| /* 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(...). | |
| */ | |
| /* 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); | |
| else | |
| png_error(png_ptr, "Call to NULL write function"); | |
| } | |
| /* 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; | |
| if (png_ptr == NULL) | |
| return; | |
| check = fwrite(data, 1, length, (png_FILE_p)(png_ptr->io_ptr)); | |
| if (check != length) | |
| png_error(png_ptr, "Write Error"); | |
| } | |
| /* 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. | |
| */ | |
| void /* PRIVATE */ | |
| png_flush(png_structrp png_ptr) | |
| { | |
| if (png_ptr->output_flush_fn != NULL) | |
| (*(png_ptr->output_flush_fn))(png_ptr); | |
| } | |
| 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); | |
| } | |
| /* 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; | |
| if (write_data_fn != NULL) | |
| png_ptr->write_data_fn = write_data_fn; | |
| else | |
| png_ptr->write_data_fn = png_default_write_data; | |
| png_ptr->write_data_fn = write_data_fn; | |
| if (output_flush_fn != NULL) | |
| png_ptr->output_flush_fn = output_flush_fn; | |
| else | |
| png_ptr->output_flush_fn = png_default_flush; | |
| png_ptr->output_flush_fn = output_flush_fn; | |
| /* 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"); | |
| } | |
| } | |