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Inside Macintosh: Imaging With QuickDraw /

Chapter 5 - Graphics Devices / Graphics Devices Reference

Data Structures /

DeviceLoopFlags

When you use the DeviceLoop procedure (described on page 5-28), you can change its default behavior by using the flags parameter to specify one or more members of the set of flags defined by the DeviceLoopFlags data type. These flags are described here; if you want to use the default behavior of DeviceLoop, pass in the flags parameter 0 in your C code or an empty set ([ ]) in your Pascal code.

TYPE DeviceLoopFlags = 
SET OF               {for flags parameter of DeviceLoop}
   (singleDevices,   {DeviceLoop doesn't group similar graphics }
                     { devices when calling drawing procedure}
   dontMatchSeeds,   {DeviceLoop doesn't consider ctSeed fields }
                     { of ColorTable records for graphics }
                     { devices when comparing them}
   allDevices);      {DeviceLoop ignores value of drawingRgn }
                     { parameter--instead, it calls drawing }
                     { procedure for every screen}

Field Description

singleDevices

If this flag is not set, DeviceLoop calls your drawing procedure only once for each set of similar graphics devices, and the first one found is passed as the target device. (It is assumed to be representative of all the similar graphics devices.) If you set the singleDevices flag, then DeviceLoop does not group similar graphics devices--that is, those having identical pixel depths, black-and-white or color settings, and matching color table
seeds--when it calls your drawing procedure.

dontMatchSeeds

If you set the dontMatchSeeds flag, then DeviceLoop doesn't consider color table seeds when comparing graphics devices for similarity; DeviceLoop ignores this flag if you set the singleDevices flag. Used primarily by the Palette Manager, the ctSeed field of a ColorTable record is described in the chapter "Color QuickDraw" in this book.

allDevices

If you set the allDevices flag, DeviceLoop ignores the drawingRgn parameter and calls your drawing procedure for every graphics device. The value of current graphics port's visRgn field is not affected when you set this flag.