Inside Macintosh: QuickDraw GX Graphics /

Chapter 4 - Geometric Operations / Geometric Operations Reference

Functions / Finding Geometric Information About Shapes

GXGetShapeLength

You can use the GXGetShapeLength function to determine the length of a particular contour or of all contours of a shape.

gxWide *GXGetShapeLength(gxShape source, long index, 
                         gxWide *length);

source

A reference to the shape containing the contour.

index

The index of the contour you want to measure. You may specify a value of 0 for this parameter to measure all contours.

length

A pointer to a gxWide value. On return, this value indicates the length of the indicated contour.

function result

The length of the indicated contour.

DESCRIPTION

The GXGetShapeLength function returns as the function result the length of the perimeter of a particular contour of a shape. This function calculates the length of the contour as defined in the shape's geometry; it does not consider transformations to the shape made by the shape's transform.

For empty and full shapes, this function posts the warning shape_does_not_have_length. For point shapes, it returns zero. For solid polygon and path shapes, this function calculates the length as if the shape had the closed-frame shape fill.

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 warning shape_does_not_have_length
picture	Returns the length of the specified picture item or the sum of the length of all picture items
text	Posts the warning shape_does_not_have_length
glyph	Posts the warning shape_does_not_have_length
layout	Posts the warning shape_does_not_have_length

ERRORS, WARNINGS, AND NOTICES

Errors
out_of_memory
shape_is_nil
parameter_is_nil	(debugging version)
contour_is_less_than_zero	(debugging version)
Warnings
contour_out_of_range
shape_does_not_have_length	(debugging version)
unable_to_traverse_open_contour_that_starts_or_ends_off_the_curve
	(debugging version)

SEE ALSO

For an example using this function, see "Finding the Length of a Contour" beginning on page 4-42.

For information about the contours of the various geometric shapes, see Chapter 2, "Geometric Shapes," in this book.

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