Inside Macintosh: Apple Game Sprockets Guide /

Chapter 2 - DrawSprocket / DrawSprocket Reference

DrawSprocket Functions / Drawing and Double Buffering

DSpContext_GetDirtyRectGridUnits

Use the DSpContext_GetDirtyRectGridUnits function to find out the size of the base dirty rectangle grid cell for a context.

OSStatus DSpContext_GetDirtyRectGridUnits (
DSpContextReference inContext,
UInt32 *outCellPixelWidth,
UInt32 *outCellPixelHeight);

inContext

A reference to a context for which you want to know the base size of the dirty rectangle grid cells.

outCellPixelWidth

On exit, the width of the grid cell in pixels.

outCellPixelHeight

On exit, the height of the grid cell in pixels.

function result

A result code.

DESCRIPTION

The DSpContext_GetDirtyRectGridUnits function takes, in the inContext parameter, a reference to a context and returns, in the outCellPixelWidth and outCellPixelHeight parameters, the width and height of a base grid cell in pixels. The grid cell size is based on a number of machine characteristics such as the bus width and L1 cache size. When you specify a grid cell size with the DSpContext_SetDirtyRectGridSize function, DrawSprocket rounds the requested size to a multiple of the base grid cell size.

CALLING RESTRICTIONS

Do not call this function during an interrupt.