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Inside Macintosh: QuickDraw GX Environment and Utilities /

Chapter 7 - QuickDraw GX Stream Format / QuickDraw GX Stream Format Reference

Style Object Omit Byte Constants and Data Types

Text Face Style Omit Byte Masks and Shifts

The gxOmitFaceMask enumeration defines which bits in an omit byte correspond to the data compression opcode for the field descriptors in the gxTextFace structure. The sequence of data is also defined. The omit byte and its related data sequence is given in the section "Text Face Data" beginning on page 7-39.

enum gxOmitFaceMask {
   gxOmitFaceLayersMask = 0xC0,
   gxOmitFaceMappingMask= 0x30
};

Constant descriptions

gxOmitFaceLayersMask

The mask used to select the data compression bits for the faceLayers field descriptor.

gxOmitFaceMappingMask

The mask used to select the data compression bits for the advanceMapping field descriptor.

Once one of the gxOmitFaceMask enumeration masks has been used to select a data compression opcode for a field descriptor in the gxTextFace structure, the corresponding bit shift from the gxOmitFaceShift enumeration can be applied to the selected bits. The selected bits must be moved to the right by the indicated number of bits to isolate the data compression opcode so that it can be compared to other values.

enum gxOmitFaceShift {
   gxOmitFaceLayersShift = 6,
   gxOmitFaceMappingShift= 4
};

Constant descriptions

gxOmitFaceLayersShift

The bit shift required to isolate the compression bits for the faceLayers field descriptor.

gxOmitFaceMappingShift

The bit shift required to isolate the compression bits for the advanceMapping field descriptor.

SEE ALSO

The section "Text Face Data" beginning on page 7-39 provides a full descrtiption of the gxTextFace structure.