Inside Macintosh: QuickDraw GX Objects /

Chapter 6 - Transform Objects / Transform Objects Reference

Functions / Transforming Shapes by Modifying Shape Geometries

GXRotateShape

You can use the GXRotateShape function to rotate a shape around a specified origin.

void GXRotateShape(gxShape target, Fixed degrees, 
                   Fixed xOffset, Fixed yOffset);

target

A reference to the shape you want to rotate.

degrees

The number of degrees to rotate the shape.

xOffset

The horizontal coordinate of the origin to rotate the shape around.

yOffset

The vertical coordinate of the origin to rotate the shape around.

DESCRIPTION

The GXRotateShape function rotates the shape referenced by the target parameter by the number of degrees specified in the degrees parameter around the origin specified by the xOffset and yOffset parameters.

This function rotates the target shape in one of two ways:

• If the target shape's gxMapTransformShape attribute is cleared, the function recalculates the control points of the shape's geometry to effect the rotation.
• If the target shape's gxMapTransformShape attribute is set, this function is identical to the GXRotateTransform function; it recalculates the mapping matrix of the target shape's transform object to effect the rotation. If the target shape shares this transform object with other shapes, QuickDraw GX makes a copy of the transform object, associates the copy with the target shape, and makes changes to the copy.

The target shape can be any shape type. However, if the target shape is an empty shape, a full shape, or a picture shape, this function has no effect unless the shape's gxMapTransformShape attribute is set.

The coordinates of the origin are specified in geometry space.

ERRORS, WARNINGS, AND NOTICES

Errors
out_of_memory
shape_is_nil
shape_access_not_allowed	(debugging version)
Warnings
rotate_shape_out_of_range
graphic_type_cannot_be_moved
Notices (debugging version)
mapping_unaffected

SEE ALSO

For an example of the use of this function, see Listing 6-4 on page 6-25.

To rotate a shape by altering the mapping property of its transform object, you can also use the GXRotateTransform function, described on page 6-62.