RLE_GETROW(3)RLE_GETROW(3)NAMErle_getrow - Read a scanline of pixels from an RLE file.
rle_getrow( the_hdr, rows );
rle_hdr * the_hdr;
rle_pixel ** rows;
Rle_getrow reads information for a single scanline from the input file
each time it is called. The_hdr should point to the structure initial‐
ized by rle_get_setup(3). The array rows should contain pointers to
arrays of characters, into which the scanline data will be written.
There should be as many elements in rows as there are primary colors in
the input file (typically 1 or 3), and the scanline arrays must be
indexable up to the maximum X coordinate, as specified by the_hdr→xmax.
rle_getrow returns the y value of the scanline just read. This will
always be 1 greater than the y value from the scanline previously read,
and starts at the_hdr→ymin. Only those channels enabled by
the_hdr→bits will be returned.
If an alpha channel is present in the input and enabled (by
RLE_SET_BIT, see rle_hdr(3)), then rows should include a -1 entry.
(I.e., rows[-1] should point to a valid scanline array.) The easiest
way to ensure this is to use rle_row_alloc(3) to allocate rows.
Rle_getrow will continue to return scanlines even after the end of the
input file has been reached, incrementing the return scanline number
each time it is called. The calling program should use some other ter‐
mination criterion (such as the scanline number reaching the_hdr→ymax,
or explicitly testing testing for end of file on the input with
feof(infile). The second test may fail if rle_getrow has encountered a
logical EOF in the file. The first will always work eventually.)
The code below reads the first two 3 color scanlines of 512 pixels from
an RLE file on the standard input.
char scanline, *rows;
int row, i;
rle_dflt_hdr.rle_file = stdin;
rle_get_setup( &rle_dflt_hdr );
for ( row = 0; row < 2; row++ )
for ( i = 0; i < 3; i++ )
rows[i] = scanline[row][i];
rle_getrow( &rle_dflt_hdr, rows );
SEE ALSOrle_hdr(3), rle_row_alloc(3), rle_row_free(3), rle_get_setup(3),
rle_getraw(3), rle_getskip(3), rle_putrow(3), librle(3), RLE(5).
Spencer W. Thomas, Todd Fuqua
University of Utah
4th Berkeley Distribution 2/2/87 RLE_GETROW(3)