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Inside Macintosh: QuickDraw GX Environment and Utilities /

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

Ink Object Omit Byte Constants and Data Types

Transfer Component Omit Byte Masks and Shifts

The gxOmitTransferComponentMask1 enumeration defines which bits in an omit byte correspond to the data compression opcode for the field descriptors in the gxTransferComponent structure. The sequence of data is also defined. The omit byte and its related data sequence is given in the section "Transfer Mode Data" beginning on page 7-44.

enum gxOmitTransferComponentMask1 {
   gxOmitTransferComponentModeMask           = 0x80,
   gxOmitTransferComponentFlagsMask          = 0x40,
   gxOmitTransferComponentSourceMinimumMask  = 0x30,
   gxOmitTransferComponentSourceMaximumMask  = 0x0C,
   gxOmitTransferComponentDeviceMinimumMask  = 0x03
};

Constant descriptions

gxOmitTransferComponentModeMask

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

gxOmitTransferComponentFlagsMask

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

gxOmitTransferComponentSourceMinimumMask

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

gxOmitTransferComponentSourceMaximumMask

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

gxOmitTransferComponentDeviceMinimumMask

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

Once one of the gxOmitTransferComponentMask1 enumeration masks has been used to select a data compression opcode for a field descriptor in the gxTransferComponent structure, the corresponding bit shift from the gxOmitTransferComponentShift1 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 gxOmitTransferComponentShift1 {
   gxOmitTransferComponentModeShift          = 7,
   gxOmitTransferComponentFlagsShift         = 6,
   gxOmitTransferComponentSourceMinimumShift = 4,
   gxOmitTransferComponentSourceMaximumShift = 2,
   gxOmitTransferComponentDeviceMinimumShift = 0
};

Constant descriptions

gxOmitTransferComponentModeShift

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

gxOmitTransferComponentFlagsShift

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

gxOmitTransferComponentSourceMinimumShift

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

gxOmitTransferComponentSourceMaximumShift

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

gxOmitTransferComponentDeviceMinimumShift

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

The gxOmitTransferComponentMask2 enumeration defines which bits in a second omit byte correspond to the data compression opcode for additional field descriptors in the gxTransferComponent structure. The sequence of data is also continued. The omit byte and its related data sequence is given in the section "Transfer Mode Data" beginning on page 7-44.

enum gxOmitTransferComponentMask2 {
   gxOmitTransferComponentDeviceMaximumMask  = 0xC0,
   gxOmitTransferComponentClampMinimumMask   = 0x30,
   gxOmitTransferComponentClampMaximumMask   = 0x0C,
   gxOmitTransferComponentOperandMask        = 0x03
};

Constant descriptions

gxOmitTransferComponentDeviceMaximumMask

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

gxOmitTransferComponentClampMinimumMask

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

gxOmitTransferComponentClampMaximumMask

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

gxOmitTransferComponentOperandMask

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

Once one of the gxOmitTransferComponentMask2 enumeration masks has been used to select a data compression opcode for a field descriptor in the gxTransferComponent structure, the corresponding bit shift from the gxOmitTransferComponentShift2 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 gxOmitTransferComponentShift2 {
   gxOmitTransferComponentDeviceMaximumShift = 6,
   gxOmitTransferComponentClampMinimumShift  = 4,
   gxOmitTransferComponentClampMaximumShift  = 2,
   gxOmitTransferComponentOperandShift       = 0
};

Constant descriptions

gxOmitTransferComponentDeviceMaximumShift

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

gxOmitTransferComponentClampMinimumShift

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

gxOmitTransferComponentClampMaximumShift

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

gxOmitTransferComponentOperandShift

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