replace the old value with the new
          1 - or the old value with the new
          2 - xor the old value with the new
          3 - and the old value with the new
          4 - add the new value to the old
Higher values indicate other options -- these can be combined with the values
above by addition.
          8 - CenterPoint: the BOX parameter is a single point (x,y); the data
              block will be centered at that point in BLKBUF

**See Also:**\\
[[jvs:cigal|CIGAL Home]], 
[[jvs:cigal:manual|CIGAL Manual]], 
[[jvs:cigal:manual:chapter6|RealTime List]], 
[[jvs:cigal:manual:help|Manual Help]]