Inside Macintosh: QuickDraw GX Objects /

Chapter 6 - Transform Objects / Transform Objects Reference

Functions / Creating and Manipulating Transform Objects

GXEqualTransform

You can use the GXEqualTransform function to determine if two transform objects are equal.

boolean GXEqualTransform(gxTransform one, gxTransform two);

one

A reference to one of the transform objects to test for equality.

two

A reference to the other transform object to test for equality.

function result

true if the transform specified by the one parameter is equal to the transform specified by the two parameter; otherwise false.

DESCRIPTION

The GXEqualTransform function determines whether the transform object referenced by the one parameter is equal to the transform object referenced by the two parameter.

For two transform objects to be equal, they must have identical clip shape geometries, mappings, hit-test parameters, and view port lists. Their owner count and tag list need not be identical.

SPECIAL CONSIDERATIONS

Note that for two clips to be identical means more than having identical dimensions. For example, a polygon clip might have the same dimensions as a path or rectangle, but shapes with different shape types are never identical. You can call the GXSimplifyShape function to convert the clips to their simplest form.

ERRORS, WARNINGS, AND NOTICES

Errors
out_of_memory
transform_is_nil

SEE ALSO

To make a copy of a transform object that is equal by the criteria of this function, use the GXCopyToTransform function, described on page 6-35.

The GXSimplifyShape function is described in the geometric operations chapter of Inside Macintosh: QuickDraw GX Graphics.