## Presentation Device Driver Reference for OS/2

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### GreGetWindowViewportXform

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    Syntax
    Parameters
    Returns
    Glossary

Simulation support:

This function is simulated by a handling routine in the graphics engine.

Description

GreGetWindowViewportXform queries the current window or viewport transform matrix. On completion, paXformData is an array of two-dimensional values defining the current window or viewport transform matrix.

This function can be hooked by the presentation driver.

    #define INCL_GRE_XFORMS

    #include <os2.h>

    HDC       hdc;          /*  Device context handle. */

    PXFORM    paXformData;  /*  Pointer to return data. */

    PVOID     pInstance;    /*  Pointer to instance data. */

    ULONG     lFunction;    /*  High-order WORD=flags; low-order WORD=NGreGetWindowViewportXform. */

    BOOL      fSuccess;     /*  Return codes. */

    fSuccess = GreGetWindowViewportXform(hdc,

                 paXformData, pInstance, lFunction);