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Java > Open Source Codes > org > openlaszlo > iv > flash > util > JPEGHelper


1 /*
2  * $Id: JPEGHelper.java,v 1.2 2002/02/15 23:44:28 skavish Exp $
3  *
4  * ===========================================================================
5  *
6  * The JGenerator Software License, Version 1.0
7  *
8  * Copyright (c) 2000 Dmitry Skavish (skavish@usa.net). All rights reserved.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions are met:
12  *
13  * 1. Redistributions of source code must retain the above copyright
14  * notice, this list of conditions and the following disclaimer.
15  *
16  * 2. Redistributions in binary form must reproduce the above copyright
17  * notice, this list of conditions and the following disclaimer in
18  * the documentation and/or other materials provided with the
19  * distribution.
20  *
21  * 3. The end-user documentation included with the redistribution, if
22  * any, must include the following acknowlegement:
23  * "This product includes software developed by Dmitry Skavish
24  * (skavish@usa.net, http://www.flashgap.com/)."
25  * Alternately, this acknowlegement may appear in the software itself,
26  * if and wherever such third-party acknowlegements normally appear.
27  *
28  * 4. The name "The JGenerator" must not be used to endorse or promote
29  * products derived from this software without prior written permission.
30  * For written permission, please contact skavish@usa.net.
31  *
32  * 5. Products derived from this software may not be called "The JGenerator"
33  * nor may "The JGenerator" appear in their names without prior written
34  * permission of Dmitry Skavish.
35  *
36  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
37  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
38  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
39  * DISCLAIMED. IN NO EVENT SHALL DMITRY SKAVISH OR THE OTHER
40  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
41  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
42  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
43  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
44  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
45  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
46  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
47  * SUCH DAMAGE.
48  *
49  */
50
51 package org.openlaszlo.iv.flash.util;
52
53 import org.openlaszlo.iv.flash.api.*;
54 import org.openlaszlo.iv.flash.api.image.*;
55 import java.io.*;
56
57 /**
58  * Simple JPEG scanner helping in extracting image's width and height.
59  *
60  * @author Dmitry Skavish
61  */
62 public class JPEGHelper {
63
64     public static final int M_SOF0 = 0xC0;
65     public static final int M_SOF1 = 0xC1;
66     public static final int M_SOF2 = 0xC2;
67     public static final int M_SOF3 = 0xC3;
68     public static final int M_SOF5 = 0xC5;
69     public static final int M_SOF6 = 0xC6;
70     public static final int M_SOF7 = 0xC7;
71     public static final int M_SOF9 = 0xC9;
72     public static final int M_SOF10 = 0xCA;
73     public static final int M_SOF11 = 0xCB;
74     public static final int M_SOF13 = 0xCD;
75     public static final int M_SOF14 = 0xCE;
76     public static final int M_SOF15 = 0xCF;
77     public static final int M_SOI = 0xD8;
78     public static final int M_EOI = 0xD9;
79     public static final int M_SOS = 0xDA;
80     public static final int M_APP14 = 0xEE;
81
82     public static JPEGBitmap.JPEGInfo getInfo( byte[] b, int p, int end ) {
83         if( Util.getUByte(b[p])!=0xff || Util.getUByte(b[p+1])!=M_SOI ) return null;
84
85         JPEGBitmap.JPEGInfo info = new JPEGBitmap.JPEGInfo();
86         // Default to progressive
87 info.type = 1;
88
89         p += 2; // skip SOI
90 // Find SOF0 marker
91 while( p < end ) {
92             if( Util.getUByte(b[p]) == 0xff ) {
93                 int id = Util.getUByte(b[p+1]);
94                 int len = Util.getUWord(b[p+3], b[p+2]);
95                 switch( id ) {
96                     case M_EOI:
97                         return info; // no SOF0
98 case M_SOF0:
99                     case M_SOF1:
100                     case M_SOF3:
101                     case M_SOF5:
102                     case M_SOF7:
103                     case M_SOF9:
104                     case M_SOF11:
105                     case M_SOF13:
106                     case M_SOF15:
107                         // Not progressive
108 info.type = 0;
109                         // Fall through
110 case M_SOF2:
111                     case M_SOF6:
112                     case M_SOF10:
113                     case M_SOF14: {
114                        info.precision = b[p+4];
115                        info.height = Util.getUWord(b[p+6], b[p+5]);
116                        info.width = Util.getUWord(b[p+8], b[p+7]);
117                        info.num_comps = Util.getUByte(b[p+9]);
118                        //compID[0] = GB(fp+10);
119 //compID[1] = GB(fp+13);
120 //compID[2] = GB(fp+16);
121 return info;
122                     }
123                 }
124                 p += len+2;
125             } else {
126                 p++;
127             }
128         }
129
130         return info;
131     }
132 }
133
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