/// <summary>
/// Gets the GPS time offset from EXIF timestamp
/// assumes no camera date set 10years in future, but may be 10years behind if reset to default
/// </summary>
/// <param name="filename"></param>
/// <returns>
/// float to 0.05 hr +12 -> -12 valid, 99999 not an image, 99901 no GPS time
/// camera name
/// </returns>
public static CameraTimeOffset GetEXIFtime_diff(string filename)
{
Exif_Ext.EXIF_Data exif_Data = new Exif_Ext.EXIF_Data(filename);
switch (exif_Data.Status)
{
case "ok":
if (exif_Data.CameraName is null)
{
exif_Data.CameraName = "---";
}
if (exif_Data.GPSUTCDate == DateTime.MinValue)
{
return(new CameraTimeOffset(exif_Data.CameraName, 99901));
}
DateTime localGPStime = GPSMethods.GetLocalTimefromGPS(exif_Data.GPSLatitude, exif_Data.GPSLongitude, exif_Data.GPSUTCDate);
TimeSpan lastCameraOffset = exif_Data.CameraDate.Subtract(localGPStime);
//float timedif = (float)Math.Round(lastCameraOffset.TotalHours,1);
double roundto = 0.05;
float timedif = (float)(Math.Ceiling(lastCameraOffset.TotalHours / roundto) * roundto);
CameraTimeOffset thisOffset = new CameraTimeOffset(exif_Data.CameraName, -1 * timedif);
return(thisOffset);
case "Not Image":
return(new CameraTimeOffset("Not Image", 99999));
default:
//error occurred
return(new CameraTimeOffset("Exception", 99999));
}
}
/// <summary>
/// update EXIF datetime from GPS Data.
/// optional rename file to correct DateTime
/// https://oozcitak.github.io/exiflibrary/articles/ReadFile.html
/// </summary>
/// <param name="filename">input filename. full path</param>
/// <param name="outPutFolderName">folder to save fixed file. empty to use same.</param>
/// <param name="RenameFile">rename output to date_time</param>
/// <returns></returns>
///
public static string FixEXIFtimestamp(string filename)
{
bool keepExistingFile = true;
FileInfo fi = new FileInfo(filename);
if (string.IsNullOrEmpty(outPutFolderName))
{
outPutFolderName = fi.Directory.FullName;
keepExistingFile = false;
OverwriteFile = true;
}
if (fi.Name == "Thumbs.db")
{
return(""); //dont process
}
ExifLibrary.ImageFile exiffile;
try
{
exiffile = ExifLibrary.ImageFile.FromFile(filename);
}
catch (ExifLibrary.NotValidImageFileException)
{
if (RenameVids)
{
//does the name match datetime yyyyMMdd_HHmmss
string saveVName;
char[] separators = new char[] { '_', '-' };
string[] dateparts = Path.GetFileNameWithoutExtension(fi.Name).Split(separators, StringSplitOptions.RemoveEmptyEntries);
string stdfmt = string.Format("{0}-{1}", dateparts[0], dateparts[1]);
bool success = DateTime.TryParseExact(
stdfmt,
"yyyyMMdd-HHmmss",
CultureInfo.CurrentCulture,
DateTimeStyles.AssumeLocal,
out DateTime fileNameDate);
if (success)
{
//rename the file as date_time
var nextGPStime = fileNameDate.Add(lastCameraOffset);
string newName = nextGPStime.ToString("yyyyMMdd_HHmmss");
newName += fi.Extension;
saveVName = Path.Combine(outPutFolderName, newName);
if (OverwriteFile && saveVName == fi.FullName)
{
keepExistingFile = false;
}
else
{
keepExistingFile = true;
};
}
else
{
return("");
}
if (!keepExistingFile)
{
fi.MoveTo(saveVName); //rename file; //delete the redundant original as saved to new folder or new name
}
else
{
fi.CopyTo(saveVName);
} //keep existing
return(saveVName);
}
else
{
return("");
}
}
catch (Exception)
{
throw;
}
// GPS latitude is a custom type with three rational values
// representing degrees/minutes/seconds of the latitude
var gpsLatTag = exiffile.Properties.Get <GPSLatitudeLongitude>(ExifTag.GPSLatitude);
var gpsLongTag = exiffile.Properties.Get <GPSLatitudeLongitude>(ExifTag.GPSLongitude);
var gpsDate = exiffile.Properties.Get <ExifDate>(ExifTag.GPSDateStamp);
var gpsTime = exiffile.Properties.Get <GPSTimeStamp>(ExifTag.GPSTimeStamp);
string cameramodel = exiffile.Properties.Get(ExifTag.Model).Value.ToString();
if (!cameraTimeOffsetbase.ContainsKey(cameramodel))
{
throw new Exception("unexpected camera model");
}
TimeSpan baseOffset = cameraTimeOffsetbase[cameramodel];
if (!cameraTimeOffset.ContainsKey(cameramodel))
{
cameraTimeOffset.Add(cameramodel, baseOffset);
lastCameraOffset = baseOffset;
}
else
{
lastCameraOffset = cameraTimeOffset[cameramodel];
}
ExifProperty exifDatetag = exiffile.Properties.Get(ExifTag.DateTimeOriginal);
if (exifDatetag == null)
{
exifDatetag = exiffile.Properties.Get(ExifTag.DateTime);
}
DateTime cameraDateTime = (exifDatetag as ExifDateTime).Value;
DateTime localGPStime;
if (gpsDate is null)
{
//use lastCameraOffset;
if (OffsetUseFixed)
{
lastCameraOffset = baseOffset;
}
localGPStime = cameraDateTime.Add(lastCameraOffset);
//ExifProperty exifDateOriginal = exiffile.Properties.Get(ExifTag.DateTimeOriginal);
exiffile.Properties.Set(ExifTag.DateTime, localGPStime);
exiffile.Properties.Set(ExifTag.DateTimeOriginal, localGPStime);
}
else
{
var gpsLatTagR = exiffile.Properties.Get <ExifEnumProperty <GPSLatitudeRef> >(ExifTag.GPSLatitudeRef);
var gpsLongTagR = exiffile.Properties.Get <ExifEnumProperty <GPSLongitudeRef> >(ExifTag.GPSLongitudeRef);
float gpsLat = gpsLatTag.ToFloat();
if (gpsLat > 0 && gpsLatTagR.Value == GPSLatitudeRef.South)
{
gpsLat *= -1; //North = 1, south = -1
}
float gpsLong = gpsLongTag.ToFloat();
if (gpsLong > 0 && gpsLongTagR.Value == GPSLongitudeRef.West)
{
gpsLong *= -1; //east=1, west=-1
}
DateTime UTCDateTime = gpsDate.Value + new TimeSpan((int)gpsTime.Hour, (int)gpsTime.Minute, (int)gpsTime.Second);
localGPStime = GPSMethods.GetLocalTimefromGPS(gpsLat, gpsLong, UTCDateTime);
lastCameraOffset = localGPStime.Subtract(cameraDateTime); //save for next time
if (!cameraTimeOffset.ContainsKey(cameramodel))
{
cameraTimeOffset.Add(cameramodel, lastCameraOffset);
}
else
{
cameraTimeOffset[cameramodel] = lastCameraOffset;
}
// ExifProperty exifDateOriginal = exiffile.Properties.Get(ExifTag.DateTimeOriginal);
exiffile.Properties.Set(ExifTag.DateTime, localGPStime);
exiffile.Properties.Set(ExifTag.DateTimeOriginal, localGPStime);
}
string saveName;
if (RenameFile_asDate)
{
//rename the file as date_time
string newName = localGPStime.ToString("yyyyMMdd_HHmmss");
int uniquenum = 0;
saveName = Path.Combine(outPutFolderName, newName + fi.Extension);
while (File.Exists(saveName) && saveName != fi.FullName)
{
uniquenum++;
saveName = Path.Combine(outPutFolderName, newName + string.Format("-{0}", uniquenum) + fi.Extension);
}
if (OverwriteFile && saveName != fi.FullName)
{
keepExistingFile = false;
}
else
{
keepExistingFile = true;
};
}
else
{
saveName = Path.Combine(outPutFolderName, filename);
}
if (!keepExistingFile)
{
fi.Delete(); //delete the redundant original as saved to new folder or new name
}
exiffile.Save(saveName); //save exif data back to file
return(saveName);
}
