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1
51 package org.apache.fop.image.analyser;
52
53 import java.io.BufferedInputStream  ;
55 import java.io.IOException ;
56
57
62 public class JPEGReader extends AbstractImageReader {
63
64
71 protected static final int MARK = 0xff; protected static final int NULL = 0x00; protected static final int SOF1 = 0xc0; protected static final int SOF2 = 0xc1; protected static final int SOF3 = 0xc2; protected static final int SOFA = 0xca; protected static final int APP0 = 0xe0; protected static final int APPF = 0xef; protected static final int SOS = 0xda; protected static final int SOI = 0xd8; protected static final int JPG_SIG_LENGTH = 2;
82
83 protected byte[] header;
84
85 public boolean verifySignature(String uri, BufferedInputStream fis)
86 throws IOException {
87 this.imageStream = fis;
88 this.setDefaultHeader();
89 boolean supported = ((header[0] == (byte)0xff)
90 && (header[1] == (byte)0xd8));
91 if (supported) {
92 setDimension();
93 return true;
94 } else
95 return false;
96 }
97
98 public String getMimeType() {
99 return "image/jpeg";
100 }
101
102 protected void setDefaultHeader() throws IOException {
103 this.header = new byte[JPG_SIG_LENGTH];
104 try {
105 this.imageStream.mark(JPG_SIG_LENGTH + 1);
106 this.imageStream.read(header);
107 this.imageStream.reset();
108 } catch (IOException ex) {
109 try {
110 this.imageStream.reset();
111 } catch (IOException exbis) {}
112 throw ex;
113 }
114 }
115
116 protected void setDimension() throws IOException {
117 try {
118 int marker = NULL;
119 long length, skipped;
120 outer:
121 while (imageStream.available() > 0) {
122 while ((marker = imageStream.read()) != MARK) {
123 ;
124 }
125 do {
126 marker = imageStream.read();
127 } while (marker == MARK);
128 switch (marker) {
129 case SOI:
130 break;
131 case NULL:
132 break;
133 case SOF1:
134 case SOF2:
135 case SOF3: case SOFA:
137 this.skip(3);
138 this.height = this.read2bytes();
139 this.width = this.read2bytes();
140 break outer;
141 default:
142 length = this.read2bytes();
143 skipped = this.skip(length - 2);
144 if (skipped != length - 2)
145 throw new IOException ("Skipping Error");
146 }
147 }
148 } catch (IOException ioe) {
149 try {
150 this.imageStream.reset();
151 } catch (IOException exbis) {}
152 throw ioe;
153 }
154 }
155
156 protected int read2bytes() throws IOException {
157 int byte1 = imageStream.read();
158 int byte2 = imageStream.read();
159 return (int)((byte1 << 8) | byte2);
160 }
161
162 protected long skip(long n) throws IOException {
163 long discarded = 0;
164 while (discarded != n) {
165 imageStream.read();
166 discarded++;
167 }
168 return discarded; }
170
171 }
172
173 |
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