Through ExifInterface, some attribute information during taking pictures can be written into the picture file, including latitude and longitude information. This article introduces a method to write latitude and longitude coordinates into JPEG image files!
Core code
/**
* Floating point latitude and longitude values are converted into degree and minute and second format
*
* @param coord
* @return
*/
public String decimalToDMS(double coord) {
String output, degrees, minutes, seconds;
// gets the modulus the coordinate divided by one (MOD1).
// in other words gets all the numbers after the decimal point.
// . mod := -79.982195 % 1 == 0.982195
//
// next get the integer part of the coord. On other words the whole
// number part.
// . intPart := -79
double mod = coord % 1;
int intPart = (int) coord;
// set degrees to the value of intPart
// . degrees := "-79"
degrees = (intPart);
// next times the MOD1 of degrees by 60 so we can find the integer part
// for minutes.
// get the MOD1 of the new coord to find the numbers after the decimal
// point.
// . coord := 0.982195 * 60 == 58.9317
// mod := 58.9317 % 1 == 0.9317
//
// next get the value of the integer part of the coord.
// . intPart := 58
coord = mod * 60;
mod = coord % 1;
intPart = (int) coord;
if (intPart < 0) {
// Convert number to positive if it's negative.
intPart *= -1;
}
// set minutes to the value of intPart.
// . minutes = "58"
minutes = (intPart);
// do the same again for minutes
// . coord := 0.9317 * 60 == 55.902
// . intPart := 55
coord = mod * 60;
intPart = (int) coord;
if (intPart < 0) {
// Convert number to positive if it's negative.
intPart *= -1;
}
// set seconds to the value of intPart.
// . seconds = "55"
seconds = (intPart);
// I used this format for android but you can change it
// to return in whatever format you like
// . output = "-79/1,58/1,56/1"
output = degrees + "/1," + minutes + "/1," + seconds + "/1";
// Standard output of D°M′S″
// output = degrees + "°" + minutes + "'" + seconds + "\"";
return output;
}
/**
* Write latitude and longitude information into JPEG picture file
*
* @param picPath
* JPEG image file path
* @param dLat
* Latitude
* @param dLon
* Longitude
*/
public void writeLatLonIntoJpeg(String picPath, double dLat, double dLon) {
File file = new File(picPath);
if (()) {
try {
ExifInterface exif = new ExifInterface(picPath);
String tagLat = exif
.getAttribute(ExifInterface.TAG_GPS_LATITUDE);
String tagLon = exif
.getAttribute(ExifInterface.TAG_GPS_LONGITUDE);
if (tagLat == null && tagLon == null) // No latitude and longitude information{
(ExifInterface.TAG_GPS_LATITUDE,
decimalToDMS(dLat));
(ExifInterface.TAG_GPS_LATITUDE_REF,
dLat > 0 ? "N" : "S"); // Distinguish between the north and south hemispheres (ExifInterface.TAG_GPS_LONGITUDE,
decimalToDMS(dLon));
(ExifInterface.TAG_GPS_LONGITUDE_REF,
dLon > 0 ? "E" : "W"); // Distinguish between East and West Meridians
();
}
} catch (Exception e) {
}
}
}
Test code
String strImgPath = getImageCachePath() + + "";
ExifInterface eif = new ExifInterface(strImgPath);
String lat = (ExifInterface.TAG_GPS_LATITUDE);
String latRef = (ExifInterface.TAG_GPS_LATITUDE_REF);
String lon = (ExifInterface.TAG_GPS_LONGITUDE);
String lonRef = (ExifInterface.TAG_GPS_LONGITUDE_REF);
("Latitude Ref - " + latRef);
("Latitude - " + lat);
("Longitude Ref - " + lonRef);
("Longitude - " + lon);
if (lat == null && lon == null) // Write it if there is no location information{
writeLatLonIntoJpeg(strImgPath, 39.23456, 116.123456);
}
First run result
05-22 17:36:24.566: I/(17966): Latitude Ref - null 05-22 17:36:24.566: I/(17966): Latitude - null 05-22 17:36:24.566: I/(17966): Longitude Ref - null 05-22 17:36:24.566: I/(17966): Longitude - null
The original image has no location information, and write to a location is simulated by calling writeLatLonIntoJpeg(strImgPath, 39.23456, 116.123456).
Second run result
05-22 17:37:11.446: I/(17966): Latitude Ref - N 05-22 17:37:11.446: I/(17966): Latitude - 39/1,14/1,4/1 05-22 17:37:11.446: I/(17966): Longitude Ref - E 05-22 17:37:11.446: I/(17966): Longitude - 116/1,7/1,24/1
The above android implementation of writing location information into JPEG image files is all the content I share with you. I hope you can give you a reference and I hope you can support me more.