GPR_$INQ_BITMAP_POINTER GPR Calls GPR_$INQ_BITMAP_POINTER
NAME
gpr_$inq_bitmap_pointer - returns a pointer to a bitmap.
FORMAT
gpr_$inq_bitmap_pointer (bitmap_desc, storage_ptr, storage_line_width,
status)
DESCRIPTION
This routine returns a pointer to bitmap storage in virtual address
space. Also returns offset in memory from beginning of one scan line to
the next.
A program can use the information returned by this call to access indivi-
dual bits.
Each scan line (horizontal line of a bitmap) starts on a word boundary.
The parameter storage_line_width gives the offset in memory from the
beginning of one scan line to the beginning of the next, in units of 16-
bit words.
When a program uses the parameter storage_ptr to access the screen bitmap
on a monochrome system that uses a simulated color map, then pixels which
are white have a pixel value of 1 and pixels that are black have a pixel
value of 0, regardless of any calls to gpr_$set_color_map. In other
words, the pixel value itself specifies the color of the pixel: the pixel
value is not used as an index into the color map. On systems that have
the color map in hardware, the pixel value is used as an index into the
color map. The color of the pixel is determined by the color value in
the color map.
Input Parameters
bitmap_desc
Descriptor of the bitmap, in gpr_$bitmap_desc_t format. This is a
4-byte integer.
Output Parameters
storage_ptr
Start address of bitmap in virtual address space. This is a 4-byte
integer.
storage_line_width
Number of 16-bit words in virtual memory between the beginning of
one of the bitmap's scan lines and the next. This is a 2-byte
integer.
status
Completion status, in status_$t format.
SEE ALSO
gpr_$inq_disp_characteristics, gpr_$disp_char_t.
NOTES
On monochromatic devices, use gpr_$inq_disp_characteristics to determine
whether the color map is simulated or in hardware.
If the cursor is active, the cursor pattern appears in the bitmap.
A program cannot use this routine on a bitmap which is a display manager
pad (i.e., a frame mode bitmap).