VioRegister
Description
This call registers an alternate video subsystem within a session.
Syntax
VioRegister
(ModuleName, EntryPoint, FunctionMask1, FunctionMask2)
Parameters
- ModuleName (PSZ) - input
- Address of the ASCIIZ string containing the 1-8 character file name of the subsystem. The maximum length of the ASCIIZ string is 9 bytes including the terminating byte of zero. The module must be a dynamic link library but the name supplied must not include the .DLL extension.
- EntryPoint (PSZ) - input
- Address of the ASCIIZ name string containing the dynamic link entry point name of the routine in the subsystem to receive control when any of the registered functions is called. The maximum length of the ASCIIZ string is 33 bytes including the terminating byte of zero.
- FunctionMask1 (ULONG) - input
- A bit mask where each bit identifies a video function being registered. The bit definitions are shown below. The first word pushed onto the stack contains the high-order 16 bits of the function mask, and the second word contains the low-order 16 bits.
BIT REGISTERED FUNCTION BIT REGISTERED FUNCTION
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ-
31 VioPrtScToggle 15 VioWrtCharStr
30 VioEndPopUp 14 VioWrtTTY
29 VioPopUp 13 VioWrtNCell
28 VioSavRedrawUndo 12 VioWrtNAttr
27 VioSavRedrawWait 11 VioWrtNChar
26 VioScrUnLock 10 VioReadCellStr
25 VioScrLock 9 VioReadCharStr
24 VioPrtSc 8 VioShowBuf
23 VioGetAnsi 7 VioSetMode
22 VioSetAnsi 6 VioSetCurType
21 VioScrollRt 5 VioSetCurPos
20 VioScrollLf 4 VioGetPhysBuf
19 VioScrollDn 3 VioGetBuf
18 VioScrollUp 2 VioGetMode
17 VioWrtCellStr 1 VioGetCurType
16 VioWrtCharStrAtt 0 VioGetCurPos
- FunctionMask2 (ULONG) - input
- A bit mask where each bit identifies a video function being registered. The bit mask has the format shown below. The first word pushed onto the stack contains the high order 16 bits of the function mask, and the second word contains the low order 16 bits. Unused bits are reserved and must be set to zero.
Bit Description 31-9 Reserved, set to zero 8 VioSetState 7 VioGetState 6 VioSetFont 5 VioGetCp 4 VioSetCp 3 VioGetConfig 2 VioGetFont 1 VioModeUndo 0 VioModeWait
Return Code
rc (USHORT) - return
Return code descriptions are:
- 0 NO_ERROR
- 349 ERROR_VIO_INVALID_MASK
- 403 ERROR_VIO_INVALID_ASCIIZ
- 426 ERROR_VIO_REGISTER
- 430 ERROR_VIO_ILLEGAL_DURING_POPUP
- 465 ERROR_VIO_DETACHED
- 494 ERROR_VIO_EXTENDED_SG
Remarks
An alternate video subsystem must register which video calls it handles. The default OS/2 video subsystem is the Base Video Subsystem.
When any of the registered functions are called, control is routed to EntryPoint. When this routine is entered, four additional values (5 words) are pushed onto the stack.
The first value is the index number (Word) of the routine being called. The second value is a near pointer (Word). The third value is the caller'sDSregister( Word ) . Thefourthvalueisthereturnaddress( DWord )totheVIOrouter .
For example, if VioSetCurPos were a registered function, the stack would appear as if the following instruction sequence were executed if VioSetCurPos were called and control routed to EntryPoint:
ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³ PUSH WORD Row ³ ³ PUSH WORD Column ³ ³ PUSH WORD VioHandle ³ ³ CALL FAR VioSetCurPos ³ ³ PUSH WORD Index ³ ³ CALL NEAR Entry point in Vio router ³ ³ PUSH WORD Caller's DS ³ ³ CALL FAR Dynamic link entry point ³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
The index numbers that correspond to the registered functions are listed below:
VioGetPhysBuf
22 VioSetAnsi
1 VioGetBuf
23 VioGetAnsi
2 VioShowBuf
24 VioPrtSc
3 VioGetCurPos
25 VioScrLock
4 VioGetCurType
26 VioScrUnLock
5 VioGetMode
27 VioSavRedrawWait
6 VioSetCurPos
28 VioSavRedrawUndo
7 VioSetCurType
29 VioPopUp
8 VioSetMode
30 VioEndPopUp
9 VioReadCharStr
31 VioPrtScToggle
10 VioReadCellStr
32 VioModeWait
11 VioWrtNChar
33 VioModeUndo
12 VioWrtNAttr
34 VioGetFont
13 VioWrtNCell
35 VioGetConfig
14 VioWrtCharStr
36 VioSetCp
15 VioWrtCharStrAtt
37 VioGetCp
16 VioWrtCellStr
38 VioSetFont
17 VioWrtTTY
39 VioGetState
18 VioScrollUp
40 VioSetState
19 VioScrollDn
20 VioScrollLf
21 VioScrollRt
When a registered function returns to the video router, the return code is interpreted as follows:
- Return code = 0
- No error. Do not invoke the corresponding Base Video Subsystem routine. Return to caller with Return code = 0.
- Return code = -1
- No error. Invoke the corresponding Base Video Subsystem routine. Return to caller with Return code = return code from Base Video Subsystem.
- Return code = error (not 0 or -1)
- Do not invoke the corresponding Base Video Subsystem routine. Return to caller with Return code = error.
When an application registers a replacement for VioPopUp within a session, the registered routine is only invoked when that session is in the foreground. If VioPopUp is issued when that session is in the background, the OS/2 default routine is invoked.
An alternate video subsystem should be designed so the routines registered do not cause any hard errors when they are invoked. Otherwise, a system lockout occurs. Code and data segments of registered routines, that might be loaded from diskette, must be preloaded.
All VIO functions within a session are serialized on a thread basis. That is, when an alternate video subsystem receives control, it can safely assume that it is not called again from the same session until the current call has completed.