Inside Macintosh: QuickDraw GX Graphics /

Chapter 4 - Geometric Operations / Geometric Operations Reference

Functions / Determining and Reversing Contour Direction

GXReverseShape

You can use the GXReverseShape function to reverse the order of the geometric points in a shape's contour.

void GXReverseShape(gxShape target, long contour);

target

A reference to the shape containing the contour.

contour

The number of the contour you want to reverse. You may specify a value of 0 for this parameter to indicate all contours.

DESCRIPTION

The GXReverseShape function reverses the order of the geometric points of the contour specified by the contour parameter in the shape specified by the target parameter.

If you specify a value of 0 for the contour parameter, this function reverses the order of the geometric points in each contour of the target shape, but does not affect the order of the contours themselves. If the target shape is a rectangle shape, this function converts it to a polygon shape before reversing the direction.

You can use this function to control how QuickDraw GX

• draws shapes with a winding shape fill
• draws shapes with the gxInsideFrameStyle or gxOutsideFrameStyle style attribute set
• places dashes on a dashed contour
• insets shape geometries

If you provide a target shape that is not one of the geometric shape types, this function performs the actions described in the following table:

Shape type	Action taken
bitmap	Posts the error illegal_type_for_shape
picture	Posts the error illegal_type_for_shape
text	Posts the error illegal_type_for_shape
glyph	Posts the error illegal_type_for_shape
layout	Posts the error illegal_type_for_shape

ERRORS, WARNINGS, AND NOTICES

Errors
out_of_memory
shape_is_nil
contour_is_less_than_zero	(debugging version)
illegal_type_for_shape	(debugging version)
Warnings
contour_out_of_range
shape_access_not_allowed

SEE ALSO

For examples using this function, see "Determining and Reversing Contour Direction" beginning on page 4-23.

To determine the direction of a contour, use the GXGetShapeDirection function, described on page 4-68.

For a discussion of geometric points, see the Chapter 2, "Geometric Shapes."

For a discussion of contour direction, see "Contours and Contour Direction" beginning on page 4-4.

For a discussion of dashes and the gxInsideFrameStyle or gxOutsideFrameStyle style attributes, see the Chapter 3, "Geometric Styles," in this book.

For a description of the GXInsetShape function, see page 4-94.

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