1 /* 2 * Copyright (C) 2007 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package android.media; 18 19 import java.io.IOException; 20 import java.text.ParsePosition; 21 import java.text.SimpleDateFormat; 22 import java.util.Date; 23 import java.util.HashMap; 24 import java.util.Map; 25 import java.util.TimeZone; 26 27 /** 28 * This is a class for reading and writing Exif tags in a JPEG file. 29 */ 30 public class ExifInterface { 31 // The Exif tag names 32 /** Type is int. */ 33 public static final String TAG_ORIENTATION = "Orientation"; 34 /** Type is String. */ 35 public static final String TAG_DATETIME = "DateTime"; 36 /** Type is String. */ 37 public static final String TAG_MAKE = "Make"; 38 /** Type is String. */ 39 public static final String TAG_MODEL = "Model"; 40 /** Type is int. */ 41 public static final String TAG_FLASH = "Flash"; 42 /** Type is int. */ 43 public static final String TAG_IMAGE_WIDTH = "ImageWidth"; 44 /** Type is int. */ 45 public static final String TAG_IMAGE_LENGTH = "ImageLength"; 46 /** String. Format is "num1/denom1,num2/denom2,num3/denom3". */ 47 public static final String TAG_GPS_LATITUDE = "GPSLatitude"; 48 /** String. Format is "num1/denom1,num2/denom2,num3/denom3". */ 49 public static final String TAG_GPS_LONGITUDE = "GPSLongitude"; 50 /** Type is String. */ 51 public static final String TAG_GPS_LATITUDE_REF = "GPSLatitudeRef"; 52 /** Type is String. */ 53 public static final String TAG_GPS_LONGITUDE_REF = "GPSLongitudeRef"; 54 /** Type is String. */ 55 public static final String TAG_EXPOSURE_TIME = "ExposureTime"; 56 /** Type is String. */ 57 public static final String TAG_APERTURE = "FNumber"; 58 /** Type is String. */ 59 public static final String TAG_ISO = "ISOSpeedRatings"; 60 61 /** 62 * The altitude (in meters) based on the reference in TAG_GPS_ALTITUDE_REF. 63 * Type is rational. 64 */ 65 public static final String TAG_GPS_ALTITUDE = "GPSAltitude"; 66 67 /** 68 * 0 if the altitude is above sea level. 1 if the altitude is below sea 69 * level. Type is int. 70 */ 71 public static final String TAG_GPS_ALTITUDE_REF = "GPSAltitudeRef"; 72 73 /** Type is String. */ 74 public static final String TAG_GPS_TIMESTAMP = "GPSTimeStamp"; 75 /** Type is String. */ 76 public static final String TAG_GPS_DATESTAMP = "GPSDateStamp"; 77 /** Type is int. */ 78 public static final String TAG_WHITE_BALANCE = "WhiteBalance"; 79 /** Type is rational. */ 80 public static final String TAG_FOCAL_LENGTH = "FocalLength"; 81 /** Type is String. Name of GPS processing method used for location finding. */ 82 public static final String TAG_GPS_PROCESSING_METHOD = "GPSProcessingMethod"; 83 84 // Constants used for the Orientation Exif tag. 85 public static final int ORIENTATION_UNDEFINED = 0; 86 public static final int ORIENTATION_NORMAL = 1; 87 public static final int ORIENTATION_FLIP_HORIZONTAL = 2; // left right reversed mirror 88 public static final int ORIENTATION_ROTATE_180 = 3; 89 public static final int ORIENTATION_FLIP_VERTICAL = 4; // upside down mirror 90 public static final int ORIENTATION_TRANSPOSE = 5; // flipped about top-left <--> bottom-right axis 91 public static final int ORIENTATION_ROTATE_90 = 6; // rotate 90 cw to right it 92 public static final int ORIENTATION_TRANSVERSE = 7; // flipped about top-right <--> bottom-left axis 93 public static final int ORIENTATION_ROTATE_270 = 8; // rotate 270 to right it 94 95 // Constants used for white balance 96 public static final int WHITEBALANCE_AUTO = 0; 97 public static final int WHITEBALANCE_MANUAL = 1; 98 private static SimpleDateFormat sFormatter; 99 100 static { 101 System.loadLibrary("exif_jni"); 102 sFormatter = new SimpleDateFormat("yyyy:MM:dd HH:mm:ss"); 103 sFormatter.setTimeZone(TimeZone.getTimeZone("UTC")); 104 } 105 106 private String mFilename; 107 private HashMap<String, String> mAttributes; 108 private boolean mHasThumbnail; 109 110 // Because the underlying implementation (jhead) uses static variables, 111 // there can only be one user at a time for the native functions (and 112 // they cannot keep state in the native code across function calls). We 113 // use sLock to serialize the accesses. 114 private static final Object sLock = new Object(); 115 116 /** 117 * Reads Exif tags from the specified JPEG file. 118 */ 119 public ExifInterface(String filename) throws IOException { 120 mFilename = filename; 121 loadAttributes(); 122 } 123 124 /** 125 * Returns the value of the specified tag or {@code null} if there 126 * is no such tag in the JPEG file. 127 * 128 * @param tag the name of the tag. 129 */ 130 public String getAttribute(String tag) { 131 return mAttributes.get(tag); 132 } 133 134 /** 135 * Returns the integer value of the specified tag. If there is no such tag 136 * in the JPEG file or the value cannot be parsed as integer, return 137 * <var>defaultValue</var>. 138 * 139 * @param tag the name of the tag. 140 * @param defaultValue the value to return if the tag is not available. 141 */ 142 public int getAttributeInt(String tag, int defaultValue) { 143 String value = mAttributes.get(tag); 144 if (value == null) return defaultValue; 145 try { 146 return Integer.valueOf(value); 147 } catch (NumberFormatException ex) { 148 return defaultValue; 149 } 150 } 151 152 /** 153 * Returns the double value of the specified rational tag. If there is no 154 * such tag in the JPEG file or the value cannot be parsed as double, return 155 * <var>defaultValue</var>. 156 * 157 * @param tag the name of the tag. 158 * @param defaultValue the value to return if the tag is not available. 159 */ 160 public double getAttributeDouble(String tag, double defaultValue) { 161 String value = mAttributes.get(tag); 162 if (value == null) return defaultValue; 163 try { 164 int index = value.indexOf("/"); 165 if (index == -1) return defaultValue; 166 double denom = Double.parseDouble(value.substring(index + 1)); 167 if (denom == 0) return defaultValue; 168 double num = Double.parseDouble(value.substring(0, index)); 169 return num / denom; 170 } catch (NumberFormatException ex) { 171 return defaultValue; 172 } 173 } 174 175 /** 176 * Set the value of the specified tag. 177 * 178 * @param tag the name of the tag. 179 * @param value the value of the tag. 180 */ 181 public void setAttribute(String tag, String value) { 182 mAttributes.put(tag, value); 183 } 184 185 /** 186 * Initialize mAttributes with the attributes from the file mFilename. 187 * 188 * mAttributes is a HashMap which stores the Exif attributes of the file. 189 * The key is the standard tag name and the value is the tag's value: e.g. 190 * Model -> Nikon. Numeric values are stored as strings. 191 * 192 * This function also initialize mHasThumbnail to indicate whether the 193 * file has a thumbnail inside. 194 */ 195 private void loadAttributes() throws IOException { 196 // format of string passed from native C code: 197 // "attrCnt attr1=valueLen value1attr2=value2Len value2..." 198 // example: 199 // "4 attrPtr ImageLength=4 1024Model=6 FooImageWidth=4 1280Make=3 FOO" 200 mAttributes = new HashMap<String, String>(); 201 202 String attrStr; 203 synchronized (sLock) { 204 attrStr = getAttributesNative(mFilename); 205 } 206 207 // get count 208 int ptr = attrStr.indexOf(' '); 209 int count = Integer.parseInt(attrStr.substring(0, ptr)); 210 // skip past the space between item count and the rest of the attributes 211 ++ptr; 212 213 for (int i = 0; i < count; i++) { 214 // extract the attribute name 215 int equalPos = attrStr.indexOf('=', ptr); 216 String attrName = attrStr.substring(ptr, equalPos); 217 ptr = equalPos + 1; // skip past = 218 219 // extract the attribute value length 220 int lenPos = attrStr.indexOf(' ', ptr); 221 int attrLen = Integer.parseInt(attrStr.substring(ptr, lenPos)); 222 ptr = lenPos + 1; // skip pas the space 223 224 // extract the attribute value 225 String attrValue = attrStr.substring(ptr, ptr + attrLen); 226 ptr += attrLen; 227 228 if (attrName.equals("hasThumbnail")) { 229 mHasThumbnail = attrValue.equalsIgnoreCase("true"); 230 } else { 231 mAttributes.put(attrName, attrValue); 232 } 233 } 234 } 235 236 /** 237 * Save the tag data into the JPEG file. This is expensive because it involves 238 * copying all the JPG data from one file to another and deleting the old file 239 * and renaming the other. It's best to use {@link #setAttribute(String,String)} 240 * to set all attributes to write and make a single call rather than multiple 241 * calls for each attribute. 242 */ 243 public void saveAttributes() throws IOException { 244 // format of string passed to native C code: 245 // "attrCnt attr1=valueLen value1attr2=value2Len value2..." 246 // example: 247 // "4 attrPtr ImageLength=4 1024Model=6 FooImageWidth=4 1280Make=3 FOO" 248 StringBuilder sb = new StringBuilder(); 249 int size = mAttributes.size(); 250 if (mAttributes.containsKey("hasThumbnail")) { 251 --size; 252 } 253 sb.append(size + " "); 254 for (Map.Entry<String, String> iter : mAttributes.entrySet()) { 255 String key = iter.getKey(); 256 if (key.equals("hasThumbnail")) { 257 // this is a fake attribute not saved as an exif tag 258 continue; 259 } 260 String val = iter.getValue(); 261 sb.append(key + "="); 262 sb.append(val.length() + " "); 263 sb.append(val); 264 } 265 String s = sb.toString(); 266 synchronized (sLock) { 267 saveAttributesNative(mFilename, s); 268 commitChangesNative(mFilename); 269 } 270 } 271 272 /** 273 * Returns true if the JPEG file has a thumbnail. 274 */ 275 public boolean hasThumbnail() { 276 return mHasThumbnail; 277 } 278 279 /** 280 * Returns the thumbnail inside the JPEG file, or {@code null} if there is no thumbnail. 281 * The returned data is in JPEG format and can be decoded using 282 * {@link android.graphics.BitmapFactory#decodeByteArray(byte[],int,int)} 283 */ 284 public byte[] getThumbnail() { 285 synchronized (sLock) { 286 return getThumbnailNative(mFilename); 287 } 288 } 289 290 /** 291 * Stores the latitude and longitude value in a float array. The first element is 292 * the latitude, and the second element is the longitude. Returns false if the 293 * Exif tags are not available. 294 */ 295 public boolean getLatLong(float output[]) { 296 String latValue = mAttributes.get(ExifInterface.TAG_GPS_LATITUDE); 297 String latRef = mAttributes.get(ExifInterface.TAG_GPS_LATITUDE_REF); 298 String lngValue = mAttributes.get(ExifInterface.TAG_GPS_LONGITUDE); 299 String lngRef = mAttributes.get(ExifInterface.TAG_GPS_LONGITUDE_REF); 300 301 if (latValue != null && latRef != null && lngValue != null && lngRef != null) { 302 try { 303 output[0] = convertRationalLatLonToFloat(latValue, latRef); 304 output[1] = convertRationalLatLonToFloat(lngValue, lngRef); 305 return true; 306 } catch (IllegalArgumentException e) { 307 // if values are not parseable 308 } 309 } 310 311 return false; 312 } 313 314 /** 315 * Return the altitude in meters. If the exif tag does not exist, return 316 * <var>defaultValue</var>. 317 * 318 * @param defaultValue the value to return if the tag is not available. 319 */ 320 public double getAltitude(double defaultValue) { 321 double altitude = getAttributeDouble(TAG_GPS_ALTITUDE, -1); 322 int ref = getAttributeInt(TAG_GPS_ALTITUDE_REF, -1); 323 324 if (altitude >= 0 && ref >= 0) { 325 return (double) (altitude * ((ref == 1) ? -1 : 1)); 326 } else { 327 return defaultValue; 328 } 329 } 330 331 /** 332 * Returns number of milliseconds since Jan. 1, 1970, midnight. 333 * Returns -1 if the date time information if not available. 334 * @hide 335 */ 336 public long getDateTime() { 337 String dateTimeString = mAttributes.get(TAG_DATETIME); 338 if (dateTimeString == null) return -1; 339 340 ParsePosition pos = new ParsePosition(0); 341 try { 342 Date datetime = sFormatter.parse(dateTimeString, pos); 343 if (datetime == null) return -1; 344 return datetime.getTime(); 345 } catch (IllegalArgumentException ex) { 346 return -1; 347 } 348 } 349 350 /** 351 * Returns number of milliseconds since Jan. 1, 1970, midnight UTC. 352 * Returns -1 if the date time information if not available. 353 * @hide 354 */ 355 public long getGpsDateTime() { 356 String date = mAttributes.get(TAG_GPS_DATESTAMP); 357 String time = mAttributes.get(TAG_GPS_TIMESTAMP); 358 if (date == null || time == null) return -1; 359 360 String dateTimeString = date + ' ' + time; 361 if (dateTimeString == null) return -1; 362 363 ParsePosition pos = new ParsePosition(0); 364 try { 365 Date datetime = sFormatter.parse(dateTimeString, pos); 366 if (datetime == null) return -1; 367 return datetime.getTime(); 368 } catch (IllegalArgumentException ex) { 369 return -1; 370 } 371 } 372 373 private static float convertRationalLatLonToFloat( 374 String rationalString, String ref) { 375 try { 376 String [] parts = rationalString.split(","); 377 378 String [] pair; 379 pair = parts[0].split("/"); 380 double degrees = Double.parseDouble(pair[0].trim()) 381 / Double.parseDouble(pair[1].trim()); 382 383 pair = parts[1].split("/"); 384 double minutes = Double.parseDouble(pair[0].trim()) 385 / Double.parseDouble(pair[1].trim()); 386 387 pair = parts[2].split("/"); 388 double seconds = Double.parseDouble(pair[0].trim()) 389 / Double.parseDouble(pair[1].trim()); 390 391 double result = degrees + (minutes / 60.0) + (seconds / 3600.0); 392 if ((ref.equals("S") || ref.equals("W"))) { 393 return (float) -result; 394 } 395 return (float) result; 396 } catch (NumberFormatException e) { 397 // Some of the nubmers are not valid 398 throw new IllegalArgumentException(); 399 } catch (ArrayIndexOutOfBoundsException e) { 400 // Some of the rational does not follow the correct format 401 throw new IllegalArgumentException(); 402 } 403 } 404 405 private native boolean appendThumbnailNative(String fileName, 406 String thumbnailFileName); 407 408 private native void saveAttributesNative(String fileName, 409 String compressedAttributes); 410 411 private native String getAttributesNative(String fileName); 412 413 private native void commitChangesNative(String fileName); 414 415 private native byte[] getThumbnailNative(String fileName); 416 } 417
