Truxton exif get heading

This retrieves the heading of the device. This corresponds to the [Heading] column of the [EXIF] table in the database.

Syntax

double truxton_exif_get_heading( uint64_t exif_handle );

Parameters

exif_handle

This handle comes from calling truxton_exif_create() or truxton_file_create_exif().

Return value

The direction the imaging device was pointed at the time the image was taken.

Sample

void dump_exif( uint64_t exif_handle )
{
   double floating_point_value = 0.0;
   uint64_t integer_value = 0;

   char id[ 65 ];

   truxton_exif_get_id( exif_handle, id, sizeof( id ) );
   printf( "ID: %s\n", id );

   truxton_exif_get_file_id( exif_handle, id, sizeof( id ) );
   printf( "File ID: %s\n", id );

   truxton_exif_get_media_id( exif_handle, id, sizeof( id ) );
   printf( "Media ID: %s\n", id );

   truxton_exif_get_make( exif_handle, id, sizeof( id ) );
   printf( "Make: %s\n", id );

   truxton_exif_get_model( exif_handle, id, sizeof( id ) );
   printf( "Model: %s\n", id );

   truxton_exif_get_body_serial_number( exif_handle, id, sizeof( id ) );
   printf( "Body serial number: %s\n", id );

   truxton_exif_get_lens_serial_number( exif_handle, id, sizeof( id ) );
   printf( "Lens serial number: %s\n", id );

   integer_value = truxton_exif_get_device_time( exif_handle );
   printf( "Device Time: %" PRIu64 "\n", integer_value );

   integer_value = truxton_exif_get_gps_time( exif_handle );
   printf( "GPS Time: %" PRIu64 "\n", integer_value );

   floating_point_value = truxton_exif_get_focal_length( exif_handle );
   printf( "35mm Focal Length: %lf\n", floating_point_value );

   floating_point_value = truxton_exif_get_heading( exif_handle );
   printf( "Heading: %lf degrees\n", floating_point_value );

   floating_point_value = truxton_exif_get_latitude( exif_handle );
   printf( "Latitude: %lf degrees\n", floating_point_value );

   floating_point_value = truxton_exif_get_longitude( exif_handle );
   printf( "Longitude: %lf degrees\n", floating_point_value );

   floating_point_value = truxton_exif_get_altitude( exif_handle );
   printf( "Altitude: %lf meters\n", floating_point_value );

   integer_value = truxton_exif_get_shutter_count( exif_handle );
   printf( "Shutter Count: %" PRIu64 "\n", integer_value );

   integer_value = truxton_exif_get_offset( exif_handle );
   printf( "EXIF Data Block found at offset %" PRIu64 "\n", integer_value );

   integer_value = truxton_exif_get_gps_time_offset( exif_handle );
   printf( "GPS Time offset: %" PRIu64 "\n", integer_value );

   integer_value = truxton_exif_get_device_time_offset( exif_handle );
   printf( "Device Time offset: %" PRIu64 "\n", integer_value );

   integer_value = truxton_exif_get_latitude_offset( exif_handle );
   printf( "Latitude offset: %" PRIu64 "\n", integer_value );

   integer_value = truxton_exif_get_longitude_offset( exif_handle );
   printf( "Longitude offset: %" PRIu64 "\n", integer_value );

   integer_value = truxton_exif_get_altitude_offset( exif_handle );
   printf( "Altitude offset: %" PRIu64 "\n", integer_value );

   integer_value = truxton_exif_get_heading_offset( exif_handle );
   printf( "Heading offset: %" PRIu64 "\n", integer_value );

   integer_value = truxton_exif_get_focal_length_offset( exif_handle );
   printf( "Focal Length offset: %" PRIu64 "\n", integer_value );

   integer_value = truxton_exif_get_shutter_count_offset( exif_handle );
   printf( "Shutter Count offset: %" PRIu64 "\n", integer_value );

   integer_value = truxton_exif_get_thumbnail_offset_offset( exif_handle );
   printf( "Thumbnail Offset offset: %" PRIu64 "\n", integer_value );

   integer_value = truxton_exif_get_thumbnail_length_offset( exif_handle );
   printf( "Thumbnail Length offset: %" PRIu64 "\n", integer_value );

   integer_value = truxton_exif_get_make_offset( exif_handle );
   printf( "Make offset: %" PRIu64 "\n", integer_value );

   integer_value = truxton_exif_get_model_offset( exif_handle );
   printf( "Model offset: %" PRIu64 "\n", integer_value );

   integer_value = truxton_exif_get_body_serial_number_offset( exif_handle );
   printf( "Body Serial Number offset: %" PRIu64 "\n", integer_value );

   integer_value = truxton_exif_get_lens_serial_number_offset( exif_handle );
   printf( "Lens Serial Number offset: %" PRIu64 "\n", integer_value );
}

The PRIu64 in the sample code above is a standard way of formatting a 64-bit unsigned integer in C. Over the years, different compilers on different operating systems used different format specifiers for things, these PRI macros, along with some tricky string concatenation the compilers perform for you, allow you to maintain a single code base without a bunch of macro magic.