For the virtual mouse device driver, the virtual video device driver provides a VDHRequestVDD function, as well as several direct interfaces for pointer drawing operations.
The following VDHRequestVDD service is provided:
VDHRequestVDD
(
HVDD hvddVideo,
HVDM hvdm,
INT iFunc, /* Virtual video device */
/* driverEVREQ_POSTMOUSE (4) */
PVOID pReqIn, /* Undefined. */
PVOID pReqOut /* Undefined. */
); /* Returns TRUE. */
The virtual mouse device driver must return the address of a function that
permits the virtual video device driver to obtain mouse position and button
status during processing of the INT 10h, Query Light Pen function, when
light pen emulation is enabled for the active DOS session. Also, whenever
the DOS session changes video modes (including the initial mode change that
takes place during DOS-session creation), the virtual video device driver
notifies the virtual mouse device driver driver of the new mode and screen
dimensions.
The POSTMOUSE notification is intended to be called whenever the mouse is about to record a button transition event (that is, button going down or button coming up). Its purpose is to notify the virtual video device driver that a video event is likely to occur.
The direct-call interfaces are exported by way of the following VDHRequestVDD to the virtual mouse device driver during the creation of the first DOS session. (To avoid introducing a loading-order dependency, they are not exported during virtual device driver initialization.)
VDHRequestVDD
(
HVDD hvddMouse,
HVDM hvdm,
INT iFunc, /* iFunc = VMDEVREQ_REGISTER (1) */
PVMREG pvmreg, /* Pointer to VMREG structure */
PVMFUNC pvmfunc /* Pointer to VMFUNC structure */
); /* Returns TRUE */
where VMREG is a structure containing all the direct-call addresses:
typedef struct vmreg_s
{
ULONG nb; /* Size of structure, in */
/* bytes (24) */
PFNSHOWPTR pfnShowPtr; /* Ptr to show pointer fn. */
PFNHIDEPTR pfnHidePtr; /* Ptr to hide pointer fn. */
PFNDEFTEXT pfnDefTextPtr; /* Ptr to define text
/* pointer fn. */
PFNDEFGRAPH pfnDefGraphPtr;/* Ptr to define graphics
/* pointer fn. */
PFNSETPAGE pfnSetPtrPage; /* Ptr to set pointer */
/* page fn. */
PFNSETLPEN pfnSetLPenEm; /* Ptr to enable/disable */
/* lpen fn. */
} VMREG;
and where VMFUNC is a structure in which the virtual mouse device driver must return the address of its own exported function to return mouse position and button status:
typedef struct vmfunc_s
{
ULONG nb; /* Size of structure, */
/* in bytes (8) */
PFNQUERYSTAT pfnQueryStatus; /* Ptr to query virtual */
/* status proc. */
} VMFUNC;
The virtual video device driver also uses VDHRequestVDD to notify the virtual mouse device driver of changes in video mode:
VDHRequestVDD
(
HVDD hvddMouse,
HVDM hvdm,
INT iFunc, /* VMDEVREQ_SETSIZE (2) */
PVMSS pvmss, /* Pointer to VMSS structure */
PVOID pReqOut /* Undefined */
);
where VMSS is a structure containing the following information:
typedef struct vmss_s
{
ULONG nb; /* Size of structure, in bytes (36)*/
LONG lMode; /* Video mode (for example, */
/* 00h-13h, or -1) */
ULONG ulWidth; /* Width of screen, in pels */
ULONG ulHeight; /* Height of screen, in pels */
ULONG ulCellWidth; /* Width of screen cells, in pels */
ULONG ulCellHeight;/* Height of screen cells, in pels */
ULONG ulPtrWidth; /* Width of pointer drawing size, */
/* in pels */
ULONG ulPtrHeight; /* Height of pointer drawing size, */
/* in pels */
ULONG ulUnitWidth; /* Width of pointer drawing unit, */
/* in pels */
} VMSS;
The direct-call interfaces supplied by virtual video device drivers are defined as follows:
BOOL FNSHOWPTR VVShowPtr
(
HVDM hvdm, /* DOS session handle, */
/* or CURRENT_VDM */
ULONG xNew, /* Horizontal pel (NOT cell) */
/* coordinate */
ULONG yNew /* Vertical pel (NOT cell) */
/* coordinate */
); /* Returns TRUE unless ptr */
/* drawing disabled */
BOOL FNHIDEPTR VVHidePtr
(
HVDM hvdm /* DOS session handle, or */
/* CURRENT_VDM */
); /* Returns TRUE unless ptr */
/* drawing disabled*/ */
BOOL FNDEFTEXT VVDefTextPtr
(
HVDM hvdm, /* DOS session handle, or */
/* CURRENT_VDM */
ULONG ulANDMask, /* Screen mask */
ULONG ulXORMask, /* Pointer mask */
BOOL fHW /* TRUE to use hardware cursor */
); /* Returns TRUE */
BOOL FNDEFGRAPH VVDefGraphPtr
(
HVDM hvdm, /* DOS session handle, or */
/* CURRENT_VDM */
USHORT ausMasks[], /* Screen mask, followed by */
/* pointer mask */
ULONG xHot, /* Relative horizontal hot-spot
/* coordinate */
ULONG yHot /* Relative vertical hot-spot */
/* coordinate */
); /* Returns TRUE */
BOOL FNSETPAGE VVSetPtrPage
(
HVDM hvdm, /* DOS session handle, or */
/* CURRENT_VDM */
ULONG ulPage /* Video page number */
); /* Returns TRUE */
BOOL FNSETLPEN VVSetLPenEm
(
HVDM hvdm, /* DOS session handle, or */
/* CURRENT_VDM */
BOOL fEnable /* TRUE to enable emulation */
); /* Returns TRUE */
For reference, the function supplied by a virtual mouse device driver to a virtual video device driver is defined as follows:
BOOL FNQUERYSTAT VMQueryStatus
(
HVDM hvdm, /* DOS session handle, or */
/* CURRENT_VDM */
PVMSTAT pvmstat /* Pointer to VMSTAT info structure */
); /* Returns TRUE */
where VMSTAT is a structure containing:
typedef struct vmstat_s
{
BOOL fPtrHidden; /* Visual pointer status */
ULONG x; /* Current virtual x position */
ULONG y; /* Current virtual y position */
ULONG flButtons; /* Current button status */
} VMSTAT;
/*
** Button status bit definitions
*/
#define BUTBIT_LEFT 0x0001
#define BUTBIT_RIGHT 0x0002
#define BUTBIT_CENTER 0x0004
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