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#define INCL_GPITRANSFORMS
 
BOOL GpiRotate(hps, pmatlf, flType, fxAngle, pptl)
HPS hps;             /* presentation-space handle               */
PMATRIXLF pmatlf;    /* pointer to structure with matrix        */
LONG flType;         /* transformation type                     */
FIXED fxAngle;       /* pointer to variable with rotation angle */
PPOINTL pptl;        /* pointer to structure with center point  */
 
The GpiRotate function creates a transformation that can be used to rotate
objects around a given point. GpiRotate either adds the specified rotation
to an existing transformation or replaces the existing transformation with
the rotation. The new transformation can be used in a subsequent call to any
transformation function.
 
Parameter  Description
────────────────────────────────────────────────────────────────────────────
 
hps        Identifies the presentation space.
 
pmatlf     Points to the MATRIXLF structure that contains the transformation
           matrix.
 
flType     Specifies how the specified matrix should be used to modify the
           transformation. It can be one of the following values:
 
           Value              Meaning
           ─────────────────────────────────────────────────────────────────
           TRANSFORM_ADD      Additive. The specified transformation matrix
                              is combined with the existing transformation,
                              with the existing transformation first, the
                              new transformation second. This option is
                              useful for incremental updates to
                              transformations.
 
           TRANSFORM_REPLACE  New/replace. The previous transformation is
                              discarded and replaced by the specified
                              transformation matrix.
 
fxAngle    Specifies the rotation (in degrees) to use.
 
pptl       Points to the POINTL structure that contains the coordinates of a
           point, relative to the origin, that defines the center of
           rotation.
 
Return Value
 
The return value is GPI_OK if the function is successful or GPI_ERROR if an
error occurs.
 
Errors
 
Use the WinGetLastError function to retrieve the error value, which may be
the following:
 
     PMERR_INV_TRANSFORM_TYPE
 
See Also
 
GpiScale, GpiSetDefaultViewMatrix, GpiSetModelTransformMatrix,
GpiSetSegmentTransformMatrix, GpiSetViewingTransformMatrix, GpiTranslate,
WinGetLastError, FIXED, MATRIXLF, POINTL
 
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