Inside Macintosh: QuickDraw GX Objects /

Chapter 7 - View-Related Objects / View-Related Objects Reference

View Port Functions / Manipulating View Port Object Properties

GXGetHalftoneDeviceAngle

You can use the GXGetHalftoneDeviceAngle function to determine the actual angle a halftone is drawn with on a particular view device.

Fixed GXGetHalftoneDeviceAngle(gxViewDevice source, 
                              const gxHalftone *data);

source

A reference to the view device whose halftone angle you wish to examine.

data

A pointer to a halftone structure that specifies the characteristics of a halftone.

function result

The halftone angle as it would be drawn on the view device.

DESCRIPTION

The GXGetHalftoneDeviceAngle function returns the actual angle that the specified halftone would be drawn with on the source view device. The contents of the halftone structure pointed to by the data parameter are not changed.

The halftone angle on the view device may be different from the one you set with the GXSetViewPortHalftone function because the view device's resolution interacts with the halftone frequency, which specifies the dot size in cells per inch, and the view device's grid pattern.

ERRORS, WARNINGS, AND NOTICES

Errors
invalid_viewDevice_reference

SEE ALSO

For information about the halftone property, see "Halftone" beginning on page 7-13.

To get the halftone of a view port, use the GXGetViewPortHalftone function, described on page 7-81.

To obtain a list of view devices that intersect a view port, use the GXGetViewPortViewDevices function, described on page 7-94.