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3.4 Eval callbacks

VIPS lets you attach callbacks to image descriptors. These are functions you provide which VIPS will call when certain events occur. There are several events you can listen out for, seen the manual page for im_add_eval_callback() for full details.

Eval callbacks are called repeatedly during evaluation and can be used by user-interface programs to give feedback about the progress of evaluation.



John Cupitt 2004-11-02