168 lines
5.5 KiB
C
168 lines
5.5 KiB
C
|
|
/* pngwio.c - functions for data output
|
|
*
|
|
* Last changed in libpng 1.6.24 [August 4, 2016]
|
|
* Copyright (c) 1998-2002,2004,2006-2014,2016 Glenn Randers-Pehrson
|
|
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
|
|
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
|
|
*
|
|
* This code is released under the libpng license.
|
|
* For conditions of distribution and use, see the disclaimer
|
|
* and license in png.h
|
|
*
|
|
* This file provides a location for all output. Users who need
|
|
* special handling are expected to write functions that have the same
|
|
* arguments as these and perform similar functions, but that possibly
|
|
* use different output methods. Note that you shouldn't change these
|
|
* functions, but rather write replacement functions and then change
|
|
* them at run time with png_set_write_fn(...).
|
|
*/
|
|
|
|
#include "pngpriv.h"
|
|
|
|
#ifdef PNG_WRITE_SUPPORTED
|
|
|
|
/* Write the data to whatever output you are using. The default routine
|
|
* writes to a file pointer. Note that this routine sometimes gets called
|
|
* with very small lengths, so you should implement some kind of simple
|
|
* buffering if you are using unbuffered writes. This should never be asked
|
|
* to write more than 64K on a 16-bit machine.
|
|
*/
|
|
|
|
void /* PRIVATE */
|
|
png_write_data(png_structrp png_ptr, png_const_bytep data, png_size_t length)
|
|
{
|
|
/* NOTE: write_data_fn must not change the buffer! */
|
|
if (png_ptr->write_data_fn != NULL )
|
|
(*(png_ptr->write_data_fn))(png_ptr, png_constcast(png_bytep,data),
|
|
length);
|
|
|
|
else
|
|
png_error(png_ptr, "Call to NULL write function");
|
|
}
|
|
|
|
#ifdef PNG_STDIO_SUPPORTED
|
|
/* This is the function that does the actual writing of data. If you are
|
|
* not writing to a standard C stream, you should create a replacement
|
|
* write_data function and use it at run time with png_set_write_fn(), rather
|
|
* than changing the library.
|
|
*/
|
|
void PNGCBAPI
|
|
png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
|
|
{
|
|
png_size_t check;
|
|
|
|
if (png_ptr == NULL)
|
|
return;
|
|
|
|
check = fwrite(data, 1, length, (png_FILE_p)(png_ptr->io_ptr));
|
|
|
|
if (check != length)
|
|
png_error(png_ptr, "Write Error");
|
|
}
|
|
#endif
|
|
|
|
/* This function is called to output any data pending writing (normally
|
|
* to disk). After png_flush is called, there should be no data pending
|
|
* writing in any buffers.
|
|
*/
|
|
#ifdef PNG_WRITE_FLUSH_SUPPORTED
|
|
void /* PRIVATE */
|
|
png_flush(png_structrp png_ptr)
|
|
{
|
|
if (png_ptr->output_flush_fn != NULL)
|
|
(*(png_ptr->output_flush_fn))(png_ptr);
|
|
}
|
|
|
|
# ifdef PNG_STDIO_SUPPORTED
|
|
void PNGCBAPI
|
|
png_default_flush(png_structp png_ptr)
|
|
{
|
|
png_FILE_p io_ptr;
|
|
|
|
if (png_ptr == NULL)
|
|
return;
|
|
|
|
io_ptr = png_voidcast(png_FILE_p, (png_ptr->io_ptr));
|
|
fflush(io_ptr);
|
|
}
|
|
# endif
|
|
#endif
|
|
|
|
/* This function allows the application to supply new output functions for
|
|
* libpng if standard C streams aren't being used.
|
|
*
|
|
* This function takes as its arguments:
|
|
* png_ptr - pointer to a png output data structure
|
|
* io_ptr - pointer to user supplied structure containing info about
|
|
* the output functions. May be NULL.
|
|
* write_data_fn - pointer to a new output function that takes as its
|
|
* arguments a pointer to a png_struct, a pointer to
|
|
* data to be written, and a 32-bit unsigned int that is
|
|
* the number of bytes to be written. The new write
|
|
* function should call png_error(png_ptr, "Error msg")
|
|
* to exit and output any fatal error messages. May be
|
|
* NULL, in which case libpng's default function will
|
|
* be used.
|
|
* flush_data_fn - pointer to a new flush function that takes as its
|
|
* arguments a pointer to a png_struct. After a call to
|
|
* the flush function, there should be no data in any buffers
|
|
* or pending transmission. If the output method doesn't do
|
|
* any buffering of output, a function prototype must still be
|
|
* supplied although it doesn't have to do anything. If
|
|
* PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile
|
|
* time, output_flush_fn will be ignored, although it must be
|
|
* supplied for compatibility. May be NULL, in which case
|
|
* libpng's default function will be used, if
|
|
* PNG_WRITE_FLUSH_SUPPORTED is defined. This is not
|
|
* a good idea if io_ptr does not point to a standard
|
|
* *FILE structure.
|
|
*/
|
|
void PNGAPI
|
|
png_set_write_fn(png_structrp png_ptr, png_voidp io_ptr,
|
|
png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn)
|
|
{
|
|
if (png_ptr == NULL)
|
|
return;
|
|
|
|
png_ptr->io_ptr = io_ptr;
|
|
|
|
#ifdef PNG_STDIO_SUPPORTED
|
|
if (write_data_fn != NULL)
|
|
png_ptr->write_data_fn = write_data_fn;
|
|
|
|
else
|
|
png_ptr->write_data_fn = png_default_write_data;
|
|
#else
|
|
png_ptr->write_data_fn = write_data_fn;
|
|
#endif
|
|
|
|
#ifdef PNG_WRITE_FLUSH_SUPPORTED
|
|
# ifdef PNG_STDIO_SUPPORTED
|
|
|
|
if (output_flush_fn != NULL)
|
|
png_ptr->output_flush_fn = output_flush_fn;
|
|
|
|
else
|
|
png_ptr->output_flush_fn = png_default_flush;
|
|
|
|
# else
|
|
png_ptr->output_flush_fn = output_flush_fn;
|
|
# endif
|
|
#else
|
|
PNG_UNUSED(output_flush_fn)
|
|
#endif /* WRITE_FLUSH */
|
|
|
|
#ifdef PNG_READ_SUPPORTED
|
|
/* It is an error to read while writing a png file */
|
|
if (png_ptr->read_data_fn != NULL)
|
|
{
|
|
png_ptr->read_data_fn = NULL;
|
|
|
|
png_warning(png_ptr,
|
|
"Can't set both read_data_fn and write_data_fn in the"
|
|
" same structure");
|
|
}
|
|
#endif
|
|
}
|
|
#endif /* WRITE */
|