Merge Control Command (HP-GL/2)

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Merge Control Command (HP-GL/2)

The Merge Control (MC) command specifies the raster operation
(ROP's) to be performed in HP-GL/2. Raster Operations specify how
source, destination, and patterns are combined to produce final
images. This command supports all 256 Microsoft Windows ternary
(ROP3) raster-operation codes.

MC [mode, [opcode] ] ;

Merge Control Command (HP-GL/2)

1

For opcode ROP values refer to Table 2-6, Logical Operation.

mode

Note

This command is the HP-GL/2 version of the PCL Logical Operation
command.

This command sets a ROP value which affects not only HP-GL/2
operation but also the PCL ROP value.

The MC command is defaulted by an IN command.

Parameter

Format Functional

Range Default

mode

clamped integer

0 or 1

0 (ROP 252)

opcode clamped

integer 0...255

1

168, 252

0 = opcode value is ignored; printer sets ROP to 252.

1 = opcode value is used as the ROP value. If no opcode value is

sent, printer sets ROP to 168. If opcode is out of range (some
value other then 0-255), the command is ignored and the
default ROP of 252 is used. (For example: MC1,60; MC1,60-;
MC1,+60; MC1,60+;
all set the ROP to 60; however, MC1,-60;
or MC1,300; set the ROP to the default value (252).

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Printer-Specific Differences 2-29

Note

When using the MC command, some pattern types will not produce
the expected ROP result. This only occurs when using the FT (Fill
Type) command pattern types 1, 2, 3, and 4, and the ROP includes an
XOR operation. (This problem is due to the fact that these patterns
are the result of a vector operation and do not produce raster data for
use by a ROP operation.) All other Fill Type command patterns
(types, 10, 11, 21, or 22) operate as expected.

opcode

The operation code (opcode) specifies the logical operations that are
performed on a source, destination, and patterned image prior to
drawing the final image. The opcodes are created by listing all
possible combinations of a single pattern, source and destination
pixel, and constructing the desired final pixel values. The following
table shows three common opcodes (also see Table 2-6).

Table 2-3. Common Opcodes

Pixel Combinations

Desired Destination Values

Pattern Pixel

Source Pixel

Destination

Pixel

Source

Overwrite

Transparency

(TR command)

Source

Destination

0

0

0

0

0

0

0

0

1

0

1

1

0

1

0

1

1

1

0

1

1

1

1

0

1

0

0

0

0

0

1

0

1

0

1

1

1

1

0

1

1

1

1

1

1

1

1

0

Resulting Opcode

204 (0xCC)

238 (0xEE)

102 (0x66)

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2-30 Printer-Specific Differences

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