png_set_progressive_read_fn -- set progressive read callback functions


#include <png.h>

void png_set_progressive_read_fn(png_structp png_ptr, png_voidp user_ptr, png_progressive_info_ptr info_callback, png_progressive_row_ptr row_callback, png_progressive_end_ptr end_callback);


png_set_progressive_read_fn() shall provide function callbacks for which shall be called for processing image data by png_process_data(). "info_callback" shall be called to process header information, "row_callback" shall be called when each row is completed and "end_callback" shall be called to process end of image information. png_set_progressive_read_fn() must be called even if all callback functions are NULL. The user-defined structure pointed to by "user_ptr" may be retrieved from inside the callbacks using function get_progressive_ptr().