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Diffstat (limited to 'pngwio.c')
| -rw-r--r-- | pngwio.c | 234 |
1 files changed, 234 insertions, 0 deletions
diff --git a/pngwio.c b/pngwio.c new file mode 100644 index 0000000..371a4fa --- /dev/null +++ b/pngwio.c @@ -0,0 +1,234 @@ + +/* pngwio.c - functions for data output + * + * Last changed in libpng 1.2.13 November 13, 2006 + * For conditions of distribution and use, see copyright notice in png.h + * Copyright (c) 1998-2006 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 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(...). + */ + +#define PNG_INTERNAL +#include "png.h" +#ifdef PNG_WRITE_SUPPORTED + +/* 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_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 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. */ +#ifndef USE_FAR_KEYWORD +void PNGAPI +png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length) +{ + png_uint_32 check; + + if(png_ptr == NULL) return; +#if defined(_WIN32_WCE) + if ( !WriteFile((HANDLE)(png_ptr->io_ptr), data, length, &check, NULL) ) + check = 0; +#else + check = fwrite(data, 1, length, (png_FILE_p)(png_ptr->io_ptr)); +#endif + 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) + +void PNGAPI +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" */ + png_FILE_p io_ptr; + + if(png_ptr == NULL) return; + /* Check if data really is near. If so, use usual code. */ + near_data = (png_byte *)CVT_PTR_NOCHECK(data); + io_ptr = (png_FILE_p)CVT_PTR(png_ptr->io_ptr); + if ((png_bytep)near_data == data) + { +#if defined(_WIN32_WCE) + if ( !WriteFile(io_ptr, near_data, length, &check, NULL) ) + check = 0; +#else + check = fwrite(near_data, 1, length, io_ptr); +#endif + } + 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 */ +#if defined(_WIN32_WCE) + if ( !WriteFile(io_ptr, buf, written, &err, NULL) ) + err = 0; +#else + err = fwrite(buf, 1, written, io_ptr); +#endif + 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 /* PRIVATE */ +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) +void PNGAPI +png_default_flush(png_structp png_ptr) +{ +#if !defined(_WIN32_WCE) + png_FILE_p io_ptr; +#endif + if(png_ptr == NULL) return; +#if !defined(_WIN32_WCE) + io_ptr = (png_FILE_p)CVT_PTR((png_ptr->io_ptr)); + if (io_ptr != NULL) + fflush(io_ptr); +#endif +} +#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. + 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 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 PNGAPI +png_set_write_fn(png_structp 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 !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 */ + if (png_ptr->read_data_fn != NULL) + { + png_ptr->read_data_fn = NULL; + png_warning(png_ptr, + "Attempted to set both read_data_fn and write_data_fn in"); + png_warning(png_ptr, + "the same structure. Resetting read_data_fn to 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 +#endif /* PNG_WRITE_SUPPORTED */ |