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Inside Macintosh: QuickDraw GX Environment and Utilities /

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

Shape Object Omit Byte Constants and Data Types

Text Shape Omit Byte Masks and Shifts

The gxOmitTextMask enumeration defines which bits in an omit byte correspond to the data compression opcode for parameters of the GXNewText function. The sequence of data is also defined. The omit byte and its related data sequence is given in the section "Text Shape Data" beginning on page 7-32.

enum gxOmitTextMask {
   gxOmitTextCharactersMask   = 0xC0,
   gxOmitTextPositionXMask    = 0x30,
   gxOmitTextPositionYMask    = 0x0C,
   gxOmitTextDataMask         = 0x02
};

Constant descriptions

gxOmitTextCharactersMask

The mask used to select the data compression bits for the charCount parameter.

gxOmitTextPositionXMask

The mask used to select the data compression bits for the position.X parameter.

gxOmitTextPositionYMask

The mask used to select the data compression bits for the position .Y parameter.

gxOmitTextDataMask

The mask used to select the data compression bits for the text parameter.

Once one of the gxOmitTextMask enumeration masks has been used to select a data compression opcode for the parameters of the GXNewText function, the corresponding bit shift from the gxOmitTextShift 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 gxOmitTextShift {
   gxOmitTextCharactersShift  = 6,
   gxOmitTextPositionXShift   = 4,
   gxOmitTextPositionYShift   = 2,
   gxOmitTextDataShift        = 1
};

Constant descriptions

gxOmitTextCharactersShift

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

gxOmitTextPositionXShift

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

gxOmitTextPositionYShift

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

gxOmitTextDataShift

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