im_incheck(3) checks image descriptors

Other Alias

im_outcheck, im_iocheck


#include <vips.h>

int im_incheck( in )
IMAGE *in;

int im_outcheck( out )
IMAGE *out;

int im_iocheck( in, out)
IMAGE *in, *out;


im_incheck(3) checks that an image descriptor is suitable for WIO input (ie. all of its pels can be found from im->data). If possible, it transforms the descriptor to make WIO input ok using the following rules:

IM_PARTIAL: the descriptor is magically turned into an IM_SETBUF descriptor. Memory is allocated and the image generated into that. The old partial callbacks are closed down, and the descriptor reformed as a IM_SETBUF.

IM_OPENOUT: if the descriptor has been written to, it is automatically `rewound,` that is, it is closed and reopened as an IM_MMAPIN descriptor.

IM_SETBUF: just checks that the descriptor has been written to.

See the manual page for im_setupout(3) for a skeleton program.

im_outcheck(3) checks that a descriptor is suitable for WIO output with im_writeline(3). If it sees an IM_PARTIAL image, it turns it magically into an IM_SETBUF image.

im_iocheck(3) simply calls in_incheck(3) for image in and im_outcheck(3) for image out.


All functions returns 0 on success and -1 on error.


im_open(3), im_cp_desc(3), im_setupout(3), im_makerw(3).


National Gallery


J. Cupitt - 23/7/93