0,0 → 1,164 |
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/* pngwio.c - functions for data output |
* |
* Last changed in libpng 1.6.0 [February 14, 2013] |
* Copyright (c) 1998-2013 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(...). |
*/ |
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#include "pngpriv.h" |
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#ifdef PNG_WRITE_SUPPORTED |
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/* 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); |
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else |
png_error(png_ptr, "Call to NULL write function"); |
} |
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#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; |
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if (png_ptr == NULL) |
return; |
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check = fwrite(data, 1, length, (png_FILE_p)(png_ptr->io_ptr)); |
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if (check != length) |
png_error(png_ptr, "Write Error"); |
} |
#endif |
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/* 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; |
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#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; |
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else |
png_ptr->output_flush_fn = png_default_flush; |
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# else |
png_ptr->output_flush_fn = output_flush_fn; |
# endif |
#endif /* PNG_WRITE_FLUSH_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 /* PNG_WRITE_SUPPORTED */ |