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<html><head><title>dlib C++ Library - pngrio.c</title></head><body bgcolor='white'><pre> |
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<font color='#009900'>/* pngrio.c - functions for data input |
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* |
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* Last changed in libpng 1.6.0 [February 14, 2013] |
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* Copyright (c) 1998-2013 Glenn Randers-Pehrson |
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* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) |
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* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) |
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* |
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* This code is released under the libpng license. |
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* For conditions of distribution and use, see the disclaimer |
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* and license in png.h |
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* |
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* This file provides a location for all input. Users who need |
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* special handling are expected to write a function that has the same |
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* arguments as this and performs a similar function, but that possibly |
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* has a different input method. Note that you shouldn't change this |
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* function, but rather write a replacement function and then make |
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* libpng use it at run time with png_set_read_fn(...). |
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*/</font> |
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<font color='#0000FF'>#include</font> "<a style='text-decoration:none' href='pngpriv.h.html'>pngpriv.h</a>" |
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<font color='#0000FF'>#ifdef</font> PNG_READ_SUPPORTED |
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<font color='#009900'>/* Read the data from whatever input you are using. The default routine |
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* reads from a file pointer. Note that this routine sometimes gets called |
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* with very small lengths, so you should implement some kind of simple |
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* buffering if you are using unbuffered reads. This should never be asked |
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* to read more then 64K on a 16 bit machine. |
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*/</font> |
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<font color='#0000FF'><u>void</u></font> <font color='#009900'>/* PRIVATE */</font> |
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<b><a name='png_read_data'></a>png_read_data</b><font face='Lucida Console'>(</font>png_structrp png_ptr, png_bytep data, png_size_t length<font face='Lucida Console'>)</font> |
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<b>{</b> |
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<font color='#BB00BB'>png_debug1</font><font face='Lucida Console'>(</font><font color='#979000'>4</font>, "<font color='#CC0000'>reading %d bytes</font>", <font face='Lucida Console'>(</font><font color='#0000FF'><u>int</u></font><font face='Lucida Console'>)</font>length<font face='Lucida Console'>)</font>; |
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<font color='#0000FF'>if</font> <font face='Lucida Console'>(</font>png_ptr<font color='#5555FF'>-</font><font color='#5555FF'>></font>read_data_fn <font color='#5555FF'>!</font><font color='#5555FF'>=</font> NULL<font face='Lucida Console'>)</font> |
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<font face='Lucida Console'>(</font><font color='#5555FF'>*</font><font face='Lucida Console'>(</font>png_ptr<font color='#5555FF'>-</font><font color='#5555FF'>></font>read_data_fn<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font><font face='Lucida Console'>(</font>png_ptr, data, length<font face='Lucida Console'>)</font>; |
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<font color='#0000FF'>else</font> |
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<font color='#BB00BB'>png_error</font><font face='Lucida Console'>(</font>png_ptr, "<font color='#CC0000'>Call to NULL read function</font>"<font face='Lucida Console'>)</font>; |
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<b>}</b> |
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<font color='#0000FF'>#ifdef</font> PNG_STDIO_SUPPORTED |
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<font color='#009900'>/* This is the function that does the actual reading of data. If you are |
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* not reading from a standard C stream, you should create a replacement |
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* read_data function and use it at run time with png_set_read_fn(), rather |
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* than changing the library. |
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*/</font> |
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<font color='#0000FF'><u>void</u></font> PNGCBAPI |
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<b><a name='png_default_read_data'></a>png_default_read_data</b><font face='Lucida Console'>(</font>png_structp png_ptr, png_bytep data, png_size_t length<font face='Lucida Console'>)</font> |
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<b>{</b> |
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png_size_t check; |
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<font color='#0000FF'>if</font> <font face='Lucida Console'>(</font>png_ptr <font color='#5555FF'>=</font><font color='#5555FF'>=</font> NULL<font face='Lucida Console'>)</font> |
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<font color='#0000FF'>return</font>; |
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<font color='#009900'>/* fread() returns 0 on error, so it is OK to store this in a png_size_t |
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* instead of an int, which is what fread() actually returns. |
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*/</font> |
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check <font color='#5555FF'>=</font> <font color='#BB00BB'>fread</font><font face='Lucida Console'>(</font>data, <font color='#979000'>1</font>, length, <font color='#BB00BB'>png_voidcast</font><font face='Lucida Console'>(</font>png_FILE_p, png_ptr<font color='#5555FF'>-</font><font color='#5555FF'>></font>io_ptr<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font>; |
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<font color='#0000FF'>if</font> <font face='Lucida Console'>(</font>check <font color='#5555FF'>!</font><font color='#5555FF'>=</font> length<font face='Lucida Console'>)</font> |
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<font color='#BB00BB'>png_error</font><font face='Lucida Console'>(</font>png_ptr, "<font color='#CC0000'>Read Error</font>"<font face='Lucida Console'>)</font>; |
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<b>}</b> |
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<font color='#0000FF'>#endif</font> |
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<font color='#009900'>/* This function allows the application to supply a new input function |
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* for libpng if standard C streams aren't being used. |
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* |
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* This function takes as its arguments: |
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* |
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* png_ptr - pointer to a png input data structure |
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* |
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* io_ptr - pointer to user supplied structure containing info about |
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* the input functions. May be NULL. |
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* |
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* read_data_fn - pointer to a new input function that takes as its |
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* arguments a pointer to a png_struct, a pointer to |
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* a location where input data can be stored, and a 32-bit |
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* unsigned int that is the number of bytes to be read. |
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* To exit and output any fatal error messages the new write |
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* function should call png_error(png_ptr, "Error msg"). |
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* May be NULL, in which case libpng's default function will |
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* be used. |
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*/</font> |
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<font color='#0000FF'><u>void</u></font> PNGAPI |
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<b><a name='png_set_read_fn'></a>png_set_read_fn</b><font face='Lucida Console'>(</font>png_structrp png_ptr, png_voidp io_ptr, |
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png_rw_ptr read_data_fn<font face='Lucida Console'>)</font> |
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<b>{</b> |
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<font color='#0000FF'>if</font> <font face='Lucida Console'>(</font>png_ptr <font color='#5555FF'>=</font><font color='#5555FF'>=</font> NULL<font face='Lucida Console'>)</font> |
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<font color='#0000FF'>return</font>; |
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png_ptr<font color='#5555FF'>-</font><font color='#5555FF'>></font>io_ptr <font color='#5555FF'>=</font> io_ptr; |
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<font color='#0000FF'>#ifdef</font> PNG_STDIO_SUPPORTED |
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<font color='#0000FF'>if</font> <font face='Lucida Console'>(</font>read_data_fn <font color='#5555FF'>!</font><font color='#5555FF'>=</font> NULL<font face='Lucida Console'>)</font> |
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png_ptr<font color='#5555FF'>-</font><font color='#5555FF'>></font>read_data_fn <font color='#5555FF'>=</font> read_data_fn; |
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<font color='#0000FF'>else</font> |
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png_ptr<font color='#5555FF'>-</font><font color='#5555FF'>></font>read_data_fn <font color='#5555FF'>=</font> png_default_read_data; |
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<font color='#0000FF'>#else</font> |
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png_ptr<font color='#5555FF'>-</font><font color='#5555FF'>></font>read_data_fn <font color='#5555FF'>=</font> read_data_fn; |
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<font color='#0000FF'>#endif</font> |
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<font color='#009900'>/* It is an error to write to a read device */</font> |
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<font color='#0000FF'>if</font> <font face='Lucida Console'>(</font>png_ptr<font color='#5555FF'>-</font><font color='#5555FF'>></font>write_data_fn <font color='#5555FF'>!</font><font color='#5555FF'>=</font> NULL<font face='Lucida Console'>)</font> |
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<b>{</b> |
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png_ptr<font color='#5555FF'>-</font><font color='#5555FF'>></font>write_data_fn <font color='#5555FF'>=</font> NULL; |
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<font color='#BB00BB'>png_warning</font><font face='Lucida Console'>(</font>png_ptr, |
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"<font color='#CC0000'>Can't set both read_data_fn and write_data_fn in the</font>" |
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"<font color='#CC0000'> same structure</font>"<font face='Lucida Console'>)</font>; |
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<b>}</b> |
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<font color='#0000FF'>#ifdef</font> PNG_WRITE_FLUSH_SUPPORTED |
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png_ptr<font color='#5555FF'>-</font><font color='#5555FF'>></font>output_flush_fn <font color='#5555FF'>=</font> NULL; |
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<font color='#0000FF'>#endif</font> |
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<b>}</b> |
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<font color='#0000FF'>#endif</font> <font color='#009900'>/* PNG_READ_SUPPORTED */</font> |
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</pre></body></html> |
