Inside Macintosh: QuickDraw GX Printing Extensions and Drivers /

Chapter 4 - Printing Messages / Printing Messages Reference

Constants and Data Types for the Raster Imaging System

Raster Offscreen Setup Structure

The raster offscreen setup structure, of data type gxOffscreenSetupRec, defines how to store raster data in offscreen memory.

struct gxOffscreenSetupRec {
   short       width;
   short       minHeight;
   short       maxHeight;
   Fixed       ramPercentage;
   long        ramSlop;
   short       depth;
   gxMapping   vpMapping;
   gxMapping   vdMapping;
   short       planes;
   gxPlaneSetupRec
               planeSetup[4];
};
typedef struct gxOffscreenSetupRec gxOffscreenSetupRec;

Field Description

width

The width in pixels of the raster.

minHeight

The minimum height in pixels. The actual height that was created for the offscreen storage is stored into this value.

maxHeight

The maximum height in pixels.

ramPercentage

The maximum percentage of available RAM to use for this storage.

ramSlop

The amount of RAM that must be left available after allocating for this storage.

depth

The depth, in bits, of each plane.

vpMapping

The mapping for offscreen view ports.

vdMapping

The mapping for offscreen view devices.

planes

The number of planes to allocate, each of which will have depth bits allocated for it.

planeSetup

The parameters of each plane, defined in the gxPlaneSetupRec structure, which is described in the next section. Four of these records are allocated because most drivers use four planes.

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