GPR_$ALLOCATE_PROJECTION GPR Calls GPR_$ALLOCATE_PROJECTION
NAME
gpr_$allocate_projection - allocates a new projection for an existing
bitmap.
FORMAT
gpr_$allocate_projection (old_projection, options, proj_format,
new_projection, status)
DESCRIPTION
This routine allocates a bitmap for the specified projection of an exist-
ing display bitmap. This projection consists of a subset of the planes
available in the pixel format.
Input Parameters
old_projection
The bitmap descriptor of an existing projection bitmap for this win-
dow, in gpr_$bitmap_desc_t format. Use the bitmap descriptor
returned by gpr_$initialize.
options
The intialization options, in gpr_$init_options_set_t format. This
is a predefined set of gpr_$init_options_t type in Pascal. C and
FORTRAN do not support set types, but you can simulate this type by
declaring a long int variable in C or an INTEGER*4 in FORTRAN. This
set has 32 members. At the present time, the only initialization
option that has been implemented is gpr_$no_clear, which specifies
not to clear the screen. This may be used in conjunction with a
display resource type of gpr_$screen. Unless you want the
gpr_$no_clear option, you should set this to a null value.
proj_format
A pointer to the projection format for the output bitmap, which is
in gpr_$proj_format_t format. This data type is a record in Pascal,
a structure in C, or an array in FORTRAN. The projection format
specifies which set of planes in the bitmap will be allocated.
Output Parameters
new_projection
The descriptor for the new bitmap, in gpr_$bitmap_desc_t format.
This is a 4-byte integer that uniquely identifies the bitmap.
status
Completion status, in status_$t format.
NOTES
Use gpr_$set_bitmap to establish an allocated bitmap as the current bit-
map.
This routine is only valid for display bitmaps.
After an application allocates a projection for an overlay, it must
immediately call gpr_$clear with the color parameter set to 0.