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/src/compiler/android/jni/ftk/pngrio.c

http://ftk.googlecode.com/
C | 205 lines | 134 code | 17 blank | 54 comment | 29 complexity | 60a0278d9e96d439e142c023301aa920 MD5 | raw file
  1
  2/* pngrio.c - functions for data input
  3 *
  4 * Last changed in libpng 1.2.43 [February 25, 2010]
  5 * Copyright (c) 1998-2010 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 input.  Users who need
 14 * special handling are expected to write a function that has the same
 15 * arguments as this and performs a similar function, but that possibly
 16 * has a different input method.  Note that you shouldn't change this
 17 * function, but rather write a replacement function and then make
 18 * libpng use it at run time with png_set_read_fn(...).
 19 */
 20
 21#define PNG_INTERNAL
 22#define PNG_NO_PEDANTIC_WARNINGS
 23#include "png.h"
 24#ifdef PNG_READ_SUPPORTED
 25
 26/* Read the data from whatever input you are using.  The default routine
 27 * reads from a file pointer.  Note that this routine sometimes gets called
 28 * with very small lengths, so you should implement some kind of simple
 29 * buffering if you are using unbuffered reads.  This should never be asked
 30 * to read more then 64K on a 16 bit machine.
 31 */
 32void /* PRIVATE */
 33png_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
 34{
 35   png_debug1(4, "reading %d bytes", (int)length);
 36 
 37   if (png_ptr->read_data_fn != NULL)
 38      (*(png_ptr->read_data_fn))(png_ptr, data, length);
 39   else
 40      png_error(png_ptr, "Call to NULL read function");
 41
 42#ifdef PNG_INDEX_SUPPORTED
 43   png_ptr->total_data_read += length;
 44#endif
 45}
 46
 47#ifdef PNG_INDEX_SUPPORTED
 48void /* PRIVATE */
 49png_seek_data(png_structp png_ptr, png_uint_32 offset)
 50{
 51   if (png_ptr->seek_data_fn != NULL)
 52      (*(png_ptr->seek_data_fn))(png_ptr, offset);
 53   else
 54      png_error(png_ptr, "Call to NULL seek function");
 55}
 56#endif
 57
 58#ifdef PNG_STDIO_SUPPORTED
 59/* This is the function that does the actual reading of data.  If you are
 60 * not reading from a standard C stream, you should create a replacement
 61 * read_data function and use it at run time with png_set_read_fn(), rather
 62 * than changing the library.
 63 */
 64#ifndef USE_FAR_KEYWORD
 65void PNGAPI
 66png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
 67{
 68   png_size_t check;
 69
 70   if (png_ptr == NULL)
 71      return;
 72   /* fread() returns 0 on error, so it is OK to store this in a png_size_t
 73    * instead of an int, which is what fread() actually returns.
 74    */
 75#ifdef _WIN32_WCE
 76   if ( !ReadFile((HANDLE)(png_ptr->io_ptr), data, length, &check, NULL) )
 77      check = 0;
 78#else
 79   check = (png_size_t)fread(data, (png_size_t)1, length,
 80      (png_FILE_p)png_ptr->io_ptr);
 81#endif
 82
 83   if (check != length)
 84      png_error(png_ptr, "Read Error");
 85}
 86#else
 87/* This is the model-independent version. Since the standard I/O library
 88   can't handle far buffers in the medium and small models, we have to copy
 89   the data.
 90*/
 91
 92#define NEAR_BUF_SIZE 1024
 93#define MIN(a,b) (a <= b ? a : b)
 94
 95static void PNGAPI
 96png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
 97{
 98   int check;
 99   png_byte *n_data;
100   png_FILE_p io_ptr;
101
102   if (png_ptr == NULL)
103      return;
104   /* Check if data really is near. If so, use usual code. */
105   n_data = (png_byte *)CVT_PTR_NOCHECK(data);
106   io_ptr = (png_FILE_p)CVT_PTR(png_ptr->io_ptr);
107   if ((png_bytep)n_data == data)
108   {
109#ifdef _WIN32_WCE
110      if ( !ReadFile((HANDLE)(png_ptr->io_ptr), data, length, &check,
111          NULL) )
112         check = 0;
113#else
114      check = fread(n_data, 1, length, io_ptr);
115#endif
116   }
117   else
118   {
119      png_byte buf[NEAR_BUF_SIZE];
120      png_size_t read, remaining, err;
121      check = 0;
122      remaining = length;
123      do
124      {
125         read = MIN(NEAR_BUF_SIZE, remaining);
126#ifdef _WIN32_WCE
127         if ( !ReadFile((HANDLE)(io_ptr), buf, read, &err, NULL) )
128            err = 0;
129#else
130         err = fread(buf, (png_size_t)1, read, io_ptr);
131#endif
132         png_memcpy(data, buf, read); /* copy far buffer to near buffer */
133         if (err != read)
134            break;
135         else
136            check += err;
137         data += read;
138         remaining -= read;
139      }
140      while (remaining != 0);
141   }
142   if ((png_uint_32)check != (png_uint_32)length)
143      png_error(png_ptr, "read Error");
144}
145#endif
146#endif
147
148/* This function allows the application to supply a new input function
149 * for libpng if standard C streams aren't being used.
150 *
151 * This function takes as its arguments:
152 * png_ptr      - pointer to a png input data structure
153 * io_ptr       - pointer to user supplied structure containing info about
154 *                the input functions.  May be NULL.
155 * read_data_fn - pointer to a new input function that takes as its
156 *                arguments a pointer to a png_struct, a pointer to
157 *                a location where input data can be stored, and a 32-bit
158 *                unsigned int that is the number of bytes to be read.
159 *                To exit and output any fatal error messages the new write
160 *                function should call png_error(png_ptr, "Error msg").
161 *                May be NULL, in which case libpng's default function will
162 *                be used.
163 */
164void PNGAPI
165png_set_read_fn(png_structp png_ptr, png_voidp io_ptr,
166   png_rw_ptr read_data_fn)
167{
168   if (png_ptr == NULL)
169      return;
170   png_ptr->io_ptr = io_ptr;
171
172#ifdef PNG_STDIO_SUPPORTED
173   if (read_data_fn != NULL)
174      png_ptr->read_data_fn = read_data_fn;
175   else
176      png_ptr->read_data_fn = png_default_read_data;
177#else
178   png_ptr->read_data_fn = read_data_fn;
179#endif
180
181   /* It is an error to write to a read device */
182   if (png_ptr->write_data_fn != NULL)
183   {
184      png_ptr->write_data_fn = NULL;
185      png_warning(png_ptr,
186         "It's an error to set both read_data_fn and write_data_fn in the ");
187      png_warning(png_ptr,
188         "same structure.  Resetting write_data_fn to NULL.");
189   }
190
191#ifdef PNG_WRITE_FLUSH_SUPPORTED
192   png_ptr->output_flush_fn = NULL;
193#endif
194}
195
196#ifdef PNG_INDEX_SUPPORTED
197void PNGAPI
198png_set_seek_fn(png_structp png_ptr, png_seek_ptr seek_data_fn)
199{
200   if (png_ptr == NULL)
201      return;
202   png_ptr->seek_data_fn = seek_data_fn;
203}
204#endif
205#endif /* PNG_READ_SUPPORTED */