Subversion Repositories Kolibri OS

Rev

Blame | Last modification | View Log | RSS feed

  1.  
  2. /* pngwio.c - functions for data output
  3.  *
  4.  * Last changed in libpng 1.6.0 [February 14, 2013]
  5.  * Copyright (c) 1998-2013 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. #endif /* PNG_WRITE_FLUSH_SUPPORTED */
  153.  
  154.    /* It is an error to read while writing a png file */
  155.    if (png_ptr->read_data_fn != NULL)
  156.    {
  157.       png_ptr->read_data_fn = NULL;
  158.  
  159.       png_warning(png_ptr,
  160.           "Can't set both read_data_fn and write_data_fn in the"
  161.           " same structure");
  162.    }
  163. }
  164. #endif /* PNG_WRITE_SUPPORTED */
  165.