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Inside Macintosh: QuickDraw GX Environment and Utilities /

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

Opcode Constants and Data Types

Bit Image Compression Opcodes

Bits 6 and 7 of the bit image compression opcode byte contain the bit image compression opcode. A constant from the gxBitImageCompression enumeration defines the compression of the bit image data sequence to immediately follow.

enum gxBitImageCompression {
   gxCopyBitImageBytesOpcode  = 0x00,
   gxRepeatBitImageBytesOpcode= 0x40,
   gxLookupBitImageBytesOpcode= 0x80,
   gxRepeatBitImageScanOpcode = 0xC0
};

Constant descriptions

gxCopyBitImageBytesOpcode

Bit image compression opcode 0.

gxRepeatBitImageBytesOpcode

Bit image compression opcode 1.

gxLookupBitImageBytesOpcode

Bit image compression opcode 2.

gxRepeatBitImageScanOpcode

Bit image compression opcode 3.

The bit image compression opcode is described in the section "New Bit Image Object Data" beginning on page 7-49.