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Member "pngcrush-1.8.13/pngwio.c" (29 Aug 2017, 5655 Bytes) of package /linux/privat/pngcrush-1.8.13.tar.gz:


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    1 
    2 /* pngwio.c - functions for data output
    3  *
    4  * Last changed in libpng 1.6.24 [August 4, 2016]
    5  * Copyright (c) 1998-2002,2004,2006-2014,2016 Glenn Randers-Pehrson
    6  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
    7  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
    8  *
    9  * This code is released under the libpng license.
   10  * For conditions of distribution and use, see the disclaimer
   11  * and license in png.h
   12  *
   13  * This file provides a location for all output.  Users who need
   14  * special handling are expected to write functions that have the same
   15  * arguments as these and perform similar functions, but that possibly
   16  * use different output methods.  Note that you shouldn't change these
   17  * functions, but rather write replacement functions and then change
   18  * them at run time with png_set_write_fn(...).
   19  */
   20 
   21 #include "pngpriv.h"
   22 
   23 #ifdef PNG_WRITE_SUPPORTED
   24 
   25 /* Write the data to whatever output you are using.  The default routine
   26  * writes to a file pointer.  Note that this routine sometimes gets called
   27  * with very small lengths, so you should implement some kind of simple
   28  * buffering if you are using unbuffered writes.  This should never be asked
   29  * to write more than 64K on a 16-bit machine.
   30  */
   31 
   32 void /* PRIVATE */
   33 png_write_data(png_structrp png_ptr, png_const_bytep data, png_size_t length)
   34 {
   35    /* NOTE: write_data_fn must not change the buffer! */
   36    if (png_ptr->write_data_fn != NULL )
   37       (*(png_ptr->write_data_fn))(png_ptr, png_constcast(png_bytep,data),
   38           length);
   39 
   40    else
   41       png_error(png_ptr, "Call to NULL write function");
   42 }
   43 
   44 #ifdef PNG_STDIO_SUPPORTED
   45 /* This is the function that does the actual writing of data.  If you are
   46  * not writing to a standard C stream, you should create a replacement
   47  * write_data function and use it at run time with png_set_write_fn(), rather
   48  * than changing the library.
   49  */
   50 void PNGCBAPI
   51 png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
   52 {
   53    png_size_t check;
   54 
   55    if (png_ptr == NULL)
   56       return;
   57 
   58    check = fwrite(data, 1, length, (png_FILE_p)(png_ptr->io_ptr));
   59 
   60    if (check != length)
   61       png_error(png_ptr, "Write Error");
   62 }
   63 #endif
   64 
   65 /* This function is called to output any data pending writing (normally
   66  * to disk).  After png_flush is called, there should be no data pending
   67  * writing in any buffers.
   68  */
   69 #ifdef PNG_WRITE_FLUSH_SUPPORTED
   70 void /* PRIVATE */
   71 png_flush(png_structrp png_ptr)
   72 {
   73    if (png_ptr->output_flush_fn != NULL)
   74       (*(png_ptr->output_flush_fn))(png_ptr);
   75 }
   76 
   77 #  ifdef PNG_STDIO_SUPPORTED
   78 void PNGCBAPI
   79 png_default_flush(png_structp png_ptr)
   80 {
   81    png_FILE_p io_ptr;
   82 
   83    if (png_ptr == NULL)
   84       return;
   85 
   86    io_ptr = png_voidcast(png_FILE_p, (png_ptr->io_ptr));
   87    fflush(io_ptr);
   88 }
   89 #  endif
   90 #endif
   91 
   92 /* This function allows the application to supply new output functions for
   93  * libpng if standard C streams aren't being used.
   94  *
   95  * This function takes as its arguments:
   96  * png_ptr       - pointer to a png output data structure
   97  * io_ptr        - pointer to user supplied structure containing info about
   98  *                 the output functions.  May be NULL.
   99  * write_data_fn - pointer to a new output function that takes as its
  100  *                 arguments a pointer to a png_struct, a pointer to
  101  *                 data to be written, and a 32-bit unsigned int that is
  102  *                 the number of bytes to be written.  The new write
  103  *                 function should call png_error(png_ptr, "Error msg")
  104  *                 to exit and output any fatal error messages.  May be
  105  *                 NULL, in which case libpng's default function will
  106  *                 be used.
  107  * flush_data_fn - pointer to a new flush function that takes as its
  108  *                 arguments a pointer to a png_struct.  After a call to
  109  *                 the flush function, there should be no data in any buffers
  110  *                 or pending transmission.  If the output method doesn't do
  111  *                 any buffering of output, a function prototype must still be
  112  *                 supplied although it doesn't have to do anything.  If
  113  *                 PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile
  114  *                 time, output_flush_fn will be ignored, although it must be
  115  *                 supplied for compatibility.  May be NULL, in which case
  116  *                 libpng's default function will be used, if
  117  *                 PNG_WRITE_FLUSH_SUPPORTED is defined.  This is not
  118  *                 a good idea if io_ptr does not point to a standard
  119  *                 *FILE structure.
  120  */
  121 void PNGAPI
  122 png_set_write_fn(png_structrp png_ptr, png_voidp io_ptr,
  123     png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn)
  124 {
  125    if (png_ptr == NULL)
  126       return;
  127 
  128    png_ptr->io_ptr = io_ptr;
  129 
  130 #ifdef PNG_STDIO_SUPPORTED
  131    if (write_data_fn != NULL)
  132       png_ptr->write_data_fn = write_data_fn;
  133 
  134    else
  135       png_ptr->write_data_fn = png_default_write_data;
  136 #else
  137    png_ptr->write_data_fn = write_data_fn;
  138 #endif
  139 
  140 #ifdef PNG_WRITE_FLUSH_SUPPORTED
  141 #  ifdef PNG_STDIO_SUPPORTED
  142 
  143    if (output_flush_fn != NULL)
  144       png_ptr->output_flush_fn = output_flush_fn;
  145 
  146    else
  147       png_ptr->output_flush_fn = png_default_flush;
  148 
  149 #  else
  150    png_ptr->output_flush_fn = output_flush_fn;
  151 #  endif
  152 #else
  153    PNG_UNUSED(output_flush_fn)
  154 #endif /* WRITE_FLUSH */
  155 
  156 #ifdef PNG_READ_SUPPORTED
  157    /* It is an error to read while writing a png file */
  158    if (png_ptr->read_data_fn != NULL)
  159    {
  160       png_ptr->read_data_fn = NULL;
  161 
  162       png_warning(png_ptr,
  163           "Can't set both read_data_fn and write_data_fn in the"
  164           " same structure");
  165    }
  166 #endif
  167 }
  168 #endif /* WRITE */