DEVESC_GETAPERTURE

GreEscape DEVESC_GETAPERTURE

Simulation support

This function is mandatory for display drivers supporting software motion video. For other drivers, it is simulated by a handling routine in the graphics engine.

Description

GreEscape DEVESC_GETAPERTURE returns the size and physical address of the video aperture. For example, it would return "0A000h" and "64KB" for most Super VGA adapters. Care must be taken to determine if VGA emulation is active. If it is, a nonconflicting aperture is returned for the aperture address.

When multiple video adapters are present, this call returns the information for the adapter in use by the Presentation Manager for displaying the desktop.

Syntax

GreEscape(hdc, lCode, lInCount, pbInData, plOutCount, pbOutData);

Parameters

hdc (HDC) - input

Device context handle.

lCode (LONG) - input

DEVESC_GETAPERTURE escape code.

lInCount (LONG) - input

The handling routine should ignore this parameter.

pbInData (PBYTE) - input

The handling routine should ignore this parameter.

plOutCount (PLONG) - input

Number of bytes pointed to by pOutData.

pbOutData (PLONG) - input

Pointer to an APERTURE structure containing:

ulPhysAddr The physical address of the video memory aperture that the calling routine should use.

ulApertureSize The size in bytes of the video memory aperture.

ulScanLineSize The offset in VRAM between scan lines.

This value tells the caller how many bytes of VRAM (not visible memory) are used for each scan line. For example, an 800-byte visible scan line could be mapped onto a 1024-byte physical scan line.

rctlScreen A rectangle describing the visible region of VRAM.

For example, a 640 x 480 screen would normally return an upper-left corner of (0,0) and a lower-right corner of (639,479).

Returns

rc (LONG) - returns

Return Code.

The handling routine returns:

DEV_OK

Successful

DEVESC_NOTIMPLEMENTED

Escape is not implemented for the specified code

DEVESC_ERROR

Error

Sample Source Code

Declaration:

#define INCL_GRE_DEVICE
#include <os2.h>

HDC       hdc;           /* Device context handle. */
LONG      lCode;         /* DEVESC_GETAPERTURE escape code. */
LONG      lInCount;      /* The handling routine should ignore this parameter. */
PBYTE     pbInData;      /* The handling routine should ignore this parameter. */
PLONG     plOutCount;    /* Number of bytes pointed to by pOutData. */
PLONG     pbOutData;
LONG      rc;            /* Return Code. */

rc = GreEscape(hdc, lCode, lInCount, pbInData,
        plOutCount, pbOutData);