From 2fa7dfc4c0e4b8bdacab94728590a5e7a253aa1c Mon Sep 17 00:00:00 2001
From: tsteven4 <tsteven4@f51c46e8-681c-474f-0cfe-069cfd0219fb>
Date: Tue, 2 Apr 2013 23:09:10 +0000
Subject: [PATCH] exif fixes. supply default speed_ref for the reader. report
 undefined alt_refs in the reader. correctly output the gps tag version tag in
 the writer. use the correct value for the altitude reference tag in the
 writer so that negative altitudes are correctly written.

---
 gpsbabel/exif.cc | 27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/gpsbabel/exif.cc b/gpsbabel/exif.cc
index 848c76d08..5e906b013 100644
--- a/gpsbabel/exif.cc
+++ b/gpsbabel/exif.cc
@@ -20,6 +20,14 @@
 
  */
 
+/*
+ * Exif specifications can be found at
+ * 2012, version 2.3: http://www.cipa.jp/english/hyoujunka/kikaku/pdf/DC-008-2012_E.pdf
+ * 2010, version 2.3: http://www.cipa.jp/english/hyoujunka/kikaku/pdf/DC-008-2010_E.pdf
+ * 2002, version 2.2: http://www.exif.org/Exif2-2.PDF
+ * 1998, version 2.1: http://www.exif.org/Exif2-1.PDF
+ */
+
 #include <ctype.h>
 #include <math.h>
 #include <stdlib.h>
@@ -134,6 +142,8 @@ static char* exif_fout_name;
 
 static char* opt_filename, *opt_overwrite, *opt_frame, *opt_name;
 
+static gbuint8 writer_gps_tag_version[4] = {2, 0, 0, 0};
+
 arglist_t exif_args[] = {
   { "filename", &opt_filename, "Set waypoint name to source filename", "Y", ARGTYPE_BOOL, ARG_NOMINMAX },
   { "frame", &opt_frame, "Time-frame (in seconds)", "10", ARGTYPE_INT, "0", NULL },
@@ -676,7 +686,7 @@ exif_waypt_from_exif_app(exif_app_t* app)
   char lat_ref = '\0';
   char lon_ref = '\0';
   char alt_ref = 0;
-  char speed_ref = '\0';
+  char speed_ref = 'K';
   char* datum = NULL;
   char mode = '\0';
   double gpsdop = unknown_alt;
@@ -780,7 +790,7 @@ exif_waypt_from_exif_app(exif_app_t* app)
 
   if (alt != unknown_alt) {
     double sign;
-    switch (alt_ref != 0) {
+    switch (alt_ref) {
     case 0:
       sign = 1.0;
       break;
@@ -790,7 +800,7 @@ exif_waypt_from_exif_app(exif_app_t* app)
       break;
 
     default:
-      warning(MYNAME ": Invalid GPSAltitudeRef (%d)! Using 0 (= Sea level).\n", alt_ref);
+      warning(MYNAME ": Invalid GPSAltitudeRef (%d)! Using default value 0 (= Sea level).\n", alt_ref);
       sign = 1.0;
     }
     wpt->altitude = sign * alt;
@@ -1255,7 +1265,7 @@ exif_write_apps(void)
       exif_tag_t* tag;
 
       exif_put_long(IFD0, IFD0_TAG_GPS_IFD_OFFS, 0, 0);
-      exif_put_long(GPS_IFD, GPS_IFD_TAG_VERSION, 0, 2);
+      exif_put_value(GPS_IFD, GPS_IFD_TAG_VERSION, EXIF_TYPE_BYTE, 4, 0, writer_gps_tag_version);
 
       sortqueue(&exif_app->ifds, exif_sort_ifds_cb);
 
@@ -1424,7 +1434,6 @@ exif_wr_deinit(void)
 static void
 exif_write(void)
 {
-  char alt_ref = 0;
   time_t frame;
 
   exif_wpt_ref = NULL;
@@ -1468,7 +1477,7 @@ exif_write(void)
     const waypoint* wpt = exif_wpt_ref;
 
     exif_put_long(IFD0, IFD0_TAG_GPS_IFD_OFFS, 0, 0);
-    exif_put_long(GPS_IFD, GPS_IFD_TAG_VERSION, 0, 2);
+    exif_put_value(GPS_IFD, GPS_IFD_TAG_VERSION, EXIF_TYPE_BYTE, 4, 0, writer_gps_tag_version);
     exif_put_str(GPS_IFD, GPS_IFD_TAG_DATUM, "WGS-84");
 
     exif_put_str(GPS_IFD, GPS_IFD_TAG_LATREF, wpt->latitude < 0 ? "S" : "N");
@@ -1480,6 +1489,12 @@ exif_write(void)
       exif_remove_tag(GPS_IFD, GPS_IFD_TAG_ALT);
       exif_remove_tag(GPS_IFD, GPS_IFD_TAG_ALTREF);
     } else {
+      gbuint8 alt_ref;
+      if (wpt->altitude >= 0.0) {
+        alt_ref = 0;
+      } else {
+        alt_ref = 1;
+      }
       exif_put_value(GPS_IFD, GPS_IFD_TAG_ALTREF, EXIF_TYPE_BYTE, 1, 0, &alt_ref);
       exif_put_double(GPS_IFD, GPS_IFD_TAG_ALT, 0, wpt->altitude);
     }
-- 
2.30.2