--- /dev/null
+package tim.prune.jpeg.drew;\r
+\r
+import java.io.*;\r
+\r
+/**\r
+ * Class to perform read functions of Jpeg files, returning specific file segments\r
+ * Based on Drew Noakes' Metadata extractor at http://drewnoakes.com\r
+ */\r
+public class JpegSegmentReader\r
+{\r
+ /** Start of scan marker */\r
+ private static final byte SEGMENT_SOS = (byte)0xDA;\r
+\r
+ /** End of image marker */\r
+ private static final byte MARKER_EOI = (byte)0xD9;\r
+\r
+ /** APP0 Jpeg segment identifier -- Jfif data. */\r
+ public static final byte SEGMENT_APP0 = (byte)0xE0;\r
+ /** APP1 Jpeg segment identifier -- where Exif data is kept. */\r
+ public static final byte SEGMENT_APP1 = (byte)0xE1;\r
+ /** APP2 Jpeg segment identifier. */\r
+ public static final byte SEGMENT_APP2 = (byte)0xE2;\r
+ /** APP3 Jpeg segment identifier. */\r
+ public static final byte SEGMENT_APP3 = (byte)0xE3;\r
+ /** APP4 Jpeg segment identifier. */\r
+ public static final byte SEGMENT_APP4 = (byte)0xE4;\r
+ /** APP5 Jpeg segment identifier. */\r
+ public static final byte SEGMENT_APP5 = (byte)0xE5;\r
+ /** APP6 Jpeg segment identifier. */\r
+ public static final byte SEGMENT_APP6 = (byte)0xE6;\r
+ /** APP7 Jpeg segment identifier. */\r
+ public static final byte SEGMENT_APP7 = (byte)0xE7;\r
+ /** APP8 Jpeg segment identifier. */\r
+ public static final byte SEGMENT_APP8 = (byte)0xE8;\r
+ /** APP9 Jpeg segment identifier. */\r
+ public static final byte SEGMENT_APP9 = (byte)0xE9;\r
+ /** APPA Jpeg segment identifier -- can hold Unicode comments. */\r
+ public static final byte SEGMENT_APPA = (byte)0xEA;\r
+ /** APPB Jpeg segment identifier. */\r
+ public static final byte SEGMENT_APPB = (byte)0xEB;\r
+ /** APPC Jpeg segment identifier. */\r
+ public static final byte SEGMENT_APPC = (byte)0xEC;\r
+ /** APPD Jpeg segment identifier -- IPTC data in here. */\r
+ public static final byte SEGMENT_APPD = (byte)0xED;\r
+ /** APPE Jpeg segment identifier. */\r
+ public static final byte SEGMENT_APPE = (byte)0xEE;\r
+ /** APPF Jpeg segment identifier. */\r
+ public static final byte SEGMENT_APPF = (byte)0xEF;\r
+ /** Start Of Image segment identifier. */\r
+ public static final byte SEGMENT_SOI = (byte)0xD8;\r
+ /** Define Quantization Table segment identifier. */\r
+ public static final byte SEGMENT_DQT = (byte)0xDB;\r
+ /** Define Huffman Table segment identifier. */\r
+ public static final byte SEGMENT_DHT = (byte)0xC4;\r
+ /** Start-of-Frame Zero segment identifier. */\r
+ public static final byte SEGMENT_SOF0 = (byte)0xC0;\r
+ /** Jpeg comment segment identifier. */\r
+ public static final byte SEGMENT_COM = (byte)0xFE;\r
+\r
+ /** Magic numbers to mark the beginning of all Jpegs */\r
+ private static final int MAGIC_JPEG_BYTE_1 = 0xFF;\r
+ private static final int MAGIC_JPEG_BYTE_2 = 0xD8;\r
+\r
+\r
+ /**\r
+ * Obtain the Jpeg segment data from the specified file\r
+ * @param inFile File to read\r
+ * @return Jpeg segment data from file\r
+ * @throws JpegException on file read errors or exif data errors\r
+ */\r
+ public static JpegSegmentData readSegments(File inFile) throws JpegException\r
+ {\r
+ JpegSegmentData segmentData = new JpegSegmentData();\r
+\r
+ BufferedInputStream bStream = null;\r
+\r
+ try\r
+ {\r
+ bStream = new BufferedInputStream(new FileInputStream(inFile));\r
+ int offset = 0;\r
+ // first two bytes should be jpeg magic number\r
+ int magic1 = bStream.read() & 0xFF;\r
+ int magic2 = bStream.read() & 0xFF;\r
+ checkMagicNumbers(magic1, magic2);\r
+\r
+ offset += 2;\r
+ // Loop around segments found\r
+ do\r
+ {\r
+ // next byte is 0xFF\r
+ byte segmentIdentifier = (byte) (bStream.read() & 0xFF);\r
+ if ((segmentIdentifier & 0xFF) != 0xFF)\r
+ {\r
+ throw new JpegException("expected jpeg segment start identifier 0xFF at offset "\r
+ + offset + ", not 0x" + Integer.toHexString(segmentIdentifier & 0xFF));\r
+ }\r
+ offset++;\r
+ // next byte is <segment-marker>\r
+ byte thisSegmentMarker = (byte) (bStream.read() & 0xFF);\r
+ offset++;\r
+ // next 2-bytes are <segment-size>: [high-byte] [low-byte]\r
+ byte[] segmentLengthBytes = new byte[2];\r
+ bStream.read(segmentLengthBytes, 0, 2);\r
+ offset += 2;\r
+ int segmentLength = ((segmentLengthBytes[0] << 8) & 0xFF00) | (segmentLengthBytes[1] & 0xFF);\r
+ // segment length includes size bytes, so subtract two\r
+ segmentLength -= 2;\r
+ if (segmentLength > bStream.available())\r
+ throw new JpegException("segment size would extend beyond file stream length");\r
+ else if (segmentLength < 0)\r
+ throw new JpegException("segment size would be less than zero");\r
+ byte[] segmentBytes = new byte[segmentLength];\r
+ bStream.read(segmentBytes, 0, segmentLength);\r
+ offset += segmentLength;\r
+ if ((thisSegmentMarker & 0xFF) == (SEGMENT_SOS & 0xFF))\r
+ {\r
+ // The 'Start-Of-Scan' segment comes last so break out of loop\r
+ break;\r
+ }\r
+ else if ((thisSegmentMarker & 0xFF) == (MARKER_EOI & 0xFF))\r
+ {\r
+ // the 'End-Of-Image' segment - should already have exited by now\r
+ break;\r
+ }\r
+ else\r
+ {\r
+ segmentData.addSegment(thisSegmentMarker, segmentBytes);\r
+ }\r
+ // loop through to the next segment\r
+ }\r
+ while (true);\r
+ }\r
+ catch (FileNotFoundException fnfe)\r
+ {\r
+ throw new JpegException("Jpeg file not found");\r
+ }\r
+ catch (IOException ioe)\r
+ {\r
+ throw new JpegException("IOException processing Jpeg file: " + ioe.getMessage(), ioe);\r
+ }\r
+ finally\r
+ {\r
+ try\r
+ {\r
+ if (bStream != null) {\r
+ bStream.close();\r
+ }\r
+ }\r
+ catch (IOException ioe) {\r
+ throw new JpegException("IOException processing Jpeg file: " + ioe.getMessage(), ioe);\r
+ }\r
+ }\r
+ // Return the result\r
+ return segmentData;\r
+ }\r
+\r
+\r
+ /**\r
+ * Helper method that validates the Jpeg file's magic number.\r
+ * @param inMagic1 first half of magic number\r
+ * @param inMagic2 second half of magic number\r
+ * @throws JpegException if numbers do not match magic numbers expected\r
+ */\r
+ private static void checkMagicNumbers(int inMagic1, int inMagic2) throws JpegException\r
+ {\r
+ if (inMagic1 != MAGIC_JPEG_BYTE_1 || inMagic2 != MAGIC_JPEG_BYTE_2)\r
+ {\r
+ throw new JpegException("not a jpeg file");\r
+ }\r
+ }\r
+}
\ No newline at end of file
projects / GpsPrune.git / blobdiff