## Presentation Device Driver Reference for OS/2

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### GreEscape DEVESC_GETAPERTURE - 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).

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