png_set_write_fn
Name
png_set_write_fn -- set user-defined function for writing a PNG stream
Synopsis
void
png_set_write_fn
(png_structp
png_ptr, png_voidp
io_ptr, png_rw_ptr
write_data_fn, png_flush_ptr
output_flush_fn);
Description
png_set_write_fn() sets the write_data_fn as the output function for writing PNG
files instead of using standard C I/O stream functions.
png_ptr - pointer to output data structure png_struct
io_ptr - pointer to user-defined structure containing information about
the output functions. This value may be NULL.
write_data_fn - pointer to new output function that shall take the following
arguments:
- a pointer to a png_struct
- a pointer to a structure where output data can be stored
- 32-bit unsigned int to indicate number of bytes to write
The output function should invoke png_error() to handle any fatal
errors and png_warning() to handle non-fatal errors.
flush_data_fn - pointer to a new flush function that shall take a pointer to
a png_struct as argument. This function shall flush any
remaining data in buffers used by the output function. If the
output function does not buffer output, a function prototype
must still be supplied.