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annotate libs/libpng/pngrio.c @ 20:2b85d05df3f2

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animation controls for easier screenshot grabbing
author John Tsiombikas <nuclear@member.fsf.org>
date Fri, 02 Oct 2015 04:54:55 +0300
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nuclear@2 1
nuclear@2 2 /* pngrio.c - functions for data input
nuclear@2 3 *
nuclear@2 4 * Last changed in libpng 1.2.30 [August 15, 2008]
nuclear@2 5 * For conditions of distribution and use, see copyright notice in png.h
nuclear@2 6 * Copyright (c) 1998-2008 Glenn Randers-Pehrson
nuclear@2 7 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
nuclear@2 8 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
nuclear@2 9 *
nuclear@2 10 * This file provides a location for all input. Users who need
nuclear@2 11 * special handling are expected to write a function that has the same
nuclear@2 12 * arguments as this and performs a similar function, but that possibly
nuclear@2 13 * has a different input method. Note that you shouldn't change this
nuclear@2 14 * function, but rather write a replacement function and then make
nuclear@2 15 * libpng use it at run time with png_set_read_fn(...).
nuclear@2 16 */
nuclear@2 17
nuclear@2 18 #define PNG_INTERNAL
nuclear@2 19 #include "png.h"
nuclear@2 20 #if defined(PNG_READ_SUPPORTED)
nuclear@2 21
nuclear@2 22 /* Read the data from whatever input you are using. The default routine
nuclear@2 23 reads from a file pointer. Note that this routine sometimes gets called
nuclear@2 24 with very small lengths, so you should implement some kind of simple
nuclear@2 25 buffering if you are using unbuffered reads. This should never be asked
nuclear@2 26 to read more then 64K on a 16 bit machine. */
nuclear@2 27 void /* PRIVATE */
nuclear@2 28 png_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
nuclear@2 29 {
nuclear@2 30 png_debug1(4, "reading %d bytes\n", (int)length);
nuclear@2 31 if (png_ptr->read_data_fn != NULL)
nuclear@2 32 (*(png_ptr->read_data_fn))(png_ptr, data, length);
nuclear@2 33 else
nuclear@2 34 png_error(png_ptr, "Call to NULL read function");
nuclear@2 35 }
nuclear@2 36
nuclear@2 37 #if !defined(PNG_NO_STDIO)
nuclear@2 38 /* This is the function that does the actual reading of data. If you are
nuclear@2 39 not reading from a standard C stream, you should create a replacement
nuclear@2 40 read_data function and use it at run time with png_set_read_fn(), rather
nuclear@2 41 than changing the library. */
nuclear@2 42 #ifndef USE_FAR_KEYWORD
nuclear@2 43 void PNGAPI
nuclear@2 44 png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
nuclear@2 45 {
nuclear@2 46 png_size_t check;
nuclear@2 47
nuclear@2 48 if (png_ptr == NULL) return;
nuclear@2 49 /* fread() returns 0 on error, so it is OK to store this in a png_size_t
nuclear@2 50 * instead of an int, which is what fread() actually returns.
nuclear@2 51 */
nuclear@2 52 #if defined(_WIN32_WCE)
nuclear@2 53 if ( !ReadFile((HANDLE)(png_ptr->io_ptr), data, length, &check, NULL) )
nuclear@2 54 check = 0;
nuclear@2 55 #else
nuclear@2 56 check = (png_size_t)fread(data, (png_size_t)1, length,
nuclear@2 57 (png_FILE_p)png_ptr->io_ptr);
nuclear@2 58 #endif
nuclear@2 59
nuclear@2 60 if (check != length)
nuclear@2 61 png_error(png_ptr, "Read Error");
nuclear@2 62 }
nuclear@2 63 #else
nuclear@2 64 /* this is the model-independent version. Since the standard I/O library
nuclear@2 65 can't handle far buffers in the medium and small models, we have to copy
nuclear@2 66 the data.
nuclear@2 67 */
nuclear@2 68
nuclear@2 69 #define NEAR_BUF_SIZE 1024
nuclear@2 70 #define MIN(a,b) (a <= b ? a : b)
nuclear@2 71
nuclear@2 72 static void PNGAPI
nuclear@2 73 png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
nuclear@2 74 {
nuclear@2 75 int check;
nuclear@2 76 png_byte *n_data;
nuclear@2 77 png_FILE_p io_ptr;
nuclear@2 78
nuclear@2 79 if (png_ptr == NULL) return;
nuclear@2 80 /* Check if data really is near. If so, use usual code. */
nuclear@2 81 n_data = (png_byte *)CVT_PTR_NOCHECK(data);
nuclear@2 82 io_ptr = (png_FILE_p)CVT_PTR(png_ptr->io_ptr);
nuclear@2 83 if ((png_bytep)n_data == data)
nuclear@2 84 {
nuclear@2 85 #if defined(_WIN32_WCE)
nuclear@2 86 if ( !ReadFile((HANDLE)(png_ptr->io_ptr), data, length, &check, NULL) )
nuclear@2 87 check = 0;
nuclear@2 88 #else
nuclear@2 89 check = fread(n_data, 1, length, io_ptr);
nuclear@2 90 #endif
nuclear@2 91 }
nuclear@2 92 else
nuclear@2 93 {
nuclear@2 94 png_byte buf[NEAR_BUF_SIZE];
nuclear@2 95 png_size_t read, remaining, err;
nuclear@2 96 check = 0;
nuclear@2 97 remaining = length;
nuclear@2 98 do
nuclear@2 99 {
nuclear@2 100 read = MIN(NEAR_BUF_SIZE, remaining);
nuclear@2 101 #if defined(_WIN32_WCE)
nuclear@2 102 if ( !ReadFile((HANDLE)(io_ptr), buf, read, &err, NULL) )
nuclear@2 103 err = 0;
nuclear@2 104 #else
nuclear@2 105 err = fread(buf, (png_size_t)1, read, io_ptr);
nuclear@2 106 #endif
nuclear@2 107 png_memcpy(data, buf, read); /* copy far buffer to near buffer */
nuclear@2 108 if (err != read)
nuclear@2 109 break;
nuclear@2 110 else
nuclear@2 111 check += err;
nuclear@2 112 data += read;
nuclear@2 113 remaining -= read;
nuclear@2 114 }
nuclear@2 115 while (remaining != 0);
nuclear@2 116 }
nuclear@2 117 if ((png_uint_32)check != (png_uint_32)length)
nuclear@2 118 png_error(png_ptr, "read Error");
nuclear@2 119 }
nuclear@2 120 #endif
nuclear@2 121 #endif
nuclear@2 122
nuclear@2 123 /* This function allows the application to supply a new input function
nuclear@2 124 for libpng if standard C streams aren't being used.
nuclear@2 125
nuclear@2 126 This function takes as its arguments:
nuclear@2 127 png_ptr - pointer to a png input data structure
nuclear@2 128 io_ptr - pointer to user supplied structure containing info about
nuclear@2 129 the input functions. May be NULL.
nuclear@2 130 read_data_fn - pointer to a new input function that takes as its
nuclear@2 131 arguments a pointer to a png_struct, a pointer to
nuclear@2 132 a location where input data can be stored, and a 32-bit
nuclear@2 133 unsigned int that is the number of bytes to be read.
nuclear@2 134 To exit and output any fatal error messages the new write
nuclear@2 135 function should call png_error(png_ptr, "Error msg"). */
nuclear@2 136 void PNGAPI
nuclear@2 137 png_set_read_fn(png_structp png_ptr, png_voidp io_ptr,
nuclear@2 138 png_rw_ptr read_data_fn)
nuclear@2 139 {
nuclear@2 140 if (png_ptr == NULL) return;
nuclear@2 141 png_ptr->io_ptr = io_ptr;
nuclear@2 142
nuclear@2 143 #if !defined(PNG_NO_STDIO)
nuclear@2 144 if (read_data_fn != NULL)
nuclear@2 145 png_ptr->read_data_fn = read_data_fn;
nuclear@2 146 else
nuclear@2 147 png_ptr->read_data_fn = png_default_read_data;
nuclear@2 148 #else
nuclear@2 149 png_ptr->read_data_fn = read_data_fn;
nuclear@2 150 #endif
nuclear@2 151
nuclear@2 152 /* It is an error to write to a read device */
nuclear@2 153 if (png_ptr->write_data_fn != NULL)
nuclear@2 154 {
nuclear@2 155 png_ptr->write_data_fn = NULL;
nuclear@2 156 png_warning(png_ptr,
nuclear@2 157 "It's an error to set both read_data_fn and write_data_fn in the ");
nuclear@2 158 png_warning(png_ptr,
nuclear@2 159 "same structure. Resetting write_data_fn to NULL.");
nuclear@2 160 }
nuclear@2 161
nuclear@2 162 #if defined(PNG_WRITE_FLUSH_SUPPORTED)
nuclear@2 163 png_ptr->output_flush_fn = NULL;
nuclear@2 164 #endif
nuclear@2 165 }
nuclear@2 166 #endif /* PNG_READ_SUPPORTED */