| |
| /* pngwio.c - functions for data output |
| * |
| * libpng 1.00 |
| * For conditions of distribution and use, see copyright notice in png.h |
| * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc. |
| * Copyright (c) 1996, 1997 Andreas Dilger |
| * Copyright (c) 1998, Glenn Randers-Pehrson |
| * March 7, 1998 |
| * |
| * This file provides a location for all output. Users which need |
| * special handling are expected to write functions which have the same |
| * arguments as these, and perform similar functions, but 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(...). |
| */ |
| |
| #define PNG_INTERNAL |
| #include "png.h" |
| |
| /* 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 then 64K on a 16 bit machine. */ |
| |
| void |
| png_write_data(png_structp png_ptr, png_bytep data, png_size_t length) |
| { |
| if (png_ptr->write_data_fn != NULL ) |
| (*(png_ptr->write_data_fn))(png_ptr, data, length); |
| else |
| png_error(png_ptr, "Call to NULL write function"); |
| } |
| |
| #if !defined(PNG_NO_STDIO) |
| /* This is the function which 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. */ |
| #ifndef USE_FAR_KEYWORD |
| static void |
| png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length) |
| { |
| png_uint_32 check; |
| |
| check = fwrite(data, 1, length, (FILE *)(png_ptr->io_ptr)); |
| if (check != length) |
| { |
| png_error(png_ptr, "Write Error"); |
| } |
| } |
| #else |
| /* this is the model-independent version. Since the standard I/O library |
| can't handle far buffers in the medium and small models, we have to copy |
| the data. |
| */ |
| |
| #define NEAR_BUF_SIZE 1024 |
| #define MIN(a,b) (a <= b ? a : b) |
| |
| static void |
| png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length) |
| { |
| png_uint_32 check; |
| png_byte *near_data; /* Needs to be "png_byte *" instead of "png_bytep" */ |
| FILE *io_ptr; |
| |
| /* Check if data really is near. If so, use usual code. */ |
| near_data = (png_byte *)CVT_PTR_NOCHECK(data); |
| io_ptr = (FILE *)CVT_PTR(png_ptr->io_ptr); |
| if ((png_bytep)near_data == data) |
| { |
| check = fwrite(near_data, 1, length, io_ptr); |
| } |
| else |
| { |
| png_byte buf[NEAR_BUF_SIZE]; |
| png_size_t written, remaining, err; |
| check = 0; |
| remaining = length; |
| do |
| { |
| written = MIN(NEAR_BUF_SIZE, remaining); |
| png_memcpy(buf, data, written); /* copy far buffer to near buffer */ |
| err = fwrite(buf, 1, written, io_ptr); |
| if (err != written) |
| break; |
| else |
| check += err; |
| data += written; |
| remaining -= written; |
| } |
| while (remaining != 0); |
| } |
| if (check != length) |
| { |
| png_error(png_ptr, "Write Error"); |
| } |
| } |
| |
| #endif |
| #endif |
| |
| /* 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. */ |
| #if defined(PNG_WRITE_FLUSH_SUPPORTED) |
| void |
| png_flush(png_structp png_ptr) |
| { |
| if (png_ptr->output_flush_fn != NULL) |
| (*(png_ptr->output_flush_fn))(png_ptr); |
| } |
| |
| #if !defined(PNG_NO_STDIO) |
| static void |
| png_default_flush(png_structp png_ptr) |
| { |
| FILE *io_ptr; |
| io_ptr = (FILE *)CVT_PTR((png_ptr->io_ptr)); |
| if (io_ptr != NULL) |
| 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 which takes as its |
| arguments a pointer to a png_struct, a pointer to |
| data to be written, and a 32-bit unsigned int which 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. |
| flush_data_fn - pointer to a new flush function which 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 ouput, 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. */ |
| void |
| png_set_write_fn(png_structp png_ptr, png_voidp io_ptr, |
| png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn) |
| { |
| png_ptr->io_ptr = io_ptr; |
| |
| #if !defined(PNG_NO_STDIO) |
| 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 |
| |
| #if defined(PNG_WRITE_FLUSH_SUPPORTED) |
| #if !defined(PNG_NO_STDIO) |
| if (output_flush_fn != NULL) |
| png_ptr->output_flush_fn = output_flush_fn; |
| else |
| png_ptr->output_flush_fn = png_default_flush; |
| #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 */ |
| png_ptr->read_data_fn = NULL; |
| } |
| |
| #if defined(USE_FAR_KEYWORD) |
| #if defined(_MSC_VER) |
| void *png_far_to_near(png_structp png_ptr,png_voidp ptr, int check) |
| { |
| void *near_ptr; |
| void FAR *far_ptr; |
| FP_OFF(near_ptr) = FP_OFF(ptr); |
| far_ptr = (void FAR *)near_ptr; |
| if(check != 0) |
| if(FP_SEG(ptr) != FP_SEG(far_ptr)) |
| png_error(png_ptr,"segment lost in conversion"); |
| return(near_ptr); |
| } |
| # else |
| void *png_far_to_near(png_structp png_ptr,png_voidp ptr, int check) |
| { |
| void *near_ptr; |
| void FAR *far_ptr; |
| near_ptr = (void FAR *)ptr; |
| far_ptr = (void FAR *)near_ptr; |
| if(check != 0) |
| if(far_ptr != ptr) |
| png_error(png_ptr,"segment lost in conversion"); |
| return(near_ptr); |
| } |
| # endif |
| # endif |