Legacy Document

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

Bitmap Shape Omit Byte Masks and Shifts

The gxOmitBitmapMask1 enumeration defines which bits in an omit byte correspond to the data compression opcode for the field descriptors in the gxBitmap structure. The sequence of data is also defined. The omit byte and its related data sequence is given in the section "Bitmap Shape Data" beginning on page 7-32.

enum gxOmitBitmapMask1 {
   gxOmitBitmapImageMask      = 0xC0,
   gxOmitBitmapWidthMask      = 0x30,
   gxOmitBitmapHeightMask     = 0x0C,
   gxOmitBitmapRowBytesMask   = 0x03
};

Constant descriptions

gxOmitBitmapImageMask

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

gxOmitBitmapWidthMask

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

gxOmitBitmapHeightMask

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

gxOmitBitmapRowBytesMask

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

Once one of the gxOmitBitmapMask1 enumeration masks has been used to select a data compression opcode for a field descriptor in the gxBitmap structure, the corresponding bit shift from the gxOmitBitmapShift1 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 gxOmitBitmapShift1 {
   gxOmitBitmapImageShift     = 6,
   gxOmitBitmapWidthShift     = 4,
   gxOmitBitmapHeightShift    = 2,
   gxOmitBitmapRowBytesShift  = 0
};

Constant descriptions

gxOmitBitmapImageShift

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

gxOmitBitmapWidthShift

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

gxOmitBitmapHeightShift

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

gxOmitBitmapRowBytesShift

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

The gxOmitBitmapMask2 enumeration defines which bits in a second omit byte correspond to the data compression opcode for additional field descriptors in the gxBitmap structure. The sequence of data is also defined. The omit byte and its related data sequence is given in the section "Bitmap Shape Data" beginning on page 7-32.

enum gxOmitBitmapMask2 {
   gxOmitBitmapPixelSizeMask  = 0xC0,
   gxOmitBitmapSpaceMask      = 0x30,
   gxOmitBitmapSetMask        = 0x0C,
   gxOmitBitmapProfileMask    = 0x03
};

Constant descriptions

gxOmitBitmapPixelSizeMask

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

gxOmitBitmapSpaceMask

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

gxOmitBitmapSetMask

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

gxOmitBitmapProfileMask

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

Once one of the gxOmitBitmapMask2 enumeration masks has been used to select a data compression opcode for a field descriptor in the gxBitmap structure, the corresponding bit shift from the gxOmitBitmapShift2 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 gxOmitBitmapShift2 {
   gxOmitBitmapPixelSizeShift = 6,
   gxOmitBitmapSpaceShift     = 4,
   gxOmitBitmapSetShift       = 2,
   gxOmitBitmapProfileShift   = 0
};

Constant descriptions

gxOmitBitmapPixelSizeShift

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

gxOmitBitmapSpaceShift

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

gxOmitBitmapSetShift

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

gxOmitBitmapProfileShift

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

The gxOmitBitmapMask3 enumeration defines which bits in a third omit byte correspond to the data compression opcode for additional field descriptors in the gxBitmap structure. The sequence of data is also defined. The omit byte and its related data sequence is given in the section "Bitmap Shape Data" beginning on page 7-32.

enum gxOmitBitmapMask3 {
   gxOmitBitmapPositionXMask = 0xC0,
   gxOmitBitmapPositionYMask = 0x30
};

Constant descriptions

gxOmitBitmapPositionXMask

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

gxOmitBitmapPositionYMask

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

Once one of the gxOmitBitmapMask3 enumeration masks has been used to select a data compression opcode for a field descriptor in the gxBitmap structure, the corresponding bit shift from the gxOmitBitmapShift3 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 gxOmitBitmapShift3 {
   gxOmitBitmapPositionXShift = 6,
   gxOmitBitmapPositionYShift = 4
};

Constant descriptions

gxOmitBitmapPositionXShift

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

gxOmitBitmapPositionYShift

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