//--------------------------------------------------------------------------
// Parsing of GPS info from exif header.
//
// Matthias Wandel, Dec 1999 - Dec 2002
//--------------------------------------------------------------------------
#include "jhead.h"
#include <string.h>
#include <utils/Log.h>
#define TAG_GPS_LAT_REF 1
#define TAG_GPS_LAT 2
#define TAG_GPS_LONG_REF 3
#define TAG_GPS_LONG 4
#define TAG_GPS_ALT_REF 5
#define TAG_GPS_ALT 6
#define TAG_GPS_TIMESTAMP 7
#define TAG_GPS_PROCESSING_METHOD 27
#define TAG_GPS_DATESTAMP 29
static TagTable_t GpsTags[]= {
{ 0x00, "GPSVersionID", FMT_BYTE, 4},
{ 0x01, "GPSLatitudeRef", FMT_STRING, 2},
{ 0x02, "GPSLatitude", FMT_URATIONAL, 3},
{ 0x03, "GPSLongitudeRef", FMT_STRING, 2},
{ 0x04, "GPSLongitude", FMT_URATIONAL, 3},
{ 0x05, "GPSAltitudeRef", FMT_BYTE, 1},
{ 0x06, "GPSAltitude", FMT_URATIONAL, 1},
{ 0x07, "GPSTimeStamp", FMT_SRATIONAL, 3},
{ 0x08, "GPSSatellites", FMT_STRING, -1},
{ 0x09, "GPSStatus", FMT_STRING, 2},
{ 0x0A, "GPSMeasureMode", FMT_STRING, 2},
{ 0x0B, "GPSDOP", FMT_SRATIONAL, 1},
{ 0x0C, "GPSSpeedRef", FMT_STRING, 2},
{ 0x0D, "GPSSpeed", FMT_SRATIONAL, 1},
{ 0x0E, "GPSTrackRef", FMT_STRING, 2},
{ 0x0F, "GPSTrack", FMT_SRATIONAL, 1},
{ 0x10, "GPSImgDirectionRef", FMT_STRING, -1},
{ 0x11, "GPSImgDirection", FMT_SRATIONAL, 1},
{ 0x12, "GPSMapDatum", FMT_STRING, -1},
{ 0x13, "GPSDestLatitudeRef", FMT_STRING, 2},
{ 0x14, "GPSDestLatitude", FMT_SRATIONAL, 3},
{ 0x15, "GPSDestLongitudeRef", FMT_STRING, 2},
{ 0x16, "GPSDestLongitude", FMT_SRATIONAL, 3},
{ 0x17, "GPSDestBearingRef", FMT_STRING, 1},
{ 0x18, "GPSDestBearing", FMT_SRATIONAL, 1},
{ 0x19, "GPSDestDistanceRef", FMT_STRING, 2},
{ 0x1A, "GPSDestDistance", FMT_SRATIONAL, 1},
{ 0x1B, "GPSProcessingMethod", FMT_STRING, -1},
{ 0x1C, "GPSAreaInformation", FMT_STRING, -1},
{ 0x1D, "GPSDateStamp", FMT_STRING, 11},
{ 0x1E, "GPSDifferential", FMT_SSHORT, 1},
};
static const char ExifAsciiPrefix[] = { 0x41, 0x53, 0x43, 0x49, 0x49, 0x0, 0x0, 0x0 };
#define MAX_GPS_TAG (sizeof(GpsTags) / sizeof(TagTable_t))
#define EXIF_ASCII_PREFIX_LEN (sizeof(ExifAsciiPrefix))
// Define the line below to turn on poor man's debugging output
#undef SUPERDEBUG
#ifdef SUPERDEBUG
#define printf LOGE
#endif
int IsGpsTag(const char* tag) {
return strstr(tag, "GPS") == tag;
}
TagTable_t* GpsTagToTagTableEntry(unsigned short tag)
{
unsigned int i;
for (i = 0; i < MAX_GPS_TAG; i++) {
if (GpsTags[i].Tag == tag) {
printf("found tag %d", tag);
int format = GpsTags[i].Format;
if (format == 0) {
printf("tag %s format not defined", GpsTags[i].Desc);
return NULL;
}
return &GpsTags[i];
}
}
printf("tag %d NOT FOUND", tag);
return NULL;
}
int GpsTagToFormatType(unsigned short tag)
{
unsigned int i;
for (i = 0; i < MAX_GPS_TAG; i++) {
if (GpsTags[i].Tag == tag) {
printf("found tag %d", tag);
int format = GpsTags[i].Format;
if (format == 0) {
printf("tag %s format not defined", GpsTags[i].Desc);
return -1;
}
return format;
}
}
printf("tag %d NOT FOUND", tag);
return -1;
}
int GpsTagNameToValue(const char* tagName)
{
unsigned int i;
for (i = 0; i < MAX_GPS_TAG; i++) {
if (strcmp(GpsTags[i].Desc, tagName) == 0) {
printf("found GPS tag %s val %d", GpsTags[i].Desc, GpsTags[i].Tag);
return GpsTags[i].Tag;
}
}
printf("GPS tag %s NOT FOUND", tagName);
return -1;
}
//--------------------------------------------------------------------------
// Process GPS info directory
//--------------------------------------------------------------------------
void ProcessGpsInfo(unsigned char * DirStart, int ByteCountUnused, unsigned char * OffsetBase, unsigned ExifLength)
{
int de;
unsigned a;
int NumDirEntries;
NumDirEntries = Get16u(DirStart);
#define DIR_ENTRY_ADDR(Start, Entry) (Start+2+12*(Entry))
if (ShowTags){
printf("(dir has %d entries)\n",NumDirEntries);
}
ImageInfo.GpsInfoPresent = TRUE;
strcpy(ImageInfo.GpsLat, "? ?");
strcpy(ImageInfo.GpsLong, "? ?");
ImageInfo.GpsAlt[0] = 0;
for (de=0;de<NumDirEntries;de++){
unsigned Tag, Format, Components;
unsigned char * ValuePtr;
int ComponentSize;
unsigned ByteCount;
unsigned char * DirEntry;
DirEntry = DIR_ENTRY_ADDR(DirStart, de);
if (DirEntry+12 > OffsetBase+ExifLength){
ErrNonfatal("GPS info directory goes past end of exif",0,0);
return;
}
Tag = Get16u(DirEntry);
Format = Get16u(DirEntry+2);
Components = Get32u(DirEntry+4);
if ((Format-1) >= NUM_FORMATS) {
// (-1) catches illegal zero case as unsigned underflows to positive large.
ErrNonfatal("Illegal number format %d for tag %04x", Format, Tag);
continue;
}
ComponentSize = BytesPerFormat[Format];
ByteCount = Components * ComponentSize;
#ifdef SUPERDEBUG
printf("GPS tag %x format %s #components %d componentsize %d bytecount %d", Tag, formatStr(Format), Components, ComponentSize,
ByteCount);
#endif
if (ByteCount > 4){
unsigned OffsetVal;
OffsetVal = Get32u(DirEntry+8);
// If its bigger than 4 bytes, the dir entry contains an offset.
if (OffsetVal+ByteCount > ExifLength){
// Bogus pointer offset and / or bytecount value
ErrNonfatal("Illegal value pointer for tag %04x", Tag,0);
continue;
}
ValuePtr = OffsetBase+OffsetVal;
}else{
// 4 bytes or less and value is in the dir entry itself
ValuePtr = DirEntry+8;
}
switch(Tag){
char FmtString[21];
char TempString[50];
double Values[3];
case TAG_GPS_LAT_REF:
ImageInfo.GpsLat[0] = ValuePtr[0];
ImageInfo.GpsLatRef[0] = ValuePtr[0];
ImageInfo.GpsLatRef[1] = '\0';
break;
case TAG_GPS_LONG_REF:
ImageInfo.GpsLong[0] = ValuePtr[0];
ImageInfo.GpsLongRef[0] = ValuePtr[0];
ImageInfo.GpsLongRef[1] = '\0';
break;
case TAG_GPS_LAT:
case TAG_GPS_LONG:
if (Format != FMT_URATIONAL){
ErrNonfatal("Inappropriate format (%d) for GPS coordinates!", Format, 0);
}
strcpy(FmtString, "%0.0fd %0.0fm %0.0fs");
for (a=0;a<3;a++){
int den, digits;
den = Get32s(ValuePtr+4+a*ComponentSize);
digits = 0;
while (den > 1 && digits <= 6){
den = den / 10;
digits += 1;
}
if (digits > 6) digits = 6;
FmtString[1+a*7] = (char)('2'+digits+(digits ? 1 : 0));
FmtString[3+a*7] = (char)('0'+digits);
Values[a] = ConvertAnyFormat(ValuePtr+a*ComponentSize, Format);
}
sprintf(TempString, FmtString, Values[0], Values[1], Values[2]);
if (Tag == TAG_GPS_LAT){
strncpy(ImageInfo.GpsLat+2, TempString, 29);
}else{
strncpy(ImageInfo.GpsLong+2, TempString, 29);
}
sprintf(TempString, "%d/%d,%d/%d,%d/%d",
Get32s(ValuePtr), Get32s(4+(char*)ValuePtr),
Get32s(8+(char*)ValuePtr), Get32s(12+(char*)ValuePtr),
Get32s(16+(char*)ValuePtr), Get32s(20+(char*)ValuePtr));
if (Tag == TAG_GPS_LAT){
strncpy(ImageInfo.GpsLatRaw, TempString, 31);
}else{
strncpy(ImageInfo.GpsLongRaw, TempString, 31);
}
break;
case TAG_GPS_ALT_REF:
ImageInfo.GpsAlt[0] = (char)(ValuePtr[0] ? '-' : ' ');
ImageInfo.GpsAltRef = (char)ValuePtr[0];
break;
case TAG_GPS_ALT:
sprintf(ImageInfo.GpsAlt + 1, "%.2fm",
ConvertAnyFormat(ValuePtr, Format));
ImageInfo.GpsAltRaw.num = Get32u(ValuePtr);
ImageInfo.GpsAltRaw.denom = Get32u(4+(char *)ValuePtr);
break;
case TAG_GPS_TIMESTAMP:
snprintf(ImageInfo.GpsTimeStamp,
sizeof(ImageInfo.GpsTimeStamp), "%d:%d:%d",
(int) ConvertAnyFormat(ValuePtr, Format),
(int) ConvertAnyFormat(ValuePtr + 8, Format),
(int) ConvertAnyFormat(ValuePtr + 16, Format)
);
break;
case TAG_GPS_DATESTAMP:
strncpy(ImageInfo.GpsDateStamp, (char*)ValuePtr, sizeof(ImageInfo.GpsDateStamp));
break;
case TAG_GPS_PROCESSING_METHOD:
if (ByteCount > EXIF_ASCII_PREFIX_LEN &&
memcmp(ValuePtr, ExifAsciiPrefix, EXIF_ASCII_PREFIX_LEN) == 0) {
int length =
ByteCount < GPS_PROCESSING_METHOD_LEN + EXIF_ASCII_PREFIX_LEN ?
ByteCount - EXIF_ASCII_PREFIX_LEN : GPS_PROCESSING_METHOD_LEN;
memcpy(ImageInfo.GpsProcessingMethod,
(char*)(ValuePtr + EXIF_ASCII_PREFIX_LEN), length);
ImageInfo.GpsProcessingMethod[length] = 0;
} else {
LOGW("Unsupported encoding for GPSProcessingMethod");
}
break;
}
if (ShowTags){
// Show tag value.
if (Tag < MAX_GPS_TAG){
printf(" %s =", GpsTags[Tag].Desc);
}else{
// Show unknown tag
printf(" Illegal GPS tag %04x=", Tag);
}
switch(Format){
case FMT_UNDEFINED:
// Undefined is typically an ascii string.
case FMT_STRING:
// String arrays printed without function call (different from int arrays)
{
printf("\"");
for (a=0;a<ByteCount;a++){
int ZeroSkipped = 0;
if (ValuePtr[a] >= 32){
if (ZeroSkipped){
printf("?");
ZeroSkipped = 0;
}
putchar(ValuePtr[a]);
}else{
if (ValuePtr[a] == 0){
ZeroSkipped = 1;
}
}
}
printf("\"\n");
}
break;
default:
// Handle arrays of numbers later (will there ever be?)
for (a=0;;){
PrintFormatNumber(ValuePtr+a*ComponentSize, Format, ByteCount);
if (++a >= Components) break;
printf(", ");
}
printf("\n");
}
}
}
}