GSLOP(3g,L) AIX Technical Reference GSLOP(3g,L)
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gslop
PURPOSE
Specifies the logical operation used when drawing lines.
C SYNTAX
int gslop_ (operation)
int *operation;
FORTRAN SYNTAX
INTEGER function gslop (operation)
INTEGER operation
PASCAL SYNTAX
FUNCTION gslop_ (
VAR operation INTEGER;
): INTEGER [PUBLIC];
DESCRIPTION
The gslop subroutine specifies the logical operation used for drawing the GSL
line-oriented, fill, save/restore, and polymarker primitives. It does not
apply to the text primitives.
Parameters
operation Indicates the logical operation to perform between the
primitive being drawn and the current contents of the frame
buffer.
In the following table, please note:
o The source pixels represent bits of data to be merged in
some way with the corresponding bits of data in the
destination rectangle.
o The first three columns of the table specify the
operations you can perform, and the Code column contains
the corresponding value you should specify for the
operation parameter.
o A ~ (tilde) represents the logical INVERSE.
Processed November 7, 1990 GSLOP(3g,L) 1
GSLOP(3g,L) AIX Technical Reference GSLOP(3g,L)
Type of Logical Type of Code
Source Operation Destination
Destination clear 0
Set Destination 15
No operation Destination 5
~Destination 10
Source REPLACE Destination 3
Source AND Destination 1
Source AND ~Destination 2
Source Exclusive-or Destination 6
Source OR Destination 7
Source OR ~Destination 11
~Source REPLACE Destination 12
~Source AND Destination 4
~Source AND ~Destination 8
~Source Exclusive-or Destination 9
~Source OR Destination 13
~Source OR ~Destination 14
Replace (3) is the default logical operation.
Only REPLACE, AND, OR, and Exclusive-or (codes 3, 1, 7, and 6, respectively),
are supported for VGA displays.
For printers, the operations performed are the same as those for displays,
except that a value of 0 turns the color off, and a value of 15 changes the
color to white.
For plotters, the default and only valid logical operation is logical OR. The
plotters interpret this as an overstrike. The GSL performs each of the boolean
operations for each bit of the source and destination color values enabled by
the plane mask. The destination receives the color value that results from the
operation.
The logical operations are performed on the color index rather than the color
itself. This can cause some operations on color displays to produce results
that are not expected.
RETURN VALUE
GS_SUCC Successful.
GS_LONS Logical operation not supported.
Processed November 7, 1990 GSLOP(3g,L) 2