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<h1>jpegSize.cpp</h1><a href="jpegSize_8cpp.html">Go to the documentation of this file.</a><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="preprocessor">#include "<a class="code" href="jpegSize_8h.html">jpegSize.h</a>"</span>
<a name="l00002"></a>00002
<a name="l00003"></a>00003 <span class="preprocessor">#include <stdio.h></span>
<a name="l00004"></a>00004
<a name="l00005"></a>00005 <span class="comment">/*</span>
<a name="l00006"></a>00006 <span class="comment"> Most of the code that follows was adapted from IJG's rdjpgcom.c file.</span>
<a name="l00007"></a>00007 <span class="comment"> </span>
<a name="l00008"></a>00008 <span class="comment"> * Copyright (C) 1994-1997, Thomas G. Lane.</span>
<a name="l00009"></a>00009 <span class="comment"> * This file is part of the Independent JPEG Group's software.</span>
<a name="l00010"></a>00010 <span class="comment"> *</span>
<a name="l00011"></a>00011 <span class="comment"> * This file contains a very simple stand-alone application that displays</span>
<a name="l00012"></a>00012 <span class="comment"> * the text in COM (comment) markers in a JFIF file.</span>
<a name="l00013"></a>00013 <span class="comment"> * This may be useful as an example of the minimum logic needed to parse</span>
<a name="l00014"></a>00014 <span class="comment"> * JPEG markers.</span>
<a name="l00015"></a>00015 <span class="comment"> */</span>
<a name="l00016"></a>00016
<a name="l00017"></a>00017 <span class="comment">/* Return next input byte, or EOF if no more */</span>
<a name="l00018"></a><a class="code" href="jpegSize_8cpp.html#79d8075203f66de43561298655e7066a">00018</a> <span class="preprocessor">#define NEXTBYTE() getc(infile)</span>
<a name="l00019"></a>00019 <span class="preprocessor"></span>
<a name="l00020"></a>00020 <span class="comment">/*</span>
<a name="l00021"></a>00021 <span class="comment"> * JPEG markers consist of one or more 0xFF bytes, followed by a marker</span>
<a name="l00022"></a>00022 <span class="comment"> * code byte (which is not an FF). Here are the marker codes of interest</span>
<a name="l00023"></a>00023 <span class="comment"> * in this program. (See jdmarker.c for a more complete list.)</span>
<a name="l00024"></a>00024 <span class="comment"> */</span>
<a name="l00025"></a>00025
<a name="l00026"></a><a class="code" href="jpegSize_8cpp.html#e747795c32cea1314b49e9b7d65be454">00026</a> <span class="preprocessor">#define M_SOF0 0xC0 </span><span class="comment">/* Start Of Frame N */</span>
<a name="l00027"></a><a class="code" href="jpegSize_8cpp.html#b58d501dd163fdd0dee4ba6907e191a0">00027</a> <span class="preprocessor">#define M_SOF1 0xC1 </span><span class="comment">/* N indicates which compression process */</span>
<a name="l00028"></a><a class="code" href="jpegSize_8cpp.html#eeeb620f261aa6b63448de940c7a7714">00028</a> <span class="preprocessor">#define M_SOF2 0xC2 </span><span class="comment">/* Only SOF0-SOF2 are now in common use */</span>
<a name="l00029"></a><a class="code" href="jpegSize_8cpp.html#7f09d1c601661800967c5d7e447d5a1f">00029</a> <span class="preprocessor">#define M_SOF3 0xC3</span>
<a name="l00030"></a><a class="code" href="jpegSize_8cpp.html#ce7276c4a30808cd6fe74abda2f16ad6">00030</a> <span class="preprocessor"></span><span class="preprocessor">#define M_SOF5 0xC5 </span><span class="comment">/* NB: codes C4 and CC are NOT SOF markers */</span>
<a name="l00031"></a><a class="code" href="jpegSize_8cpp.html#3f5a3446a533760babdfd4d0f775e97c">00031</a> <span class="preprocessor">#define M_SOF6 0xC6</span>
<a name="l00032"></a><a class="code" href="jpegSize_8cpp.html#3805e83e6b1e8f52a78f1b6cb0668133">00032</a> <span class="preprocessor"></span><span class="preprocessor">#define M_SOF7 0xC7</span>
<a name="l00033"></a><a class="code" href="jpegSize_8cpp.html#5a510cc3009a14911acbbe7ddb378776">00033</a> <span class="preprocessor"></span><span class="preprocessor">#define M_SOF9 0xC9</span>
<a name="l00034"></a><a class="code" href="jpegSize_8cpp.html#a718681ce1acfa7622ad9776404cfa98">00034</a> <span class="preprocessor"></span><span class="preprocessor">#define M_SOF10 0xCA</span>
<a name="l00035"></a><a class="code" href="jpegSize_8cpp.html#51ac607f59c2730811fd514561770966">00035</a> <span class="preprocessor"></span><span class="preprocessor">#define M_SOF11 0xCB</span>
<a name="l00036"></a><a class="code" href="jpegSize_8cpp.html#8ba4457ac8573d317b4562303197c72e">00036</a> <span class="preprocessor"></span><span class="preprocessor">#define M_SOF13 0xCD</span>
<a name="l00037"></a><a class="code" href="jpegSize_8cpp.html#e3a73495aaced1aacd8577dac2dbe22e">00037</a> <span class="preprocessor"></span><span class="preprocessor">#define M_SOF14 0xCE</span>
<a name="l00038"></a><a class="code" href="jpegSize_8cpp.html#6e4ec1d092fa9aaaa3a8a18aa1ee4381">00038</a> <span class="preprocessor"></span><span class="preprocessor">#define M_SOF15 0xCF</span>
<a name="l00039"></a><a class="code" href="jpegSize_8cpp.html#ce3e2c7b5e5b844c165f813bb68a3d37">00039</a> <span class="preprocessor"></span><span class="preprocessor">#define M_SOI 0xD8 </span><span class="comment">/* Start Of Image (beginning of datastream) */</span>
<a name="l00040"></a><a class="code" href="jpegSize_8cpp.html#43056e27046e8d6327320714a5a0b0f0">00040</a> <span class="preprocessor">#define M_EOI 0xD9 </span><span class="comment">/* End Of Image (end of datastream) */</span>
<a name="l00041"></a><a class="code" href="jpegSize_8cpp.html#f5fdac2a556ee915b65b295faff22ead">00041</a> <span class="preprocessor">#define M_SOS 0xDA </span><span class="comment">/* Start Of Scan (begins compressed data) */</span>
<a name="l00042"></a><a class="code" href="jpegSize_8cpp.html#d451ca014ccbfa47701a7d4bebace89a">00042</a> <span class="preprocessor">#define M_APP0 0xE0 </span><span class="comment">/* Application-specific marker, type N */</span>
<a name="l00043"></a><a class="code" href="jpegSize_8cpp.html#8f9c892cd81b369ded8e70dc9363043b">00043</a> <span class="preprocessor">#define M_APP12 0xEC </span><span class="comment">/* (we don't bother to list all 16 APPn's) */</span>
<a name="l00044"></a><a class="code" href="jpegSize_8cpp.html#ee6946f4084da1cf5c9bc225b072c3e5">00044</a> <span class="preprocessor">#define M_COM 0xFE </span><span class="comment">/* COMment */</span>
<a name="l00045"></a>00045
<a name="l00046"></a>00046 <span class="preprocessor">#ifdef DONT_USE_B_MODE </span><span class="comment">/* define mode parameters for fopen() */</span>
<a name="l00047"></a>00047 <span class="preprocessor">#define READ_BINARY "r"</span>
<a name="l00048"></a>00048 <span class="preprocessor"></span><span class="preprocessor">#else</span>
<a name="l00049"></a>00049 <span class="preprocessor"></span><span class="preprocessor">#ifdef VMS </span><span class="comment">/* VMS is very nonstandard */</span>
<a name="l00050"></a>00050 <span class="preprocessor">#define READ_BINARY "rb", "ctx=stm"</span>
<a name="l00051"></a>00051 <span class="preprocessor"></span><span class="preprocessor">#else </span><span class="comment">/* standard ANSI-compliant case */</span>
<a name="l00052"></a><a class="code" href="jpegSize_8cpp.html#7032a5e02e3a69b9bb87efd768bffabc">00052</a> <span class="preprocessor">#define READ_BINARY "rb"</span>
<a name="l00053"></a>00053 <span class="preprocessor"></span><span class="preprocessor">#endif</span>
<a name="l00054"></a>00054 <span class="preprocessor"></span><span class="preprocessor">#endif</span>
<a name="l00055"></a>00055 <span class="preprocessor"></span>
<a name="l00056"></a><a class="code" href="jpegSize_8cpp.html#f19157da745ecb3f2b088c8f3a10c0a7">00056</a> FILE * <a class="code" href="jpegSize_8cpp.html#f19157da745ecb3f2b088c8f3a10c0a7">infile</a>;
<a name="l00057"></a>00057
<a name="l00058"></a>00058 <span class="keywordtype">bool</span> <a class="code" href="jpegSize_8cpp.html#c9692d87db7c729416c07817a3d884ef">process_SOFn</a> (<span class="keywordtype">int</span>& <a class="code" href="blur_8cpp.html#2474a5474cbff19523a51eb1de01cda4">width</a>, <span class="keywordtype">int</span>& <a class="code" href="blur_8cpp.html#d12fc34ce789bce6c8a05d8a17138534">height</a>);
<a name="l00059"></a>00059 <span class="keywordtype">bool</span> <a class="code" href="jpegSize_8cpp.html#c8503f8433f75c15d731b738830b8eb6">skip_variable</a> ();
<a name="l00060"></a>00060 <span class="keywordtype">bool</span> <a class="code" href="jpegSize_8cpp.html#1a6d29eb9df11f99d0120690c59390cd">read_1_byte</a> (<span class="keywordtype">int</span>* res);
<a name="l00061"></a>00061 <span class="keywordtype">bool</span> <a class="code" href="jpegSize_8cpp.html#b72572dd497b42bbe207831d9e3a71e3">read_2_bytes</a> (<span class="keywordtype">unsigned</span> <span class="keywordtype">int</span>* res);
<a name="l00062"></a>00062 <span class="keywordtype">bool</span> <a class="code" href="jpegSize_8cpp.html#03a794f9a32e547280feb641b6f482b7">first_marker</a> (<span class="keywordtype">int</span>* res);
<a name="l00063"></a>00063 <span class="keywordtype">bool</span> <a class="code" href="jpegSize_8cpp.html#3dc947c90667a67ece81b9e877575164">next_marker</a> (<span class="keywordtype">int</span>* res);
<a name="l00064"></a>00064
<a name="l00065"></a><a class="code" href="jpegSize_8h.html#15dc90155bd20ad6b903b548af5690ae">00065</a> <span class="keywordtype">bool</span> <a class="code" href="jpegSize_8cpp.html#15dc90155bd20ad6b903b548af5690ae">getJPEGSize</a>( <span class="keyword">const</span> <span class="keywordtype">char</span>* filename, <span class="keywordtype">int</span>& <a class="code" href="blur_8cpp.html#2474a5474cbff19523a51eb1de01cda4">width</a>, <span class="keywordtype">int</span>& <a class="code" href="blur_8cpp.html#d12fc34ce789bce6c8a05d8a17138534">height</a> )
<a name="l00066"></a>00066 {
<a name="l00067"></a>00067 <span class="comment">//open file</span>
<a name="l00068"></a>00068 <span class="keywordflow">if</span> ((<a class="code" href="jpegSize_8cpp.html#f19157da745ecb3f2b088c8f3a10c0a7">infile</a> = fopen(filename, <a class="code" href="jpegSize_8cpp.html#7032a5e02e3a69b9bb87efd768bffabc">READ_BINARY</a>)) == NULL)
<a name="l00069"></a>00069 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00070"></a>00070
<a name="l00071"></a>00071 <span class="comment">//this is scan_JPEG_header (int verbose)</span>
<a name="l00072"></a>00072 <span class="comment">//Parse the marker stream until SOFn is seen;</span>
<a name="l00073"></a>00073 <span class="keywordtype">int</span> marker;
<a name="l00074"></a>00074
<a name="l00075"></a>00075 <span class="comment">//Expect SOI at start of file</span>
<a name="l00076"></a>00076 <span class="keywordflow">if</span> (!<a class="code" href="jpegSize_8cpp.html#03a794f9a32e547280feb641b6f482b7">first_marker</a>(&marker))
<a name="l00077"></a>00077 {
<a name="l00078"></a>00078 fclose(<a class="code" href="jpegSize_8cpp.html#f19157da745ecb3f2b088c8f3a10c0a7">infile</a>);
<a name="l00079"></a>00079 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00080"></a>00080 }
<a name="l00081"></a>00081
<a name="l00082"></a>00082 <span class="comment">/* Scan miscellaneous markers until we reach SOFn. */</span>
<a name="l00083"></a>00083 <span class="keywordflow">for</span> (;;)
<a name="l00084"></a>00084 {
<a name="l00085"></a>00085 <span class="keywordflow">if</span>(!<a class="code" href="jpegSize_8cpp.html#3dc947c90667a67ece81b9e877575164">next_marker</a>(&marker))
<a name="l00086"></a>00086 {
<a name="l00087"></a>00087 fclose(<a class="code" href="jpegSize_8cpp.html#f19157da745ecb3f2b088c8f3a10c0a7">infile</a>);
<a name="l00088"></a>00088 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00089"></a>00089 }
<a name="l00090"></a>00090
<a name="l00091"></a>00091 <span class="keywordflow">switch</span> (marker)
<a name="l00092"></a>00092 {
<a name="l00093"></a>00093 <span class="comment">/* Note that marker codes 0xC4, 0xC8, 0xCC are not, and must not be,</span>
<a name="l00094"></a>00094 <span class="comment"> * treated as SOFn. C4 in particular is actually DHT.</span>
<a name="l00095"></a>00095 <span class="comment"> */</span>
<a name="l00096"></a>00096 <span class="keywordflow">case</span> <a class="code" href="jpegSize_8cpp.html#e747795c32cea1314b49e9b7d65be454">M_SOF0</a>: <span class="comment">/* Baseline */</span>
<a name="l00097"></a>00097 <span class="keywordflow">case</span> <a class="code" href="jpegSize_8cpp.html#b58d501dd163fdd0dee4ba6907e191a0">M_SOF1</a>: <span class="comment">/* Extended sequential, Huffman */</span>
<a name="l00098"></a>00098 <span class="keywordflow">case</span> <a class="code" href="jpegSize_8cpp.html#eeeb620f261aa6b63448de940c7a7714">M_SOF2</a>: <span class="comment">/* Progressive, Huffman */</span>
<a name="l00099"></a>00099 <span class="keywordflow">case</span> <a class="code" href="jpegSize_8cpp.html#7f09d1c601661800967c5d7e447d5a1f">M_SOF3</a>: <span class="comment">/* Lossless, Huffman */</span>
<a name="l00100"></a>00100 <span class="keywordflow">case</span> <a class="code" href="jpegSize_8cpp.html#ce7276c4a30808cd6fe74abda2f16ad6">M_SOF5</a>: <span class="comment">/* Differential sequential, Huffman */</span>
<a name="l00101"></a>00101 <span class="keywordflow">case</span> <a class="code" href="jpegSize_8cpp.html#3f5a3446a533760babdfd4d0f775e97c">M_SOF6</a>: <span class="comment">/* Differential progressive, Huffman */</span>
<a name="l00102"></a>00102 <span class="keywordflow">case</span> <a class="code" href="jpegSize_8cpp.html#3805e83e6b1e8f52a78f1b6cb0668133">M_SOF7</a>: <span class="comment">/* Differential lossless, Huffman */</span>
<a name="l00103"></a>00103 <span class="keywordflow">case</span> <a class="code" href="jpegSize_8cpp.html#5a510cc3009a14911acbbe7ddb378776">M_SOF9</a>: <span class="comment">/* Extended sequential, arithmetic */</span>
<a name="l00104"></a>00104 <span class="keywordflow">case</span> <a class="code" href="jpegSize_8cpp.html#a718681ce1acfa7622ad9776404cfa98">M_SOF10</a>: <span class="comment">/* Progressive, arithmetic */</span>
<a name="l00105"></a>00105 <span class="keywordflow">case</span> <a class="code" href="jpegSize_8cpp.html#51ac607f59c2730811fd514561770966">M_SOF11</a>: <span class="comment">/* Lossless, arithmetic */</span>
<a name="l00106"></a>00106 <span class="keywordflow">case</span> <a class="code" href="jpegSize_8cpp.html#8ba4457ac8573d317b4562303197c72e">M_SOF13</a>: <span class="comment">/* Differential sequential, arithmetic */</span>
<a name="l00107"></a>00107 <span class="keywordflow">case</span> <a class="code" href="jpegSize_8cpp.html#e3a73495aaced1aacd8577dac2dbe22e">M_SOF14</a>: <span class="comment">/* Differential progressive, arithmetic */</span>
<a name="l00108"></a>00108 <span class="keywordflow">case</span> <a class="code" href="jpegSize_8cpp.html#6e4ec1d092fa9aaaa3a8a18aa1ee4381">M_SOF15</a>: <span class="comment">/* Differential lossless, arithmetic */</span>
<a name="l00109"></a>00109 <span class="keywordflow">if</span>(!<a class="code" href="jpegSize_8cpp.html#c9692d87db7c729416c07817a3d884ef">process_SOFn</a>(width, height))
<a name="l00110"></a>00110 {
<a name="l00111"></a>00111 fclose(<a class="code" href="jpegSize_8cpp.html#f19157da745ecb3f2b088c8f3a10c0a7">infile</a>);
<a name="l00112"></a>00112 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00113"></a>00113 }
<a name="l00114"></a>00114 <span class="keywordflow">else</span>
<a name="l00115"></a>00115 {
<a name="l00116"></a>00116 fclose(<a class="code" href="jpegSize_8cpp.html#f19157da745ecb3f2b088c8f3a10c0a7">infile</a>);
<a name="l00117"></a>00117 <span class="keywordflow">return</span> <span class="keyword">true</span>;
<a name="l00118"></a>00118 }
<a name="l00119"></a>00119 <span class="keywordflow">case</span> <a class="code" href="jpegSize_8cpp.html#f5fdac2a556ee915b65b295faff22ead">M_SOS</a>: <span class="comment">/* stop before hitting compressed data */</span>
<a name="l00120"></a>00120 {
<a name="l00121"></a>00121 fclose(<a class="code" href="jpegSize_8cpp.html#f19157da745ecb3f2b088c8f3a10c0a7">infile</a>);
<a name="l00122"></a>00122 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00123"></a>00123 }
<a name="l00124"></a>00124 <span class="keywordflow">case</span> <a class="code" href="jpegSize_8cpp.html#43056e27046e8d6327320714a5a0b0f0">M_EOI</a>: <span class="comment">/* in case it's a tables-only JPEG stream */</span>
<a name="l00125"></a>00125 {
<a name="l00126"></a>00126 fclose(<a class="code" href="jpegSize_8cpp.html#f19157da745ecb3f2b088c8f3a10c0a7">infile</a>);
<a name="l00127"></a>00127 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00128"></a>00128 }
<a name="l00129"></a>00129 <span class="keywordflow">default</span>: <span class="comment">/* Anything else just gets skipped */</span>
<a name="l00130"></a>00130 <a class="code" href="jpegSize_8cpp.html#c8503f8433f75c15d731b738830b8eb6">skip_variable</a>(); <span class="comment">/* we assume it has a parameter count... */</span>
<a name="l00131"></a>00131 <span class="keywordflow">break</span>;
<a name="l00132"></a>00132 }
<a name="l00133"></a>00133 } <span class="comment">/* end loop */</span>
<a name="l00134"></a>00134
<a name="l00135"></a>00135
<a name="l00136"></a>00136 <span class="comment">//cout << "ERROR!\n";</span>
<a name="l00137"></a>00137 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00138"></a>00138
<a name="l00139"></a>00139 }
<a name="l00140"></a>00140
<a name="l00141"></a>00141
<a name="l00142"></a>00142 <span class="comment">/*</span>
<a name="l00143"></a>00143 <span class="comment"> * Read the initial marker, which should be SOI.</span>
<a name="l00144"></a>00144 <span class="comment"> * For a JFIF file, the first two bytes of the file should be literally</span>
<a name="l00145"></a>00145 <span class="comment"> * 0xFF M_SOI. To be more general, we could use next_marker, but if the</span>
<a name="l00146"></a>00146 <span class="comment"> * input file weren't actually JPEG at all, next_marker might read the whole</span>
<a name="l00147"></a>00147 <span class="comment"> * file and then return a misleading error message...</span>
<a name="l00148"></a>00148 <span class="comment"> */</span>
<a name="l00149"></a><a class="code" href="jpegSize_8cpp.html#03a794f9a32e547280feb641b6f482b7">00149</a> <span class="keywordtype">bool</span> <a class="code" href="jpegSize_8cpp.html#03a794f9a32e547280feb641b6f482b7">first_marker</a> (<span class="keywordtype">int</span>* res)
<a name="l00150"></a>00150 {
<a name="l00151"></a>00151 <span class="keywordtype">int</span> c1, c2;
<a name="l00152"></a>00152 c1 = <a class="code" href="jpegSize_8cpp.html#79d8075203f66de43561298655e7066a">NEXTBYTE</a>();
<a name="l00153"></a>00153 c2 = <a class="code" href="jpegSize_8cpp.html#79d8075203f66de43561298655e7066a">NEXTBYTE</a>();
<a name="l00154"></a>00154 <span class="keywordflow">if</span> (c1 != 0xFF || c2 != <a class="code" href="jpegSize_8cpp.html#ce3e2c7b5e5b844c165f813bb68a3d37">M_SOI</a>)
<a name="l00155"></a>00155 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00156"></a>00156 <span class="keywordflow">else</span>
<a name="l00157"></a>00157 {
<a name="l00158"></a>00158 *res = c2;
<a name="l00159"></a>00159 <span class="keywordflow">return</span> <span class="keyword">true</span>;
<a name="l00160"></a>00160 }
<a name="l00161"></a>00161 }
<a name="l00162"></a>00162
<a name="l00163"></a>00163 <span class="comment">/*</span>
<a name="l00164"></a>00164 <span class="comment"> * Find the next JPEG marker and return its marker code.</span>
<a name="l00165"></a>00165 <span class="comment"> * We expect at least one FF byte, possibly more if the compressor used FFs</span>
<a name="l00166"></a>00166 <span class="comment"> * to pad the file.</span>
<a name="l00167"></a>00167 <span class="comment"> * There could also be non-FF garbage between markers. The treatment of such</span>
<a name="l00168"></a>00168 <span class="comment"> * garbage is unspecified; we choose to skip over it but emit a warning msg.</span>
<a name="l00169"></a>00169 <span class="comment"> * NB: this routine must not be used after seeing SOS marker, since it will</span>
<a name="l00170"></a>00170 <span class="comment"> * not deal correctly with FF/00 sequences in the compressed image data...</span>
<a name="l00171"></a>00171 <span class="comment"> */</span>
<a name="l00172"></a><a class="code" href="jpegSize_8cpp.html#3dc947c90667a67ece81b9e877575164">00172</a> <span class="keywordtype">bool</span> <a class="code" href="jpegSize_8cpp.html#3dc947c90667a67ece81b9e877575164">next_marker</a> (<span class="keywordtype">int</span>* res)
<a name="l00173"></a>00173 {
<a name="l00174"></a>00174 <span class="keywordtype">int</span> c;
<a name="l00175"></a>00175 <span class="keywordtype">int</span> discarded_bytes = 0;
<a name="l00176"></a>00176
<a name="l00177"></a>00177 <span class="comment">/* Find 0xFF byte; count and skip any non-FFs. */</span>
<a name="l00178"></a>00178 <span class="keywordflow">if</span>(!<a class="code" href="jpegSize_8cpp.html#1a6d29eb9df11f99d0120690c59390cd">read_1_byte</a>(&c))
<a name="l00179"></a>00179 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00180"></a>00180 <span class="keywordflow">while</span> (c != 0xFF)
<a name="l00181"></a>00181 {
<a name="l00182"></a>00182 discarded_bytes++;
<a name="l00183"></a>00183 <span class="keywordflow">if</span>(!<a class="code" href="jpegSize_8cpp.html#1a6d29eb9df11f99d0120690c59390cd">read_1_byte</a>(&c))
<a name="l00184"></a>00184 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00185"></a>00185 }
<a name="l00186"></a>00186 <span class="comment">/* Get marker code byte, swallowing any duplicate FF bytes. Extra FFs</span>
<a name="l00187"></a>00187 <span class="comment"> * are legal as pad bytes, so don't count them in discarded_bytes.</span>
<a name="l00188"></a>00188 <span class="comment"> */</span>
<a name="l00189"></a>00189 <span class="keywordflow">do</span>
<a name="l00190"></a>00190 {
<a name="l00191"></a>00191 <span class="keywordflow">if</span>(!<a class="code" href="jpegSize_8cpp.html#1a6d29eb9df11f99d0120690c59390cd">read_1_byte</a>(&c))
<a name="l00192"></a>00192 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00193"></a>00193 } <span class="keywordflow">while</span> (c == 0xFF);
<a name="l00194"></a>00194
<a name="l00195"></a>00195 <span class="comment">// if (discarded_bytes != 0) { cout << "Warning: garbage data found in JPEG file\n"; }</span>
<a name="l00196"></a>00196
<a name="l00197"></a>00197 *res = c;
<a name="l00198"></a>00198 <span class="keywordflow">return</span> <span class="keyword">true</span>;
<a name="l00199"></a>00199 }
<a name="l00200"></a>00200
<a name="l00201"></a>00201 <span class="comment">/* Read one byte, testing for EOF */</span>
<a name="l00202"></a><a class="code" href="jpegSize_8cpp.html#1a6d29eb9df11f99d0120690c59390cd">00202</a> <span class="keywordtype">bool</span> <a class="code" href="jpegSize_8cpp.html#1a6d29eb9df11f99d0120690c59390cd">read_1_byte</a> (<span class="keywordtype">int</span>* res)
<a name="l00203"></a>00203 {
<a name="l00204"></a>00204 <span class="keywordtype">int</span> c = <a class="code" href="jpegSize_8cpp.html#79d8075203f66de43561298655e7066a">NEXTBYTE</a>();
<a name="l00205"></a>00205 <span class="keywordflow">if</span> (c == EOF)
<a name="l00206"></a>00206 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00207"></a>00207 <span class="keywordflow">else</span>
<a name="l00208"></a>00208 {
<a name="l00209"></a>00209 *res = c;
<a name="l00210"></a>00210 <span class="keywordflow">return</span> <span class="keyword">true</span>;
<a name="l00211"></a>00211 }
<a name="l00212"></a>00212 }
<a name="l00213"></a>00213
<a name="l00214"></a>00214 <span class="comment">/* Read 2 bytes, convert to unsigned int */</span>
<a name="l00215"></a>00215 <span class="comment">/* All 2-byte quantities in JPEG markers are MSB first */</span>
<a name="l00216"></a><a class="code" href="jpegSize_8cpp.html#b72572dd497b42bbe207831d9e3a71e3">00216</a> <span class="keywordtype">bool</span> <a class="code" href="jpegSize_8cpp.html#b72572dd497b42bbe207831d9e3a71e3">read_2_bytes</a> (<span class="keywordtype">unsigned</span> <span class="keywordtype">int</span>* res)
<a name="l00217"></a>00217 {
<a name="l00218"></a>00218 <span class="keywordtype">int</span> c1, c2;
<a name="l00219"></a>00219 c1 = <a class="code" href="jpegSize_8cpp.html#79d8075203f66de43561298655e7066a">NEXTBYTE</a>();
<a name="l00220"></a>00220 <span class="keywordflow">if</span> (c1 == EOF)
<a name="l00221"></a>00221 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00222"></a>00222 c2 = <a class="code" href="jpegSize_8cpp.html#79d8075203f66de43561298655e7066a">NEXTBYTE</a>();
<a name="l00223"></a>00223 <span class="keywordflow">if</span> (c2 == EOF)
<a name="l00224"></a>00224 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00225"></a>00225 *res = (((<span class="keywordtype">unsigned</span> int) c1) << 8) + ((<span class="keywordtype">unsigned</span> <span class="keywordtype">int</span>) c2);
<a name="l00226"></a>00226 <span class="keywordflow">return</span> <span class="keyword">true</span>;
<a name="l00227"></a>00227 }
<a name="l00228"></a>00228
<a name="l00229"></a>00229 <span class="comment">/*</span>
<a name="l00230"></a>00230 <span class="comment"> * Most types of marker are followed by a variable-length parameter segment.</span>
<a name="l00231"></a>00231 <span class="comment"> * This routine skips over the parameters for any marker we don't otherwise</span>
<a name="l00232"></a>00232 <span class="comment"> * want to process.</span>
<a name="l00233"></a>00233 <span class="comment"> * Note that we MUST skip the parameter segment explicitly in order not to</span>
<a name="l00234"></a>00234 <span class="comment"> * be fooled by 0xFF bytes that might appear within the parameter segment;</span>
<a name="l00235"></a>00235 <span class="comment"> * such bytes do NOT introduce new markers.</span>
<a name="l00236"></a>00236 <span class="comment"> */</span>
<a name="l00237"></a><a class="code" href="jpegSize_8cpp.html#c8503f8433f75c15d731b738830b8eb6">00237</a> <span class="keywordtype">bool</span> <a class="code" href="jpegSize_8cpp.html#c8503f8433f75c15d731b738830b8eb6">skip_variable</a> ()
<a name="l00238"></a>00238 <span class="comment">/* Skip over an unknown or uninteresting variable-length marker */</span>
<a name="l00239"></a>00239 {
<a name="l00240"></a>00240 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> length;
<a name="l00241"></a>00241
<a name="l00242"></a>00242 <span class="comment">/* Get the marker parameter length count */</span>
<a name="l00243"></a>00243 <span class="keywordflow">if</span>(!<a class="code" href="jpegSize_8cpp.html#b72572dd497b42bbe207831d9e3a71e3">read_2_bytes</a>(&length))
<a name="l00244"></a>00244 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00245"></a>00245 <span class="comment">/* Length includes itself, so must be at least 2 */</span>
<a name="l00246"></a>00246 <span class="keywordflow">if</span> (length < 2)
<a name="l00247"></a>00247 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00248"></a>00248 length -= 2;
<a name="l00249"></a>00249 <span class="comment">/* Skip over the remaining bytes */</span>
<a name="l00250"></a>00250 <span class="keywordflow">while</span> (length > 0)
<a name="l00251"></a>00251 {
<a name="l00252"></a>00252 <span class="keywordtype">int</span> tmp;
<a name="l00253"></a>00253 <span class="keywordflow">if</span>(!<a class="code" href="jpegSize_8cpp.html#1a6d29eb9df11f99d0120690c59390cd">read_1_byte</a>(&tmp))
<a name="l00254"></a>00254 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00255"></a>00255 length--;
<a name="l00256"></a>00256 }
<a name="l00257"></a>00257 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00258"></a>00258 }
<a name="l00259"></a>00259
<a name="l00260"></a>00260 <span class="comment">//Process a SOFn marker - get image dimensions</span>
<a name="l00261"></a><a class="code" href="jpegSize_8cpp.html#c9692d87db7c729416c07817a3d884ef">00261</a> <span class="keywordtype">bool</span> <a class="code" href="jpegSize_8cpp.html#c9692d87db7c729416c07817a3d884ef">process_SOFn</a> (<span class="keywordtype">int</span>& <a class="code" href="blur_8cpp.html#2474a5474cbff19523a51eb1de01cda4">width</a>, <span class="keywordtype">int</span>& <a class="code" href="blur_8cpp.html#d12fc34ce789bce6c8a05d8a17138534">height</a>)
<a name="l00262"></a>00262 {
<a name="l00263"></a>00263 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> length;
<a name="l00264"></a>00264 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> image_height, image_width;
<a name="l00265"></a>00265 <span class="keywordtype">int</span> data_precision;
<a name="l00266"></a>00266
<a name="l00267"></a>00267 <span class="keywordflow">if</span>(!<a class="code" href="jpegSize_8cpp.html#b72572dd497b42bbe207831d9e3a71e3">read_2_bytes</a>(&length) ||
<a name="l00268"></a>00268 !<a class="code" href="jpegSize_8cpp.html#1a6d29eb9df11f99d0120690c59390cd">read_1_byte</a>(&data_precision) ||
<a name="l00269"></a>00269 !<a class="code" href="jpegSize_8cpp.html#b72572dd497b42bbe207831d9e3a71e3">read_2_bytes</a>(&image_height) ||
<a name="l00270"></a>00270 !<a class="code" href="jpegSize_8cpp.html#b72572dd497b42bbe207831d9e3a71e3">read_2_bytes</a>(&image_width) )
<a name="l00271"></a>00271 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00272"></a>00272
<a name="l00273"></a>00273 width = (int) image_width;
<a name="l00274"></a>00274 height = (int) image_height;
<a name="l00275"></a>00275 <span class="keywordflow">return</span> <span class="keyword">true</span>;
<a name="l00276"></a>00276 }
</pre></div></div>
<hr size="1"><address style="text-align: right;"><small>Generated on Sun Aug 23 02:34:26 2009 for AlbumShaper by
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