pngrio.c File Reference

#include "pngpriv.h"

Functions
void	png_read_data (png_structrp png_ptr, png_bytep data, size_t length)
void PNGCBAPI	png_default_read_data (png_structp png_ptr, png_bytep data, size_t length)
void PNGAPI	png_set_read_fn (png_structrp png_ptr, png_voidp io_ptr, png_rw_ptr read_data_fn)

Function Documentation

png_read_data()

void png_read_data	(	png_structrp	png_ptr,
		png_bytep	data,
		size_t	length
	)

{
   png_debug1(4, "reading %d bytes", (int)length);
 
   if (png_ptr->read_data_fn != NULL)
      (*(png_ptr->read_data_fn))(png_ptr, data, length);
 
   else
      png_error(png_ptr, "Call to NULL read function");
}

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png_default_read_data()

void PNGCBAPI png_default_read_data	(	png_structp	png_ptr,
		png_bytep	data,
		size_t	length
	)

{
   size_t check;
 
   if (png_ptr == NULL)
      return;
 
   /* fread() returns 0 on error, so it is OK to store this in a size_t
    * instead of an int, which is what fread() actually returns.
    */
   check = fread(data, 1, length, png_voidcast(png_FILE_p, png_ptr->io_ptr));
 
   if (check != length)
      png_error(png_ptr, "Read Error");
}

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png_set_read_fn()

void PNGAPI png_set_read_fn	(	png_structrp	png_ptr,
		png_voidp	io_ptr,
		png_rw_ptr	read_data_fn
	)

{
   if (png_ptr == NULL)
      return;
 
   png_ptr->io_ptr = io_ptr;
 
#ifdef PNG_STDIO_SUPPORTED
   if (read_data_fn != NULL)
      png_ptr->read_data_fn = read_data_fn;
 
   else
      png_ptr->read_data_fn = png_default_read_data;
#else
   png_ptr->read_data_fn = read_data_fn;
#endif
 
#ifdef PNG_WRITE_SUPPORTED
   /* It is an error to write to a read device */
   if (png_ptr->write_data_fn != NULL)
   {
      png_ptr->write_data_fn = NULL;
      png_warning(png_ptr,
          "Can't set both read_data_fn and write_data_fn in the"
          " same structure");
   }
#endif
 
#ifdef PNG_WRITE_FLUSH_SUPPORTED
   png_ptr->output_flush_fn = NULL;
#endif
}

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