Inside Macintosh: QuickDraw GX Objects /

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

View Port Functions / Manipulating View Port Object Properties

GXSetViewPortDither

You can use the GXSetViewPortDither function to assign a dither level to a view port object.

void GXSetViewPortDither(gxViewPort target, long level);

target

A reference to the view port whose dither level you wish to set.

level

The new dither level.

DESCRIPTION

The GXSetViewPortDither function specifies the default dither level for the target view port. You can specify a level in the range of 0 to 16, inclusive. Levels 0 and 1 specify no dithering, otherwise the level specifies the maximum number of pixels in the dither pattern.

SPECIAL CONSIDERATIONS

You can set the ink object's attribute, gxSuppressDitherInk, if you want to ignore the view port's dither level for shapes drawn with a specific ink. For more information about ink object attributes, see the chapter "Ink Objects" in this book.

Dithering does not occur on 32 bit-per-pixel devices, regardless of the dither level.

SPECIAL CONSIDERATIONS

Version 1.0 of QuickDraw GX does not guarantee useful results for dither levels greater than 4.

ERRORS, WARNINGS, AND NOTICES

Errors
invalid_viewPort_reference
parameter_out_of_range	(debugging version)
Notices (debugging version)
dither_already_set

SEE ALSO

For examples of the use of this function, see Listing 7-1 on page 7-42 and Listing 7-13 on page 7-61.

To get a view port's dither level, use the GXGetViewPortDither function, described in the previous section.

For information about the dither property, see "Dither" beginning on page 7-10.