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Inside Macintosh: More Macintosh Toolbox /

Chapter 5 - Icon Utilities / Icon Utilities Reference

Icon Utilities Routines / Determining Whether a Point or Rectangle Is Within an Icon

RectInIconMethod

You can use the RectInIconMethod function to hit-test a rectangle against an icon obtained by your icon getter function for a specified destination rectangle and alignment.

FUNCTION RectInIconMethod (testRect: Rect; iconRect: Rect;
                           align: IconAlignmentType;
                           theMethod: IconGetter;
                           yourDataPtr: Ptr): Boolean;

testRect

The rectangle to be tested, specified in local coordinates of the current graphics port.

iconRect

The rectangle in which the icon appears, specified in local coordinates of the current graphics port.

align

A value that specifies how the icon against which to hit-test is aligned within the rectangle specified by iconRect. See the description of PlotIconID on page 5-20 for a list of constants you can use in this parameter.

theMethod

A pointer to an icon getter function.

yourDataPtr

A pointer to data that is passed to your icon getter function.

DESCRIPTION

The RectInIconMethod function hit-tests the rectangle specified by testRect against an icon mask obtained with the aid of an icon getter function and as the icon appears in the destination rectangle. The parameters iconRect and align should be the same as when the icon was last drawn. The function returns TRUE if the rectangle intersects the icon mask and FALSE if it doesn't.

RectInIconMethod passes to your icon getter function the type of the icon your function should retrieve and the value specified in the yourDataPtr parameter. The RectInIconMethod function examines the size of the rectangle and requests the appropriate icon from your icon getter function--an icon of icon type 'ICN#' or 'ics#'. Your icon getter function should return a handle to the data of the requested icon type. The RectInIconMethod function extracts the mask from the icon data that your icon getter function returns. If your icon getter function returns data that does not correspond to an icon of type 'ICN#' or type 'ics#', RectInIconMethod attempts to generate a mask from the returned data.

Your icon getter function can get the data for the icon and its mask using whatever method is appropriate to your application. For example, your application might maintain its own cache of icons (and pass a pointer to it in the yourDataPtr parameter) or use its icon getter function to get an icon from the desktop database.

SEE ALSO

For more information about icon getter functions, see page 5-58.