Inside Macintosh: QuickDraw GX Objects /

Chapter 6 - Transform Objects / Transform Objects Reference

Functions / Getting and Setting the Mapping

GXGetTransformMapping

You can use the GXGetTransformMapping function to retrieve the mapping property of a transform object.

gxMapping *GXGetTransformMapping(gxTransform source, 
                                 gxMapping *map);

source

A reference to the transform object whose mapping you want to examine.

map

A pointer to a mapping structure. On return, the structure contains the mapping matrix of the source transform.

function result

A pointer to the mapping property of the source transform. (This value is the same as the value returned in the map parameter.)

DESCRIPTION

The GXGetTransformMapping function copies the mapping matrix information from the mapping property of the source transform object into the mapping structure pointed to by the map parameter. The function also returns as its function result a pointer to this mapping structure.

Note that the returned mapping is a copy; you can alter it without affecting the mapping property of the source transform. If you call this function and alter the mapping that it returns, you can then assign that changed mapping back to the transform object by calling the GXSetTransformMapping function.

ERRORS, WARNINGS, AND NOTICES

Errors
out_of_memory
transform_is_nil
parameter_is_nil	(debugging version)

SEE ALSO

For information about the mapping property of the transform object, see the section "Mapping" beginning on page 6-10. For information about mapping matrices in general, see the mathematics chapter of Inside Macintosh: QuickDraw GX Environment and Utilities.