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annotate libs/libjpeg/jdatadst.c @ 30:8dd271942543

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fixed everything
author John Tsiombikas <nuclear@mutantstargoat.com>
date Thu, 08 Sep 2011 14:52:13 +0300
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nuclear@26 1 /*
nuclear@26 2 * jdatadst.c
nuclear@26 3 *
nuclear@26 4 * Copyright (C) 1994-1996, Thomas G. Lane.
nuclear@26 5 * This file is part of the Independent JPEG Group's software.
nuclear@26 6 * For conditions of distribution and use, see the accompanying README file.
nuclear@26 7 *
nuclear@26 8 * This file contains compression data destination routines for the case of
nuclear@26 9 * emitting JPEG data to a file (or any stdio stream). While these routines
nuclear@26 10 * are sufficient for most applications, some will want to use a different
nuclear@26 11 * destination manager.
nuclear@26 12 * IMPORTANT: we assume that fwrite() will correctly transcribe an array of
nuclear@26 13 * JOCTETs into 8-bit-wide elements on external storage. If char is wider
nuclear@26 14 * than 8 bits on your machine, you may need to do some tweaking.
nuclear@26 15 */
nuclear@26 16
nuclear@26 17 /* this is not a core library module, so it doesn't define JPEG_INTERNALS */
nuclear@26 18 #include "jinclude.h"
nuclear@26 19 #include "jpeglib.h"
nuclear@26 20 #include "jerror.h"
nuclear@26 21
nuclear@26 22
nuclear@26 23 /* Expanded data destination object for stdio output */
nuclear@26 24
nuclear@26 25 typedef struct {
nuclear@26 26 struct jpeg_destination_mgr pub; /* public fields */
nuclear@26 27
nuclear@26 28 FILE * outfile; /* target stream */
nuclear@26 29 JOCTET * buffer; /* start of buffer */
nuclear@26 30 } my_destination_mgr;
nuclear@26 31
nuclear@26 32 typedef my_destination_mgr * my_dest_ptr;
nuclear@26 33
nuclear@26 34 #define OUTPUT_BUF_SIZE 4096 /* choose an efficiently fwrite'able size */
nuclear@26 35
nuclear@26 36
nuclear@26 37 /*
nuclear@26 38 * Initialize destination --- called by jpeg_start_compress
nuclear@26 39 * before any data is actually written.
nuclear@26 40 */
nuclear@26 41
nuclear@26 42 METHODDEF(void)
nuclear@26 43 init_destination (j_compress_ptr cinfo)
nuclear@26 44 {
nuclear@26 45 my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
nuclear@26 46
nuclear@26 47 /* Allocate the output buffer --- it will be released when done with image */
nuclear@26 48 dest->buffer = (JOCTET *)
nuclear@26 49 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@26 50 OUTPUT_BUF_SIZE * SIZEOF(JOCTET));
nuclear@26 51
nuclear@26 52 dest->pub.next_output_byte = dest->buffer;
nuclear@26 53 dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
nuclear@26 54 }
nuclear@26 55
nuclear@26 56
nuclear@26 57 /*
nuclear@26 58 * Empty the output buffer --- called whenever buffer fills up.
nuclear@26 59 *
nuclear@26 60 * In typical applications, this should write the entire output buffer
nuclear@26 61 * (ignoring the current state of next_output_byte & free_in_buffer),
nuclear@26 62 * reset the pointer & count to the start of the buffer, and return TRUE
nuclear@26 63 * indicating that the buffer has been dumped.
nuclear@26 64 *
nuclear@26 65 * In applications that need to be able to suspend compression due to output
nuclear@26 66 * overrun, a FALSE return indicates that the buffer cannot be emptied now.
nuclear@26 67 * In this situation, the compressor will return to its caller (possibly with
nuclear@26 68 * an indication that it has not accepted all the supplied scanlines). The
nuclear@26 69 * application should resume compression after it has made more room in the
nuclear@26 70 * output buffer. Note that there are substantial restrictions on the use of
nuclear@26 71 * suspension --- see the documentation.
nuclear@26 72 *
nuclear@26 73 * When suspending, the compressor will back up to a convenient restart point
nuclear@26 74 * (typically the start of the current MCU). next_output_byte & free_in_buffer
nuclear@26 75 * indicate where the restart point will be if the current call returns FALSE.
nuclear@26 76 * Data beyond this point will be regenerated after resumption, so do not
nuclear@26 77 * write it out when emptying the buffer externally.
nuclear@26 78 */
nuclear@26 79
nuclear@26 80 METHODDEF(boolean)
nuclear@26 81 empty_output_buffer (j_compress_ptr cinfo)
nuclear@26 82 {
nuclear@26 83 my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
nuclear@26 84
nuclear@26 85 if (JFWRITE(dest->outfile, dest->buffer, OUTPUT_BUF_SIZE) !=
nuclear@26 86 (size_t) OUTPUT_BUF_SIZE)
nuclear@26 87 ERREXIT(cinfo, JERR_FILE_WRITE);
nuclear@26 88
nuclear@26 89 dest->pub.next_output_byte = dest->buffer;
nuclear@26 90 dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
nuclear@26 91
nuclear@26 92 return TRUE;
nuclear@26 93 }
nuclear@26 94
nuclear@26 95
nuclear@26 96 /*
nuclear@26 97 * Terminate destination --- called by jpeg_finish_compress
nuclear@26 98 * after all data has been written. Usually needs to flush buffer.
nuclear@26 99 *
nuclear@26 100 * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
nuclear@26 101 * application must deal with any cleanup that should happen even
nuclear@26 102 * for error exit.
nuclear@26 103 */
nuclear@26 104
nuclear@26 105 METHODDEF(void)
nuclear@26 106 term_destination (j_compress_ptr cinfo)
nuclear@26 107 {
nuclear@26 108 my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
nuclear@26 109 size_t datacount = OUTPUT_BUF_SIZE - dest->pub.free_in_buffer;
nuclear@26 110
nuclear@26 111 /* Write any data remaining in the buffer */
nuclear@26 112 if (datacount > 0) {
nuclear@26 113 if (JFWRITE(dest->outfile, dest->buffer, datacount) != datacount)
nuclear@26 114 ERREXIT(cinfo, JERR_FILE_WRITE);
nuclear@26 115 }
nuclear@26 116 fflush(dest->outfile);
nuclear@26 117 /* Make sure we wrote the output file OK */
nuclear@26 118 if (ferror(dest->outfile))
nuclear@26 119 ERREXIT(cinfo, JERR_FILE_WRITE);
nuclear@26 120 }
nuclear@26 121
nuclear@26 122
nuclear@26 123 /*
nuclear@26 124 * Prepare for output to a stdio stream.
nuclear@26 125 * The caller must have already opened the stream, and is responsible
nuclear@26 126 * for closing it after finishing compression.
nuclear@26 127 */
nuclear@26 128
nuclear@26 129 GLOBAL(void)
nuclear@26 130 jpeg_stdio_dest (j_compress_ptr cinfo, FILE * outfile)
nuclear@26 131 {
nuclear@26 132 my_dest_ptr dest;
nuclear@26 133
nuclear@26 134 /* The destination object is made permanent so that multiple JPEG images
nuclear@26 135 * can be written to the same file without re-executing jpeg_stdio_dest.
nuclear@26 136 * This makes it dangerous to use this manager and a different destination
nuclear@26 137 * manager serially with the same JPEG object, because their private object
nuclear@26 138 * sizes may be different. Caveat programmer.
nuclear@26 139 */
nuclear@26 140 if (cinfo->dest == NULL) { /* first time for this JPEG object? */
nuclear@26 141 cinfo->dest = (struct jpeg_destination_mgr *)
nuclear@26 142 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
nuclear@26 143 SIZEOF(my_destination_mgr));
nuclear@26 144 }
nuclear@26 145
nuclear@26 146 dest = (my_dest_ptr) cinfo->dest;
nuclear@26 147 dest->pub.init_destination = init_destination;
nuclear@26 148 dest->pub.empty_output_buffer = empty_output_buffer;
nuclear@26 149 dest->pub.term_destination = term_destination;
nuclear@26 150 dest->outfile = outfile;
nuclear@26 151 }