Inside Macintosh: QuickDraw GX Graphics /

Chapter 4 - Geometric Operations / Geometric Operations Reference

Functions / Determining Whether Two Areas Touch

GXTouchesBoundsShape

You can use the GXTouchesBoundsShape function to determine if a rectangle and a shape touch.

gxBoolean GXTouchesBoundsShape(const gxRectangle *target, 
                               gxShape test);

target

A pointer to the rectangle to test to determine if it touches a shape.

test

A reference to the shape to test to determine if it touches the rectangle.

function result

A Boolean value indicating whether the shape touches the rectangle.

DESCRIPTION

The GXTouchesBoundsShape function returns true as its function result if the rectangle specified by the target parameter touches the shape specified by the test parameter--even if they share only an edge or a point--and returns false otherwise.

This function considers the shape fill, the style modifications, and the transform mapping of the test shape. Only areas that are drawn are considered when determining touching.

If you provide a test 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	Compares bounding rectangle of bitmap
picture	Posts the error illegal_type_for_shape
text	Converts to path shape
glyph	Converts to path shape
layout	Converts to path shape

ERRORS, WARNINGS, AND NOTICES

Errors
out_of_memory
shape_is_nil
parameter_is_nil	(debugging version)
illegal_type_for_shape	(debugging version)
shape_may_not_be_a_picture	(debugging version)

SEE ALSO

For an example using this function, see "Determining Whether Two Shapes Touch" beginning on page 4-53.

For a discussion of shape fills, see Chapter 2, "Geometric Shapes," in this book.

For a discussion of style modifications, see Chapter 3, "Geometric Styles," in this book.

For a discussion of transform mappings, see the chapter "Transform Objects" in Inside Macintosh: QuickDraw GX Objects.

To determine if a rectangle touches a point, use the GXTouchesRectanglePoint function, described on page 4-96.

To determine if a rectangle contains a shape, use the GXContainsBoundsShape function, described on page 4-101.

To determine if two shapes touch, use the GXTouchesShape function, described in the next section.

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