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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
61 public class PNGReader extends AbstractImageReader {
62 protected static final int PNG_SIG_LENGTH = 24;
63 protected byte[] header;
64
65 public boolean verifySignature(String uri, BufferedInputStream fis)
66 throws IOException {
67 this.imageStream = fis;
68 this.setDefaultHeader();
69 boolean supported = ((header[0] == (byte)0x89)
70 && (header[1] == (byte)0x50)
71 && (header[2] == (byte)0x4e)
72 && (header[3] == (byte)0x47)
73 && (header[4] == (byte)0x0d)
74 && (header[5] == (byte)0x0a)
75 && (header[6] == (byte)0x1a)
76 && (header[7] == (byte)0x0a));
77 if (supported) {
78 setDimension();
79 return true;
80 } else
81 return false;
82 }
83
84 public String getMimeType() {
85 return "image/png";
86 }
87
88 protected void setDimension() {
89 int byte1 = header[16] & 0xff;
91 int byte2 = header[17] & 0xff;
92 int byte3 = header[18] & 0xff;
93 int byte4 = header[19] & 0xff;
94 long l = (long)((byte1 << 24) | (byte2 << 16) | (byte3 << 8) | byte4);
95 this.width = (int)(l);
96
97 byte1 = header[20] & 0xff;
98 byte2 = header[21] & 0xff;
99 byte3 = header[22] & 0xff;
100 byte4 = header[23] & 0xff;
101 l = (long)((byte1 << 24) | (byte2 << 16) | (byte3 << 8) | byte4);
102 this.height = (int)(l);
103
104 }
105
106 protected void setDefaultHeader() throws IOException {
107 this.header = new byte[PNG_SIG_LENGTH];
108 try {
109 this.imageStream.mark(PNG_SIG_LENGTH + 1);
110 this.imageStream.read(header);
111 this.imageStream.reset();
112 } catch (IOException ex) {
113 try {
114 this.imageStream.reset();
115 } catch (IOException exbis) {}
116 throw ex;
117 }
118 }
119
120 }
121
122 |
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