peterson@SW.MCC.COM (James Peterson) (09/03/88)
The PolyText8 command is defined in the X Protocol document (page 126) as follows Byte 0: 74 opcode Byte 1: unused Byte 2-3 4+(n+p)/4 request length Byte 4-7 DRAWABLE drawable Byte 8-11 GCONTEXT gc Byte 12-13 INT16 x Byte 14-15 INT16 y Byte 16-16+n-1 LISTofTEXTITEM8 items Byte 16+n-16+n+p padding A comment indicates that the number of bytes (p) of padding is always 0 or 1. How can this be? A TEXTITEM8 is a 1-byte length (m), followed by a 1-byte delta and m bytes of data. Assume that m is 3. Then the TEXTITEM8 is: Byte 16: 3 length Byte 17: 0 delta Byte 18: "a" Byte 19: "b" Byte 20: "c" Now we need 3 bytes of padding (bytes 21, 22, 23) to get up to a multiple of 4 bytes in the request. How do we know the number of items in the list? jim
RWS@zermatt.lcs.mit.EDU (Robert Scheifler) (09/03/88)
Date: Fri, 2 Sep 88 17:39:08 CDT
From: James Peterson <peterson%sw.MCC.COM@mcc.com>
A comment indicates that the number of bytes (p) of padding is always
0 or 1. How can this be?
As far as the server is concerned, the client is responsible for adding
an "extraneous" TEXTITEM8 with a length of zero. Xlib takes care of
this little annoyance for you.